Papers by Author: Yasushiro Nishioka

Abstract: Air-actuated valveless micropumps with dual polyimide (PI) diaphragms have been fabricated and characterized. A 5-μm-thick PI membrane was spin-coated on Si wafer, and released by Si ICP etching. The membrane was actuated by alternating air pressure of 10 kPa. The water flow-rate achieved 80 μl/min at the frequency of 1 Hz and 126 μl/min at 3Hz. Due to nice adhesion between Si and polyimide diaphragms, we could fabricate the double diaphragm micropumps with simplified fabrication processes.

Abstract: A ring-shaped low-frequency resonator operating in the in-plane (2,1) mode was designed and fabricated utilizing anodic bonding of a 9-µm-thick single-crystal silicon to a glass substrate. Although the gap between the ring and the driving electrode was relatively large (900 nm), a high quality factor of 4212 at 1.609 MHz was realized. The motional resistance was 1.853 MW. In addition, the resonant frequency was electrically tuned by varying the dc bias of drive electrodes with 21.5 ppm/V. Therefore, it was expected that this resonator could possibly replace low frequency quarts resonators of a few MHz ranges.

Abstract: Electrical characterization of ⁶⁰Co γ-ray radiation effects on pentacene-based organic thin-film-transistors having two kinds of gate insulator have been carried out. For transistors with SiO₂ gate insulator, the threshold voltage shifts are consistent with positive charge trapping in the oxide and a “rebound” effect is observed. This “rebound” effect is attributed to the negatively charged interface traps generated during irradiation. For polyimide gate insulator, the threshold voltage continually decreases with an increasing total-dose. At total-dose of 1200 Gy (Si), for the SiO₂ gate insulator, the field-effect mobility decreased by almost 80%, and for polyimide gate insulator, it decreased by 40%.