Osamu Tsuboi

A rotational comb-driven micromirror with a large deflection angle and low drive voltage

We have designed, fabricated, and tested a V-shaped torsion bar for use with a comb-driven micromirror. This torsion bar suppressed undesired sticking of the comb teeth, and enabled a large rotational angle and a low drive voltage. We observed 5-degree rotation of a comb-driven micromirror with a drive voltage of 90 V.

A 2-axis comb-driven micromirror array for 3D MEMS switches

Presents a new architecture of a 2-axis comb-driven micromirror array that combines a large deflection angle in a stationary operation, a low drive voltage, and easy scalability for a 3D MEMS switch. By using an SOI wafer with 100-/spl mu/m thick top and bottom Si layers and a 1-/spl mu/m buried oxide layer and, bulk micromachining with DRIE, we fabricated a 2-axis comb-driven micromirror array with a V-shaped torsion bar and comb teeth. The V-shaped torsion bar that has an optimized spring constant that enables both a large rotational angle and a low drive voltage without creating the undesired pull-in motion of the comb teeth. To implement a 2-axis tilt motion, we fabricated a gold bump for creating a gap under the comb teeth on the electrode substrate and mounted the mirror array substrate onto the electrode substrate by using the flip-chip-transfer technique. We fabricated an 80/spl times/80 switch chip and achieved a +/-5 degree rotation of the 2-axis stationary operation with a 60-V drive voltage.

A full-time accelerated vertical comb-driven micromirror for high speed 30-degree scanning

This paper presents a new structure and driving method for a vertical comb-driven micromirror which enables full-time acceleration and mechanical 30-degree scanning with a 4-mm long mirror. Its optimal application is as a scanning mirror for laser beam printers, replacing polygon mirrors which have technical limits in relation to scanning speed.

A multi-chip directly mounted 512-MEMS-mirror array module with a hermetically sealed package for large optical cross-connects

A 512 MEMS mirror array module with a hermetically sealed package for large optical cross-connects is constructed by using newly developed multi-chip direct mounting (MCDM) technology and is demonstrated to enable a plusmn5 degree rotation of the two-axis stationary operation under a drive voltage of 160 V, while having a high resonance frequency of 2 kHz

Si microchannel cooler integrated with high power amplifiers for base station of mobile communication systems

This study demonstrated the first application of a Si microchannel cooler integrated with bump structures to apply as a new thermal management device for the high power amplifiers (HPAs). The structure consists of an HPA chip, Si bumps, and a Si microchannel cooler. The fine pitch Si bumps with metal coating are directly connected to the electrodes close to the active areas of AlGaN/GaN HEMT HPAs. The bump functions not only as a source electrode for small ground inductance, but also as the heat transfer path from HPAs. The heat from bumps is successfully transferred by the microchannel cooler. This first prototype of a Si microchannel cooler bonded to HPAs achieved a decrease of 0.3 °C/W in total thermal resistance compared to conventional face-up mounted HPAs.

Smart power strip network and visualization server to motivate energy conservation in office

This paper describes an electric power visualization system that is developed to reduce electric power consumption in a large-scale office. A small, simple, and smart power strip is developed for practical use with a newly designed built-in contactless current sensor for each outlet. Electric power visualization server used for data acquisition from each outlet of the smart power strip and for the detection of wasted electric power is also developed. Trial service is done with the developed system in an in-house office with 93 persons and 372 outlets. A 15% reduction in power consumption is measured.

A multi-step DRIE process for a 128 /spl times/ 128 micromirror array

A multi-step DRIE process for fabricating a vertical comb-driven micromirror array with five different heights was developed. This process was used to fabricate a dual-axis 128 /spl times/ 128 micromirror array with a high resonance frequency.

Contactless power sensor for smart power strip networked to visualize energy conservation

There is a growing need for energy conservation through energy consumption in offices that have increased 40% from 1990 in Japan. Previously reported electric-power-consumption measurement systems are small for homes [1-3]. We have developed a practical system for a large-scale office. Simple and low power consumption smart power strip having a fail-free power measurement sensor was developed. System software on a server that collects power consumption data from smart power strip makes these visible to motivate user about energy conservation. A block diagram of the developed system is shown in Fig. 1.

Highly selective and sensitive gas sensors for exhaled breath analysis using CuBr thin film

We have examined a p-type semi-conductor CuBr thin film used for sensor devices that indicates the order of sensitivity to ammonia in parts per billion (ppb). The CuBr thin film also indicates excellent selectivity to ammonia among reductive gases, which additionally suggests its capacity for fast quantification of the order of seconds. Moreover, CuBr thin film can be adapted to a high-sensitivity aldehyde sensor by a surface modification. Since the fabrication process of CuBr thin film is compatible with an ordinal CMOS process, there is a potential for development into highly integrated and low power consumption sensor devices. These properties make CuBr thin film a promising candidate as a gas sensing material for human-breath analysis.

A scanning mirror with extremely high resonance frequency up to 0.51 MHz using both torsion and buckling springs

This paper reports about a single-crystalline Si mirror of around a millimeter in size used for laser beam scanning in an optical measurement system in a vacuum. The miniature mirror is capable of scanning at an extremely high-speed of up to 0.5 MHz, and uses a new rotation vibration mechanism involving both torsion and buckling springs. The mirror is fabricated using deep reactive-ion-etch (DRIE) and anodic bonding technologies. The efficacy of the new mechanism is demonstrated by measuring two fabricated scanning mirrors, one having a 0.15 MHz resonance frequency and the other a 0.51 MHz resonance frequency. This paper will explain the concept, fabrication process and discuss the experimental results.