The development of microelectromechanical systems has resulted in the rapid development of polydimethylpolysiloxane (PDMS) microfluidic devices for drug screening models. Various cell functions, such as the response of endothelial cells to fluids, have been elucidated using microfluidic devices. Additionally, organ-on-a-chip systems that include organs that are important for biological circulation, such as the heart, liver, pancreas, kidneys, and brain, have been developed. These organs realize the biological circulation system in a manner that cannot be reproduced by artificial organs; however, the flow channels between the organs are often artificially created by PDMS. In this study, we developed a microfluidic device consisting only of cells, by combining cell sheet technology with microtitanium wires. Microwires were placed between stacked fibroblast cell sheets, and the cell sheets adhered to each other, after which the microwires were removed leaving a luminal structure with a size approximately equal to the arteriolar size. The lumen structure was constructed using wires with diameters of 50, 100, 150, and 200 <italic>μ</italic>m, which were approximations of the arteriole diameters. Furthermore, using a perfusion device, we successfully perfused the luminal structure created inside the cell sheets. The results revealed that a culture solution can be supplied to a cell sheet with a very high cell density. The biofabrication technology proposed in this study can contribute to the development of organ-on-a-chip systems.

The collection capacity of common nasopharyngeal swabs and irregularities of medical personnel limit the accuracy of PCR testing. This study describes a newly designed 3D-printed swab that is combined with a 3D-printed cover to prevent the extraction of undesired nasal secretions. This swab improved the accuracy of PCR test results. The results of a series of experiments showed that, because of the mucus extraction effect, 3D-printed swabs can replace ordinary cotton swabs. The crisis of the worldwide medical supply shortage can be ameliorated to a certain extent by applying 3D printing technology. [Figure not available: see fulltext.]

Flexible and stable interconnections are critical for the next generation of shape-conformable and wearable electronics. These interconnections should have metal-like conductivity and sufficiently low stiffness that does not compromise the flexibility of the device; moreover, they must be achieved using low-temperature processes to prevent device damage. However, conventional interconnection bonding methods require additional adhesive layers, making it challenging to achieve these characteristics simultaneously. Here, we develop and characterize water vapor plasma-assisted bonding (WVPAB) that enables direct bonding of gold electrodes deposited on ultrathin polymer films. WVPAB bonds rough gold electrodes at room temperature and atmospheric pressure in ambient air. Hydroxyl groups generated by the plasma assist bonding between two gold surfaces, allowing the formation of a strong and stable interface. The applicability of WVPAB-mediated connections to ultrathin electronic systems was also demonstrated, and ultraflexible organic photovoltaics and light-emitting diodes fabricated on separate films were successfully interconnected via ultrathin wiring films.

In this study, the spontaneous microstructure tuning of TiO2 was observed by aging the ethanol/water TiO2 paste for up to 20 days at ambient conditions. A dynamic light scattering study reveals that it formed the outstanding reproducible TiO2 microstructure with a ∼200 nm average particle size and stabilizes in 6 to 20 days under an ambient atmosphere. Interestingly, the as-deposited day 15 sample spontaneously changed its crystallinity upon keeping the paste at ambient conditions; meanwhile the day 0 sample showed an amorphous structure. A dense, uniform, and stable TiO2 electrode was cast on a fluorine doped-tin oxide substrate using the electrospray technique. We exploit the spontaneous evolution of the TiO2 nanopowder to revisit the fabrication procedure of the TiO2 photoelectrode for dye-sensitized solar cells (DSSCs). The controlled microstructure TiO2 film was used in DSSCs, which, to the best of our knowledge, achieved the highest power conversion efficiency of 9.65% using N719 dye in sensitizing the TiO2 photoanode.

Human induced pluripotent stem (iPS) cell-derived cardiomyocytes are used forin vitropharmacological and pathological studies worldwide. In particular, the functional assessment of cardiac tissues created from iPS cell-derived cardiomyocytes is expected to provide precise prediction of drug effects and thus streamline the process of drug development. However, the current format of electrophysiological and contractile assessment of cardiomyocytes on a rigid substrate is not appropriate for cardiac tissues that beat dynamically. Here, we show a novel simultaneous measurement system for contractile force and extracellular field potential of iPS cell-derived cardiac cell sheet-tissues using 500 nm-thick flexible electronic sheets. It was confirmed that the developed system is applicable for pharmacological studies and assessments of excitation-contraction coupling-related parameters, such as the electro-mechanical window. Our results indicate that flexible electronics with cardiac tissue engineering provide an advanced platform for drug development. This system will contribute to gaining new insight in pharmacological study of human cardiac function.

Electrode arrays are widely used for multipoint recording of electrophysiological activities, and organic electronics have been utilized to achieve both high performance and biocompatibility. However, extracellular electrode arrays record the field potential instead of the membrane potential itself, resulting in the loss of information and signal amplitude. Although much effort has been dedicated to developing intracellular access methods, their threedimensional structures and advanced protocols prohibited implementation with organic electronics. Here, we show an organic electrochemical transistor (OECT) matrix for the intracellular action potential recording. The driving voltage of sensor matrix simultaneously causes electroporation so that intracellular action potentials are recorded with simple equipment. The amplitude of the recorded peaks was larger than that of an extracellular field potential recording, and it was further enhanced by tuning the driving voltage and geometry of OECTs. The capability of miniaturization and multiplexed recording was demonstrated through a 4 × 4 action potential mapping using a matrix of 5- × 5-μm2 OECTs. Those features are realized using a mild fabrication process and a simple circuit without limiting the potential applications of functional organic electronics.

Temperature control is a critical factor in PCR for efficient DNA amplification. The main aim is to achieve tight control and high rate of heating and cooling for a portable, cost-effective PCR device. This speed depends on reduction of the thermal mass of the PCR heating part. The common methods used to decrease the device's thermal mass or heating/cooling time are to improve desirable device structural design and to choose a better heating and cooling mechanism with robust controller. Increasing the thermal mass provides a good temperature distribution on the heater surface, but it delays the heat transfer. Therefore, removing thermal mass makes the controller struggle to provide a high temperature uniformity distribution on Peltier surface. In this paper, we provide a cost-effective PCR heating/cooling system using Peltier element. This system is controlled using adaptive FLC with bang-bang as a hybrid controller to provide good accuracy with maximum available temperature changing rate. The results show that in cooling, the adaptive FLC with bang-bang controller is faster by 20 % than the normal PD-like FLC, however in heating it is faster by 5 to 10 %. The adaptive FLC provided steady state error 3 % and 1.5 % less than the normal FLC at denaturation and annealing steps, respectively. Temperature distribution is tested using thermal camera. The device is validated by performing conventional PCR. The amplification product was analyzed by electrophoresis on a 1.5 % agarose gel then stained with ethidium bromide and the products show successfully amplified.

