We propose a noise reduction method for unsteady pressure-sensitive paint (PSP) data based on modal expansion, the coefficients of which are determined from time-series data at optimally placed points. In this study, the proper orthogonal decomposition (POD) mode calculated from the time-series PSP data is used as a modal basis. Based on the POD modes, the points that effectively represent the features of the pressure distribution are optimally placed by the sensor optimization technique. Then, the time-dependent coefficient vector of the POD modes is determined by minimizing the difference between the time-series pressure data and the reconstructed pressure at the optimal points. Here, the coefficient vector is assumed to be a sparse vector. The advantage of the proposed method is a self-contained method, while existing methods use other data, such as pressure tap data for the reduction of the noise. As a demonstration, we applied the proposed method to the PSP data measuring the Kármán vortex street behind a square cylinder. The reconstructed pressure data agreed very well with the pressures independently measured by pressure transducers. This modal-based approach will be applicable not only to PSP data but other types of experimental data.

The curing process of poly(dimethylsiloxane) (PDMS) was microscopically investigated by the single-molecule tracking method based on the diffusion motion of fluorescent dye molecules adding to the PDMS layer stored at a temperature of 308K. The PDMS layer was completely cured at 900 min after adding a curing agent. We compared the time- and ensemble-averaged mean square displacements (MSDs) of the tracked molecules at 90, 510, and 900 min after adding the curing agent into the PDMS layer. The discrepancies were observed between the time- and ensemble-averaged MSDs, indicating weak ergodicity breaking. The spatially averaged diffusion coefficient exhibited a two-step decrease: first step was rapid decrease suggesting the extent of crosslinking, and second step was slow one suggesting the increase of crosslink density. The single-molecule trajectory scale analysis revealed the heterogeneous distribution of the diffusion coefficient. By calculating the heat map from the slope of moment scaling spectrum (MSS) of each single-molecule trajectory, cluster structures were recognized. The spatial correlation of the slope of MSS decreased with the time elapsed. These results suggested the existence of the heterogeneous structure in the PDMS layer during the curing process.

A sprayable fast-responding pressure-sensitive paint (fast-PSP) has been developed to measure time-resolved small pressure fluctuation on model surfaces. To realize PSP with fast response, high robustness, and high luminescence intensity, we have developed a novel ruthenium complex-based fast-PSP. The binder layers of the proposed fast-PSP were prepared by mixing room-temperature-vulcanizing silicone (silicone) and titanium dioxide (TiO2) particles with different sizes and their effects on the properties including the time response, pressure sensitivity, and luminescence intensity were investigated. The effects of the hydrophilic and hydrophobic surface treatments of TiO2 particle on the structure and mechanical robustness of the binder layer were also studied. The developed fast-PSP was applied to the flow field measurements behind a square cylinder and was evaluated. We have succeeded in obtaining time-series data of pressure fluctuation with high accuracy even at a mean velocity of 20 m s-1.

© 2020 Author(s). A lot of studies on the dynamics of a granular impact cratering by a liquid drop have been carried out. However, the results so far are controversial due to the complex impact dynamics of a liquid drop, such as deformation, splash, and penetration into the granular bed. In this study, we focused on the dynamics of the granular impact cratering by a hydrogel sphere, which deforms without splashing and penetrating. We investigated the maximal deformation time of the sphere and the lift-off time of the grains. Both the maximal deformation time and the lift-off time are similar to each other and depend on the -1/2 power of the Young's modulus of the hydrogel sphere. This power law of the maximum deformation time is the same as an impact of a gel sphere on a flat solid surface. The angle of the ejected curtain was evaluated. The angle is larger for the impact with small deformation of the sphere than that for the impact with large deformation, and the angle is less dependent on the free-fall height. We also investigated the distributions of the ejected grains using the grains dyed by a fluorescent dye. The distribution was visualized by the fluorescent images captured before and after the impact. At the crater rim, the number of the dyed grains flying to and away are balanced. The number of the dyed grains gathered at the dimensionless distance from the crater center of 1.15, where the distance is nondimensionalized by the crater radius, is the largest. This maximum value for the number of the gathered grains is larger for the impact with small deformation than that with large deformation. This result is consistent with the dependence of the impact mode on the angle of the ejected curtain.

© 2020 We developed a simultaneous measurement technique for temperature distribution on a heated surface and gas-liquid interface motion of two-phase flows in microgap channel using temperature-sensitive paint (TSP). Since the TSP layer is optically transparent, the proposed method enables us to simultaneously measure the temperature distribution and the motion of gas-liquid interface through the TSP layer using an in-house stereoscope-like device. Since the refractive index of gas-phase differs from that of liquid-phase, the luminescent intensity of TSP in gas-phase varies from that in liquid-phase even though the temperatures are same in both phases. Then, we proposed a correction method for temperature distribution in gas-phase. To validate the proposed method, the temperature distribution measurements were conducted in liquid single-phase flow. The Nusselt numbers calculated from the measured temperatures were in good agreement with the Sieder-Tate equation. Then, we measured the temperature distributions for the boiling flows under several heated temperature conditions. The temperature distributions at growing bubble and bubble coalescence were successfully measured. TSP is useful method for investigating the temperature distribution in two-phase flows.

© 2019 by the authors; licensee MDPI, Basel, Switzerland.

© 2019 American Physical Society.

© 2019 Elsevier B.V.

© 2018 Elsevier Ltd

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

© 2018 The Royal Society of Chemistry

© 2018 International Heat Transfer Conference. All rights reserved. Boiling and Two-phase flow in narrow channel has been recently proposed for cooling the heat sources directly in application of thermal management for electronic devices. Many researches were carried out to investigate the mechanism of heat transfer in the narrow channel. In this study, the boiling heat transfer and gas-liquid behavior on the heated surface in narrow channel is investigated experimentally by using Temperature-Sensitive Paint (TSP). Experiments are performed in a single rectangular narrow channel having 10 mm width, 35 mm heated length and 0.5 mm height and using FC-72 as a test fluid. TSP coated on the heated wall located at upper side of the channel is used to obtain the local temperature and subsequently local heat flux distribution. In addition, simultaneous flow visualizations are conducted to observe and explore the flow boiling in narrow channel. Flow rate of FC-72 is 24-30 ml/min and heated water at 45-50 ◦C is used as a heat source for boiling of the test fluid. Pressure at the inlet of the test section is about 50 kPa. As a result, the heat flux in the thin liquid film region that is located around bubbles is 4-5 times higher than that of other region.

We have proposed an instant method for painting of pressure- and temperature-sensitive paints (PSP and TSP) using a commercial inkjet printer. This method enables us to finely and separately paint PSP and TSP to prevent them from being mixed and the interaction between PSP and TSP dyes. Moreover, the pressure-sensitivity of inkjet-printed PSP was similar to those of conventional PSPs. We consider this method is promising to measure pressure distribution with temperature variation, because the printing pattern of PSP and TSP is easily designed by an illustration software to adjust pressure distribution of interest. The pressure distribution induced by jet impingement was measured by the grid pattern of PSP and TSP as a demonstration. The pattern of PSP and TSP was well-defined; thus, the emissions from PSP and TSP can be easily separated and analyzed even when the emissions were captured by a CCD camera at the same time. This is also an advantage of our method. The pressure distribution agreed well with the pressures measured by pressure taps. (C) 2017 Elsevier B.V. All rights reserved.

Industrial applications of cellulose nanofibres (CNFs) include the additive to a wide range of materials from display and cosmetic to pigment inks. Many of these expected applications are based on the mixture of colloidal particles and CNFs in aqueous dispersion. In particular, the mixed dispersion is typically processed in such a way that the droplet or shallow wide volume of dispersion is dried on the substrate or container. In this work, the basic physical properties that these diverse kinds of potential applications share in common are focused on. The colloidal films were fabricated consisting of polystyrene particles and CNFs under the condition of various concentration combinations through the drying of aqueous dispersion in polystyrene well plates. It has been found that the films fabricated from higher concentrations of CNF tend to peel-off spontaneously in the drying process. The basic mechanism of phenomenon is attributed to the contraction of CNFs during the drying by hydrogen bonding between the filaments.

Single particle/molecule tracking is widely used for the evaluation of diffusion coefficients using diverse tracking algorithms. Many of them require the subtle decision of displacement threshold parameter to enable the appropriate tracking, though it depends on both of the diffusion coefficient itself and the measurement system. A simple and highly transferable technique is proposed to overcome this difficulty based on the evaluation of diffusion coefficient from the peak position of the distribution of squared displacements in the logarithmic scale. In combination with its linear dependence on time, this protocol is remarkably robust against the too large value of the displacement threshold including that covers the whole image. Furthermore, the proposed technique is compatible with many of the existing algorithms by construction.

Gas-surface interaction is studied by the molecular dynamics method to investigate qualitatively characteristics of accommodation coefficients. A large number of trajectories of gas molecules colliding to and scattering from a surface are statistically analyzed to calculate the energy (thermal) accommodation coefficient (EAC) and the tangential momentum accommodation coefficient (TMAC). Considering experimental measurements of the accommodation coefficients, the incident velocities are stochastically sampled to represent a bulk condition. The accommodation coefficients for noble gases showqualitative coincidencewith experimental values. To investigate characteristics of these accommodation coefficients in detail, the gas-surface interaction is parametrically studied by varying the molecular mass of gas, the gas-surface interaction strength, and the molecular size of gas, one by one. EAC increases with increasing every parameter, while TMAC increases with increasing the interaction strength, but decreases with increasing the molecular mass and the molecular size. Thus, contradictory results in experimentally measured TMAC for noble gases could result from the difference between the surface conditions employed in the measurements in the balance among the effective parameters of molecular mass, interaction strength, and molecular size, due to surface roughness and/ or adsorbed molecules. The accommodation coefficients for a thermo-fluid dynamics field with a temperature difference between gas and surface and a bulk flow at the same time are also investigated.

The conductive heat transfer through a gas confined between two concentric spherical shells maintained at different temperatures is investigated from the free-molecular to the continuum flow regime. The heat flux, measured using a recently proposed experimental system to extract the thermal accommodation coefficient, is compared with analytical expressions and numerical results. From this comparison it is found that in the free-molecular flow limit, the experimental data are well explained by the analytical expression for the arbitrary radius and temperature ratios of the spherical surfaces. In the continuum limit, the temperature dependence of the thermal conductivity coefficient should be considered in the analytical expression. In the transitional flow regime, a revised function for the heat flux interpolation is proposed to give better fitting to the numerical results. By employing these knowledge, the thermal accommodation coefficient extraction procedure for the system is revised, and it is shown that the recalculated accommodation coefficient allows to reproduce well the measured heat flux. (C) 2017 Elsevier Ltd. All rights reserved.

We report that the addition of a small amount of cellulose nanofibers (CNFs) into an aqueous dispersion of colloidal particles suppresses the coffee-ring effect when the dispersion dries on a solid substrate, as revealed by the computational analysis of experimental time-series images and by particle image velocimetry. The addition of CNFs is much more effective than the increase of colloidal particle concentration at the same weight percentage; it is also more environment friendly than the use of typical molecular surfactants. This finding is promising for the fabrication of metamaterials from colloidal dispersions and for ink printing in electronics, where CNFs can also serve as a substrate for flexible devices.

In the present study, the characteristics of supersonic flows in micronozzles are experimentally and computationally investigated for Reynolds numbers ranging from 618 to 5560. In the experiments, the flows are created in a rectangular contoured nozzle whose heights at its throat and exit are 286 and 500 mu m, respectively. The number-density distribution along the nozzle centerline is measured using the laser-induced fluorescence technique under an underexpanded condition for each Reynolds number. The experimental results reveal that the underexpanded flow expands along the streamwise direction in a range where the cross-sectional area of the nozzle is constant although the flow in such a range has been believed to be compressed owing to friction. The results also reveal that the unexpected range where the flow expands extends with a decrease in Reynolds number. In the computations, the Navier-Stokes equations are solved numerically. The computational results agree very well with the experimental results; i.e., the computational code used in the present study is validated by the experiments. By using the computational results, the reason for the appearance of the phenomena peculiar to supersonic micronozzle flows is discussed. As a result, it is found that information about the back pressure under which the flow is underexpanded can reach into the inside of a micronozzle. Such a property induces the unexpected phenomena observed in the experiments.

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient. Published by AIP Publishing.

We focus on the issue of limited number of samples in the single particle tracking (SPT) when trying to extract the diffusion anisotropy that originates from the particle asymmetry. We propose a novel evaluation technique of SPT making use of the relation of the consecutive three steps. More specifically, the trend of the angle comprised of the three positions and the displacements are plotted on a scatter diagram. The particle anisotropy dependence of the shape of the scatter diagram is examined through the data from the standard numerical model of anisotropic two-dimensional Brownian motion. Comparison with the existing method reveals the faster convergence in the evaluation. In particular, our proposed method realizes the detection of diffusion anisotropy under the conditions of not only less number of data but also larger time steps. This is of practical importance not only when the abundant data is hard to achieve but also when the rotational diffusion is fast compared to the frame rate of the camera equipment, which tends to be more common for smaller particles or molecules of interest.

