M. Mita

Japan Aerospace Exploration Agency, Chōfu, Tōkyō, Japan

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Publications (98)53.42 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We have successfully fabricated electrostatic microactuators in a flexible sheet (i.e. microactuators made of the flexible sheet). In this fabrication, we used Kapton® sheets (DU PONT-TORAY) of 25μm thick as the flexible (structural) material, one mask and one additional shadow-mask to form comb-drive electrostatic microactuators in the sheet. As the first result, we could obtain the lateral displacement of 1μm to 14μm with applied voltage from 20V to 120V. We also could drive the actuators in the sheet fixed on a curved surface.
    2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII); 06/2013
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    ABSTRACT: This paper presents a multiphysics simulation and layout design technique for complementary metal-oxide-semiconductor-microelectromechanical systems (MEMS) (CMOS-MEMS) based on an electrical circuit simulator. An equivalent circuit model for the mechanical equation of motion has been translated into a Verilog-A-compatible hardware description language (HDL) in the Cadence Virtuoso environment to attain new designing capabilities such as automatic mask-layout synthesis, design rule check, and layout-versus-schematic verification for MEMS structures. Microelectromechanical components such as parallel-plate actuator and bending suspension, whose analytical equation models are already known, are also interpreted into HDL-coded equivalent circuits. Behavior of a MEMS device, including the electrostatic displacement hysteresis and the negative spring constant effect, is numerically simulated as a lumped mass-and-spring system, which has been verified to quantitatively agree with that of the corresponding analytical simulation results. A multiphysics model for the Colpitts oscillator circuit has been built in the developed simulation environment by replacing a quartz resonator with a compact model of an electrostatic silicon resonator, and its self-excited resonance has been confirmed by the simulation after the coordination of the device and circuit parameters. A prototype conversion tool for MEMS parameterized cell has also been developed to demonstrate automatic generation of mask layouts for a silicon resonator, which has been cross-checked against the experimental measurements to verify the simulation accuracy.
    Journal of Microelectromechanical Systems 06/2013; 22(3):755-767. DOI:10.1109/JMEMS.2013.2243111
  • IEICE Electronics Express 01/2013; 10(8):20130187-20130187. DOI:10.1587/elex.10.20130187
  • M. Ataka, M. Mita, H. Fujita
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    ABSTRACT: In this paper, we present demonstrations of autonomous decentralized MEMS (ADM). The ADM is a large scale array of “monolithically integrated cell”, in which “microactuators” are integrated with a “micro sensor” and a “micro processing unit (MPU)” (Fig.1a). We applied autonomous decentralized algorithms based on “cellular automata” to our developed micro manipulator. This manipulator is not monolithically integrated one but an equivalent system to the ADM by stacking an actuator array on a sensor array (Fig.1b). We could observe smart functions of micro object manipulations.
    Micro Electro Mechanical Systems (MEMS), 2012 IEEE 25th International Conference on; 01/2012
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    ABSTRACT: An equivalent circuit model for the semi-parallel plate electrostatic torsion mirror has been developed based on the electrical circuit simulator. An analytical model for the electrostatic torque has been translated into a nonlinear dependent current source as a function of input voltages that interpret the drive voltages and the mirror angle. A use of the suspension width as a fitting parameter explained well the experimental results of frequency response and the mirror's static deflection.
    IEEJ Transactions on Sensors and Micromachines 01/2012; 132(4):77-85. DOI:10.1541/ieejsmas.132.77
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    ABSTRACT: We have been developing our original MEMS-based X-ray optics for future astronomical missions. To date, we verified the focusing of optical light and X-ray for the first time. The concept and recent advances are reviewed.
    Optical MEMS and Nanophotonics (OMN), 2012 International Conference on; 01/2012
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    ABSTRACT: We have developed an inertia-driven micro actuator for harsh environment of space. Different from the conventional PZT-driven or other actuators, the newly developed electrostatic mechanism is free from the material property change due to temperature. A mass suspended in the actuation system is designed to collide with the internal wall to give thrust by the impact-type inchworm mechanism.
    IEEJ Transactions on Sensors and Micromachines 01/2012; 132(5):96-102. DOI:10.1541/ieejsmas.132.96
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    ABSTRACT: An equivalent circuit model for the resonant-type vertical comb-driven optical MEMS (micro electro mechanical system) scanner has been developed based on the simple extension of the parallel-plate model. Both the electrostatic torque and the induction charge models are interpreted by using the equation-defined nonlinear dependent current source on the electrical circuit simulator platform. A systematic procedure has been investigated to fit the analytical model with the experimental results by using fitting parameters including the damping coefficient, the suspension width, and the comb gap. The developed simulation model has been used to verify a new control scheme to tune the scanner's oscillation amplitude in resonance by means of the pulse-width modulation of voltage at a given pulse height; the result indicates the effective use of digital electronics for the comb-driven optical scanner.
    IEEJ Transactions on Sensors and Micromachines 01/2012; 132(1):1-9. DOI:10.1541/ieejsmas.132.1