In the research and development of micro air vehicles, understanding and imitating the flight mechanism of insects presents a viable way of progressing forward. While research is being conducted on the flight mechanism of insects such as flies and dragonflies, research on beetles that can carry larger loads is limited. Here, we clarified the beetle midlegs' role in the attenuation and cessation of the wingbeat. We anatomically confirmed the connection between the midlegs and the elytra. We also further clarified which pair of legs are involved in the wingbeat attenuation mechanism, and lastly demonstrated free-flight control via remote leg muscle stimulation. Observation of multiple landings using a high-speed camera revealed that the wingbeat stopped immediately after their midlegs were lowered. Moreover, the action of lowering the midleg attenuated and often stopped the wingbeat. A miniature remote stimulation device (backpack) mountable on beetles was designed and utilized for the free-flight demonstration. Beetles in free flight were remotely induced into lowering (swing down) each leg pair via electrical stimulation, and they were found to lose significant altitude only when the midlegs were stimulated. Thus, the results of this study revealed that swinging down of the midlegs played a significant role in beetle wingbeat cessation. In the future, our findings on the wingbeat attenuation and cessation mechanism are expected to be helpful in designing bioinspired micro air vehicles.

This study investigated the function of the beetle's claw for its smooth and slipless walking and designed an artificial claw open-close cycle mechanism to mimic the beetle's walking. First, the effects of claw opening and closing on beetles' ability to attach to surfaces were examined. A beetle does not have an attachment pad, and only its claws work to grip the ground; its claw opens and closes and attaches with two sharp hooks. With their claws, beetles can smoothly walk, neither slipping on nor having their claws stuck in the surface. How do they perform smooth walking with sharp claws? In this study, we observed that beetles close their claws when they raise and swung their legs forward, while they open their claws when they lowered their legs to the ground. We then conducted non-destructive tests: their claws were forced open or closed. There was a significant difference in the trajectories of forced-closed claws compared to intact claws and forced-open claws. When their claws were forced-closed, this caused slippage in walking. On the other hand, when a claw was forced-open and its rotation was also inhibited, the claw stuck heavily in the surface, and the beetle could not walk. Based on these findings, we designed an artificial claw to open and close in the same cyclic manner as in the case of natural beetles. The performance of the artificial claw was consistent with the conclusions drawn from natural beetles: the locomotive robot with the artificial claw smoothly moved without slippage. Through these observations, non-destructive tests and performance of the bio-inspired artificial claws, this study confirmed the function of the open-close cycle of beetle claws and demonstrated and successfully adopted it for a locomotive robot.

The photovoltaic performance of perovskite solar cells (PSCs) can be improved by utilizing efficient front contact. However, it has always been a significant challenge for fabricating high-quality, scalable, controllable, and cost-effective front contact. This study proposes a realistic multi-layer front contact design to realize efficient single-junction PSCs and perovskite/perovskite tandem solar cells (TSCs). As a critical part of the front contact, we prepared a highly compact titanium oxide (TiO2) film by industrially viable Spray Pyrolysis Deposition (SPD), which acts as a potential electron transport layer (ETL) for the fabrication of PSCs. Optimization and reproducibility of the TiO2 ETL were discreetly investigated while fabricating a set of planar PSCs. As the front contact has a significant influence on the optoelectronic properties of PSCs, hence, we investigated the optics and electrical effects of PSCs by three-dimensional (3D) finite-difference time-domain (FDTD) and finite element method (FEM) rigorous simulations. The investigation allows us to compare experimental results with the outcome from simulations. Furthermore, an optimized single-junction PSC is designed to enhance the energy conversion efficiency (ECE) by > 30% compared to the planar reference PSC. Finally, the study has been progressed to the realization of all-perovskite TSC that can reach the ECE, exceeding 30%. Detailed guidance for the completion of high-performance PSCs is provided.[Figure not available: see fulltext.]

The metallization of local areas of 3D-printed plastic structures has attracted a significant amount of attention. However, metal and plastic additive manufacturing technologies are incompatible with each other due to the significant difference in their associated process temperatures. This paper proposes and demonstrates a plastic 3D printing technology that adopts electroless plating, a form of chemical metal deposition. The technology is capable of metalizing selected areas of 3D-printed plastic structures made of acrylonitrile butadiene styrene (ABS). Because electroless plating is triggered by a palladium (Pd) catalyst, this study designed and customfabricated an ABS filament that contains palladium chloride (PdCl2) as a catalyst precursor, which can be used in a fused filament fabrication (FFF) 3D printer. The 3D printer has two nozzles. One produces the main component of the ABS 3D structure using a regular filament (i.e., pure ABS without PdCl2), and the other deposits a PdCl2 -loaded ABS layer onto a selected area of interest using the custom filament. Then, the 3D-printed structure is directly immersed in a nickel (Ni) electroless plating bath. The Ni coats the selected area with strong adhesion. The proposed plastic 3D printing technology coupled with electroless plating does not require any etching (which often uses chromic acid, a very toxic chemical) or roughening of the ABS structure, which are necessary for conventional electroless plating on plastic structures for strong adhesion. Overall, the proposed 3D printing technology has several advantages, namely area-selective metallization, compatibility with regular FFF 3D printing, no damage to the printed structure, and environmental friendliness.

In classical Hodgkin lymphoma (cHL)—characterized by the presence of Hodgkin and Reed-Sternberg (HRS) cells—tumor-associated macrophages (TAMs) play a pivotal role in tumor formation. However, the significance of direct contact between HRS cells and TAMs has not been elucidated. HRS cells and TAMs are known to express PD-L1, which leads to PD-1+ CD4+ T cell exhaustion in cHL. Here, we found that PD-L1/L2 expression was elevated in monocytes co-cultured with HRS cells within 1 h, but not in monocytes cultured with supernatants of HRS cells. Immunofluorescence analysis of PD-L1/L2 revealed that their upregulation resulted in membrane transfer called “trogocytosis” from HRS cells to monocytes. PD-L1/L2 upregulation was not observed in monocytes co-cultured with PD-L1/L2-deficient HRS cells, validating the hypothesis that there is a direct transfer of PD-L1/L2 from HRS cells to monocytes. In the patients, both ligands (PD-L1/L2) were upregulated in TAMs in contact with HRS cells, but not in TAMs distant from HRS cells, suggesting that trogocytosis occurs in cHL patients. Taken together, trogocytosis may be one of the mechanisms that induces rapid upregulation of PD-L1/L2 in monocytes to evade antitumor immunity through the suppression of T cells as mediated by MHC antigen presentation.

