Updated on 2024/07/19

写真a

 
IKEHASHI, Tamio
 
Affiliation
Faculty of Science and Engineering, Graduate School of Information, Production, and Systems
Job title
Professor
Profile
2019年4月 早稲田大学大学院情報生産システム研究科 准教授
1995年 4月 株式会社 東芝
1995年 3月 東京大学大学院 理学系研究科 物理学専攻 博士課程修了(博士(理学))
 

Papers

  • A Sub-1 Hz Resonance Frequency Resonator Enabled by Multi-Step Tuning for Micro-Seismometer

    Jun Wu, Hideyuki Maekoba, Arnaud Parent, Tamio Ikehashi

    Micromachines   13 ( 1 )  2022.01

     View Summary

    We propose a sub-1 Hz resonance frequency MEMS resonator that can be used for seismometers. The low resonance frequency is achieved by an electrically tunable spring with an ultra-small spring constant. Generally, it is difficult to electrically fine-tune the resonance frequency at a near-zero spring constant because the frequency shift per voltage will diverge at the limit of zero spring constant. To circumvent this issue, we propose a multi-step electrical tuning method. We show by simulations that the resonance frequency can be tuned by 0.008 Hz/mV even in the sub-1 Hz region. The small spring constant, however, reduces the shock robustness and dynamic range of the seismometer. To prevent this, we employ a force-balanced method in which the mass displacement is nulled by the feedback force. We show that the displacement can be obtained from the voltage that generates the feedback force.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Characterization of Nonlinear Behavior of Weakly Coupled Resonators based on Nonlinearity Factor

    Tamio Ikehashi, Hideyuki Maekoba, Arnaud Parent

    IEEE Sensors Journal    2021

     View Summary

    Mode-localization is a promising method to realize high sensitivity sensors, especially in the field of MEMS. Since these sensors monitor amplitude change of weakly coupled resonators, it is important to grasp condition that induces multi-valued amplitude-frequency curve. In this paper, we provide an efficient tool to characterize the nonlinear behavior of the weakly coupled resonators. To analyze the nonlinearity, we solve a two-degrees-of-freedom (2-DoF) coupled equation of motion with nonlinear spring terms. Two approximations are employed to solve the equation; Krylov–Bogoliubov averaging method and approximation based on eigenmode amplitude-ratio at the resonances. As a result, we obtain two decoupled Duffing-like amplitude-frequency equations. We show that nonlinearity of the system is described by factors contained in the equations. The factors can be explicitly written in terms of basic parameters of the system, including coupling spring constant and nonlinear terms. Thus, instead of relying on numerical calculations, we can find parameter condition that brings about multi-valued amplitude-frequency curve. This method can also be utilized to find a condition that eliminates the nonlinearity. As an example, we apply this method to a weakly coupled resonator which uses parallel plate electrode as a coupling spring. We demonstrate the effectiveness and validity of this method by comparing the result with FEM simulations. The methodology and results presented here are general one and can be applied to various systems described by nonlinear coupled resonators.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Effects of poisoning gases on and restoration of PdCuSi metallic glass in a capacitive MEMS hydrogen sensor

    Yumi Hayashi, Hiroaki Yamazaki, Kei Masunishi, Tamio Ikehashi, Naofumi Nakamura, Akihiro Kojima

    International Journal of Hydrogen Energy   45 ( 1 ) 1187 - 1194  2020.01

     View Summary

    We investigated the effects of poisoning and restoration of PdCuSi-metallic glass (MG), which is a sensing material that offers low power consumption and fast response times when used in capacitive MEMS hydrogen sensors. Four poisoning gases were used: hexamethyldisilazane (HMDS), H2S, SO2, and NO2. Exposure to H2S resulted in metal sulfide forming at the surface of the PdCuSi-MG, although the sulfur did not diffuse into the PdCuSi-MG. Exposure to NO2 only resulted in the nitrogen being adsorbed without bonding to metals. The poisoning elements were desorbed by heating. Exposure to H2S and SO2 degraded the hydrogen sensitivity in terms of resistance of the PdCuSi-MG, although exposure to HMDS and NO2 only slowed down the response time. These degradations were recovered by heating. We next examined forming a refresher layer under PdCuSi-MG in a hydrogen sensor. The hydrogen sensitivity of the H2S-exposed hydrogen sensor was restored by performing a refresh operation for a few minutes.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • A review of capacitive MEMS hydrogen sensor using Pd-based metallic glass with fast response and low power consumption

