Akira Koide

Simulation of three-dimensional etch profile of silicon during orientation dependent anisotropic etching

A simulation program of a three-dimensional anisotropic etching profile is developed to design the fabrication processes of microstructures made of single crystal silicon. We can now predict a change in the shape of a silicon wafer having an arbitrary crystallographic orientation and an initial three dimensional shape including concave and convex edges. Contrary to the conventional method, which assumes that etch profiles are composed of limited crystallographic planes, the developed system makes it possible to use a number of different crystallographic planes. Using this system, we have developed two new processes for fabricating a three-dimensional microstructure. We called them a multi-step anisotropic etching process and a separated anisotropic etching process. This simulation system is a powerful tool for designing the new processes in fabricating three-dimensional microstructures.

Highly reliable silicon micromachined physical sensors in mass production

Abstract Silicon micromachined physical sensors such as silicon pressure sensors and accelerometers are now in mass production in response to the strong market demands. In the design of such sensors, it is most important to guarantee high reliability as well as low cost. To respond to these demands for microsensors, the designs of device structure, production processes and packaging have been investigated in detail.

Wafer-level two-step bonding process for combined sensor with two different pressure chambers

We developed a wafer-level two-step anodic bonding process for a combined sensor with two different pressure chambers: ambient and low vacuum pressure. This two-step bonding process features: a bonding and non-bonding area controlled with a glass bump array, an anodic bonding process with plastic deformation of the glass bumps at high temperature and high loading, and two different pressure chambers formed with a sequence of bonding processes.

Micromachined dispenser with high flow rate and high resolution

A micromachined dispenser with a high flow rate and high resolution for chemical analysis is described. The flow rate as a function of the actuation frequency increases linearly up to a frequency of 700 Hz with a final value of about 148 /spl mu/l/s using water as a pump medium. The dispensing accuracy is better than 1% (coefficient of variance) at a dispensing volume of 56 /spl mu/l. This dispenser shows good dispensing performance thanks to its precise valve structure and surface-treated nozzle.

Applications of Microfluidic Technology

We have developed products that apply microfluidic technology to various fields: micro-mixing servers used in the chemical development field and in the personal products industry such as perfume and cosmetics; water quality monitoring systems for monitoring water quality items in tap water systems; bio-detection systems for monitoring bacillus content in air. This technology has the advantages of quick, easy use, and efficient processing due to quicker reactions, but it is not yet widely used. For such technology to be adopted, bonding technology that can quickly bond general resin materials and surface reforming technology for obtaining long-term stability is extremely important.Copyright

A Multi-Layered Capillary Chip for High-Throughput Analysis

We fabricated a multi-layered chip consisting of four capillary chips that are optically optimised and excited with one beam. Sample fluorescent light from each capillary was detected cleanly, so the multi-layered chip is suitable for high-throughput analysis of plural samples.

Micro-Evaporator for Pretreatment of Environmental Monitoring Samples

We have developed a new microfluidic device for concentration of solvent. To increase the evaporation rate of solvent, the micro-evaporator flows the solvent as a thin sheet. The prototype of the device was tested, and it was found that 0.11 [mL/min] of water could be evaporated if it was heated with a 10 [W] heater tip.

A Micro-Reactor Equipped with Sheath-Flow Injectors for High-Speed Extraction

A micro-reactor for extracting a solute efficiently from one liquid phase into another without the need for a mechanical mixer equipped with sheath-flow injectors was fabricated. Experiments show that changing the flux ratio between the sample liquid and sheath liquid enables the new micro-reactor to control the width of the injected sample liquid down to 10 µm.