This paper reports the utilization of micro-electrical discharge machining (EDM) to process gelatin gel, which is a soft food material. The influence of the applied voltage and selected electrodes on the processed shape was investigated. In addition, using safflower oil in the process can produce narrow grooves. The results showed that micro-EDM with safflower oil can produce micro-grooves (width equal to 2 mu m), and alphabet characters can be engraved into gummy candy and jelly, which are foods containing gelatin. These findings are indicating a potentially powerful tool to produce impressive appearance by fabricating micro texture on gelatin foods.

Paper-based sensors and assays have evolved rapidly due to the conversion of paper-based microfluidics, functional paper coatings, and new electrical and optical readout techniques. Nanomaterials have gained substantial attraction as key components in paper-based sensors, as they can be coated or printed relatively easily on paper to locally control the device functionality. Here, we report a new combination of methods to fabricate carbon nanotube-based (CNT) electrodes for paper-based electrochemical sensors using a combination of laser cutting, drop-casting, and origami. We applied this process to a range of filter papers with different porosities and used their differences in three-dimensional cellulose networks to study the influence of the cellulose scaffold on the final CNT network and the resulting electrochemical detection of glucose. We found that an optimal porosity exists, which balances the benefits of surface enhancement and electrical connectivity within the cellulose scaffold of the paper-based device and demonstrates a cost-effective process for the fabrication of device arrays.

Flexible and biocompatible integrated photo-charging devices consisting of photovoltaic cells and energy storage units can provide an independent power supply for next-generation wearable electronics or biomedical devices. However, current flexible integrated devices exhibit low total energy conversion and storage efficiency and large device thickness, hindering their applicability towards efficient and stable self-powered systems. Here, a highly efficient and ultra-thin photo-charging device with a total efficiency approaching 6% and a thickness below 50 µm is reported, prepared by integrating 3-µm-thick organic photovoltaics on 40 µm-thick carbon nanotube/polymer-based supercapacitors. This flexible photo-charging capacitor delivers much higher performance compared with previous reports by tuning the electrochemical properties of the composite electrodes, which reduce the device thickness to 1/8 while improving the total efficiency by 15%. The devices also exhibit a superior operational stability (over 96% efficiency retention after 100 charge/discharge cycles for one week) and mechanical robustness (94.66% efficiency retention after 5000 times bending at a radius of around 2 mm), providing a high-power and long-term operational energy source for flexible and wearable electronics.

Vascular structures are essential for the survival of thick artificial three-dimensional (3D) tissues. However, it is difficult to create high-cell-density artificial tissue with vascular structures of a few hundred micrometers in diameter. Bioprinting technology can create artificial 3D tissues with vascular structures of a few hundred micrometers in diameter, but the cell density of bio-printed artificial 3D tissues is low. On the other hand, cell sheet technology can create high-cell-density artificial 3D tissues by stacking, but it is not possible to set small vascular structures at any place. In this study, we successfully demonstrated high-cell-density artificial 3D tissues with vascular-like structures by stacking cell sheets combined with bioprinting technology.

Total reflection x-ray fluorescence analysis is applied to trace element detection in liquid for effective environmental monitoring. This analytical approach requires x-ray total reflection mirrors. In order to achieve high sensitivity element detection, the mirrors require high surface quality for high x-ray reflectivity. Surface finishing for x-ray mirrors is typically conducted through a series of abrasive processes, such as grinding and polishing, and is thus time consuming. The purpose of this study is to streamline and enhance the surface finishing process based on unique high quality grinding techniques for the production of x-ray total reflection mirrors.

The nanopatterning of the surfaces of polymer substrates enhances the performances of photovoltaics. Ultraflexible organic photovoltaics (OPVs) are one of the promising energy harvesters for wearable electronics. A reduction in incident light angle dependence while maintaining the power conversion efficiency (PCE) is desirable for wearable electronics devices in which the angle of incident light continuously changes due to the deformation of the device. However, the nanopatterning of the ultrathin polymer substrates of ultraflexible OPVs using the reported methods is challenging because they fatally damage the substrates. Here, the fabrication of ultraflexible OPVs having a low incident light angle dependence while maintaining a PCE of 10.5% by developing ultrathin nanograting polymer substrates is reported. The nanograting-patterned fluorinated polymer enables the formation of periodic nanograting structures onto the back surface of a 1 mu m thick polymer substrate having a pitch of 760 nm and a height of 100 nm, while the opposite surface remains flat after the formation of the planarization layer. Furthermore, with the nanopatterning of the ultrathin substrate, electron-transporting layer, and active layer, the ultraflexible OPVs exhibit a PCE of 10.8%. The combination of new materials with the developed patterning method is expected to afford even greater performances.

Titanium dioxide (TiO2) based planar perovskite solar cells (PSCs) suffer from poor long-term stability and show hysteretic behaviour in the device characteristic curve. In addition to the exceptional bulk properties of the perovskite, the performance and stability are also highly dependent on the conduction band energy, conductivity, and electronic trap states of the TiO2 compact layer (CL). In this work, single-phase brookite (BK) TiO2 nanoparticles (NPs), synthesized via a hydrothermal method using a water-soluble titanium complex, are incorporated as a bridge between the perovskite and TiO2 CL. This resulted in uniform large perovskite grain growth with enhanced crystallinity, significant reduction in trap/defect sites and interfacial recombination as revealed by scanning electron microscopy (SEM), photoluminescence (PL), and impedance spectroscopy results, respectively. The resulting PSCs show highly reproducible power conversion efficiencies (PCEs) up to ∼18.2% (vs. ∼15%) with a stable performance of 18% under continuous light illumination (1 sun) at the maximum power point tracking (MPPT) in contrast to only TiO2 CL based planar devices. To the best of our knowledge, this is so far the best photo-stability data reported for brookite NP based PSCs. Based on our present study, at the end we provide further direction to enhance the stability of planar PSCs.

In this study, a new, simple, and novel oblique electrostatic inkjet (OEI) technique is developed to deposit a titanium oxide (TiO2) compact layer (CL) on fluorine-doped tin oxide (FTO) substrate without the need for a vacuum environment for the first time. The TiO2 is used as electron transport layers (ETL) in planar perovskite solar cells (PSCs). This bottom-up OEI technique enables the control of the surface morphology and thickness of the TiO2 CL by simply manipulating the coating time. The OEI-fabricated TiO2 is characterized tested and the results are compared with that of TiO2 CLs produced by spin-coating and spray pyrolysis. The OEI-deposited TiO2 CL exhibits satisfactory surface coverage and smooth morphology, conducive for the ETLs in PSCs. The power-conversion efficiencies of PSCs with OEI-deposited TiO2 CL as the ETL were as high as 13.19%. Therefore, the present study provides an important advance in the effort to develop simple, low-cost, and easily scaled-up techniques. OEI may be a new candidate for depositing TiO2 CL ETLs for highly efficient planar PSCs, thus potentially contributing to future mass production.