    Yamazaki Hiroaki, Hayashi Yumi, Masunishi Kei, Ono Daiki, Ikehashi Tamio

    ELECTRONICS AND COMMUNICATIONS IN JAPAN   102 ( 3 ) 70 - 77  2019.03  [Refereed]

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • A 3-AXIS CATCH-AND-RELEASE GYROSCOPE WITH PANTOGRAPH VIBRATION FOR LOW-POWER AND FAST START-UP APPLICATIONS

    Akiko Yuzawa, Ryunosuke Gando, Kei Masunishi, Etsuji Ogawa, Hiroki Hiraga, Yasushi Tomizawa, Tetsuro Itakura, Tamio Ikehashi

    2019 20TH INTERNATIONAL CONFERENCE ON SOLID-STATE SENSORS, ACTUATORS AND MICROSYSTEMS & EUROSENSORS XXXIII (TRANSDUCERS & EUROSENSORS XXXIII)     430 - 433  2019

     View Summary

    This paper presents the first 3-axis MEMS gyroscope that employs intermittent free vibration realized by a "Catch-and-Release (CR)" method. While CR enables drive power reduction and instant start-up, its application to multi-axis tuning-fork (TF) gyroscope is not straightforward, since the increased degrees-of-freedom is likely to induce hazardous beat during the free vibration. To prevent this, a pantograph structure is introduced, in which drive motion is constrained by fixed-length joints, thereby eliminating the spurious beat. The fabricated gyroscope shows 3-axis sensitivities of 0.3-0.6 aF/dps and <2% cross-axis sensitivities. The consecutive CR operation with a release DC voltage at 25 V and a high Q factor of 440k at 20 kHz of pantograph mode are confirmed.

  • CMOS-embedded high-power handling RF-MEMS tunable capacitor using quadruple series capacitor and slit with dielectric bridges structure

    Yamazaki Hiroaki, Kurui Yoshihiko, Saito Tomohiro, Ogawa Etsuji, Obara Kei, Gando Ryunosuke, Ono Daiki, Ikehashi Tamio

    JAPANESE JOURNAL OF APPLIED PHYSICS   57 ( 10 )  2018.10  [Refereed]

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • High sensitivity MEMS capacitive hydrogen sensor with inverted T-shaped electrode and ring-shaped palladium alloy for fast response and low power consumption

    Yamazaki Hiroaki, Hayashi Yumi, Masunishi Kei, Ono Daiki, Ikehashi Tamio

    JOURNAL OF MICROMECHANICS AND MICROENGINEERING   28 ( 9 )  2018.09  [Refereed]

    DOI

    Scopus

    25
    Citation
    (Scopus)
  • Investigation of PdCuSi metallic glass film for hysteresis-free and fast response capacitive MEMS hydrogen sensors

    Yumi Hayashi, Hiroaki Yamazaki, Daiki Ono, Kei Masunishi, Tamio Ikehashi

    International Journal of Hydrogen Energy   43 ( 19 ) 9438 - 9445  2018.05  [Refereed]

     View Summary

    In this study, we investigated PdCuSi metallic glass (MG) as a sensing material for capacitive MEMS hydrogen sensors. We first confirmed by film analysis that the fabricated PdCuSi film was MG and that it had a trigonal prism cluster. The measured pressure-composition-temperature curve of PdCuSi MG exhibited no hysteresis during hydrogen absorption and desorption. The response time was found to become faster by two orders of magnitudes compared with that of Pd polycrystal. These properties were attributed to the trigonal prism clusters. Strain was evaluated in the low hydrogen concentration regime of 0.05 vol% to 4.0 vol%, and the strain of PdCuSi MG was found to follow Sieverts' law well, indicating that hydrogen is present in the MG in a diffuse state. The hydrogen-concentration dependence of a capacitive MEMS hydrogen sensor was measured and hysteresis-free characteristics were obtained, implying advantages in hydrogen leak detection applications.

