Due to the processing limitation of photolithography, only width and length have been controllable parameters for designing mechanical characteristics of silicon micromachined structures, while thickness has been left pre-determined by the thickness of layers. The range of electromechanical properties have been, therefore, strongly limited by the practical range of these tunable parameters. In this paper, we present a universally applicable fabrication technique to realize multiple-height microstructures by locally controlling the etching depth of ICP-RIE (inductively coupled plasma-reactive ion etching). Several layers of etching masks of different materials have been prepared on the initial surface of substrate to avoid repeating photolithography on the etched surfaces. This technique enables us to have one more degree of freedom in designing MEMS structures.

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Bending processes of micro-cantilevers with constant bending moment driven by electro-static force are investigated and analyzed theoretically by using finite-difference method (FDM), Newton's method and bisection method. In this analysis, a mode boundary chart is introduced to illustrate boundaries of some deformation modes, which are categorized by the contact situation between the cantilever and an electrode substrate. From the mode boundary chart, existence of hysteresis movement of the cantilever is predicted and transition processes of deformation modes are analyzed. To confirm the usefulness of the theoretical analysis, micro-cantilevers are fabricated and cantilever's deformation curves are observed experimentally at various applied voltages. As a result, the deformation curves of cantilevers demonstrate the usefulness of the theoretical predictions.

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In this paper, a novel bulk grating in which its pitch can be changed by the shape memory alloy (SMA) actuator has been fabricated using silicon micromachining technology. The pitch-variable grating is specially designed to change the pitch easily with small force. The grating is designed to assure moderate stress by finite element method (FEM). Using the reactive ion etching, the grating has a high aspect ratio more than 10. In the diffraction experiment, more than 10% extension ratio has been obtained. The SMA actuator has been installed to the grating. Due to the two-way shape memory effect, the translation mechanism is simple and is easily controlled.

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In recent years, catheter-based interventional diagnosis and therapy have become increasingly popular. However, the operation of the catheter requires certain human skill because conventional catheters can not bend actively for steering. For the bending motion, we have developed active catheters which has many joints of Shape Memory Alloy (SMA) coil actuators in order to move like a snake. Polymer link active catheter which has link structures between the joints, and linkless type active catheters which have no joint were developed. Linkless outskeletal active catheters which have SMA coils inside the linter coil were also developed. This is suitable for practical use in a human body because of its small heat dissipation from the surface.

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This paper reports a new batch fabrication method of active catheters which have bending, torsional and extending functions for steering. The active catheter consists of shape memory alloy (SMA) coil actuators and a liner coil to return to its original shape. The SMA coil and the liner coil are connected each other using electroplating of nickel and electrodeposition of acrylic polymer. This novel method makes low cost assembly and small diameter (φ1.4mm) possible.

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The method for detecting odor samples using mono-channel QCM LB film sensor is described. The sensing film deposited on the QCM electrode was DOABr combined by PVSK as an under layer. The odor sensor was able to detect the usual frequency shift and more the viscosity of odor samples by measuring resistance shift of QCM. Single odor samples, such as benzene, hexane and chloroform can be detected by these parameters. Mixed odor samples could be also detected by adding the response time measurement.

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The resistance or impedance of a resistive humidity sensor element changes widely a factor of up-to10⁴. To process the wide range resistance/impedance change without reducing any SN ratio, this paper proposes newly developed stable signal processing circuits for a resistive humidity sensor. The humidity signal is converted in order of humidity(h)-resistance(R)-frequency(f)-time(t)-voltage(V). The functions corresponding to the conversions are a h-R, a R-f and a newly developed time-constant controlled f-V converter respectively. A h-R converter is a humidity sensor element itself. The time signal (t) is treated in the f-V converter. As the frequency and time signals are able to have a wide dynamic range, the large dynamic range of R is held through the R-f and f-V conversions. So, the reduction factor of SN ratio is minimized. The f-V converter plays roles of a voltage amplitude compressor and a linearizer. As the resultant characteristics, it has been shown that the developed circuits are accurate (±2%RH, at room temperature), stable for very long term (over 40, 000 hours) and stable against supply voltage fluctuations. In addition, controlling the function of the time-constant controlled f-V converter, an absolute humidity sensor has been obtained.

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In this paper, we tried to extract information of driving-state of gas generating sources which are located in an indoor space(e.g. oil stoves, gas ranges and so on) for recognition of human activities and environmental changes. It is necessary for extracting information of driving-state of gas generating sources that not only a signal of gas concentration in an indoor space but also signals of components in gas concentration which depend on each gas generating source are estimated. In this paper, we proposed methods to find appropriate combination of component signals of gas generating sources using Genetic Algorithm(GA). Then, uniqueness and robustness theorem in estimation by our methods are shown in computing simulations. And we shown it is possible to extract information of driving-state of gas generating sources from a gas sensor response in an actual experiment.

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