The study of flight orientation has gained more and more attention. In this study, we demonstrated a cyborg beetle for measuring body orientations in free flight, which contained a living insect platform and a miniature backpack with micro battery. While flying in a large flight chamber, the flight status of cyborg beetle could be recorded remotely. Thereafter, the effect of pitching on flight control was analyzed. According to the recorded flight data, a strong linear relationship was revealed between the pitch angles and forward accelerations, which was quantified by the Pearson's correlation coefficients and the fitting of mean forward accelerations under each pitch angle. We believe the coupling of pitch angle and forward acceleration is generated by tilted net aerodynamic force and flight air drag. The achievement of the orientation analysis would inspire a new approach to control system design of flying cyborgs and flapping-wing micro air vehicles (MAVs).

Research on the flight ability of insects has been drawing a lot of attention over the years. In this study, we investigated the effects of wing structure of insects on their flight performances by excising beetle wing membranes and replacing them with artificial ones. We measured the difference in the flight performance between intact and artificial wings which parylene thin film is replaced to natural membrane of wing with a six-axis force system and motion capture using the VICON software. The measured parameters include thrust, lift, acceleration, and deceleration. Membrane-excised beetles that were classified to be unable to fly or not flyable succeeded in flying after artificial membranes were added in place of the excised wings. The success of this repair has the potential to lead to the development of novel ways of enhancing flight performance through the evolution of artificial wing.

© 2019 IAA Herein, a new lightweight thermal protection system was proposed to reduce the weight of a re-entry capsule. The proposed system employs an ablator as a thermal protection material, and a high-temperature polyimide carbon fibre-reinforced plastic (CFRP) sandwich panel as a structure member. The sandwich panel was designed to exhibit high thermal insulation and good mechanical properties at high temperature, and simultaneously ensure that the ablator has low thickness. Three-point bending was carried out at a high temperature up to 300 °C to evaluate shear strength and flexural rigidity of the sandwich panel. Further, the proposed thermal protection system was examined using an arc-heated plasma wind tunnel to evaluate its thermal protection performance and thermal response. The shear strength and the flexural rigidity of this high-temperature structure were 76.8 and 86.9% of that at room temperature, respectively, when evaluated at 300 °C. The proposed system achieved more than 40% weight reduction while maintaining high thermal insulation and recession resistance.

In the design of electron-transport layers (ETLs) to enhance the efficiency of planar perovskite solar cells (PSCs), facile electron extraction and transport are important features. Here, we consider the effects of different titanium oxide (TiO2) polymorphs, anatase and brookite. We design and fabricate high-phase-purity, single-crystalline, highly conductive, and low-temperature (<180 °C)-processed brookite-based TiO2 heterophase junctions on fluorine-doped tin oxide (FTO) as the substrate. We test and compare single-phase anatase (A) and brookite (B) and heterophase anatase-brookite (AB) and brookite-anatase (BA) as ETLs in PSCs. The power-conversion efficiencies (PCEs) of PSCs with low-temperature-processed single-layer FTO-B as the ETL were as high as 14.92%, which is the highest reported efficiency of FTO-B-based single-layer PSC. This implies that FTO-B serves as an active phase and can be a potential candidate as an n-type ETL scaffold in planar PSCs. Moreover, the surface of highly crystalline brookite TiO2 exhibits a tendency toward interparticle necking, leading to the formation of compact scaffolds. Furthermore, PSCs with heterophase junction FTO-AB ETLs exhibited PCEs as high as 16.82%, which is superior to those of PSCs with single-phase anatase (FTO-A) and brookite (FTO-B) as the ETLs (13.86% and 14.92%, respectively). In addition, the PSCs with FTO-AB exhibited improved efficiency and decreased hysteresis compared with those with FTO-BA (13.45%) due to the suitable band alignment with the perovskite layer, which resulted in superior photogenerated charge-carrier extraction and reduced charge accumulation at the interface between the heterophase junction and perovskite. Thus, the present work presents an effective strategy by which to develop heterophase junction ETLs and manipulate the interfacial energy band to further improve the performance of planar PSCs and enable the clean and eco-friendly fabrication of low-cost mass production.

Flexible photovoltaics with extreme mechanical compliance present appealing possibilities to power Internet of Things (IoT) sensors and wearable electronic devices. Although improvement in thermal stability is essential, simultaneous achievement of high power conversion efficiency (PCE) and thermal stability in flexible organic photovoltaics (OPVs) remains challenging due to the difficulties in maintaining an optimal microstructure of the active layer under thermal stress. The insufficient thermal capability of a plastic substrate and the environmental influences cannot be fully expelled by ultrathin barrier coatings. Here, we have successfully fabricated ultraflexible OPVs with initial efficiencies of up to 10% that can endure temperatures of over 100 °C, maintaining 80% of the initial efficiency under accelerated testing conditions for over 500 hours in air. Particularly, we introduce a low-bandgap poly(benzodithiophene-cothieno[3,4-b]thiophene) (PBDTTT) donor polymer that forms a sturdy microstructure when blended with a fullerene acceptor. We demonstrate a feasible way to adhere ultraflexible OPVs onto textiles through a hot-melt process without causing severe performance degradation.

In this study, a device for measuring the action potential of cardiac cell sheets was developed. The action potential was measured using a device comprising a 2-µm-thick parylene film with a silver electrode printed on it, which was referred to as the “electronic sheet.” The thin parylene film exhibits high biocompatibility and flexibility. Therefore, it demonstrates promise for biomedical microelectromechanical system applications. In this study, a cell sheet was used because the interest it had garnered in regenerative medicine for creating cardiac tissue in vitro similar to that in vivo. A high-efficiency drug development system can be realized by combining cell sheet technology and fabricating a flexible electronic sheet. The action potential of a cardiac cell sheet from a rat was measured using the as-developed flexible electronic sheet.

Herein, a compact TiO2/Anatase (AT) titania nanoparticles (TiO2 NPs) bilayer was introduced as an electron transport layer (ETL) by comprising spray pyrolysis (SP) deposition and spin-coating (SC) technique, respectively, in planar perovskite solar cells. A SP-TiO2/SC-AT TiO2 NPs bilayer-based perovskite solar cells are facilitated more efficient electron transport, charge extraction, and low interfacial recombination, and thus leads champion efficiencies up to 17.05% by a significant decrease of J-V hysteresis, presenting almost 12% enhancement compared to the TiO2 single layer-based counterparts.