    DOI

    Scopus

    29
    Citation
    (Scopus)
  • A MEMS rate integrating gyroscope based on catch-and-release mechanism for low-noise continuous angle measurement

    Ryunosuke Gando, Shunta Maeda, Kei Masunishi, Yasushi Tomizawa, Etsuji Ogawa, Yohei Hatakeyama, Tetsuro Itakura, Tamio Ikehashi

    Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)   2018-   944 - 947  2018.04  [Refereed]

     View Summary

    We present two new techniques effective in realizing high precision MEMS Rate Integrating Gyroscope (RIG). First one is the application of the Catch-and-Release (CR) scheme, reported previously, to the RIG. We show that continuous angle measurement can be attained by catching and releasing a pair of CR-RIGs in a complementary manner. Direct angle measurement is also demonstrated by adopting a doughnut-shaped CR-RIG. Second one is a resistive tunable damper that can compensate the damping asymmetry, a major cause of the angle drift. In this tunable damper, the mechanical damping factor can be tuned by resistance and voltage. We show that the theoretical model fits well with the experimental results.

    DOI

    Scopus

    30
    Citation
    (Scopus)
  • A Review of Capacitive MEMS Hydrogen Sensor using Pd based Metallic Glass with Fast Response and Low Power Consumption

    Hiroaki Yamazaki, Yumi Hayashi, Kei Masunishi, Daiki Ono, Tamio Ikehashi

    IEEJ Transactions on Sensors and Micromachines   138 ( 7 ) 312 - 318  2018

     View Summary

    This paper addresses a capacitive MEMS hydrogen sensor using Pd based metallic glass for future hydrogen society. Firstly, we investigate PdCuSi as Pd based metallic glass (MG) and show this material is promising for capacitive MEMS hydrogen sensor. Secondly, we apply the Pd based MG to a hydrogen sensor having inverted T-shaped electrode. The sensor was fabricated by a surface micromachining process. We show that the fabricated hydrogen sensor exhibits hysteresis free and fast response property at room temperature.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • The effects of poly-SiGe on sensing properties for ultra-low-power CMOS-embedded MEMS sensors

    Yoshihiko Kurui, Hideyuki Tomizawa, Akira Fujimoto, Tomohiro Saito, Akihiro Kojima, Tamio Ikehashi, Yoshiaki Sugizaki, Hideki Shibata

    Proceedings of IEEE Sensors   2017-   1 - 3  2017.12  [Refereed]

     View Summary

    To compare Si and poly-SiGe as MEMS structural materials having 20 pm-thick, we fabricated a capacitive accelerometer on an 8-inch Si substrate using CMOS standard process and measured capacitance sensitivities of an identical sensor design. As a result, we found that the sensitivity of the SiGe sensor is 2.1 times larger than that of the Si sensor. We also confirmed that the SiGe sensor can attain lower noise level as well as lower power consumption, thanks to the higher mass density of SiGe and availability of CMOS-embedded SiGe MEMS structure. The results indicate that the poly-SiGe film is promising candidates for future CMOS-embedded sensor technology applications.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Investigation of PD-CU-SI metallic glass film for hysterisis-free and fast response capacitive mems hydrogen sensors

    Yumi Hayashi, Hiroaki Yamazaki, Daiki Ono, Kei Masunishi, Tamio Ikehashi

    TRANSDUCERS 2017 - 19th International Conference on Solid-State Sensors, Actuators and Microsystems     311 - 314  2017.07  [Refereed]

     View Summary

    We show that PdCuSi metallic glass (MG) is a promising material for Pd-based capacitive MEMS hydrogen sensors, reducing both hysteresis and response time of the sensing operation. Firstly, we demonstrate that the fabricated PdCuSi MG film exhibits no hysteresis during hydrogen absorption and desorption. Drastic reduction of the response time is also shown. We also show that, to eliminate the hysteresis and to reduce the response time, PuCuSi needs to be MG, not microcrystal. Secondly, based on the measured strain property, we show that the capacitive sensing scheme has advantage in sensing low concentration hydrogens.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • AN INTERMITTENT FREE-VIBRATION MEMS GYROSCOPE ENABLED BY CATCH-AND-RELEASE MECHANISM FOR LOW-POWER AND FAST-STARTUP APPLICATIONS