We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-) PSP. As a fast-responding PSP, polymer-ceramic (PC-) PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO2) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of Ti(O)2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 mu m, and investigate the pressure-and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

Dual-laser micro-molecular tagging velocimetry (mu MTV) for internal gaseous flows on the microscale has been successfully demonstrated. MTV is a non-intrusive optical technique suitable for gaseous flow measurement by using molecules as tracers. In our dual-laser mu MTV technique, seeded NO2 molecules in a flow were tagged by photodissociation, producing NO molecules that can be distinguished from surrounding molecules. The tagged NO molecules were traced and visualized by laser-induced fluorescence. However, the fluorescence was in the deep ultraviolet region, and a reflective objective with a finite conjugate optical system was employed for imaging on the microscale. The seeded and tagged molecules of NO2 and NO are stable in the gas phase at around room temperature and atmospheric pressure. Thus, this technique is free from condensation at the walls and is feasible for measurements of internal gaseous flow on the microscale. To demonstrate the validity of our dual-laser mu MTV technique, the cross-sectional flow velocity profile in a rectangular microchannel and flow velocities in a micronozzle were measured and compared with numerical results.

A novel fast response bi-luminophore pressure-sensitive paint (PSP) by inkjet printing of sensor-dot arrays on an anodized aluminum (AA) substrate has been developed for unsteady flow measurements. A bi-luminophore AA-PSP, which is a combination of PSP and temperature-sensitive paint (TSP), is essential for precise pressure measurements, because the PSP result needs the temperature correction. However, a conventional bi-luminophore AA-PSP prepared by a dipping method does not work well due to the interference between the PSP and TSP luminophores. To overcome this problem, we have developed isolated dot arrays of PSP and TSP formed on an anodized aluminum substrate by an inkjet printing method. In this study, platinum tetrakis (pentafluorophenyl) porphyrin (PtTFPP) and ZnS-AgInS2 (ZAIS) were employed as pressure- and temperature-sensitive dyes, respectively. A suitable solvent was chosen for each dye to form the dots with uniform, high luminescence intensity, and high sensitivity. The developed bi-luminophore AA-PSP could simultaneously measure pressure and temperature and could reduce the temperature effect of the PSP from -0.97%/K (without temperature correction) to -0.01%/K (with temperature correction). It showed a pressure response time of 17.8 +/- 0.8 mu s at 90% pressure rise to a step change of pressure, which is in the same range as a conventional AA-PSP.

Herein, we proposed the addition of an inkjet-printed conductive pattern to paper-based analytical devices (PADs) in order to expand their applications. An electric conductive pattern was easily, quickly, and inexpensively fabricated using a commercial inkjet printer. The addition of a printed electric element will enhance the applications of PADS without the loss Of properties such as cost efficiency, disposability, and portability. In this study, we applied an inkjet-printed heater to a piece of paper and investigated its characteristics. The use of the heater as a valve, concentrator, and heat :source for chemical reactions on PADs was investigated. Previously, these functions were difficult to realize with PADs the inkjet-printed heater was used as a valve and concentrator through evaporation Of the working fluid and Solvent, and was also found to be useful for providing heat for chemical reactions. Thus, the combination of printed electric circuits and PADs has many potential applications.

Pressure-sensitive paint is an experimental technique that has been developed for decades and recently applied for microscale measurements to retrieve surface pressure data. Promising results have been reported at various flow regions including transition flow, supersonic flow, and unsteady flow regimes. The experimental results acquired by pressure-sensitive paint have been compared with computational simulation and theoretical analysis, and good agreements have been established. This technique provides not only qualitative information but also quantitative data for the flow field inside microfluidic systems. This paper summarizes the methodology and applications of pressure-sensitive paint in microscale measurements as well as their usage for oxygen detection in several areas. Critical comments and future aspects of the technique have also been provided.

For heat transfer in the microscale, the interaction between the gas and the solid surface is characterized by the thermal accommodation coefficient, and is important owing to the large surface-to-volume ratio existing as a consequence of the small size. However, there are few data of the thermal accommodation coefficients on the nonmetal surfaces often employed in microdevices. In this research, a novel simplified system in a spherically symmetric configuration is proposed, achieving a low-cost measurement of the thermal accommodation coefficient for both metal and nonmetal surfaces. Tiny flat-plate samples on a heater are placed at the center of a spherical vacuum chamber, and the conductive heat flux is measured and analyzed under the assumption of a concentric spherical shells geometry based on the low-pressure method. An approximate relation for the heat flux is also employed to measure under the near free-molecular and the transitional flow regimes. The proposed novel measurement system is validated by measurements of the thermal accommodation coefficient on a platinum surface with helium, argon and xenon. The measured heat fluxes as a function of pressure are well fitted by the approximate relation, and the obtained thermal accommodation coefficients agree well with the data in the literature. Finally, the measurement is demonstrated on a nonmetal surface of glass, showing good feasibility of the measurement system. (C) 2014 American Vacuum Society.

This study is aimed to investigate the effect of different structures of acrylic polymers on the properties of temperature-sensitive paint (TSP). TSP is composed of a temperature-sensitive luminophore and a polymer binder to fix the luminophore on a model substrate. Until now, the development of TSP has been focused primarily on searching for luminophores with high-temperature sensitivity and high luminescent intensity. However, recent studies revealed that polymers had a significant effect on TSP properties as well as luminophores. In this study, we systematically studied the effects of different structures of acrylic polymers on the temperature and pressure sensitivity and luminescent intensity of europium(III) thenoyltrifluoroacetonatetrihydrate (EuTTA)-based TSP. It was experimentally observed that EuTTA with acrylic polymers with longer straight side chain showed higher temperature sensitivity and lower luminescent intensity than those with shorter ones. In addition, an acrylic polymer with branched side chain presented lower sensitivity, higher pressure sensitivity, and higher luminescent intensity than that with straight side chain. (C) 2014 Elsevier B.V. All rights reserved.

© 2014 The Japan Society of Mechanical Engineers.

A novel dual luminescent sensor, which consists of discrete dot arrays of pressure-and temperature-sensitive paints (PSP and TSP), has been developed for a precise pressure measurement on a solid surface. The sensor arrays were well-ordered by inkjet-printing of PSP and TSP solutions. Since pressure- and temperature-sensitive luminophores are isolated from each other, the dual luminescent arrays sensor avoids the interaction between the two luminophores that has been one of the major issues of conventional dual luminescent sensors. It is an advantage of the dual-array sensor that an optimal solvent and an optimal binding material can be used for each luminophore. In this study, a 2-propanol solution of PtTFPP and a toluene solution of ZnS-AgInS2 (ZAIS) nano-particles were employed as PSP and TSP solutions, respectively. The newly developed dual-array sensor could prevent the interaction between PtTFPP and ZAIS that was observed in the mixture sensor of these luminophores, and had comparable pressure and temperature sensitivities with conventional PSP or TSP. Moreover, the pressure distribution on the surface with a non-uniform temperature distribution was successfully measured by the dual-array sensor. (C) 2013 Elsevier B.V. All rights reserved.

The pressure-sensitive paint technique based on the heterodyne method was proposed for the precise pressure measurement of unsteady flow fields. This measurement is realized by detecting the beat signal that results from interference between a modulating illumination light source and a pressure fluctuation. The beat signal is captured by a camera with a considerably lower frame rate than the frequency of the pressure fluctuation. By carefully adjusting the frequency of the light and the camera frame rate, the signal at the frequency of interest is detected, while the noise signals at other frequencies are eliminated. To demonstrate the proposed method, we measured the pressure fluctuations in a resonance tube at the fundamental, second, and third harmonics. The pressure fluctuation distributions were successfully obtained and were consistent with measurements from a pressure transducer. The proposed method is a useful technique for measuring unsteady phenomena. (C) 2013 AIP Publishing LLC.

© 2013 the American Institute of Aeronautics and Astronautics, Inc.

© 2013, Springer-Verlag Berlin Heidelberg.

Luminescent semiconductor nanoparticles have been applied to temperature measurements, because their emission is intense and the emission wavelength can be adjusted by particle size. However, most of luminescent nanoparticles contain highly toxic elements such as Cd, Se, and Te. In this study, the temperature characteristics of a new low-toxic luminescent nanoparticles, ZnS-AgInS2 (ZAIS), have been investigated. The temperature sensitivity of luminescent intensity of ca. -1 %/K was comparable to other luminescent nanoparticles. The thermally induced red shift of ca. 0.1 nm/K was observed, which is similar to other nanoparticles. The measurement revealed that the oxygen sensitivity of ZAIS is negligibly small. It is also shown that ZAIS nanoparticles are photostable compared with CdSe/ZnS. As a result, ZAIS is one of the most preferable candidates to take the place of other toxic nanoparticles especially for bio-related experiments. (C) 2012 Elsevier B.V. All rights reserved.

We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS) based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED) with phosphorescent dyes whose phosphorescence can be quenched by oxygen molecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II) octaethylporphine (PtOEP) doped into poly(vinylcarbazole) (PVK) as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) (PEDOT:PSS) as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP), which is an optical pressure sensor based on photoluminescence.

© 2012 The Visualization Society of Japan

The heat flux between two coaxial cylinders was measured in the range from the free molecular to the early transitional flow regimes for extraction of the thermal accommodation coefficient using an approximate relation on the pressure dependence of the heat flux. The experimental coaxial cylinders' geometry has been traditionally implemented for the measurement of the thermal accommodation coefficient using the low-pressure method; however, the actual experimental setup was characterized by large temperature difference and large cylinders' radius ratio. Compared to the original low-pressure method, much higher pressure range was applied. In order to verify assumptions in the accommodation coefficient extraction, the heat flux under measurement conditions was simulated numerically by the nonlinear S-model kinetic equation. Very good agreement was found between the measured and the simulated heat flux. The proposed procedure of the thermal accommodation coefficient extraction was discussed in detail and verified. The temperature dependence of the thermal accommodation coefficient was also found. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4726059]

There is much demand for improvement in the performance of a hard disk drive (HDD) along with recent rapid developments of information technology. While high-speed disk rotation of a HDD is necessary to accommodate such needs, it causes disk flutter induced by pressure fluctuation on disks and degrades reliability of a HOD. In order to understand the mechanism of the fluttering phenomenon, it is important to know pressure field on the rotating disk. However, it is impossible to measure the pressure by ordinary methods such as pressure taps. Pressure-sensitive paint (PSP) is a pressure measurement technique based on the oxygen quenching of luminescence and enables us to measure the pressure non-invasively. In general, however, the temperature sensitivity of PSP makes it difficult to measure the precise pressure on the surface with temperature distribution. We measured the time-averaged pressure on the disk rotating at 10 000-20 000 rpm for the first time by adopting a temperature-insensitive PSP composed of pyrene sulfonic acid (PySO(3)H) as a luminophore. It was found that the pressure forms a concentric circular distribution and decreases toward the center of the disk. Additionally, we elucidate how disk rotational speed and spacing between co-rotating disks influence on the pressure field. (C) 2011 Elsevier Ltd. All rights reserved.

© 2012 The Japan Society of Mechanical Engineers.

© 2012 The Japan Society of Mechanical Engineers.

We have proposed a novel utilization of pressure-sensitive paint (PSP) as a luminescent dissolved oxygen (DO) sensor film, which consists of an oxygen sensing dye and polymer matrix, for time resolved DO distribution measurements. The DO measurement is based on the variation of the luminescent intensity due to oxygen quenching; thus, the unsteady DO distribution can be easily obtained from the time series emission images of the sensor film. The effect of the wettability of the sensor films on the DO sensitivity was investigated. It was clarified that the sensitivity is independent of the wettability. The feasibility test of the unsteady DO distribution measurement with the sensor film was demonstrated in the periodic oscillatory flow. The measured frequency agreed well with that measured by fluorescein seeded in the flow, showing the applicability of the DO sensor film to unsteady DO distribution measurement. (C) 2011 Elsevier B.V. All rights reserved.

We have developed a new pressure sensing tool named pressure-sensitive channel chip (PSCC) by combining the pressure-sensitive paint (PSP) technique with the poly(dimethylsiloxane) (PDMS) micro-molding technique. The PSP technique based on the oxygen quenching of luminescence is a potential diagnostic tool for pressure measurement of micro gas flows. However, the application of PSP to micro scale measurement is very difficult, because the thickness and the surface roughness of conventional PSPs cannot be neglected compared with the characteristic length of micro channels, and the spatial resolution is not enough for micro scale measurements due to the aggregations of luminophore. PSCC is fabricated with PDMS containing a pressure-sensitive luminophore; thus PSCC is a micro channel which itself works as a pressure "distribution" sensor. A micro converging-diverging nozzle with the throat width of 120 mu m was demonstrated. The pressure distribution on the nozzle surface was successfully obtained by PSCC without the shortcomings of conventional PSPs.