The objective of this study is to develop 3D food printer that can improve taste by means of creating food texture and can grant artistry which pastry chef perform by utilizing electrostatic inkjet printer high precision printing. There is a previous 3D food printer which utilizes Fused Deposition Modeling (FDM) to print chocolate. This method is to melt the material by heat and then print the material layer by layer to shape. It can only represent a rough image of the object since its print precision is rough. Furthermore, the material it can use is limited. Therefore in this study, we utilize electrostatic inkjet printing technology. By utilizing electrostatic inkjet printing, it not only enables high precision printing and grants food artistry but it also optimizes inner structure. High precision food printing is one of the important element to create food texture. We manufactured the electrostatic inkjet chocolate 3D printer and investigated its basic property. Utilized electrostatic inkjet chocolate 3D printer to print chocolate on the edible film and transfer it to a complex free surface. (C) 2017 Elsevier Ltd. All rights reserved.

Gelatin is useful for biofabrication, because it can be used for cell scaffolds and it has unique properties. Therefore, we attempted to fabricate biodevices of gelatin utilizing micro 3D printer which is able to print with high precision. However, it has been difficult to fabricate 3D structure of gelatin utilizing 3D printer, because a printed gelatin droplet on the metal plate electrode would spread before solidification. To clear this problem, we developed a new experimental set-up with a peltier device that can control temperature of the impact point. At an impact point temperature of 80 °C, the spreading of printed gelatin droplets was prevented. Therefore, we were able to print a ball gelatin. In addition, we were able to print a narrower gelatin line than at an impact point temperature of 20 °C.

Biotechnology has drastically been advanced by the development of iPS and ES cells, which are representative forms induced pluripotent stem cells. In the micro/nano bio field, the development of cells and Taylor-made medicine for a potential treatment of incurable diseases has been a center of attention. The melting point of gelatin is between 25 and 33 °C, and the sol–gel transition occurs in low temperature. This makes the deformation of this useful biomaterial easy. The examples of gelatin fiber applications are suture threads, blood vessel prosthesis, cell-growth-based materials, filter materials, and many others. Because the cell size differs depending on the species and applications, it is essential to fabricate gelatin fibers of different diameters. In this paper, we have developed a fabrication method for gelatin fibers the coacervation method. We fabricated narrow gelatin fibers having a diameter over 10 μm.

Over the past few years, many researchers have shown an interest in micro air vehicle (MAV), since it can be used for rescue mission and investigation of danger zone which is difficult for human being to enter. In recent years, many researchers try to develop high-performance MAVs, but a little attention has been given to the wing-folding mechanism of wings. When the bird and the flying insects land, they usually fold their wings. If they do not fold their wings, their movement area is limited. In this paper, we focused on the artificial wing-folding mechanism. We designed a new artificial wing that has link mechanism. With the wing-folding mechanism, the wing span was reduced to 15%. In addition, we set feathers separately on the end of wings like those of real birds. The wings make thrust force by the change of the shape of the feathers. However, the wings could not produce enough lift force to lift it. Therefore, we have come to the conclusion that it is necessary to optimize the wings design to get stronger lift force by flapping.

Tissues engineered utilizing biofabrication techniques have recently been the focus of much attention, because these bioengineered tissues have great potential to improve the quality of life of patients with various hard-to-treat diseases. Most tissues contain micro-tubular structures including blood vessels, lymphatic vessels, and bile canaliculus. Therefore, we bioengineered a micro diameter tube using alginate gel to coat the core gelatin gel. Micro-gelatin fibers were fabricated by the coacervation method and then coated with a very thin alginate gel layer by dipping. A micro diameter alginate tube was produced by dissolving the core gelatin gel. Consequently, these procedures led to the formation of micro-alginate gel tubes of various shapes and sizes. This biofabrication technique should contribute to tissue engineering research fields. (C) 2017 The Japan Society of Applied Physics

When the 3D printed structures were printed utilizing FDM 3D printer the layer grooves were generated on the structures. The layer grooves make the 3D printed structures strength decrease. Therefore authors already devised the 3D-CMF (Chemical Melting Finishing). The 3D-CMF is the method that dissolve the convex part of the layer grooves and filled in the concave part of the layer grooves and smoothen the layer grooves.3D-CMF reduces the cause of breaking of the 3D printed structures, which is considered to increase the strength. In this paper, we investigated the fundamental characteristics of the 3D-CMF and demonstrate of the change of the strength of the 3D printed structures.

Copyright © (2017) by International Astronautical Federation. All rights reserved. Our research target is to develop new light weight Thermal Protection System applying for space vehicles, such as re-entry capsule. This system consists of ablation material and high-temperature structure material. A concept of the new system was a substitution an existing structure material with high-temperature CFRP sandwich panel so that an ablator showing thermal protection is thinner. The flexural strength and rigidity of the high-temperature sandwich panel was evaluated at elevated temperature. These properties were maintained up to 300°C. Applied ablator was also developed in this study. This ablator showed higher recession resistance than existing one. The developed system showed 51% of weight reduction and improving 48% of recession resistance. Consequently, the developed system exhibited high potential as a new concept of thermal protection.

The authors focus on the Fused Deposition Modeling (FDM) 3D printer because the FDM 3D printer can print the utility resin material. It can print with low cost and therefore it is the most suitable for home 3D printer. The FDM 3D printer has the problem that it produces layer grooves on the surface of the 3D printed structure. Therefore the authors developed the 3D-Chemical Melting Finishing (3D-CMF) for removing layer grooves. In this method, a pen-style device is filled with a chemical able to dissolve the materials used for building 3D printed structures. By controlling the behavior of this pen-style device, the convex parts of layer grooves on the surface of the 3D printed structure are dissolved, which, in turn, fills the concave parts. In this study it proves the superiority of the 3D-CMF than conventional processing for the 3D printed structure. It proves utilizing the evaluation of the safety, selectively and stability. It confirms the improving of the 3D-CMF and it is confirmed utilizing the data of the surface roughness precision and the observation of the internal state and the evaluation of the mechanical characteristics.

Three-dimensional (3D) cell structures are required to fabricate artificial organ. Inkjet technology is applied for fabrication of 3D cell structures in order to fabricate artificial organ and investigate biochemical characteristics of cells in 3D cell structures. Usually cells located inside 3D cell structures get nutrition via blood vessels. In case that there are no blood vessels in the 3D cell structures, cells located inside the 3D cell structures will die of nutrition shortage. So, blood vessels are essential to fabricate 3D cell structures. When the amount and flow of nutrition is controlled, growth speed of cells will be changed. We control the flow around the cells utilizing magnetic particles and magnetic force. The magnetic particles are installed in the dish that is filled with medium, nutrition and living cells. When the magnetic particles are trapped and transported by magnetic force, the cell growth will be controlled. In this paper, we challenge to control the flow utilizing magnetic particles and magnetic force.