    Ryunosuke Gando, Haruka Kubo, Yasushi Tomizawa, Etsuji Ogawa, Shunta Maeda, Kei Masunishi, Yohei Hatakeyama, Tetsuro Itakura, Tamio Ikehashi

    30TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2017)     29 - 32  2017  [Refereed]

     View Summary

    This paper presents the first intermittent free-vibration MEMS gyroscope enabled by a "Catch-and-Release (CR)" drive mechanism, which realizes substantial power reduction and fast startup compared to existing stationary gyroscopes. In this architecture, the proof mass is captured at the maximum displacement position (catch-state), and then released to free vibration during which the Coriolis detection is performed (release-state). Thanks to the high quality factor (Q) of 72000, the released mass can be re-captured before attenuation. This CR mechanism enables instant startup and low power. The functionality and sensitivity (21.2 mu V/dps) of a prototype CR gyroscope (CR-G) are confirmed by experiments.

  • A Catch-and-Release Drive MEMS Gyroscope with Enhanced Sensitivity By Mode-Matching

    Ryunosuke Gando, Haruka Kubo, Kei Masunishi, Yasushi Tomizawa, Etsuji Ogawa, Shunta Maeda, Yohei Hatakeyama, Tetsuro Itakura, Tamio Ikehashi

    2017 4TH IEEE INTERNATIONAL SYMPOSIUM ON INERTIAL SENSORS AND SYSTEMS (INERTIAL)     50 - 53  2017  [Refereed]

     View Summary

    This paper presents a novel MEMS gyroscope that employs intermittent free vibration and mode matching. An intermittent operation is realized by a "Catch-and-Release (CR)" technique, which enables significant reduction of the drive power. Sensitivities of the mode-matching and mode-split conditions are investigated by electrostatically tuning the sense-mode frequency. A sensitivity as high as 2.14 mV/dps, 52 times higher than the mode-split case, is obtained when the drive and sense frequency difference Delta f is reduced to 50 Hz. Optimization for mode matching and quadrature nulling is also demonstrated.

  • A HIGH SENSITIVITY MEMS CAPACITIVE HYDROGEN SENSOR WITH INVERTED T-SHAPED ELECTRODE AND RING-SHAPED PALLADIUM

    2017 19TH INTERNATIONAL CONFERENCE ON SOLID-STATE SENSORS, ACTUATORS AND MICROSYSTEMS (TRANSDUCERS)     226 - 229  2017  [Refereed]

  • The effects of poly-SiGe on sensing properties for ultra-low-power CMOS-embedded MEMS sensors

    2017 IEEE SENSORS     181 - 183  2017  [Refereed]

  • Evaluation of Gas Permeability for Micro-scale Thin Polymer Film with Encapsulated MEMS Damped Oscillator

    Ryunosuke Gando, Naofumi Nakamura, Yumi Hayashi, Daiki Ono, Kei Masunishi, Yasushi Tomizawa, Hiroaki Yamazaki, Tamio Ikehashi, Yoshiaki Sugizaki, Hideki Shibata

    2014 IEEE SENSORS    2014  [Refereed]

     View Summary

    We present a practical method to evaluate gas permeability for thin polymer films using an encapsulated micro-electro-mechanical-system (MEMS) oscillator. Previously, we have developed a hermetic thin-film dome structure for RF-MEMS tunable capacitor, using conventional back-end-of-the-line (BEOL) processes. The dome is made of multiple layers including a polymer film, whose gas permeability is an important factor with respect to productivity and reliability. So far, it had been difficult to evaluate the gas permeability for such small and thin polymer films with sub-millimeter diameter and micron-scale thickness. In this evaluation method, the pressure dependence of air-damping oscillation is used to measure the permeability. As a demonstration, we carried out a permeability measurement of a 0.5-mm-diameter dome sealed with a thin (1 mu m) polymer film. The resulting permeability coefficient is found to be 1X10(-16) mol/m/Pa/s, at room temperature.