The tangential momentum accommodation coefficient (TMAC) was investigated experimentally from the mass flow rate through a single microtube under the slip flow and the early part of the transition regime. The measurements were carried out by the constant-volume method under the mean Knudsen number smaller than 0.3, which is based on the mean pressure of the inlet and the outlet of the microtube, to apply the second-order slip boundary condition. To measure TMACs on various materials, quite large microtube was employed, which require the reduction in leakage. TMAC was obtained from the slip coefficient determined by the relation of the mass flow rate to the mean Knudsen number. The obtained mass flow rate was well explained by the theoretical equation. TMACs of deactivated-fused silica with argon, nitrogen, and oxygen were measured, showing the tangential momentum was not accommodated completely to the surface, and the values showed good agreement with previous studies. From the comparison between microtubes with different inner diameter, it is showed that TMAC is determined mainly by gas species and surface material.

© 2011 The Japan Society of Mechanical Engineers.

For the development of micro- and nano-technology, it has been strongly desired to understand thermo-fluid phenomena inside or around micro- and nano-devices. An optical measurement technique based on the absorption and the emission of photons by molecules is useful for experimental analyses of thermo-fluid phenomena of micro and nanoflows. The pressure-sensitive paint (PSP) technique is a potential diagnostic tool for pressure measurements of micro/nano gas flows because it works as a so-called "molecular sensor". However, the micro-scale measurement of PSP has been limited by the aggregation of the luminescent molecules and their thick film due to the use of a polymer binder. In our previous work, we adopted the Langmuir-Blodgett (LB) technique to fabricate pressure-sensitive molecular film (PSMF) with ordered molecular assemblies, and investigated properties of PSMF. In this study, a novel approach to enhance the luminescent intensity of PSMF is proposed, and the pressure distribution in a micro-nozzle is successfully measured by using PSMF. Moreover, we compared the pressure distribution measured by PSMF with that numerically analyzed by the direct simulation monte carlo (DSMC) method, showing good agreement with each other.

© 2011 The Japan Society of Mechanical Engineers.

© 2012 The Japan Society of Mechanical Engineers.

Pressure-sensitive paint (PSP) has the potential as a diagnostic tool for pressure measurement in high Knudsen number regime because it works as a so-called "molecular sensor". However, there are few reports concerning application of PSP to micro-devices, because conventional PSPs are too thick owing to polymer binders. In our previous work, we adopted the Langmuir-Blodgett (LB) technique to fabricate the pressure-sensitive molecular film (PSMF) using Pd(II) Mesoporphyrin IX (PdMP), which has pressure sensitivity only in the low pressure range (below 130 Pa). In this study, aiming for pressure measurement under an atmospheric pressure condition, we have constructed four samples of PSMFs composed of Pt(II) Mesoporphyrin IX (PtMP), Pt(II) Mesoporphyrin IX dimethylester (PtMPDME), Pt(II) Protoporphyrin IX (PtPP) and Cu(II) Mesoporphyrin IX dimethylester (CuMPDME) as luminescent molecules. The pressure sensitivity of those PSMFs was measured, and it was clarified that the pressure sensitivity of PSMF-PtMP is the highest among the four samples. Moreover, the temperature dependency of PSMF-PtMP was investigated, and we found that the temperature dependency of PSMF is dominated not by the oxygen diffusion in the layer, but by non-radiative deactivation process of excited luminescent molecules.

© 2009 The Visualization Society of Japan

The pressure-sensitive paint (PSP) is a very useful tool to measure pressure distributions on surfaces. In general, a measured pressure distribution by the paint shows good agreement with that by pressure taps. The paint is considered to represent the thermodynamic pressure. Recently, the paint has been adopted to rarefied gas flows and micro/nanoflows, i.e. high Knudsen number regime, and exhibited feasibility of pressure measurement in wide range of flows. In this study, we have discussed the physical meaning of luminescent intensity emitted from the paint through high Knudsen number regime measurements. It is known that a pressure tap shows good agreement with surface pressure and not with thermodynamic pressure in this regime, because of the temperature jump. High Knudsen number flow is required to be treated as a molecular flow; thus we discussed the PSP measurement mechanism by the molecular kinetic theory. The pressure profile of PSP was examined by a DSMC numerical result, and it was verified that PSP indicates the surface pressure. The temperature sensitivity was also investigated analytically in detail in continuum flow regime to discuss the suggestion that "PSP measures pressure, not density" [H. Bell, E.T. Schairer, L.A. Hand, R.D. Mehta, Surface pressure measurements using luminescent coatings, Annu. Rev. Fluid Mech. 33 (2001) 155-206]. From these analyses, however, we suggest that PSP measures a number flux of oxygen molecules toward the surface. The effect of a macroscopic flow against PSP in high Knudsen number flow is also discussed. (C) 2009 Elsevier B. V. All rights reserved.

In late years, the necessity of high Knudsen number flows, such as highly rarefied gas flows with large mean free path and gaseous flows around nanodevices with small characteristic length have increased significantly, especially in fields of researches on space technology, surface science, fabrication of thin film for semi-conductor and so on. In this paper, we describe mainly the optical diagnostic techniques for the high Knudsen number flows, such as laser induced fluorescence (LIF), resonantly enhanced multiphoton ionization (REMPI) and pressure sensitive molecular film (PSMF), and our experimental results obtained by the use of the techniques, i.e., applications of LIF to visualization of flow field structures including complicated shock wave system and to a measurement of rotational temperature, establishment of a REMPI system and its application to detection of rotational nonequilibrium in highly rarefied gas flows, and development of the suitable PSMF for low density and micro-scale gas flows.

© 2009 The Visualization Society of Japan

The flow around MEMS (Micro Electro Mechanical System) is so-called the high-Knudsen number flow. The flow field cannot be treated as a continuum and the thermal conduction must not be treated by ordinary Fourier's law. In high-Knudsen number flows, the gas-surface interaction becomes important and the energy accommodation coefficient, an empirical parameter, is often used to analyze heat transport phenomena. The energy accommodation coefficient is different depending on combination of surface and gas. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon and oxygen in contact with platinum surface by the Low-Pressure (LP) method, using the theoretical heat flux equation expanded to transition regime. The experimental result was compared with previous result by Thomas and Olmer (1943), which reported a relation between the energy accommodation coefficient and the surface temperature, and they are good agreement.

To analyze micro/nano scale flows, we need to adopt a measurement technique in the molecular level. The pressure sensitive molecular film (PSMF) technique employs interaction between luminophores and oxygen molecules; hence it is suitable for pressure measurement in the flows. Previously, we researched the pressure sensitivity and the temperature dependence of PSMF. Typically, luminophores of PSMF are easily degraded by light and oxygen molecules, and it is very important to consider the photo-degradation in the measurement. In this study, we studied the photo-degradation of PSMF under two different pressure conditions to reveal the effect of oxygen molecules. Additionally, the time profile of the photo-degradation was measured. From the asymptotical behavior, it was clarified that the pre-illumination reduced the photo-degradation. We successfully obtained the pressure distribution of a micro-nozzle by pre-illuminated PSMF.

© 2008 The Japan Society of Mechanical Engineers.

Non-uniform pressure distribution on shrouded co-rotating disks at high speed causes disk flutter. For stable rotation of disks at high speed, it is necessary to analyze pressure distribution on the disk surfaces and understand the mechanism of the disk flutter. To clarify the behavior of the flow around high-speed co-rotating disks, we have measured pressure distribution of disk surfaces by means of pressure sensitive paint. As a result, it is clarified that the pressure difference between the outer part and the inner part of the middle disk of the triple co-rotating disks is larger than that of the top disk, and the average pressure on the middle disk is lower than that of the top disk.

To analyze a micro/nano scale flow, we need to adopt a measurement technique that treats the flow as a molecular flow, because the flow cannot be treated as continuum. The pressure sensitive molecular film (PSMF) technique employs interaction between molecules, hence it is suitable for pressure measurement in the flow. We developed PSMF that is effective in the low pressure range. Typically, effective pressure range of PSMF depends mainly on the kind of luminophores. In this study, we adopt new luminophores in order to develop a new PSMF for near-atmospheric pressure range. Furthermore, because luminophores of PSMF are easily deteriorated by light, it is very important to consider photo-deterioration in pressure measurement by PSMF. In this study, we also analyzed photo-deterioration of PSMF to clarify basic photo-deterioration feature of PSMF.

© 2008 The Japan Society of Mechanical Engineers.

Experimental analyses of thermo-fluid phenomena of micro- and nano-flows with high Knudsen number need the measurement techniques based on interaction of atoms or molecules with photons. The pressure-sensitive paint (PSP) technique has potential as a diagnostic tool for pressure measurement in the high Knudsen number regime because it works as a so-called "molecular sensor". However, application of PSP to micro devices is very difficult because the conventional PSP is too thick owing to the use of polymer binder and does not have sufficient spatial resolution for pressure measurement of micro-flows. In this study, we have adopted the Langmuir-Blodgett (LB) technique to fabricate pressure sensitive molecular films (PSMFs) using Pd(II) Octaethylporphine (PdOEP) and Pd(II) Mesoporphyrin IX (PdMP) to resolve ordinary PSPs problems, and have tested these PSMFs to evaluate the feasibility of the pressure measurement around micro-devices. It is clarified that the PSMF composed of PdMP has higher sensitivity than that of PdOEP. Since it is also considered that the sensitivity of PSMFs can be increased by introducing arachidic acid (AA) as spacer molecules of LB films to prevent the aggregation of luminescent molecules, we have produced PSMFs with several molar ratio of PdMP to AA. At the most suitable ratio, the PSMF has high sensitivity in the low pressure region with high Knudsen number, even if the amount of the luminescent molecules in the PSMF layer is smaller than that in conventional PSPs. This result indicates that the PSMF is feasible to measure the pressure in high Knudsen number flows such as micro-flows.

© 2007 The Japan Society of Mechanical Engineers.

© 2006 The Japan Society of Mechanical Engineers.

The Brownian motions of ZnS-AgInS2 (ZAIS) nanoparticles in a poly(dimethylsiloxane) (PDMS) layer were observed using the single-particle tracking (SPT) technique. The positions of each nanoparticle can be detected with spatial resolution of O(10 nm), and reflect the environment near each nanoparticles
thus, SPT can obtain information on the nanoscale structure or the spatial heterogeneity of the medium. In this study, ZAIS nanoparticles were illuminated by an excitation laser, and the emission of the nanoparticle was taken by using an EM-CCD camera. We analyzed each motion of the nanoparticle in the PDMS layer under two conditions: before and after adding a curing agent. The histograms of the diffusion coefficients had single peak for all of the particles in the layer before adding the curing agent and some particles in the layer after adding the one. On the other hand, the histogram of the other particles had two peaks. This indicates these particles diffused in the heterogeneous layer, showing spatial heterogeneous curing process in the layer.

Thermal transpiration (thermal creep) flow, which is induced only by temperature gradient along a channel, is one of the most interesting phenomena in micro gas flows. The thermal transpiration flow has been studied both numerically and experimentally; however, the detailed condition inside a channel has not been enough studied experimentally, and it makes difficult to compare numerical and experimental results directly. In this study, the pressure distribution on a micro channel surface in thermal transpiration flow was measured by means of the Pressure-Sensitive Paint (PSP) technique. And the pressure distribution was a convex profile along the channel.

A sprayable fast pressure-sensitive paint (PSP) has been developed to measure pressure fluctuation on models made of non-aluminum-alloy materials with complex shapes. It is important to distribute a pressure-sensitive dye only over the surface to improve responsiveness of the fast PSP. In this study, fast PSP's were prepared by applying the solution of a pressure-sensitive dye onto a pre-coated porous binary layer and the effect of the solvents of dye solution was investigated. By choosing a polymer dissolving solvent for the dye solution, one could succeed to develop a PtTFPP based PSP with a pressure response time of 17.8 μs at 90 % pressure rise to a step change of pressure. This was about 10 times faster than a previous fast PSP (191μs) using a polymer dissolving solvent for dye solution.

The pressure-sensitive paint (PSP) technique is an optical technique for measuring surface pressure on a model surface. The PSP technique has been used in wind-tunnel tests because of its great advantages such as non-intrusive and global pressure measurement. In general, PSP is painted by a sprayer by hand, resulting in low reproducibility. In this study, we used a commercial inkjet printer for printing PSP on substrates. PSP was printed on three substrates: chromatography paper, label seal, and viewgraph. We investigated the pressure and temperature sensitivities of these PSPs. PSP printed on the chromatography paper showed the best characteristics among them. And, we succeeded in preparation of PSP using the commercial inkjet printer.

Along with the development of micro- and nano-technologies, gas-surface interaction becomes important due to large surface area-to-volume ratio in micro-scale gas flows. In such flows, the Knudsen number (Kn) is often employed as a parameter of rarefaction of flows. When 0.01<Kn≦0.1, a flow is classified as the slip flow with a finite velocity slip at boundary. In this regime, the mass flow rate increases from the rate in the continuum regime because of the velocity slip. The mass flow rate depends on the combination of molecule and surface. In this study, we measured the mass flow rate of water molecules to investigate the characteristics on gas properties. The constant-volume technique was employed for measuring the mass flow rate through a micro channel. The obtained results suggested that the adsorption of water molecules on the measurement system influenced the accurate measurement of the mass flow rate.