3D printer is expected to spread currently. This paper describes the processing method of modifying the FDM printed products. We get the characteristics of each of the processing by evaluation using the time and surface roughness.

In recent days, green technology that is based on solar cell is highly focused for sustainable society. So, the efficiency of Si type of solar cell is drastically improved. On the other hand, dye-sensitized solar cell (DSC) is also highly focused because of flexibility and design in spite of low efficiency. To clear the low efficiency problem, many studies on the development of dye and titania were carried out. Because the dye was developed, then the absorbed wavelength became broad and the absorption ratio on each wavelength was increased. Due to the study on titania, unique shapes of titania were suggested and the absorption characteristics were improved. In spite that many studies on chemical view were carried out, few studies on fabrication process were carried out. So, we focused on fabrication of titania layer of DSC. Usually, the titania layer was fabricated by the doctor blade method or the screen print method. The inside of the fabricated titania layer utilizing the ordinary method had little porous. In the case that the porous titania layer was formed, then the flow of electricity was increased due to the increased surface of titania layer. We applied the electrostatic inkjet method for fabrication of the titania layer because the porous layer was formed due to evaporation effect utilizing the electrostatice inkjet method. We already formed porous titania layer and achieved the efficiency improvement. In this paper, we investigated the fundamental characteristics on fabrication of porous titania layer utilizing the evaporation effect. The experimental set-up to investigate the characteristics was shown as follows. Titania paste was filled with the ink tank. Nozzle was installed at the end of the tank. FTO glass electrode was set on the XY linear stage and the rotation stage. When the high voltage was applied between the nozzle and the glass electrode, small droplets were ejected because the electrostatic inkjet method was took place. Formation and ejection of the small droplets were observed with a high-speed camera and a light. The evaluation of the porous titania layer was carried out with the SEM and XRR. We investigated the characteristics of the porous titania layer in case that the rotation speed was changed.

<p>Gelatin has unique properties. The form is changed by temperature. In addition, the melting point is around 37 degree C. For these reasons, gelatin is useful for biofabrication. We are able to fabricate biodevices of biomaterials with cave utilizing gelatin. In this study, we spun gelatin fibers utilizing three methods. We were able to fabricate micro gelatin fibers which diameter was 20~200 μm. Each methods have merits and demerits. Therefore, utilizing three methods, we were able to fabricate complex structures of micro gelatin fibers.</p>

Dye-sensitized solar cell (DSC) is highly focused because of low-cost. Generally, DSC was composed of photoelectrode, dye, electrolyte, and counter electrode (CE). Sputter-coated Pt on the fluorine doped tin oxide (FTO) electrode was mainly used as CE, however it was expensive and low speed fabrication. In this study, we tried to apply the spray mode of the electrostatic inkjet printing for fabrication of CE. Fundamental characteristics were investigated with the spray-coated Pt CE, the sputter-coated Pt CE, and FTO CE. Conversion efficiency was very low in case of FTO CE. Efficiency of spray-coated Pt CE was 3.6%. The efficiency was a little lower than that of commonly used sputter-coated Pt CE because Pt was not completely coated on the FTO glass by the inkjet printing. These results indicated that spray-coated Pt on FTO glass had possibility to be used as CE of DSC. (C) 2014 The Japan Society of Applied Physics

The precision printing of biomaterials is essential for fabricating bio devices, and two-dimensional (2D) and three-dimensional (3D) cell structures. To fabricate 3D cell structure artificially, biomaterials should be installed between cells to support the gravity force of cells. In general, the viscosity of ink from biomaterials is relatively high. An electrostatic inkjet is used for the bioprinting of cells and biomaterials because it has good merits, i.e., high printing resolution and good capability to eject highly viscous ink. In this paper, gelatin, an important biomaterial is printed using an electrostatic inkjet. The width of the finest printed line is 6 m. The precisely printed line can be used as a scaffold of living cells. (C) 2014 The Japan Society of Applied Physics

Micro air vehicle (MAV) is highly focused by many researchers because the MAV can investigate the condition of disaster site and accident site that is difficult to investigate for human being. Usually, design of the aircraft wing is inspired by birds and flying insects. Resently, dragonfly is a good research target because the dragonfly has high flight performances and high robustness. In order to develop the MAV that is inspired by the dragonfly, it is important to investigate the aerodynamic characteristics of micro structures on the dragonfly's wing. The cross section of the dragonfly's wing is corrugated. The effect of the corrugated shape is already investigated and applied to windmills for weak wind. On the other hand, the effect of micro spikes on the dragonfly's wing is not investigated in spite that the number of the spikes are more than three thusands. So, we focus on the micro spikes on the wing vein of dragonfly. Firstly, we prepared the handmade artificial wings with micro spikes. The fabricated artificial wing had 150 micro spikes whose length wass 600~700 μm. We investigated the aerodynamic characteristics of the micro spikes on these artificial wings. Some merits of micro spikes were observed in spite that the length and the number of spikes were different from those of the natural wing. So, we challenged to fabricate highly realistic artificial wing and investigate the aerodynamic characteristics of the wing. A metal mold with micro holes was fabricated by the electrical discharge machining (EDM) process. Melted chitosan was applied on the mold and spread into the hole of the mold. After the solidification of chitosan, artificial wing with 400 micro spikes was fabricated. These wings had 400 micro spikes whose height is 100 μm.

Micro biofabrication technologies have been developing aiming to fabricate 3D artificial organs, 3D scaffolds, and complex tissue structures. We are now developing a new inkjet bio-printing method via electrostatic phenomenon. The merits of the new method are of high resolution, and of ability to eject highly viscous liquid and media. In this paper, we attempted to apply the proposed method for precision printing cells and biomaterials. Living cells and scaffolds have successfully been printed and the biochemical characteristics have been investigated. A 3D cell structure which had a cavity to create blood vessels has also successfully fabricated by this method. (C) 2014 CIRP.

Solar cell is one of the key technologies in this century because this has possibility to clear energy problems. We tried to pattern good titania layer of dye-sensitized solar cell (DSC) utilizing electrostatic inkjet. The electrostatic inkjet has good merit
that is ability to eject highly viscous liquid. We applied the merit for patterning titania paste on fluorine-doped tin oxide (FTO) glass. In this paper, we investigated fundamental characteristics to pattern titania layer on FTO glass because efficiency depends on thickness of titania layer. © 2013 The Japan Society of Applied Physics.