  • A creep-immune electrostatic actuator for RF-MEMS tunable capacitor

    Etsuji Ogawa, Tamio Ikehashi, Tomohiro Saito, Hiroaki Yamazaki, Kei Masunishi, Yasushi Tomizawa, Tatsuya Ohguro, Yoshiaki Sugizaki, Yoshiaki Toyoshima, Hideki Shibata

    SENSORS AND ACTUATORS A-PHYSICAL   169 ( 2 ) 373 - 377  2011.10  [Refereed]

     View Summary

    A high creep-immunity MEMS actuator is proposed for RF-MEMS tunable capacitor. The creep-immunity is attained using silicon nitride, SiN, for the spring portions, where the stress is concentrated. Compared with an aluminum spring, the creep-induced deformation is reduced by a factor of 23 at 100 degrees C. We also confirmed by a billion cycle test that the SiN spring does not develop a brittle fracture. (C), 2011 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • A long-term reliability analysis of a creep-immune RF-MEMS tunable capacitor

    Etsuji Ogawa, Kei Masunishi, Tamio Ikehashi, Tomohiro Saito, Hiroaki Yamazaki, Yasushi Tomizawa, Yoshiaki Sugizaki

    2011 16th International Solid-State Sensors, Actuators and Microsystems Conference, TRANSDUCERS'11     2466 - 2469  2011  [Refereed]

     View Summary

    Actuators used in RF-MEMS tunable capacitors have an issue of creep-induced deformation. The creep is caused by a ductile-metal beam which is indispensable to attain the low loss. To avoid this issue, we previously reported an actuator structure that uses a brittle material, silicon nitride (SiN), at the stress-concentrated spring portions [1]. The present paper aims to clarify a long-term creep immunity of the actuator. We first determined parameters of Norton's law by measurements and then carried out Finite Element Method (FEM) simulations. As a result, we found that the shift of the up-state capacitance is 2.2% after keeping the actuator in down-state position for 3 years at 85°C. © 2011 IEEE.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • A High Power-Handling RF MEMS Tunable Capacitor Using Quadruple Series Capacitor Structure

    Hiroaki Yamazaki, Tamio Ikehashi, Tomohiro Saito, Etsuji Ogawa, Takayuki Masunaga, Tatsuya Ohguro, Yoshiaki Sugizaki, Hideki Shibata

    2010 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST (MTT)     1138 - 1141  2010  [Refereed]

     View Summary

    This paper presents an RF MEMS tunable capacitor that achieves an excellent power-handling property with relatively low actuation voltage. The tunable capacitor consists of two fixed MIM (Metal-Insulator-Metal) capacitors and two MEMS capacitor elements, all connected in series. This quadruple series capacitor (QSC) structure enables reduction of the actuation voltage without sacrificing the power-handling capability, since the MIM capacitor reduces the RF voltage amplitude applied to the MEMS capacitors. The measured result demonstrates +36dBm hot-switching at 85 degrees C with 21V pull-in voltage.

  • Lithographical bending control method for a piezoelectric actuator

    Tamio Ikehashi, Etsuji Ogawa, Hiroaki Yamazaki, Tatsuya Ohguro

    INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES   1 ( 1 ) 37 - 42  2009.02  [Refereed]

     View Summary

    This paper presents the theoretical formulation of a lithographical bending control (LBC) method that uses lithographical degrees of freedom to control the bending of a multilayered beam. LBC is applied to a piezoelectric actuator that uses PZT as the piezoelectric material. The theoretical model is compared with measurements using a weakly fixed bridge structure suited for curvature measurement.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Highly reliable and manufacturable in-line wafer-level hermetic packages for RF MEMS variable capacitor

    Akihiro Kojima, Yoshiaki Shimooka, Yoshiaki Sugizaki, Mitsuyoshi Endo, Hiroaki Yamazaki, Etsuji Ogawa, Tamio Ikehashi, Tatsuya Ohguro, Susumu Obata, Takeshi Miyagi, Ikuo Mori, Yoshiaki Toyoshima, Hideki Shibata