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    ABSTRACT: A newly developed multi-physics simulation tool for MEMS (microelectromechanical systems) has been applied to a branched suspension structure to study the versatility of analysis. More than two suspension modules or actuator modules can be connected to a mass module that solves the equation of motion without modifying the internal equivalent circuit module, thanks to the carefully designed signal handling method, where displacement and velocity are interpreted as voltage while mechanical force as electrical current. A 4-bit microelectromechanical digital-to-analog converter of displacement has been modeled as a verification to reproduce the micromechanical behavior.
    IEEJ Transactions on Sensors and Micromachines 01/2012; 132(3):64-65. DOI:10.1541/ieejsmas.132.64
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    ABSTRACT: An electrostatic micro actuator with an electrical contact between the electrodes is known to show a limit-cycle behavior due to the combination of electrostatic pull-in and release. We newly used an electrical circuit simulator to make an equivalent circuit model to reproduce the limit-cycle by multi-physics simulation. This simulation results were found to explain the experimenntally observed behavior of the developedMEMS voltage to frequency convertor (VFC).
    IEEJ Transactions on Sensors and Micromachines 01/2012; 132(7):189-194. DOI:10.1541/ieejsmas.132.189
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    ABSTRACT: A lithium-ion battery was developed using off-the-shelf pouch cells and launched with a small scientific satellite “REIMEI.” The cells were potted with polyurethane or epoxy resin to protect the battery from vacuum in space. Preliminary experimental test results of pouch cells potted in a soft aluminum cap suggested that the cells tended to swell in vacuum, although they had been reinforced with the resins. Bread board models (BBMs), in which pouch cells were potted with resins in a hard aluminum case, were fabricated for cycle life performance tests in the laboratory. The test results indicated that the performance of epoxy-potted BBM was superior to that of the polyurethane-potted BBM. The measured cell resistance implied that the electrolyte solution leaked through the polyurethane resin, resulting in premature deterioration. The epoxy resin was used for the flight battery. The end-of-discharge-voltage (EoDV) trend of the flight battery on orbit was compared with the laboratory test results corrected based on a post-launch cycle test using a fresh cell. The corrected EoDV trend in the laboratory was in good agreement with the on-orbit trend for the early cycle period, indicating that the on-orbit battery was not inadvertently affected by conditions in space.
    Journal of Power Sources 10/2011; 196(20):8755-8763. DOI:10.1016/j.jpowsour.2011.06.051
  • Y. Fukushima, M. Mita
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    ABSTRACT: This paper proposes an algorithm of onboard mission replanning using the orthogonal array experiment design approach to solve the problem of repairing of the original mission plan without human operator interventions. The orthogonal array plays an important role to create a group of tentative plans more efficiently than heuristics that is commonly used in standard onboard planning applications. The key idea to implement the proposing mission replanning software is the expression of an operational plan by a "script". Most spacecraft mission plans are defined as a sequence of system-built-in commands, whereas this "script" contains not only the usual plans but also "logic" type commands. The logic type command is expressed in a form of a program fragment such as "IF A THEN DO B". To make a further discussion on the proposing idea, this paper also shows a result of an experiment using an autonomous underwater vehicle. The onboard software is based on the proposing software architecture and the replanning algorithm to demonstrate its feasibility in an actual circumstance.
    Space Mission Challenges for Information Technology (SMC-IT), 2011 IEEE Fourth International Conference on; 09/2011
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    ABSTRACT: The plasticity of covalently bonded materials is a subject at the forefront of materials science, bearing on a wide range of technological and fundamental aspects. However, covalent materials fracture in a brittle manner when the deformation exceeds just a few per cent. It is predicted that a macroscopically brittle material like silicon can show nanoscale plasticity. Here we report the exceptional plasticity observed in silicon nanocontacts ('nanobridges') at room temperature using a special experimental setup combining a transmission electron microscope and a microelectromechanical system. When accounting for surface diffusion, we succeeded in elongating the nanocontact into a wire-like structure, with a fivefold increase in volume, up to more than twenty times the original length. Such a large plasticity was caused by the stress-assisted diffusion and the sliding of the intergranular, amorphous-like material among the nanocrystals.
    Nanotechnology 09/2011; 22(35):355704. DOI:10.1088/0957-4484/22/35/355704
  • Y. Fukushima, M. Mita
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    ABSTRACT: In this paper we propose an algorithm of onboard mission replanning using the orthogonal array to solve the problem of repairing of the original mission plan without human operator interventions. The orthogonal array plays an important role to create a group of tentative plans more efficiently than heuristics that is commonly used in standard onboard planning applications. The key idea to implement the proposing mission replanning software is the expression of an operational plan by a “script”. Most spacecraft mission plans are defined as a sequence of system-built-in commands, whereas this “script” contains not only the usual plans but also “logic” type commands. The logic type command is expressed in a form of a program fragment such as “IF A THEN DO B”. To make a further discussion on the proposing idea, this paper also shows a result of an experiment using an autonomous underwater vehicle. The onboard software is based on the proposing software architecture and the replanning algorithm to demonstrate its feasibility in an actual circumstance.