Along with the development of microtechnology, the gas-surface interaction becomes important due to large surface area-to-volume ratio in micro-scale flows. As a parameter on gas-surface interaction related to a flow rate, Tangential Momentum Accommodation Efficient (TMAC) is often employed. TMAC represents the degree on tangential momentum exchange between molecule and surface. In this study, TMAC was measured for several gas species to investigate the characteristics on gas properties. The constant-volume technique was employed for measuring the mass flow rate through a microchannel. Monatomic gases of helium, argon and xenon were employed as test gases. The microchannel was made of Fused Silica as non-metal material. TMAC was calculated by comparing the measured mass flow rate and the theoretical one with the second order slip boundary condition. The obtained results suggested that the molecular weight has only small influence on TMAC.

The diffusion process of nanoparticles in a polymer matrix was studied by the single-particle tracking (SPT) method. ZnS-AgInS2 (ZAIS) nanoparticles were dispersed in poly(dimethylsiloxane) (PDMS) and were tracked before and 20 hours after adding a curing agent in the PDMS. The averaged diffusion coefficients of the ZAIS nanoparticles in PDMS 20 hours after adding the curing agent was 1/2 of that without the curing agent. While the diffusion coefficients of the nanoparticles in the PDMS without the curing agent were of similar value, that in the PDMS in the curing process showed broad distribution in value.

It has been desired to measure pressure distribution in a micro channel for understanding micro-scale thermo-fluid phenomena. Pressure-sensitive paint (PSP) technique is an optical measurement technique using luminescent molecules, seemed to be suitable for analysis of micro/nano flow. However, the spatial resolution of PSP is insufficient for applying to micro-scale measurements due to the aggregation of the luminescent molecules. Therefore, we fabricated pressure-sensitive molecular film (PSMF) by Langmuir-Blodgett (LB) method. LB method can fabricate very thin molecular film with controlling the intermolecular spacing of luminescent molecules. PSMF fabricated by this method has enough high spatial resolution to measure micro-gas flows. The pressure distribution in a micro channel with a bend of 90° was measured by PSMF. The low pressure region was found at near the inner wall behind the bend suggesting the flow separation. Additionally, the high pressure area downstream of the separation region was observed, indicating the flow reattachment.

Knudsen pump is a pump based on thermal transpiration, which is a specific phenomenon in a high Knudsen number flow. Since the pump does not have any moving parts and can be miniaturized to micro scale, it is a favorable pump in micro electro mechanical system (MEMS). However, there are many points to be clarified on characteristics and performances of Knudsen pumps. In this study, a Knudsen pump with commercially available parts and porous membranes was fabricated, and effects of temperature difference and the number of membranes on pressure difference and time constant for pressure time variation were investigated. The fabricated Knudsen pump with four membranes generated about 70 Pa from an atmosphere with temperature difference of 71 K with four membranes. The pressure difference was proportional to the temperature difference and the number of membrane, while the time constants were independent of them. This result suggested that the Knudsen pump was able to generate higher pressure difference or flow rate with increasing in the number of membranes.

Recently, micro gaseous flow has been a novel research filed along with the development in the micro technology. In the micro gaseous flow, the Knudsen number, which is a ratio of the mean free path to the characteristic length of the system, becomes large, and such a high Knudsen number flow should be investigated as a molecular flow. We organized a session meeting in the Japanese Society for Mechanical Engineers for the investigation on the micro gaseous flow. The closed discussions by the members gave the deep insight to the field, but much more interaction in the research network in future is expected for the further progress in the field. The recent developments in the measurement techniques for the micro gaseous flow in our group have been introduced.

Gas flows through a micro-channel were experimentally studied by using PSCC (Pressure-Sensitive Channel Chip). PSCC is a micro-channel fabricated by PDMS containing a pressure-sensitive dye, and then it works as both a micro-channel and PSP (Pressure-Sensitive Paint). The micro-channel (PSCC) with 200 x 91 mu m cross section and 2.0 mm long was fabricated. The pressure distribution with the inlet and outlet pressures of 101 kPa and 30 kPa was successfully measured. The measured pressure distribution indicates that the gas flow near the exit of the channel should be treated as compressible flow and the gas flow was choked at the end.

Pressure-sensitive paints (PSP) and pressure-sensitive molecular film (PSMF) are drawing much attention, since the techniques enable us to measure pressure/oxygen concentration distribution with high spatial resolution. A measurement system of PSP/PSMF is generally composed of a sensor layer (PSP/PSMF itself), an illumination light source, a photodetector, and optics such as optical filters and mirrors. Since dye molecules in a sensor layer are photo-excited by an illumination light, the measurement system needs optical windows to transmit UV light for the illumination light and needs an optical filter to eliminate the illumination light, which also reduces the luminescence detected by a photo-detector. We have proposed a novel concept of a pressure sensor called electroluminescent pressure/oxygen sensor (ELPS/ELOS) based on oxygen quenching of electroluminescence without an external illumination light source. The sensor was fabricated as an organic light-emitting device (OLED) with phosphorescent dyes whose phosphorescence can be quenched by oxygen molecules, and with a polymer electrode which permeates oxygen molecules. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is comparable to that of conventional PSP.

Flows inside micro-systems are so-called high-Knudsen number flows. The flow field cannot be treated as a continuum and the thermal conduction can not be described by ordinary Fourier's law. In high-Knudsen number flows, gas-surface interaction becomes significant and the energy accommodation coefficient is often employed to analyze heat transport phenomena. The energy accommodation coefficient varies depending on combination of surface materials and gas species. Thus, it is important to measure the accurate energy accommodation coefficient for each pair of surface material and gas species. In this study, we obtained the energy accommodation coefficients for nitrogen and oxygen in contact with a platinum surface in accordance with the Low-Pressure method using the theoretical heat flux equation expanded to transition regime. The experimentally obtained energy accommodation coefficients were compared with previous results in the literature as a function of surface temperature, showing good agreement with each other.

In pressure-sensitive paint (PSP) measurements, pressure is deduced from the luminescence intensity of PSP. Since the intensity depends not only on pressure but also on temperature, a PSP result has to be compensated by the temperature of a surface to which PSP is applied. In this paper, we propose a novel combined pressure and temperature sensor composed of PSP and TSP dot arrays. PtTFPP and CdSe/ZnS were adopted as PSP and TSP luminophores, respectively. PtTFPP is widely used as PSP luminophore, and CdSe/ZnS has several favorable features as TSP luminophore such as tunable luminescence peak wavelength, narrow full width at half maximum, high quantum yield and broad absorption band. The dot array sensor was fabricated by inkjet printing of the luminophores. We examined its photostability under an illumination light, pressure and temperature sensitivities. Each luminophore is separately arranged in dot array; thus the interaction between both luminophores is prevented. The dot array sensor has pressure sensitivity of 0.62 %/kPa as a pressure sensor, and temperature sensitivity of -0.61%/K as a temperature sensor

In this paper, we proposed long-lifetime fluorescent measurement by compensation of photo-bleaching with the difference of photo intensity. In this method, difference of fluorescent intensity is compensated using single exponential function to make the difference amount uniform between two fluorescent intensities. We evaluated the dependencies of measurement lifetime by fluorescent lifetime and the sensitivity by the decay coefficient of fluorescent lifetime by numerical simulation. From these results, the proposed method has much higher sensitivity and longer lifetime to conventional compensation method of photo-bleaching. We demonstrate the photosynthesis activity of single Synechocystis sp. PCC 6803 in the micro chamber with gas barrier layer.

We developed a novel single cell measurement of photosynthesis activity using fluorescent oxygen sensor in a microchamber with gas barrier wall. We used Synechocystis sp. PCC 6803, which is a series of cyanobacteria. The chamber wall contains oxygen sensor and gas barrier wall to measure the dissolved oxygen concentration in the chamber. The oxygen concentration is changed by aerobic respiration and photosynthesis of Synechocystis. The variation of the oxygen concentration was used for evaluation of aerobic respiration and photosynthesis of single Synechocystis. To achieve precise oxygen measurement, we used our proposed compensation method for photo-degradation of fluorescence. We demonstrated photosynthesis evaluation of single Synechocystis and calculated the photosynthetic performance of sugar production of single Synechocystis. © 2012 IEEE.

Molecular beams have been used for diagnoses of solid surfaces and gas-surface interactions. For molecular beams of polyatomic gases, it is important to clarify the distribution over the energy states of the internal degree of freedom. In this study, the rotational energy distribution in a nitrogen molecular beam was spectroscopically measured by the (2+2)N 2-REMPI (Resonantly Enhanced Multiphoton Ionization) technique. REMPI is known to have very high detection sensitivity, which allows us to detect molecules under the very low number density condition like in a molecular beam. A REMPI spectrum indicates the rotational energy distribution of molecules, and is not affected by secondary electrons, which simplifies the analysis. The molecular beam was generated using a Kantrowitz-Grey type beam source. The measured REMPI spectra were well fitted by a theoretical spectrum with the Boltzmann distribution, and the rotational temperatures were obtained. Since the supersonic freejet was employed as a beam source, the rotational temperature in the molecular beam was analyzed in accordance with the frozen rotational temperature in a supersonic freejet using the parameter p0d, which is a product of the source pressure p0 and the orifice diameter d. It was found that the rotational temperature is well described as a function of the parameter p0d under the fixed source tempearture condition. © 2012 American Institute of Physics.

In this paper, we proposed long-lifetime and high-sensitive measurement using fluorescent intensity by compensation of photo-bleaching with the difference compensation for cell measurement. Photo-bleaching of fluorescence is one of the most crucial factors to cause measurement error in physiological measurement. In our approach, difference of fluorescent intensity between imaging time is compensated using single exponential function to make the difference amount uniform in each imaging time. We evaluated the dependencies of measurable time and the sensitivity by fluorescent lifetime and the decay coefficient of fluorescent lifetime using numerical simulation. From these results, the proposed method has much higher sensitivity and longer measurable time against conventional compensation method of photo-bleaching. By using the proposed method, we demonstrate the photosynthesis activity of single Synechocystis sp. PCC 6803 in the micro chamber with gas barrier layer. © 2012 IEEE.

Optical measurement techniques are useful for experimental studies on micro gas flows, which enable us to non-intrusively measure the flows with a high spatial resolution. The pressure-sensitive paint (PSP) technique, which is based on the emission of photons from luminophore, is a potential diagnostic tool for pressure measurement of micro gas flows. However, measurements by conventional PSPs are limited to the sub-millimeter order spatial resolution of ca. 200 mu m, indicating the difficulty of the micro scale measurements. The present study proposes pressure-sensitive channel chip (PSCC) which is a micro channel with the capability of measuring pressure. We focused on the poly(dimethylsiloxane) (PDMS) micro-molding technique, which is one of the most popular techniques to fabricate a micro channel easily. Moreover, PDMS is a polymer used as a binder in PSP because of high optical transparency, gas permeability, and gas diffusivity. Thus, we developed a micro channel by the PDMS micro-molding technique with mixing a pressure-sensitive luminophore into PDMS: i.e. a micro channel fabricated by PSP, which is named PSCC. A flow through a micro converging-diverging nozzle with the throat width of 120 mu m was demonstrated. The pressure distribution on the nozzle surface was successfully obtained by PSCC.

In pressure-sensitive paint (PSP) measurements, pressure is deduced from the luminescence intensity of PSP. Since the intensity depends not only on pressure but also on temperature, PSP results have to be compensated by the surface temperature; thus, we combined temperature-sensitive paint (TSP) with PSP for the compensation. PtTFPP and CdSe/ZnS were adopted as pressure and temperature sensitive luminophores, respectively. In this paper, we report the pressure and temperature sensitivities and the photostability of the combined sensor around an atmospheric pressure and room temperature.

The tangential momentum accommodation coefficient was measured from the gaseous flow through a single microtube. The mass flow rate was measured by the constant volume technique, where the rate is related to time rate of pressure variation in a fixed volume tank. The measured mass flow rate was fitted by the theoretical mass flow rate expressed by the slip velocity at the surface to deduce the slip coefficient, which can be related to the tangential accommodation coefficient. The mean Knudsen number, which is determined as the mean pressure of the inlet and the outlet, was set to be below 0.32, where the second-order slip boundary condition was suggested to be valid. The measurement system was designed to allow using a microtube with large diameter of several hundred micrometers. Since low pressure environment was essential for large Knudsen number condition for the flow through such large microtube, a low leakage measurement system realized by applying the UHV technology is needed. Applicability of sub millimeters size microtubes allowed us to measure the tangential momentum accommodation coefficients on various materials. In this study, we measured the tangential momentum accommodation coefficients on an engineering metal surface for various gas species.

Pressure-sensitive paint (PS?) is an optical measurement technique based on the photo-chemical reaction between oxygen and luminescent molecules, and has potential as a diagnostic tool for pressure measurement in the high Knudsen number regime. However, the application of PSP to micro flow measurement is not straightforward, because conventional PSPs are too thick owing to their polymer binder. In our previous work, we fabricated pressure-sensitive molecular film (PSMF) by using the Langmuir-Blodgett (LB) technique. In this study, we investigated the temperature dependency of Pt(II) Mesoporphyrin IX (PtMP) based PSMF, and found that the temperature dependency of the pressure sensitivity is very small. Moreover, we have applied PSMF to the pressure measurement of micro gas flows through the 170 mu m width micro channel and the 100 mu m width micro nozzle, and the pressure distributions were successfully obtained.