The goal of this study is to fabricate precision three-dimensional (3D) biodevices those are micro fluidics and artificial organs utilizing digital fabrication. Digital fabrication is fabrication method utilizing inkjet technologies. Electrostatic inkjet is one of the inkjet technologies. The electrostatic inkjet method has following two merits; those are high resolution to print and ability to eject highly viscous liquid. These characteristics are suitable to print biomaterials precisely. We are now applying for bioprint. In this paper, the electrostatic inkjet method is applied for fabrication of 3D biodevices that has cave like blood vessel. When aqueous solution of sodium alginate is printed to aqueous solution of calcium chloride, calcium alginate is produced. 3D biodevices are fabricated in case that calcium alginate is piled. (C) 2013 The Japan Society of Applied Physics

The Dye-Sensitized Solar Cell (DSC) has been attracting the attention of many researchers due to its good characteristics such as low cost, flexibility, and colorful panel. Normally DSC is produced by dipping a titania- coated FTO electrode in the dye solution for over three hours to adsorb dye onto the titania layer of the DSC. We have been investigating fundamental characteristics of the electrostatic inkjet. Ejected droplets are charged because of high voltage application. Since the dye adsorption process depends on charge, charged dye gives a preferable effect to the adsorption process to shorten the adsorption time. In this study, an experimental set-up of an electrostatic inkjet was constructed to print dye on a titania-coated FTO electrode. We have investigated the fundamental characteristics of the dye-printed DSC by changing the printing time. As a result, the printing time was drastically reduced from several hours to about 14 or 15 minutes, and the efficiency proved to be about 5%, which is a comparable value to that made by ordinary production methods.

Solar cell is one of the key technologies in this century because this has possibility to clear energy problems. In this paper, we tried to pattern titania layer of dye-sensitized solar cell (DSC) utilizing PELID method. The PELID method is an inkjet fabrication method. The FEUD method has good merit; that is ability to eject highly viscous liquid. We applied the merit for patterning titania paste on FTO (Fluorine-doped Tin Oxide) glass. The thickness of titania layer was controlled by the time to print. DSC is composed of electrolyte that is sandwiched between FTO glass and Pt electrode. Titania and N3 are patterned on FTO glass. The efficiency is not so high. The main purpose of the study is to improve the efficiency. The fabrication process of the DSC was simple. Titania paste was patterned on FTO glass utilizing doctor blade. The patterned paste was dried and sintered. The thickness of the layer was controlled by the spacer between the doctor blade and the glass. In the former study, the thickness was not changed, however it is essential to determine the thickness to achieve the highest efficiency. Because best thickness will be changed by the chemical characteristics of titania, new fabrication method that can change the thickness easily should be developed. We developed the PELID method.
In this paper, we have optimized of titania layer by controlling the coating time and profile utilizing FEUD method. We have demonstrated that optimizing titania layer by PELID method is possible to improve the efficiency of the DSC.

In this paper, we fabricated soft 3D bio devices utilizing PELID (Patterning with Electrostatically-Injected Droplet) method. It is preferable to perform laboratory experiments with 3D structures in bioengineering. We have investigated mechanism and fundamental characteristics of the PELID method and now been applying for new printing technology of high image quality and 3D printing technology. The method has two merits, higher resolution than commercial printer and ability to eject with highly viscous liquid. We can eject viscous paste that viscosity is 30000 mPas. At DF 2010, I already presented that cells and scaffolds were printed to fabricate 3D cell structures because scaffolds assisted the weight of cells. Now, we should fabricate 3D structure that has cave because real 3D structure has blood vessel like cave. It is difficult to fabricate 3D structure that has cave. Gelatin is used as sacrificial layer. When the printed 3D structure is put into hot water, gelatin is removed. With this technique, we can print 3D structure that has cave. The tube filled with the liquid that contained gelatin and the tube filled with the liquid that contained calcium alginate was hanged down perpendicular to a dish. Voltage was applied between the syringes and the dish by power supplies (voltage range: -5kV similar to +5kV, Matsusada Precision Inc, Tokyo, HVR10P). The air gap was adjusted by a z-stage and the plate electrode was moved in x and y directions with two linear motors. PC controlled voltage application and motion of linear stages. We fabricated 3D bio devices.

The object of this study is to fabricate three Dimensional cell structures utilizing PELID (Patterning with ELectrostatically-Injected Droplet) method. Because it is preferable to perform laboratory experiments with 3D cell structures in tissue engineering and artificial organ. However, it is difficult to fabricate 3D cell structures because own weight of cell is above the bonding force between cells. In this paper, we printed MDCK cells and collagen as scaffolds utilizing the PELID method. We investigated growth of printed cells. Number of printed cells was increased day by day. We investigated fundamental characteristics on patterning collagen. The printed collagen was thick when the time to print was increased. These results indicated that it is possible to fabricate 3D cell structure.

Solar cell is one of the key technologies in this century because this has possibility to clear energy problems. In this paper, we tried to pattern titania layer of dye-sensitized solar cell (DSC) utilizing FEUD method. The FEUD method is an inkjet fabrication method. The PELID method has good merit; that is ability to eject highly viscous liquid. We applied the merit for patterning titania paste on FTO (Fluorine-doped Tin Oxide) glass. The thickness of titania layer was controlled by the time to print. DSC is composed of electrolyte that is sandwiched between FTO glass and Pt electrode. Titania and N3 are patterned on FTO glass. The efficiency is not so high. The main purpose of the study is to improve the efficiency. The fabrication process of the DSC was simple. Titania paste was patterned on FTO glass utilizing doctor blade. The patterned paste was dried and sintered. The thickness of the layer was controlled by the spacer between the doctor blade and the glass. In the former study, the thickness was not changed, however it is essential to determine the thickness to achieve the highest efficiency. Because best thickness will be changed by the chemical characteristics of titania, new fabrication method that can change the thickness easily should be developed. We developed the FEUD method. When the strong electric field was applied to a nozzle, small droplets were ejected by the electrostatic force.
In this paper, we applied the PELID method to pattern titania on FTO glass. The thickness of patterned titania layer was investigated.

Micro-drop injection took place when high voltage was applied between a capillary tube filled with ion conductive liquid and a metal plate electrode. Micro-drop injection has two merits; those are high resolution to print and ability to eject highly viscous liquid. Recently many researchers applied commercial inkjet for bio-printing. Main problem of this application is difficulty to print relatively highly viscous liquid. I think the merits of micro-drop injection will clear this problem. So, I applied the micro-drop injection for printing living cells and highly viscous scaffolds to make 3D cell structures. Cells were not killed in spite that high voltage was applied by micro-drop injection. Because current did not flow inside cell but around cell. In this paper, we cleared the fundamental characteristics of patterning living cells and gelatin and fabricated 3D cell cylinder utilizing micro-drop injection.