    Advanced Intelligent Mechatronics (AIM), 2011 IEEE/ASME International Conference on; 08/2011
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    ABSTRACT: We report a novel micromachined X-ray optics using DRIE formed micro mirrors for future space astronomical missions. We have fabricated a test optics and measured its imaging quality using X-rays. We have successfully verified the X-ray focusing using this type of optics for the first time in the world. The obtained angular resolution was about 20 arcmin and 3.1 mm. This result was consistent with the expected angular resolution based on the surface roughness of the DRIE formed side walls. To achieve a better angular resolution, we will condition annealing and magnetic field assisted finishing processes.
    Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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    ABSTRACT: In part I of this paper, we have proposed a novel structure of microelectromechanical-systems-based 1-D spatial light phase modulator (SLPM). We have discussed the design of the device and derived the optimum parameters to satisfy the target specifications. In part II, we focus on the fabrication process and experimental results of the device. We show that this device configuration allows us to use a simple fabrication process. We fabricated the device consisted of 24 micromirrors and realized the tilt and piston motions successfully. The measured dc (rotation angle and displacement on driving voltage) and ac (frequency response) characteristics matched well to the simulated data derived in part I. We also examined the distribution of the resonant frequencies over 24 micromirrors and verified that the variance was kept within 2%. As one of the applications of the device, we applied the device to optical beam shaping and succeeded in shaping the optical beam properly depending on the surface patterns of the SLPM. With these achievements, we show that the device can be adopted to a wide variety of applications in optical communication systems and optical signal processing.
    Journal of Microelectromechanical Systems 03/2011; 20(1-20):279 - 287. DOI:10.1109/JMEMS.2010.2090497
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    ABSTRACT: This paper proposes a novel structure of microelectromechanical-systems-based 1-D spatial light phase modulator (SLPM) that consists of a micromirror array on a silicon-on-insulator (SOI) wafer and indium tin oxide (ITO) electrodes on a glass plate. Each micromirror can exhibit bidirectional single-axis tilt, as well as up-and-down piston motions by combining the applied voltage on two ITO electrodes placed over the micromirror and the substrate of SOI (in the case that the substrate is energized, all micromirrors go down simultaneously). This device configuration enables SLPM to be fabricated by a simple process. Part I of this paper focuses on the principles and the design of the device. The optimum parameters of the device are derived to realize both tilt and piston motions, considering ways to reduce mirror warpage and crosstalk from the ITO electrode from the adjacent mirror. We simulate the dc and ac characteristics of the device and confirm that the designs that we optimized satisfy the target specifications to be widely used in optical communication systems.
    Journal of Microelectromechanical Systems 03/2011; 20(1-20):270 - 278. DOI:10.1109/JMEMS.2010.2090496
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    ABSTRACT: We report a new structure of electrostatically addressable and latchable multi-slit shutter array for the astronomical spectrograph with an improved optical and electromechanical performance using the electroplated visors.
    01/2011; DOI:10.1109/OMEMS.2011.6031033
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    ABSTRACT: X-ray optics based on MEMS technologies can provide future astronomical missions with ultra light-weight and high performance optical systems. A silicon optics was fabricated using dry etching and annealing technologies. An angular resolution evaluated in the X-ray wavelength range was about 20 arcmin in full width half maximum, corresponding to 3.1 mm. In this paper, to achieve a better angular resolution, the silicon dry etching and annealing processes are conditioned. The surface roughness of sidewalls were measured at a 100 μm scale. After the conditionings, it has been improved by a factor of four.
    01/2011; DOI:10.1109/OMEMS.2011.6031043
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    ABSTRACT: This paper describes the outline and the five years' on-orbit results of the small scientific satellite REIMEI for aurora observations and demonstrations of advanced small satellite technologies. REIMEI is a small satellite with 72 kg mass, and is provided with three-axis attitude control capabilities for aurora observations. REIMEI was launched into a nearly sun synchronous polar orbit on Aug. 23rd, 2005, from Baikonur, Kazakhstan, by Dnepr rocket. REIMEI satellite has been satisfactorily working on the orbit for five years at present as of January, 2011. Three-axis control is achieved with accuracy of 0.1° (3σ). Multi-spectrum images of aurora are taken with 8 Hz rate and 2 km spatial resolution to investigate the aurora physics. REIMEI is performing the simultaneous observation of aurora images and particle measurements. REIMEI indicates that even a small satellite launched as a piggy-back can successfully perform unique scientific mission purposes.
    Acta Astronautica 01/2011; 69:499-513. DOI:10.1016/j.actaastro.2011.05.007

Publication Stats

439 Citations
53.42 Total Impact Points

Institutions

  • 2005–2013
    • Japan Aerospace Exploration Agency
      • Institute of Space and Astronautical Science (ISAS)
      Chōfu, Tōkyō, Japan
  • 1998–2011
    • The University of Tokyo
      • Institute of Industrial Science
      Tōkyō, Japan
  • 2007
    • Gwangju Institute of Science and Technology
      Gwangju, Gwangju, South Korea
    • Tokyo Metropolitan University
      • Department of Physics
      Edo, Tōkyō, Japan
  • 2006
    • Kanagawa Academy of Science and Technology
      Kawasaki Si, Kanagawa, Japan