The flow around micro-systems is so-called the high-Knudsen number flow. The flow field cannot be treated as a continuum and the thermal conduction should not be treated by ordinary Fourier's law. In high-Knudsen number flows, the gas-surface interaction becomes important and the energy accommodation coefficient is often employed to analyze heat transport phenomena. The energy accommodation coefficient varies depending on combination of surface materials and gas species. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon in contact with platinum surface in accordance with the Low-Pressure method, using the theoretical heat flux equation expanded to transition regime. The experimental result was compared with previous result in literature, which reported a relation between the energy accommodation coefficient and the surface temperature, and they are in good agreement.

Pressure-Sensitive Paint (PSP) is a pressure sensor based on the oxygen quenching of the luminescence of luminophore. In general, the luminescent intensity of PSP depends not only on pressure but also on temperature. Therefore, it is necessary to simultaneously measure the temperature with the pressure to improve the accuracy of PSP measurement. The compound sensor composed of pressure and temperature-sensitive luminophore was developed for simultaneous measurements of pressure and temperature. However, some of such compound sensors suffer the degradation of the sensitivity and other properties. In this paper, we show the possibility of a compound PSP/TSP sensor using PtTFPP and CdSe/ZnS.

Along with the progress in micro- and nano-technologies, such as Micro Electro Mechanical Systems (MEMS) and mu-TAS (Micro-Total Analysis Systems), the Knudsen number, which is a non dimensional parameter for rarefaction, of the flow around and inside the systems becomes large. In such high Knudsen number flows, gas-surface interaction has become important for flow field analyses. To illustrate overall gas-surface interaction without any detailed processes, an accommodation coefficient, a, is the most widely used as an empirical parameter for a practical purpose. One of accommodation coefficients, the tangential momentum accommodation coefficient (TMAC) alpha(t), is in closely related to the loss of the pressure through a micro channel. Therefore, TMAC is an important coefficient for flow inside micro/nano fluidic devices. To obtain TMAC from experiments, the mass flow rate measurements in a microtube were carried out using the constant volume method. The results obtained from the experiments were analyzed in frame of the Navier-Stokes equation associated with the second order velocity slip boundary condition. The mean Knudsen number was less than 0.3, where the velocity slip boundary condition is applicable. From the mass flow rates, the slip coefficient of the boundary condition was obtained, and then, TMAC was determined. The experimental apparatus showed very low leakage rate, and TMAC was determined with a high degree of accuracy. The TMACs of the same surface material with different dimensional parameters were compared for validation of the system.

Heat transfer in micro flows has received much attention along with the development in micro- and nano-technology. In micro- and nano-flow fields, the Knudsen number, which is defined as a ratio of the molecular mean free path to the characteristic length of the system, becomes large because of the small characteristic length. In these so-called "high Knudsen number flows", the number of the collision of gas molecules to the surface is much larger than that of intermolecular collisions. Therefore, it is important for the high Knudsen number flows to understand the gas-surface interaction. Since detailed science of the gas-surface interaction is complicated, the empirical parameter called the accommodation coefficient is widely used for flow analyses of the flows.
In this study, the energy accommodation coefficient for metal surface has been measured experimentally by the Low-Pressure method, in which the energy accommodation coefficient is obtained from the pressure dependency of the heat flux in the free-molecular flow regime. It is not easy to realize the free-molecular flow condition, and, thus, the relation between the heat flux and the pressure extended to much higher pressure condition was employed in this study. Experimental geometry was designed as concentric cylinders, and heat flux between two cylinders, whose surface temperatures was different, was measured. Experimental results are reported for argon and oxygen in contact with a platinum surface. The surface temperature dependence of the energy accommodation coefficient was also studied, and verified by the results of previous work.

There appears fluttering phenomena in a hard disk drive system with high-speed disks rotating inside a closed space, leading to degrade of reading and writing performance. The precise pressure distribution on the disk may improve the performance, but there has been no report because it is very hard to measure the surface pressure using conventional techniques, such as pressure taps. While pressure sensitive paint (PSP) seems to be suitable for the pressure measurement on the disk, we have to compensate its highly temperature-sensitive characteristics of PSP, because the temperature distribution on the disk is not assumed to be uniform. We employed PySO3H based PSP, which has small temperature sensitivity, and have obtained the pressure distribution on the disk rotated at various speeds (10000-20000 rpm) successfully. The result showed that the pressure is higher at the disk outside than at the center, and forms a concentric circle distribution. Moreover, we found that the pressure difference between the inner and outer region of the disk increases as a square of disk rotation speed.

For a hard disk drive, high-speed rotation is required to achieve fast access to data on a disk. However, the high-speed rotation induces pressure fluctuation on the disk and results in disk fluttering. Therefore, it is important to investigate the pressure distribution on the disk to realize high-speed and stable disk rotation. We have measured the pressure distribution on the disk rotated at various speeds by using pressure-sensitive paint, which is appropriate for measuring the pressure of rotating objects. As a result, it is clarified that the pressure distribution forms concentric circles and the pressure difference between the outer and inner part of the disk increases with an increase in the disk rotation speed.

To analyze high Knudsen number flows, interactions of gas molecules and solid surfaces are very important. Molecular beams have been widely used to diagnose these interactions. While properties such as translational energy and momentum of molecular beam have been analyzed very well, there are very few reports analyzing rotational energy of diatomic or polyatomic molecular beam experimentally. Resonantly enhanced multi-photon ionization (REMPI) is a spectroscopic technique, which is able to measure molecular internal energy in very low density gas flows. In this study, we have tried to detect a nitrogen molecular beam by 2R+2 REMPI, and analyzed rotational energy distribution of nitrogen molecules in the molecular beam.

In the field of chemical industries, it is desired to downsize chemical reactors for easy controlling, synthesizing a wide variety of products in small quantities and so on. It is well known that flow field structure in a mixing channel changes from steady to unsteady with an increase in Reynolds number. These flow fields have been analyzed numerically, but there are few reports analyzed experimentally. We have focused on the pressure-sensitive paint (PSP) technique, which enables us to measure the distribution of oxygen concentrations. Using the PSP technique, we tried to reveal the flow field structure and evaluate the flow unsteadiness in a parallel mixing channel depending on inlet Reynolds numbers.

The pressure-sensitive paint (PSP) has potential as a diagnostic tool for pressure measurement in the high Knudsen number regime because it works as a so-called "molecular sensor". However, there arc few reports concerning application of the PSP to micro devices, because the conventional PSP is too thick owing to the use of polymer binder. In our previous work, we have adopted Langmuir-Blodgett (LB) technique to fabricate pressure sensitive molecular films (PSMFs) using Pd(II) Mesoporphyrin IX (PdMP). The PSMF based on PdMP has pressure sensitivity only at low pressure range (below 3kPa). In this study, we have constructed PSMF composed of Pt(II) Mesoporphyrin IX (PtMP) to be applied to pressure measurement near atmospheric pressure. The pressure sensitivity of PSMF based on PIMP has been tested, and it is clarified that the PSMF of PIMP has equivalent pressure sensitivity of polymer PSP. Moreover, we have applied PSMF to measurement of pressure distribution of micro-channel gas flow, showing its usefulness.

The Pressure Sensitive Paint (PSP) is very useful and easy way to obtain the pressure distribution on surfaces. Therefore the PSP has been adopted to various flow fields to obtain pressure distributions, showing good agreement with other methods, such as a pressure tap. Many kinds of flow fields have been used in the manufacturing process, like small scale, low pressure and/or high speed flows
for example, semiconductor manufacturing processes where a mean free path of gas molecules is large, and micro-/nano-systems where a characteristic length is small. Recently the PSP is applied to these high Knudsen number flows. Usually it is considered that the luminescent of the PSP represents the surface pressure, but it is not clear yet that this "pressure" means "static" or "total" pressure. The PSP is considered to be in the boundary layer, leading to the local equilibrium of oxygen molecular density between in the gas phase and in the PSP is achieved. This becomes a large problem especially in the high Knudsen number regime. The mechanism of the PSP has been mainly discussed focused on the luminescence intensity and the oxygen quenching of luminescent molecules. Here, in this study, we tried to relate the flux of oxygen molecules and the surface pressure to the luminescence intensity of the PSP, and clarify the limit of application from the molecular kinetics point of view. The main target of this problem was in the high Knudsen number and the high Mach number flow fields. Copyright © 2007 by ASME.

Pressure sensitive paint (PSP) technique is based on the interaction of oxygen molecules with luminescent molecules, and it seems suitable for analyses of high Knudsen number flows which require diagnostic tools in the molecular level. However, application of the PSP technique to micro-devices is still very difficult because of the thickness of PSP layers of the order of microns and the aggregation of luminescent molecules caused by the "painting" methods. To resolve the problems of ordinary PSPs mentioned above, we adopt the Langmuir-Blodgett (LB) method to fabricate pressure sensitive molecular films (PSMFs) having nanometer order thickness. The fundamental properties of the PSMFs such as the pressure sensitivity and the surface roughness are examined, to evaluate the feasibility of the PSMF technique for pressure measurement around micro-devices. A PSMF based on palladium(II) mesoporphyrin DC shows high pressure sensitivity in low pressure regime, while a PSMF based on platinum(II) mesoporphyrin IX is optimum for atmospheric pressure. It is also clarified that the PSMFs do not degrade the roughness of solid surfaces. The results indicate the feasibility of the PSMF technique for pressure measurement in high Knudsen number flows such as micro flows.

The Pressure Sensitive Paint (PSP) is very useful and easy way to obtain the pressure distribution on surfaces. The pressure distribution obtained by the paint shows good agreement with that by other methods, like a pressure tap. Recently, the paint has been adopted to the high Knudsen number regime. The mechanism of the PSP is mainly discussed within the framwork of the luminescence intensity and the oxygen quenching, while it is unclear that luminescence intensity is really proportional to the pressure, especially in the high Knudsen number regime. Usually it is considered that the luminescent represents a pressure, but it is not clear yet that this &quot;pressure&quot; means &quot;static&quot; or &quot;total&quot; pressure. Here, in this study, we tried to relate the flux of oxygen molecules and a pressure to the luminescence intensity, and clarify the limit of application from the molecular kinetics point of view.

Pressure sensitive paints are widely used in many applications. The pressure distribution on surfaces obtained by the paint shows good agreement with that by other methods, like a pressure tap. Recently, the paint has been adopted to high Knudsen number flows, such as rarefied gas flows and micro/nano flows. The mechanism of the paint is based on the oxygen quenching of luminescent molecules in the paint. Usually the static pressure is inversely proportional to the luminescent intensity of the paint, because of the static gas condition. In high Knudesen number flows, it is not clear whether this relation holds or not. Here, in this study, we tried to relate the number flux of oxygen molecules and the pressures to the luminescence intensity, and clarify the limit of application in high Knudsen number flows.

Gas flows in micro- and nano-systems having high Knudsen number must be treated as molecular flows, and experimental analyses of thermo-fluid phenomena in micro- and nano-systems need measurement techniques employing "molecular sensors". However, such measurement techniques are behind in development compared with molecular simulation techniques for numerical analyses. Pressure sensitive paint (PSP) technique is based on the interaction of oxygen molecules with luminescent molecules, and it seems suitable for analyses of high Knudsen number flows, which require diagnostic tools in the molecular level. In this study, we fabricate pressure sensitive molecular films (PSMF) with very small thickness based on the PSP technique and the Langmuir-Blodgett (LB) film technique. It is clarified that the PSMF composed of palladium (II) mesoporphyrin IX (PdMP) as a luminophore and arachidic acid as a buffer has comparable pressure sensitivity with conventional PSPs in low pressure regime with high Knudsen number, even if the amount of the luminescent molecules in the PSMF layer is much smaller than that in conventional PSPs. The results indicate the feasibility of PSMF technique for pressure measurement in high Knudsen number flows such as micro flows.

To measure pressure distribution in high Knudsen number regimes, we have adopted a pressure sensitive paint (PSP) technique, because the PSP works as a so-called &quot;molecular sensor&quot;. However, application of the PSP to micro-devices is very difficult because the conventional PSP is too thick owing to the use of polymer binder. Moreover, they have not sufficient spatial resolution for pressure measurement of micro-flows because of the aggregation of luminescent molecules in polymer binders. In our past work, we have adopted Langmuir-Blodgett (LB) technique to fabricate pressure sensitive molecular films (PSMFs) using Pd(II) Mesoporphyrin IX (PdMP) to resolve the problems of ordinary PSPs mentioned above. However the luminescent intensity of PSMF is low, leading to low SN ratio because the amount of luminescent molecules in the layer is small. In this study, we have applied localized surface plasmon resonance to increase luminescent intensity of PSMF and have tested PSMFs to evaluate the feasibility of the pressure measurement around the micro-devices. A PSMF with nanometer order thickness and high spatial resolution is suitable for analyses of micro-flow.