Electrostatic inkjet phenomena took place when strong electric field was applied to water pin electrode. In this paper we developed two new micro fabrication techniques utilizing electrostatic inkjet phenomena. First technique is to thin a metal rod The metal rod was set on a metal plate electrode. The diameter of the rod was controlled by the time of voltage application between the capillary tube and the metal rod The other is to punch a hole in a metal thin sheet. A shin metal sheet was set on the metal plate electrode. When the formation and locus of droplets that contained commercial etching liquid was controlled, small hole was punctured on the shin sheet. Hole diameter, less than 10 mu m to some 100 mu m was controlled by the voltage application between the sheet electrode and the capillary tube that was filled with the etching liquid

An electrohydrodynamic investigation has been carried out in a pin-to-plate gas discharge system to clarify the mechanism of repulsive force generation between a pin and plate electrode at corona discharge. Numerical calculations have been conducted in two steps. First, the axi-cylindrical static corona discharge field was calculated with the finite-element method to deduce the Coulombic body force ρ E applied to the air, where ρ is the charge density and E is the electric field, and then the induced ionic wind was calculated with the finite differential method. The calculated pressure distribution on the plate electrode was on the order of 10 Pa which was in good agreement with the measured pressure distribution. The calculated air velocity at the center was several m/s and was confirmed by a time-of-flight experiment and the velocity distribution near the pin electrode also agreed with measurements using a laser Doppler velocimeter. Pressure and wind velocity were increased at high-applied voltage. These results confirm that the ionic wind is the cause of the repulsive force to the pin electrode at the corona discharge. © 2005 Elsevier B.V. All rights reserved.

We have been investigating an electrostatic manipulation of a small particle, such as toner and carrier particles. A manipulator consisted of two parallel pin electrodes. When voltage was applied between the electrodes, electrophoresis force generated in nonuniform electrostatic field was applied to the particle near the tip of the electrode. The particle was captured by the application of the voltage and released from the manipulator by turning off the voltage application. It was possible to manipulate not only insulative but also conductive particles. However, if the particle was charged, Coulomb force and adhesion force prevented to release the particle when the voltage was turned off. This condition was apt to take place for small particles, less than 200 fun in diameter. The third electrode was introduced near the dipole electrodes to blow off the particle by the ionic wind and the validity of this system was demonstrated. An uneven electrode system without the additional separation electrode was also developed to release the attached particle independently of the position of the manipulator. Three-dimensional calculation was conducted by the Finite Difference Method and compared to the measured force.

We have been developing an electrostatic inkjet system for printers and mask-less electronic micro-circuit printing. The system consisted of a tube filled with ink and a plate electrode. When voltage was applied between the electrodes, a droplet was formed and separated at the tip of the tube periodically. Optimizing this system we have demonstrated 1,600 dpi printing on paper. However the print speed was deadly slow because this system had only single nozzle. Therefore we have been developing a multi-nozzle system that consisted of two parallel tubes filled with ink and the metal plate electrode. Three-dimensional calculation of the electric field was conducted by the Finite Difference Method to deduce the cross-talk between the electrodes and it is proposed that a new system that the waveform of the applied voltage was adjusted to cancel the cross-talk between the adjacent nozzle.

Electrohydrodynamic deformation of water surface was investigated in a pin-to-plate gas discharge system that consisted of a pin electrode made of metal and an ion-conductive water electrode. In the condition of a lower applied voltage than the corona threshold, because an extremely small electrostatic attractive force, a Coulomb force in the order of 10 μN, was induced, water lifted up in the order of several tens of micrometres at the centre. Over the threshold voltage corona discharge took place and a relatively large repulsive force, in the order of 100 μN, was induced due to the ionic wind. It depressed water in the order of several hundred micrometres at the centre. Deformation of the water level coincided with the pressure distribution on the metal plate electrode, if the surface tension of water and the Coulomb force was included in the estimation to derive the pressure distribution from the measured deformation of the water level. If the applied voltage was lower than the corona threshold, total force to the water electrode coincided with that to the pin electrode. However, it was larger than that to the pin electrode at the corona discharge because the reaction force due to the ionic wind was applied not only to the pin electrode but also to other parts of the electrode at the corona discharge. © 2005 IOP Publishing Ltd.

A preliminary investigation was conducted on formation and control of micro droplet in electrostatic Inkjet phenomena. High voltage was applied between an insulative capillary tube filled with ion-conductive water and a plate electrode. At the beginning of corona discharge, a Taylor cone was formed at the tip of the tube and the top of the cone was broken to form a very small droplet that was dispersed like mist at wide angle due to the Coulomb repulsive force of charged mist. When the applied voltage was further increased, water droplet was formed periodically. The charge to mass ratio of the droplet was measured and compared with the Rayleigh's limit. It was less than the limit because the droplet vibrated at the formation of the droplet. Another experimental set-up was constructed to control the dropping position of the droplet. A ring electrode was settled between the capillary tube and the plate electrode to control the dropping position of the droplet.

A fundamental investigation was conducted on electrostatic ink jet phenomena. High voltage was applied between an insulative capillary tube filled with ion conductive water and a metal plate electrode. A large water drop was formed and dropped from the tube at the dark discharge under conditions of appropriate voltage application and water level. The diameter of the drop was about one millimeter. At the beginning of corona discharge, however, a Taylor cone of water was formed at the tip of the tube and the tip of the cone was broken to form a very small droplet that was dispersed like mist at wide angle due to the Coulomb repulsive force of charged mist. When the applied voltage was further increased, water droplet was formed periodically. Application of adjusted pulse voltage can form a droplet of which formation is synchronized with the pulse. The diameter of the droplet depended on the applied voltage and the tube diameter. It was less than a Rayleigh's limit and agreed fairly well with a Vonnegut's limit. Preliminary printing on a paper was also demonstrated. This phenomenon is expected to be utilized for a new ink jet print head. © 2005, IS&amp
T - The Society for Imaging Science and Technology.

A new paper separation and feed mechanism is proposed to realize a highly reliable paper handling system for printers. A prototype mechanism consisted of a roller-type separation electrode coated with an insulating film, a ground electrode, and a paper pile between the electrodes. When electrostatic field was applied between the electrodes, it was confirmed that only the top paper was separated. However the applied voltage had to be increased to separate subsequent papers, because charge on the insulating film was cancelled by the attached paper. Then a biased charger roller was settled in contact with the separation electrode to charge the insulating film on the separation electrode. In this system, reliable paper separation and feed was realized and a feed speed over 600 mm/s was demonstrated.