    TRANSDUCERS 2009 - 15th International Conference on Solid-State Sensors, Actuators and Microsystems     837 - 840  2009  [Refereed]

     View Summary

    In this paper, we report a thin-film encapsulation technology for wafer-level micro-electro-mechanical systems (MEMS) variable capacitor package. The electrical characteristics of MEMS are adversely affected by moisture. In order to prevent moisture from permeating into a package, the top surface was protected with a plasma-enhanced chemical vapor deposition (PE-CVD) SiN layer. The developed packages become a hybrid thin-film hermetic encapsulation consisting of an internal shell using PE-CVD SiO, a seal layer coating with resin, and an external protective layer formed by PE-CVD SiN. The process is fully compatible with standard low-cost back-end-of-the-line (BEOL) technologies for LSIs as a wafer-level package (WLP). This hybrid structure was very effective for protecting the MEMS device from external moisture. Moreover, the electrode surface area has to be wide, because a wide range of capacities is necessary in MEMS variable capacitors. We have developed a large (1480 × 1080 μm) hermetic thin-film encapsulation as WLP. ©2009 IEEE.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Low Profile Double Resonance Frequency Tunable Antenna Using RF MEMS Variable Capacitor for Digital Terrestrial Broadcasting Reception

    Yukako Tsutsumi, Masaki Nishio, Shuichi Obayashi, Hiroki Shoki, Tamio Ikehashi, Hiroaki Yamazaki, Etsuji Ogawa, Tomohiro Saito, Tatsuya Ohguro, Tasuku Morooka

    2009 IEEE ASIAN SOLID-STATE CIRCUITS CONFERENCE (A-SSCC)     125 - 128  2009  [Refereed]

     View Summary

    It is difficult to realize the built-in antenna for wideband systems, because a frequency bandwidth of the low profile antenna is narrow. A frequency tunable antenna is a technique for wideband characteristics. In this paper a low profile double resonance frequency tunable antenna using MEMS variable capacitors is presented. It has high efficiency over a wide frequency band. Through both resonant portions from 465 to 665 MHz, the efficiency of more than -4 dB and the VSWR of less than 3 are observed in the measurement using the variable capacitor of 0.4-0.9 pF.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • An RF MEMS variable capacitor with intelligent bipolar actuation

    Tamio Ikehashi, Takayuki Miyazaki, Hiroaki Yamazaki, Atsushi Suzuki, Etsuji Ogawa, Shinji Miyano, Tomohiro Saito, Tatsuya Ohgura, Takeshi Miyagi, Yoshiaki Sugizaki, Nobuaki Otsuka, Hideki Shibata, Yoshiaki Toyoshima

    Digest of Technical Papers - IEEE International Solid-State Circuits Conference   51   575 - 637  2008  [Refereed]

     View Summary

    An RF MEMS variable capacitor module with intelligent bipolar actuation (IBA) is implemented in a driver IC to prevent stiction in electrostatic actuators. The IBA eliminates the dielectric charging of the electrostatic actuator by detecting the charge trapped in the dielectric film and reversing the electric field orientation if it exceeds a set threshold. No failure is observed up to 108 cycles at 85°C. ©2008 IEEE.

    DOI

    Scopus

    22
    Citation
    (Scopus)
  • An intelligent bipolar actuation method with high stiction immunity for RF MEMS capacitive switches and variable capacitors

    Hiroaki Yamazaki, Tamio Ikehashi, Tatsuya Ohguro, Etsuji Ogawa, Kenji Kojima, Kazunari Ishimaru, Hidemi Ishiuchi

    SENSORS AND ACTUATORS A-PHYSICAL   139 ( 1-2 ) 233 - 236  2007.09  [Refereed]

     View Summary

    We propose an intelligent bipolar actuation (IBA) method for electrostatic actuators, which can suppress stiction induced by dielectric charging. The high stiction immunity is achieved by flipping the bias voltage polarity depending on the pull-out voltage, thereby restricting the amount of charge stored in the dielectric film. (c) 2007 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    22
    Citation
    (Scopus)

▼display all

Research Projects

  • Research on Vibrometer using MEMS Resonator with Ultra-low-resonance-frequency

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    2021.04
    -
    2024.03
     