Experimental analyses of thermo-fluid phenomena of micro- and nano-flows with high Knudsen number need the measurement techniques based on interaction of atoms or molecules with photons. The pressure sensitive paint (PSP) technique has the capability to be applied to high Knudsen number flows, such as micro-flows and low density gas flows. In this study, to inspect the feasibility of PSP for measurement of pressure on a solid surface in high Knudsen number flows, fundamental properties of PSPs are examined especially in the range of pressure below 1 Torr. As an application of PSP to measurement in high Knudsen number conditions, the pressure distribution on a jet-impinging small solid surface is measured. However, application of the PSP technique to a micro-system is very difficult, because of large thickness of conventional PSPs. Therefore, we have adopted Langmuir-Blodgett (LB) method to fabricate a pressure sensitive molecular film (PSMF) applicable to pressure measurement around micro/nano devices. Finally, the dependence of luminescence intensity of PSP on the molecular number flux onto the solid surface is discussed, because molecular number flux is an important quantity to analyze the interaction between high Knudsen number flows and solid surfaces.

The pressure sensitive paint (PSP) technique has the capability to be applied to high Knudsen number flows, such as low density gas flows, micro-flows, and so on. However, applications of the PSP technique to micro/nanodevices have never been reported, because of the thickness of the conventional PSPs and of the low resolution caused by the aggregation of luminescent molecules. In this study, we have constructed ultrathin PSP films for micro/nanodevices by the Langmuir-Blodgett (LB) technique. Two luminophores are examined to select the suitable one for LB-PSP. Moreover, the dependence of luminescence intensity and oxygen sensitivity of the LB-PSP on the number of the layer is clarified.

The pressure-sensitive paint (PSP) technique has the potential as a diagnostic tool for measurements in the high Knudsen number regime because it works as a so-called &quot;molecular sensor&quot;. However, application of the PSP technique to micro-systems has never been reported because the conventional PSP is too thick owing to the use of polymer binder. We constructed PSP molecular films, using Pd(II) Octaethylporphine (PdOEP) and an amphiphilic palladium metal complex, and have examined these PSP molecular films to evaluate the possibility of application to the measurement of micro flow. It is found that the latter PSP molecular film has sufficient sensitivity in the low pressure region with high Knudsen number, even if the amount of the luminescent molecules in PSP molecular film layer is smaller than that in conventional PSP. This indicates that the PSP molecular film is feasible to measure the pressure in high Knudsen number flow such as micro flows.

圧縮性マイクロダクト流れに先端的な光計測技術を適用した．本研究の成果は以下の通りである．
(1)マイクロスケール流れ特有の超音速膨張領域が観測された．(2)超音速マイクロダクト流れには超音速風洞で見られるような垂直衝撃波や擬似衝撃波などの始動衝撃波を介した始動過程がない．(3)不足膨張状態でダクトを長くし，本来始動衝撃波が現れる長さになってもマイクロダクトでは始動衝撃波が現れない．(4)先細ノズルに接続されたマイクロダクト内の音速線はレイノルズ数が約2000になるとダクト出口から最も上流に位置する．(5)圧縮性マイクロダクト流れにおける流路壁面の圧力および壁面温度分布の計測に成功した．

高分子の年間生産量は国内だけでも1000万トンを超え，その成型加工時の高効率化による省エネルギー効果は非常に大きい．高分子材料製品の製造の高度化・高効率化につなげる基盤構築を最終目標に見据え，本研究では，高分子材料製品の加工過程において重要な硬化過程に関して，分子スケールでの熱物性評価を実施し，これとマクロに計測される熱物性データとの関係を明らかにすることを目的とした． 具体的には，単一分子計測（SMT）を実施した．巨視的にみると粘度が一様に上昇していくような高分子膜系において，SMTで計測される微小スケールでは粘性分布に空間的な不均一性が現れていることが分かった．

新しい携帯型生化学分析用の流体チップとして注目されている紙流体チップの高機能化を目指した研究を実施した．具体的には紙流体チップに電気回路を組み込むことで，単体の紙流体チップでは実現が困難であった分析の実現を目指した．特に紙への電気回路印刷技術に着目することで，安価，軽量，低体積といった紙流体チップの利点を損なうことなく高機能化を実現することを目指した．本研究では，電気回路印刷技術によって紙上へ導電性インクの塗布を行い電気素子として機能させた．また紙上での電気泳動による物質分離手法の開発を実施した．これにより紙流体チップ単体では難しかった分析を大きな周辺機器を使用せずに実現できる可能性を示した．

近年，感圧塗料(PSP)による物体表面の圧力分布計測技術が大きな注目を集めている．PSPは一般的に用いられている圧力孔による多点計測と異なり，圧力分布計測が可能であり，広い範囲への適用が期待されている．しかしPSPは絶対圧センサーで，その計測域が数kPaから数気圧にわたるため，大気圧近傍の微小な圧力変化の計測は非常に難しく，応用先が非常に限られている．本研究では，PSP計測法にヘテロダイン検出法を適用することで，PSP計測における圧力分解能の向上を目指した．励起光波長を時間変調させPSP発光とのうなり信号を計測することにより，1 kHzで変動する圧力計測において圧力分解能50 Paを達成した．

高性能冷却技術の基幹課題である沸騰熱伝達に関して，赤外線カメラなどを用いた，様々な研究が行われてきている．本研究では，透明な感温塗料（TSP）を用いた沸騰伝熱面の２次元温度分布計測技術の開発を目的とし，沸騰伝熱実験を行った．試験部は，幅10mm，長さ35mm，高さ0.5mmの狭隘流路であり，加熱源には65℃の水を用いた．TSPを塗布した伝熱面は，水と試験冷媒のFC-72の流路間に設置し，TSPが塗布されている伝熱面を鉛直下向きに設定した．実験結果より，沸騰気泡の通過に伴い伝熱面温度が上昇すること，気泡後縁外周部での温度低下と熱伝達の増大，気泡前縁内部での温度増加と熱伝達劣化を観測した．

複雑に時間変化する物体表面上の非定常流れを計測するために陽極酸化基板上に感圧感温複合センサを開発した．インクジェット装置を用いて感圧センサと感温センサをマイクロドット配列に塗布することで，色素間干渉による特性劣化が生じないセンサの開発を図った．色素に応じて適切な溶媒を選択することで，コーヒーリング現象の発生を防ぎながら感度と発光強度を最大化したセンサドットを作成することができた．作成した複合センサによって，圧力と温度を同時計測することで，温度誤差を0.97%/℃から0.02%/℃まで低減することができた．またステップ状の圧力変化に対して64 マイクロ秒の時間応答を実現した．

本研究では表面上における圧力分布を二次元的に計測可能な手法である感圧塗料（PSP）を基に，マイクロ流路そのものをセンサ化したスマートマイクロ流路を開発した．マイクロ流路の作製に広く用いられているソフトリソグラフィにおいて，材料にPSPを混ぜて流路を形成することで，流路そのものがいわばPSPとして機能するようになる．気体流れにおいて圧力，液体流れにおいて酸素濃度の二次元分布を，また，感温塗料（TSP）を用いることで温度分布計測を実現した．

マイクロ熱流体デバイス内部での流体現象を把握するため,2 光子励起過程による機能性分子の発光寿命の変化を捉えることで温度等の物理量を取得する計測法の開発を行った.その結果,パルス幅がピコ秒程度のパルスレーザーを用いることにより,感温性の色素分子の 2 光子励起発光を確認し,その発光寿命の温度依存性を確認した.また計測の高精度化のために,新規のプローブ分子,粒子の探索を行った.特に近年注目されている量子ドットなどに代表されるナノ粒子の温度センサーとしての可能性を調査した.

高クヌッセン数流れとなるマイクロ流れに適用可能な多次元多変量複合同時計測手法の開発を,同じ高クヌッセン数となる希薄気体流れの知見も有効に活用しながら試みた.まず,レーザー誘起蛍光法と分子タギングを組み合わせた速度計測手法の開発を行い,希薄気体流れ及びミニチャネル内部流れへの適用に成功し,その知見を基にマイクロ流れへの適用を試みた.また,壁面における圧力・温度・濃度計測を可能とする高秩序分子膜センサの開発を行い,マイクロ流れでの計測に成功した.

本研究では,感圧塗料(PSP)による気体流の二次元圧力計測法として有機エレクトロルミネッセンス(有機EL)技術を応用した有機EL-PSPを開発することによって,PSPによる計測精度を劇的に向上させ,PSPでは実現が困難とされている大気圧近傍での微小な圧力変化を計測する技術の確立を目的とする.
有機EL素子自体は広く開発が行われているが,PSPとして利用するためには素子に十分な酸素が透過・浸透する必要がある.そこで,基板にAl陰極,発光層,気体透過性のあるポリマ電極の順に積層し'たトップエミッション構造に着目して,素子の開発を行った。ポリマ電極としてはPEDOT:PSS(Poly(3,4ethylenedioxythiophene)poly(styrenesulfonate))を用いた.作成した素子が圧力感度を持つことを確認するために,光励起により色素分子を発光させ圧力感度を調査した.その結果,大気圧近傍の90～110kPaにおいて圧力感度を持つことが明らかとなり,PEDOT:PSSが十分な酸素透過性を有することを示した.開発した素子は圧力センサーとして十分な感度を得られたが,PEDOT:PSSの膜厚によって酸素透過率も変わるため,膜厚を調整することでさらに感度向上が期待できる.続いて,有機EL素子として機能させた際の発光を確認した.その結果,時間や輝度に課題は残るものの,発光することが確認された.以上から,陽極にPEDOT:PSSを用いたトップエミッション構造の有機EL素子は圧力感度を有することが十分期待でき,圧力センサーとして圧力計測に適用できる可能性を示した.

近年,注目を集めるマイクロ熱流体デバイス内部での流体現象の解明を可能とする計測法を開発するため,酸素分子との相互作用あるいは雰囲気温度によって発光強度が変わる色素分子をプローブとした感圧塗料(PSP),感温塗料(TSP)によるマイクロスケール計測法の確立を行った.また気液二相状態にも適用可能とするため,従来空気中での使用に限定されていたPSPの液中での特性評価を行った.さらにPSP・TSPの同時計測を可能とする複合センサーの開発に取り組んだ.

本研究では実験及び数値実験を実施することにより気体-表面相互作用の詳細を明らかにすることを目的とした.速度と方向の揃った分子線を用いて散乱形態を測定する分子線散乱実験と平均化された統計量としての経験的なパラメータであるエネルギー適応係数を結び付けることによって,相互作用の詳細を明らかにする.
まず,光学的非接触測定法である共鳴多光子イオン化(REMPI)法を用いて分子線の内部状態を明らかにすることを試みた.REMPI法はレーザー光により気体分子をイオン化する手法であり,高感度かつ回転エネルギー分布を取得できることが特徴である.排気系や真空装置を改善することにより真空装置内を超高真空に維持可能となり,窒素分子線のREMPIスペクトルの取得に成功した.その結果,導出された回転温度は理論的な並進温度とは明らかに異なっており,自由度間非平衡が生じていることが明らかとなった.
また,エネルギー適応係数に関して,金属細線を低圧力下で通電加熱することにより気体分子へのエネルギー移動量を測定するLow-Pressure法を用いて,白金表面に対する窒素,酸素,アルゴンのエネルギー適応係数の取得に成功し,既存の結果とも良い一致を示すことを確認した.さらにシリコンを用いて同様の手法による測定を試み,潜在する問題を明らかにした.
分子線散乱実験による詳細条件とエネルギー適応係数取得実験における平均化された統計量の関係を明らかにするため,分子動力学法を用いて解析した.その結果,詳細条件の結果のみを利用して定性的な予測がある程度可能なことを明らかにした.
また,固体表面に塗布することで圧力を測定可能な感圧塗料を対象として,気体-表面相互作用についての解析も実施した.感圧塗料は固体表面へ向かう数流束を計測していると考えられることが分かり,実験的に相互作用を解明する手法として有用であることが明らかとなった.

<p>Pressure-sensitive paint (PSP) is an optical and non-intrusive pressure measurement technique, and is used in wind tunnel testing. In general, PSP is applied to a model surface by a sprayer by hand, resulting in non-uniform layer. Recently, we proposed a novel PSP paint technique using an inkjet printer. This technique enable us to easily paint uniform PSP. In this study, we fabricated a combined PSP and TSP (temperature-sensitive paint) by inkjet printer. PSP and TSP were symmetrically painted on a substrate. Then, we measured the pressure and temperature distribution induced by impingement jet. The obtained pressure distribution was in good agreement with the literature.</p>

<p>The supersonic mixing field induced by a novel wall-mounted cavity having a three-dimensional shape is investigated experimentally and computationally. In the experiments, the phase-averaged pressure oscillation fields are measured by using anodized aluminum pressure-sensitive paint (AA-PSP). The experimental results are compared with the computational results obtained by solving the Navier-Stokes equations. It is found from the experimental and computational results that pressure waves propagate in the cavity and that the waves act on the jet so as that it fluctuates largely. Such large fluctuation of jet is one of the primary reasons why mixing is enhanced by using the proposed cavity.</p>

Along with the development of micro- and nano-technologies, gas-surface interaction becomes important due to large surface area-to-volume ratio in micro-scale gas flows. In such flows, the Knudsen number (Kn) is often employed as a parameter of rarefaction of flows. When 0.01<Kn≦0.1, a flow is classified as the slip flow with a finite velocity slip at boundary. In this regime, the mass flow rate increases from the rate in the continuum regime because of the velocity slip. The mass flow rate depends on the combination of molecule and surface. In this study, we measured the mass flow rate of water molecules to investigate the characteristics on gas properties. The constant-volume technique was employed for measuring the mass flow rate through a micro channel. The obtained results suggested that the adsorption of water molecules on the measurement system influenced the accurate measurement of the mass flow rate.

