Papers by Author: Ryutaro Maeda

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Authors: Sung Won Youn, Kazumi Suda, Masaharu Takahashi, Ryutaro Maeda
Abstract: This study explores the dynamic mechanical properties (e.g., storage shear modulus, loss tangent and shear viscosity) and formability of a polyimide film by visco-elasticity measurement and hot-embossing tests. The variations of storage shear modulus, tangent delta and the shear viscosity were measured as a function of the temperature for two frequencies. As a polyimide goes through its glass transition, it exhibits dramatic decreases in shear modulus and viscosity as well as the peak of tangent delta, and continues to show strong dependence on frequency and temperature. Moreover, the filling characteristics (e.g., surface appearance, replicated depth and surface roughness) of polyimide were investigated by hot-embossing tests at different temperatures using a mold with an aspect ratio of 2.5:1.
Authors: Takeshi Kobayashi, Jiunnjye Tsaur, Masaaki Ichiki, Ryutaro Maeda
Abstract: Flat PZT cantilevers have been successfully fabricated from the Pt/Ti/PZT/Pt/Ti/SiO2/SOI multi-layered structure through MEMS technologies. A displacement of the tip of the cantilever driven at 6 V is measured to be 7.6 μm and the transverse piezoelectric constant calculated from the displacement is –103 pm/V. 1D optical scanners have been designed, simulated, fabricated and tested. The rotation angles of the mirror of the scanners were 60-70% of the simulated values.
Authors: Masaaki Ichiki, Lulu Zhang, Zhen Yang, Tsuyoshi Ikehara, Ryutaro Maeda
Authors: Masaaki Ichiki, Harumi Furue, Ryosuke Kogo, Yasushi Morikawa, Kazuhiro Nonaka, Takeshi Kobayashi, Chiaki Endo, Ryutaro Maeda
Authors: Keigo Kuroda, Takayuki Komori, Hirofumi Saito, Ryuta Ikoma, Yota Kimura, Hiroki Komatsuzaki, Kenta Suzuki, Sung Won Youn, Hiroshi Hiroshima, Ryutaro Maeda, Yasushiro Nishioka
Abstract: Flexible micropumps are important components for advanced microfluidic systems. Here, polyimide (PI) for flexible micropumps was focused on. This is because PI has many advantageous properties such as good biocompatibility, high thermal stability, and superior mechanical strength. However, the difficulty in realizing an all-PI micropump lies in fabricating microstructures on PI film surfaces. In this paper, we present improved performances of a flexible all-PI micropump fabricated using high-temperature hot embossing above 320 oC that is considerably higher than its glass transition temperature of 275 oC. The fabricated micropump had diffuser/nozzle valves and a chamber with 5 mm diameter, and it was functioned by vibrating a 2-µm-thick PI diaphragm with alternating air pressures outside of the diaphragm. The flow rate of deionized water in the micropump reached to 110 μl/min at 3 Hz.
Authors: N.H. Loh, S.B. Tor, B.Y. Tay, Yoichi Murakoshi, Ryutaro Maeda
Authors: Kotaro Hanada, Yusuke Hashiura, Ryutaro Maeda, Toshio Sano, Hideaki Negishi
Authors: Masaaki Ichiki, Harumi Furue, Takeshi Kobayashi, Yasushi Morikawa, Kazuhiro Nonaka, Ryutaro Maeda
Abstract: Photovoltaic lead lanthanum zirconate titanate films in a layered structure of different crystallographic orientations are fabricated by an optimized metalorganic deposition method. Such films of (001) orientation exhibit a photovoltaic electrical power of approximately 20 times higher than that of random films. The anisotropic optical properties of the oriented films, including dark conductivity, photoconductivity and photovoltaic tensor surfaces, are obtained quantitatively. These results show that the photovoltaic output current and power of the oriented films are highly improved to be equal to those of semiconductors and suitable for application in the optical sensor of micro-electro-mechanical systems.
Authors: Masaaki Ichiki, Takeshi Kobayashi, Harumi Furue, Yasushi Morikawa, Kazuhiro Nonaka, Chiaki Endo, Ryutaro Maeda
Abstract: This paper reports on the formation of film structures and the highly improved photovoltaic output current of the lead lanthanum zirconate titanate (PLZT) employed. The photovoltaic effect of ferroelectrics has the advantage of its simple mechanisms of non-bias applications which are indispensable for semiconductor p-n junctions. But the output current of PLZT bulk is too low for use as a device current source. The PLZT film structure exhibited μA output current upon light illumination. The photovoltaic current of the PLZT film was more than 102 times than that of bulk PLZT. These differences are due to the characteristics of the design of the film including the configuration of the electrode. The PLZT film also has the advantage of easy output control and suitability for use on Si. Results show that the photovoltaic effect of the ferroelectric film is useful as the current source for micro-electro-mechanical systems (MEMS).
Authors: H. Takagi, Ryutaro Maeda, N. Hosoda, Tadatomo Suga
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