Misc

  • An RF-MEMS tunable capacitor with CMOS driver IC

    SUGIZAKI Yoshiaki, IKEHASHI Tamio, YAMAZAKI Hiroaki, SAITO Tomohiro, OGAWA Etsuji, SHIMOOKA Yoshiaki, SHIBATA Hideki

    IEICE technical report. Component parts and materials   111 ( 326 ) 13 - 18  2011.11

     View Summary

    An RF-MEMS tunable capacitor with CMOS driver IC has been developed. In order to improve MEMS reliability, an IBA circuit has been proposed and implemented in CMOS driver IC. QSC structure has been also proposed to improve power handling and creep immunity. Furthermore WLP thin-film dome has been newly developed that provides small size, low cost, as well as higher reliability.

    CiNii

 

Syllabus

▼display all

 

Sub-affiliation

  • Faculty of Science and Engineering   School of Fundamental Science and Engineering

Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

Internal Special Research Projects

  • 超低共振周波数MEMS共振器を用いた振動計の研究

    2021   Jun Wu, Chengzhi Yi

     View Summary

    本研究では小型・軽量で振動変位を直接計測できる変位地震計タイプのMEMS振動計の研究を行っている。この振動計は微小サイズでありながら極めて低い共振周波数を有している。一般にサイズが小さくなるとマスが軽くなるため共振周波数が大きくなる傾向があるが、本研究では負のバネ定数をもつ電極構造を利用することにより、合成バネ定数を極めて小さくして低共振周波数化を実現している。また耐衝撃性を確保するためフォース・バランス機構を採用している。本構造は地震計や超小型重力計にも応用できる。今年度は制御系設計を進めるとともに、デバイスの試作を実施した。制御系設計では、共振周波数の値を維持できる機構を導入した。

  • モード局在化センサにおけるばね定数の無限小化による感度向上の研究

    2020   Zhiqiang Chen

     View Summary

    &nbsp;Sensors using mode localization can attain high sensitivity with the use of weakly coupled resonators. In mode-localized tilt sensors, the sensitivity is known to be proportional to Δ𝑘/𝑘𝑐, where Δ𝑘 is a spring constant shift caused by a tilting and 𝑘𝑐 is a stiffness of the coupling spring. This suggests that high sensitivity can be attained at 𝑘𝑐→0. In view of this, we considered a structure that can attain 𝑘𝑐→0. In the proposed structure, the small coupling spring 𝑘𝑐 is attained by combining a mechanical spring and an "electrical spring" which is composed by parallel plate electrodes. Due to the electrostatic attractive force, the electrical spring behave as a spring with negative spring constant. The effective spring constant of the electrical spring can be tuned a voltage applied to the electrode. Thus by optimizing the voltage, the total spring constant can be made zero. The voltage tunability also enables compensation of temperature dependence and process variation of the spring constant. Using a FEM simulator, we have designed a mode-localized tilt sensor that possesses this coupling spring and verified that the spring constant can be made zero by optimizing the voltage. We also confirmed the increase of sensitivity at 𝑘𝑐→0.&nbsp;

  • モード局在化センサにおけるばね定数の無限小化による感度向上の研究

    2020   Zhiqiang Chen

     View Summary

     Recently, mode localization is extensively surveyed to make high sensitivity sensors such as mass sensors and accelerometers. In these sensors, physical quantities are derived from amplitude change of weakly coupled resonators. An issue of this approach is the bending of frequency-amplitude curve caused by nonlinearity of the spring. The nonlinearity will become prominent if we employ electrostatic force to realize the small coupling spring, which is an effective method to enhance the sensitivity. To analyze the nonlinearity, we first solved the coupled resonator system including nonlinear spring effects. By using the method of averaging, we derived equations that represents nonlinear amplitude frequency curves. The derived equations are found to be very useful in analyzing the nonlinearity of the coupled resonator system. The validity of the results are verified by FEM simulations. According to the result, the nonlinear behavior is highly dependent on the resonant modes and also on spring constant shift caused by measurements. This analysis paves the way to cancel or reduce the nonlinearity by measuring specific modes.&nbsp;