The pressure-sensitive paint (PSP) technique is an optical technique for measuring surface pressure on a model surface. The PSP technique has been used in wind-tunnel tests because of its great advantages such as non-intrusive and global pressure measurement. In general, PSP is painted by a sprayer by hand, resulting in low reproducibility. In this study, we used a commercial inkjet printer for printing PSP on substrates. PSP was printed on three substrates: chromatography paper, label seal, and viewgraph. We investigated the pressure and temperature sensitivities of these PSPs. PSP printed on the chromatography paper showed the best characteristics among them. And, we succeeded in preparation of PSP using the commercial inkjet printer.

Thermal transpiration (thermal creep) flow, which is induced only by temperature gradient along a channel, is one of the most interesting phenomena in micro gas flows. The thermal transpiration flow has been studied both numerically and experimentally; however, the detailed condition inside a channel has not been enough studied experimentally, and it makes difficult to compare numerical and experimental results directly. In this study, the pressure distribution on a micro channel surface in thermal transpiration flow was measured by means of the Pressure-Sensitive Paint (PSP) technique. And the pressure distribution was a convex profile along the channel.

Along with the development of microtechnology, the gas-surface interaction becomes important due to large surface area-to-volume ratio in micro-scale flows. As a parameter on gas-surface interaction related to a flow rate, Tangential Momentum Accommodation Efficient (TMAC) is often employed. TMAC represents the degree on tangential momentum exchange between molecule and surface. In this study, TMAC was measured for several gas species to investigate the characteristics on gas properties. The constant-volume technique was employed for measuring the mass flow rate through a microchannel. Monatomic gases of helium, argon and xenon were employed as test gases. The microchannel was made of Fused Silica as non-metal material. TMAC was calculated by comparing the measured mass flow rate and the theoretical one with the second order slip boundary condition. The obtained results suggested that the molecular weight has only small influence on TMAC.

マイクロ熱流体デバイスでは，作動流体が液体のものを中心にデバイスの内部流動の研究が進められてきているが，気液二相流，気体流に関する研究はまだその初期段階である．気体流は，マイクロスケールでは高クヌッセン数流れに分類され，気体を連続体として扱うことができず，速度滑りや温度飛躍，熱遷移流など特異な物理現象が壁面近傍で顕在化することが知られている．これらは壁面と気体分子との相互作用によって生じると考えられており，マイクロスケールの熱流動場の理解において壁面上での物理量の計測が極めて重要である．著者らはこれまでにLangmuir-Blodgett(LB)法によって感圧塗料(PSP)を分子膜化したPSMF(Pressure-Sensitive Molecular Film)を作製し，マイクロスケールでの圧力分布計測を実施している．またPSMFに比べ簡便な手法として，マイクロ流路そのものをPSP化したPSCC(Pressue-Sensitive Channel Chip)も開発し，マイクロスケールでの圧力分布計測を可能としている．本稿ではこれらの作製法，計測例を示す．

A fast response pressure-sensitive dot array sensor has been developed by means of an inkjet printing technique on an anodized aluminum substrate, which has been used for unsteady flow measurements. However, PtTFPP based dot array sensor has several problems: non-uniform distribution of luminescent intensity due to "coffee ring effect" and low luminescent intensity. To solve these problems, we fabricated the PtTFPP-based dot array sensor on an anodized aluminum substrate with hydrophobic treatment. The hydrophobic treatment was applied to an anodized aluminum in three ways: dipping in the solution of dodecanoic acid in hexadecane, dipping in the solution of dodecanoic acid in water, and spraying the fluorine hydrophobic coat. The effect of the three hydrophobic treatments on the characteristics of PSP dots was investigated.

It has been desired to measure pressure distribution in a micro channel for understanding micro-scale thermo-fluid phenomena. Pressure-sensitive paint (PSP) technique is an optical measurement technique using luminescent molecules, seemed to be suitable for analysis of micro/nano flow. However, the spatial resolution of PSP is insufficient for applying to micro-scale measurements due to the aggregation of the luminescent molecules. Therefore, we fabricated pressure-sensitive molecular film (PSMF) by Langmuir-Blodgett (LB) method. LB method can fabricate very thin molecular film with controlling the intermolecular spacing of luminescent molecules. PSMF fabricated by this method has enough high spatial resolution to measure micro-gas flows. The pressure distribution in a micro channel with a bend of 90° was measured by PSMF. The low pressure region was found at near the inner wall behind the bend suggesting the flow separation. Additionally, the high pressure area downstream of the separation region was observed, indicating the flow reattachment.

By means of an inkjet printing device, a pressure-sensitive dot array sensor has been developed for unsteady pressure measurements. A conventional bi-luminophore anodized aluminum Pressure-Sensitive Paint (AA-PSP) prepared by a dipping method does not work well due to the interference between the two luminophores. To avoid this problem, we developed a pressure-sensitive dot array sensor on an anodized aluminum substrate using Ru(dpp)3 as a pressure-sensitive luminophore dissolved in four solvents: methanol, dichloromethane, chloroform, and the mixed solvent of dichloromethane and chloroform. Formed PSP dots exhibited significantly different properties including the luminescence intensity distribution inside the dot and pressure sensitivity by the solvents. As a result, the PSP solutions with dichloromethane or the mixed solution of dichloromethane and chloroform, which evaporated quicker than other solvents, formed dots with the uniform distribution of luminescence and showed that comparable pressure sensitivity with conventional AA-PSP prepared by a dipping method.

Knudsen pump is a pump based on thermal transpiration, which is a specific phenomenon in a high Knudsen number flow. Since the pump does not have any moving parts and can be miniaturized to micro scale, it is a favorable pump in micro electro mechanical system (MEMS). However, there are many points to be clarified on characteristics and performances of Knudsen pumps. In this study, a Knudsen pump with commercially available parts and porous membranes was fabricated, and effects of temperature difference and the number of membranes on pressure difference and time constant for pressure time variation were investigated. The fabricated Knudsen pump with four membranes generated about 70 Pa from an atmosphere with temperature difference of 71 K with four membranes. The pressure difference was proportional to the temperature difference and the number of membrane, while the time constants were independent of them. This result suggested that the Knudsen pump was able to generate higher pressure difference or flow rate with increasing in the number of membranes.

Recently, micro gaseous flow has been a novel research filed along with the development in the micro technology. In the micro gaseous flow, the Knudsen number, which is a ratio of the mean free path to the characteristic length of the system, becomes large, and such a high Knudsen number flow should be investigated as a molecular flow. We organized a session meeting in the Japanese Society for Mechanical Engineers for the investigation on the micro gaseous flow. The closed discussions by the members gave the deep insight to the field, but much more interaction in the research network in future is expected for the further progress in the field. The recent developments in the measurement techniques for the micro gaseous flow in our group have been introduced.

In this paper, we proposed long-lifetime fluorescent measurement by compensation of photo-bleaching with the difference of photo intensity. In this method, difference of fluorescent intensity is compensated using single exponential function to make the difference amount uniform between two fluorescent intensities. We evaluated the dependencies of measurement lifetime by fluorescent lifetime and the sensitivity by the decay coefficient of fluorescent lifetime by numerical simulation. From these results, the proposed method has much higher sensitivity and longer lifetime to conventional compensation method of photo-bleaching. We demonstrate the photosynthesis activity of single Synechocystis sp. PCC 6803 in the micro chamber with gas barrier layer.

Flows inside micro-systems are so-called high-Knudsen number flows. The flow field cannot be treated as a continuum and the thermal conduction can not be described by ordinary Fourier's law. In high-Knudsen number flows, gas-surface interaction becomes significant and the energy accommodation coefficient is often employed to analyze heat transport phenomena. The energy accommodation coefficient varies depending on combination of surface materials and gas species. Thus, it is important to measure the accurate energy accommodation coefficient for each pair of surface material and gas species. In this study, we obtained the energy accommodation coefficients for nitrogen and oxygen in contact with a platinum surface in accordance with the Low-Pressure method using the theoretical heat flux equation expanded to transition regime. The experimentally obtained energy accommodation coefficients were compared with previous results in the literature as a function of surface temperature, showing good agreement with each other.

In pressure-sensitive paint (PSP) measurements, pressure is deduced from the luminescence intensity of PSP. Since the intensity depends not only on pressure but also on temperature, a PSP result has to be compensated by the temperature of a surface to which PSP is applied. In this paper, we propose a novel combined pressure and temperature sensor composed of PSP and TSP dot arrays. PtTFPP and CdSe/ZnS were adopted as PSP and TSP luminophores, respectively. PtTFPP is widely used as PSP luminophore, and CdSe/ZnS has several favorable features as TSP luminophore such as tunable luminescence peak wavelength, narrow full width at half maximum, high quantum yield and broad absorption band. The dot array sensor was fabricated by inkjet printing of the luminophores. We examined its photostability under an illumination light, pressure and temperature sensitivities. Each luminophore is separately arranged in dot array; thus the interaction between both luminophores is prevented. The dot array sensor has pressure sensitivity of 0.62 %/kPa as a pressure sensor, and temperature sensitivity of -0.61%/K as a temperature sensor

The flow around micro-systems is so-called the high-Knudsen number flow. The flow field cannot be treated as a continuum and the thermal conduction should not be treated by ordinary Fourier's law. In high-Knudsen number flows, the gas-surface interaction becomes important and the energy accommodation coefficient is often employed to analyze heat transport phenomena. The energy accommodation coefficient varies depending on combination of surface materials and gas species. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon in contact with platinum surface in accordance with the Low-Pressure method, using the theoretical heat flux equation expanded to transition regime. The experimental result was compared with previous result in literature, which reported a relation between the energy accommodation coefficient and the surface temperature, and they are in good agreement.

Pressure-Sensitive Paint (PSP) is a pressure sensor based on the oxygen quenching of the luminescence of luminophore. In general, the luminescent intensity of PSP depends not only on pressure but also on temperature. Therefore, it is necessary to simultaneously measure the temperature with the pressure to improve the accuracy of PSP measurement. The compound sensor composed of pressure and temperature-sensitive luminophore was developed for simultaneous measurements of pressure and temperature. However, some of such compound sensors suffer the degradation of the sensitivity and other properties. In this paper, we show the possibility of a compound PSP/TSP sensor using PtTFPP and CdSe/ZnS.

It is important to understand the behavior of oxygen concentration distribution inside micro-channels for the improvement of micro devices or fuel cells. Most of oxygen sensors such as galvanic or polaro-graphic type cannot be used for unsteady measurements in a small system because of their long response time and large probe heads. We focused on pressure sensitive paint (PSP) for the measurement of the oxygen concentration dissolved in the water in a small system. Up to the present, the PSP techniques have been mainly applied to gas-flows. However, the PSP technique is based on the oxygen quenching of luminescent molecules and would be used in both gas and liquid-flows. In this paper, we investigated the oxygen sensitivity of three types of PSP in the water, and selected a suitable polymer for a binder of PSP.

In order to analyze high Knudsen number flows, it is important to understand the interactions of gas molecules and solid surfaces. Molecular beams have been used to study these interactions. Properties such as the translational energy and momentum of a molecular beam have been analyzed very well; however, there are very few reports analyzing the rotational energy of diatomic or polyatomic molecular beam experimentally. Resonantly enhanced multi-photon ionization (REMPI) is a spectroscopic technique, which is able to measure molecular internal energy distribution in very low density gas flows. In this study, we have detected and analyzed the rotational energy distribution in a nitrogen molecular beam by 2R+2 REMPI.

To analyze micro-scale flows, we need a measurement technique of the molecular level. The pressure-sensitive paint (PSP) technique employs the interactions between luminophores and oxygen molecules; hence it is suitable for pressure measurement in the flows. However, there are few reports concerning application of PSP to fnicro-flows, because conventional PSPs are too thick owing to their polymer binders. Therefore, we had developed pressure-sensitive molecular film (PSMF) with a thickness of about 1Onm by using the Langmuir-Blodgett (LB) technique, and obtained the pressure distribution on the surface along micro-channels. PSMF is, however, inferior to the ordinary PSP in the signal-to-noise ratio, because of the small amount of luminophores in the film. In this study, based on PSP and soft lithography techniques, we have developed a novel micro fluidic channel itself has a pressure sensitive property, emitting appreciable luminescence. Additionally, we investigated the pressure sensitivity of this new PSP device, and measured the pressure along a micro-nozzle.

The micro flows such as flow around MEMS (Micro Electro Mechanical System), are so-called the high-Knudsen number flow. In these flows, the gas-surface interaction becomes important. The energy accommodation coefficient, which is an empirical parameter defined by Knudsen, is often used to analyze heat transport phenomena. The energy accommodation coefficient varies depending on the combination of surface and gas. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon and oxygen in contact with platinum surface by the Low-Pressure (LP) method, using the theoretical heat flux equation expanded to transition regime. The experimental results were compared with the previous results by Thomas and Olmer(1943), which reported a relation between the energy accommodation coefficient and the surface temperature. Our results are in good agreement with their results.

Along with the developments of the Micro Electro Mechanical Systems (MEMS), the Knudsen number, which is the non-dimensional parameter for rarefaction, of the flow inside such systems becomes large. In these high Knudsen number flows, a gas-surface interaction has become important. To illustrate the gas-surface interaction, an accommodation coefficient α is widely used as an empirical parameter. The tangential momentum accommodation coefficient (TMAC), one of the accommodation coefficients, has close relation to the pressure loss through a micro channel. Therefore, TMAC is an important coefficient for micro flow analyses. To obtain TMAC experimentally, the mass flow rate measurements in microtubes were carried out using the constant volume method. Since the mean Knudsen number was less than 0.3, the velocity slip boundary condition is applicable. The results obtained experimentally were analyzed in frame of the Navier-Stokes equation associated with the second order velocity slip boundary condition. Then the slip coefficient of the boundary condition was obtained, and finally TMAC was determined.

The PSP technique is a nonintrusive pressure measurement method based on the oxygen quenching of the luminescence of luminophore. Since the PSP measurement is generally affected by temperature changes, it is difficult to precisely measure the pressure on a surface with non-uniform temperature distribution. In this study, we focused on pyrene sulfonic acid (PySO_3H) as a luminophore of PSP. It is known that the PySO_3H has two peaks in the emission spectra which have opposite temperature-dependent properties. Temperature effects can be eliminated by measuring the luminescence at an appropriate wavelength band between these two peaks. We successfully obtained the time-averaged pressure distribution on the rotating disk by the use of PySO_3H. The pressure shows a concentric circle distribution and decreases toward the disk center at every rotational speed (10000-20000rpm). It is also found that the pressure difference between the inner and the outer region of the disk is proportional to the square of the disk angular velocity.

The flow around MEMS (Micro Electro Mechanical System) is so-called the high-Knudsen number flow. The flow field cannot be treated as a continuum and the thermal conduction must not be treated by ordinary Fourier's law. In high-Knudsen number flows, the gas-surface interaction becomes important and the energy accommodation coefficient, an empirical parameter, is often used to analyze heat transport phenomena. The energy accommodation coefficient is different depending on combination of surface and gas. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon and oxygen in contact with platinum surface by the Low-Pressure (LP) method, using the theoretical heat flux equation expanded to transition regime. The experimental result was compared with previous result by Thomas and Olmer (1943), which reported a relation between the energy accommodation coefficient and the surface temperature, and they are good agreement.

To analyze micro/nano scale flows, we need to adopt a measurement technique in the molecular level. The pressure sensitive molecular film (PSMF) technique employs interaction between luminophores and oxygen molecules; hence it is suitable for pressure measurement in the flows. Previously, we researched the pressure sensitivity and the temperature dependence of PSMF. Typically, luminophores of PSMF are easily degraded by light and oxygen molecules, and it is very important to consider the photo-degradation in the measurement. In this study, we studied the photo-degradation of PSMF under two different pressure conditions to reveal the effect of oxygen molecules. Additionally, the time profile of the photo-degradation was measured. From the asymptotical behavior, it was clarified that the pre-illumination reduced the photo-degradation. We successfully obtained the pressure distribution of a micro-nozzle by pre-illuminated PSMF.

In the field of chemical industries, it is desired to downsize chemical reactors for easy controlling, synthesizing a wide variety of products in small quantities and so on. It is well known that flow field structure in a mixing channel changes from steady to unsteady with an increase in Reynolds number. These flow fields have been analyzed numerically, but there are few reports analyzed experimentally. We have focused on the pressure-sensitive paint (PSP) technique, which enables us to measure the distribution of oxygen concentrations. Using the PSP technique, we tried to reveal the flow field structure and evaluate the flow unsteadiness in a parallel mixing channel depending on inlet Reynolds numbers.

For a hard disk drive, high-speed rotation is required to achieve fast access to data on a disk. However, the high-speed rotation induces pressure fluctuation on the disk and results in disk fluttering. Therefore, it is important to investigate the pressure distribution on the disk to realize high-speed and stable disk rotation. We have measured the pressure distribution on the disk rotated at various speeds by using pressure-sensitive paint, which is appropriate for measuring the pressure of rotating objects. As a result, it is clarified that the pressure distribution forms concentric circles and the pressure difference between the outer and inner part of the disk increases with an increase in the disk rotation speed.

To analyze high Knudsen number flows, interactions of gas molecules and solid surfaces are very important. Molecular beams have been widely used to diagnose these interactions. While properties such as translational energy and momentum of molecular beam have been analyzed very well, there are very few reports analyzing rotational energy of diatomic or polyatomic molecular beam experimentally. Resonantly enhanced multi-photon ionization (REMPI) is a spectroscopic technique, which is able to measure molecular internal energy in very low density gas flows. In this study, we have tried to detect a nitrogen molecular beam by 2R+2 REMPI, and analyzed rotational energy distribution of nitrogen molecules in the molecular beam.

The pressure sensitive paint (PSP) is very useful and easy way to obtain the pressure distribution on surfaces. Recently, PSP has been applied to various flow fields, like high Knudsen number flows. In this study, we discuss on measurement mechanism of PSP, especially in high Knudsen number regime. It is well known that a pressure tap shows good agreement with surface pressure, and not gas pressure in this regime. Therefore, a PSP experimental result is examined by DSMC method, and compared with gas and surface pressures. We suggest that PSP measures a number flux toward a surface.

The pressure-sensitive paint (PSP) technique has potential as a diagnostic tool for pressure measurement of micro gas-flows because it is based on interaction of molecules with photons. However, the application of the PSP to micro-flows is very difficult, because the conventional PSP is too thick owing to polymer binder. In our previous work, we adopted Langmuir-Blodgett technique to fabricate a pressure sensitive molecular film (PSMF). In this study, we have constructed PSMF composed of Pt(II) Mesoporphyrin IX (PtMP) to be applied to pressure measurement near atmospheric pressure condition. The pressure sensitivity of PSMF-PtMP was tested, and it was clarified that the PSMF-PtMP has equivalent pressure sensitivity of polymer PSPs (e.g. PtOEP/GP-197). Moreover, we have applied PSMF to pressure measurement of a gas flow through the 170μm width micro-channel, and the pressure distribution on the surface along the channel was successfully obtained.

Non-uniform pressure distribution on shrouded co-rotating disks at high speed causes disk flutter. For stable rotation of disks at high speed, it is necessary to analyze pressure distribution on the disk surfaces and understand the mechanism of the disk flutter. To clarify the behavior of the flow around high-speed co-rotating disks, we have measured pressure distribution of disk surfaces by means of pressure sensitive paint. As a result, it is clarified that the pressure difference between the outer part and the inner part of the middle disk of the triple co-rotating disks is larger than that of the top disk, and the average pressure on the middle disk is lower than that of the top disk.

To analyze a micro/nano scale flow, we need to adopt a measurement technique that treats the flow as a molecular flow, because the flow cannot be treated as continuum. The pressure sensitive molecular film (PSMF) technique employs interaction between molecules, hence it is suitable for pressure measurement in the flow. We developed PSMF that is effective in the low pressure range. Typically, effective pressure range of PSMF depends mainly on the kind of luminophores. In this study, we adopt new luminophores in order to develop a new PSMF for near-atmospheric pressure range. Furthermore, because luminophores of PSMF are easily deteriorated by light, it is very important to consider photo-deterioration in pressure measurement by PSMF. In this study, we also analyzed photo-deterioration of PSMF to clarify basic photo-deterioration feature of PSMF.

Pressure sensitive paints are widely used in many applications. The pressure distribution on surfaces obtained by the paint shows good agreement with that by other methods, like a pressure tap. Recently, the paint has been adopted to high Knudsen number flows, such as rarefied gas flows and micro/nano flows. The mechanism of the paint is based on the oxygen quenching of luminescent molecules in the paint. Usually the static pressure is inversely proportional to the luminescent intensity of the paint, because of the static gas condition. In high Knudesen number flows, it is not clear whether this relation holds or not. Here, in this study, we tried to relate the number flux of oxygen molecules and the pressures to the luminescence intensity, and clarify the limit of application in high Knudsen number flows.

The Pressure Sensitive Paint (PSP) is very useful and easy way to obtain the pressure distribution on surfaces. The pressure distribution obtained by the paint shows good agreement with that by other methods, like a pressure tap. Recently, the paint has been adopted to the high Knudsen number regime. The mechanism of the PSP is mainly discussed within the framwork of the luminescence intensity and the oxygen quenching, while it is unclear that luminescence intensity is really proportional to the pressure, especially in the high Knudsen number regime. Usually it is considered that the luminescent represents a pressure, but it is not clear yet that this "pressure" means "static" or "total" pressure. Here, in this study, we tried to relate the flux of oxygen molecules and a pressure to the luminescence intensity, and clarify the limit of application from the molecular kinetics point of view.

The pressure-sensitive paint (PSP) technique has the potential as a diagnostic tool for measurement in the high Knudsen number regime because it works as a so-called "molecular sensor". However, application of the PSP technique to micro-systems is difficult because the conventional PSP is too thick owing to the use of polymer binder and does not have sufficient spatial resolution for pressure measurement of micro-flows. We constructed pressure sensitive molecular film (PSMF), using Platinum (II) MesoporphyrinIX (PtMP) as a luminescent molecule, and have examined our PSMF to evaluate the possibility of application to the measurement of micro-flows. It is clarified that the pressure sensitivity of PtMP based PSMF is equal to the that of conventional polymer PSP. The pressure distribution on the solid surface interacting with supersonic free-jet can be measured with PSMF composed of PtMP. This indicates that the PSMF is feasible to measure the pressure in high Knudsen number flows such as micro-flows.

To measure pressure distribution in high Knudsen number regimes, we have adopted a pressure sensitive paint (PSP) technique, because the PSP works as a so-called "molecular sensor". However, application of the PSP to micro-devices is very difficult because the conventional PSP is too thick owing to the use of polymer binder. Moreover, they have not sufficient spatial resolution for pressure measurement of micro-flows because of the aggregation of luminescent molecules in polymer binders. In our past work, we have adopted Langmuir-Blodgett (LB) technique to fabricate pressure sensitive molecular films (PSMFs) using Pd(II) Mesoporphyrin IX (PdMP) to resolve the problems of ordinary PSPs mentioned above. However the luminescent intensity of PSMF is low, leading to low SN ratio because the amount of luminescent molecules in the layer is small. In this study, we have applied localized surface plasmon resonance to increase luminescent intensity of PSMF and have tested PSMFs to evaluate the feasibility of the pressure measurement around the micro-devices. A PSMF with nanometer order thickness and high spatial resolution is suitable for analyses of micro-flow.

Experimental analyses of thermo-fluid phenomena of micro- and nano-flows with high Knudsen number need the measurement techniques based on interaction of atoms or molecules with photons. The pressure sensitive paint (PSP) technique has the capability to be applied to high Knudsen number flows, such as micro-flows and low density gas flows. In this study, to inspect the feasibility of PSP for measurement of pressure on a solid surface in high Knudsen number flows, fundamental properties of PSPs are examined especially in the range of pressure below 1 Torr. As an application of PSP to measurement in high Knudsen number conditions, the pressure distribution on a jet-impinging small solid surface is measured. However, application of the PSP technique to a micro-system is very difficult, because of large thickness of conventional PSPs. Therefore, we have adopted Langmuir-Blodgett (LB) method to fabricate a pressure sensitive molecular film (PSMF) applicable to pressure measurement around micro/nano devices. Finally, the dependence of luminescence intensity of PSP on the molecular number flux onto the solid surface is discussed, because molecular number flux is an important quantity to analyze the interaction between high Knudsen number flows and solid surfaces.

The pressure-sensitive paint (PSP) technique has the potential as a diagnostic tool for measurements in the high Knudsen number regime because it works as a so-called "molecular sensor". However, application of the PSP technique to micro-systems has never been reported because the conventional PSP is too thick owing to the use of polymer binder. We constructed PSP molecular films, using Pd(II) Octaethylporphine (PdOEP) and an amphiphilic palladium metal complex, and have examined these PSP molecular films to evaluate the possibility of application to the measurement of micro flow. It is found that the latter PSP molecular film has sufficient sensitivity in the low pressure region with high Knudsen number, even if the amount of the luminescent molecules in PSP molecular film layer is smaller than that in conventional PSP. This indicates that the PSP molecular film is feasible to measure the pressure in high Knudsen number flow such as micro flows.

The pressure sensitive paint (PSP) technique has the capability to be applied to high Knudsen number flows, such as low density gas flows, micro-flows, and so on. However, applications of the PSP technique to micro/nanodevices have never been reported, because of the thickness of the conventional PSPs and of the low resolution caused by the aggregation of luminescent molecules. In this study, we have constructed ultrathin PSP films for micro/nanodevices by the Langmuir-Blodgett (LB) technique. Two luminophores are examined to select the suitable one for LB-PSP. Moreover, the dependence of luminescence intensity and oxygen sensitivity of the LB-PSP on the number of the layer is clarified.