Coils and actuators are finding an increasing number of uses in various fields. The demand for microcoils and microactuators is increasing due to the recent progress in downsizing and the increasing sophistication of various industrial products. Actuators account for a large percentage of the total volume and weight of many product compared with other parts and devices that are typically included. However, coils are unsuitable for miniaturization because of their structure. Therefore, we have proposed the use of high aspect ratio microcoils in order to reduce their size and to increase their performance. To realize microcoils such as these, we have developed a fabrication process based on three-dimensional deep X-ray lithography and metallization techniques. We have also used a dipping method in order to obtain thick layers of photoresist on metal bar with diameters of 1 mm. In this paper, we have fabricated microcoils with 10 μm line widths, 20 μm pitch, and aspect ratio of over 5. There is every expectation that high performance microcoils with high aspect ratio coil lines could be manufactured by this process, despite their miniature size.

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A detailed design procedure for a tactile sensor for compliance detection is developed. The sensor principle is based on the concept of applying two springs, with considerably different stiffnesses, to soft tissue for compliance detection. The spring stiffnesses are chosen to be associated with the soft tissue properties. The sensor design parameters are optimized to give high sensitivity and linearity of the sensor output with taking into account the effect of crosstalk between two springs due to the tissue deformation. A finite element model is developed to investigate the sensor performance with the designed parameters using two types of spring end, namely cubic and spherical in shape. The results show a significant stability of reading with the cubic end rather than the spherical one during pushing the sensor against a tissue. Finally, the same finite element model is used with changing the distance between the spring ends to show the crosstalk effect due to the tissue deformation.

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Cantilever-type tactile sensors of silicon-polymer beam structures were fabricated by surface micromachining and covering with elastomers. Two kinds of elastomers with different Young's modulus PDMS and urethane gel have been used to control deflection of the cantilevers and adjust the sensitivity cantilever-type tactile sensors. The resistance change of the sensor with PDMS has linear dependence on normal and shear stresses, but that of the sensor with urethane gel is nonliner to normal and shear stresses. However, the sensitivity of urethane gel type sensor is about 30 times larger than PDMS type sensor.

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Among few existing applications of Microstructured Optical Fibers, a new device for measurement of low gas concentration was designed. Developed set-up based on a Photonic Bandgap Fiber (PBGF), which was used as a gas cell. Proposed technique allowed reducing gas sample volume to 0.01 cc. The gas flow inside core of fiber was simulated and result was confirmed experimentally. During the experimental work several types of fibers of various parameters were specially designed, produced and used. Core diameters ranged from 10.9 μm to 700 μm. Various cutting techniques for fibers were investigated.

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We theoretically and experimentally evaluated the damping effect in a rotational resonator with a comb-drive actuator and sensor. The resonator was fabricated from an SOI wafer and has a fan-shaped mass. The underlying substrate was removed using back side deep reactive ion etching. One set of comb electrodes was attached to each side of the mass: one for electrostatic driving and the other for capacitive detection. In our theoretical analysis, the dynamics of the resonator were simplified so that they could be represented by a lumped system. In this lumped system, the damping coefficient was estimated by assuming the damping to be slide film damping and the air flow to be a Stokes flow. The phase shift due to the slide film damping of thick air layers was included in the lumped system. In the experimental evaluation, one side of the rotational combs was removed step-by-step and a half of the mass using a laser trimming tool so that the individual damping effects caused by the comb electrodes and mass could be determined quantitatively. We compared the experimental results with the results of the theoretical analysis and found that the difference in the damping coefficients between the experimental results and results of the theoretical analysis was less than 40%.

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A thin film Pirani vacuum sensor having a single micro-heater and two diode temperature sensors composed of pn junction diodes on the sensing cantilever, fabricated by micromachining technologies, is driven by a constant applied voltage driving mode using the diode heater to enhance the pressure sensitivity. In these experiments new diode-sensors are used as a temperature sensor, which has a proportional output signal voltage ΔV to the absolute temperature T as ΔV=αT. These new type diode-sensors are useful to measure the temperature difference ΔT between these diode sensors. In this pressure sensing the null detection method is adopted for accurate measurements. In the low pressure range such as 1×10^-3-1×10⁰ Pa the diode-thermistor will be useful because of its higher temperature sensitivity. It is demonstrated that this thin film Pirani vacuum sensor can measure the wide pressure range of 1×10^-3 to 1×10⁵ Pa, which is about 2 order wider pressure range than that of usual Pirani gauge.

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In this paper, we propose a method for improving the robustness of odor classification against humidity change when the odor concentration changes dynamically. We apply a short-time Fourier transform (STFT) to sensor responses to obtain the frequency characteristics, and then employ a stepwise discriminant analysis to select the frequency components effective for the odor classification. We improve the classification performance by selecting the components robust against humidity change and combining them with humidity data. Using a learning vector quantization (LVQ) method, we successfully achieved high classification rate even if the odor concentration changed dynamically and irregularly at different humidity levels whereas the classification rate was insufficient in the case of using only magnitudes of sensor responses.

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This paper reports on the design and simulation of a novel MEMS based convective gyroscope which can independently detect three components of angular rate. The sensor was designed with standard bulk MEMS technology. The 3D jet flow was simulated in the confined space formed by MEMS compatible laminated-structures. The configuration of the sensor consists of a PZT diaphragm, caps, in-plane tungsten hotwires located on the surface of a 0.4mm-thick circular silicon frame with diameter of 10mm. The simulated scale factors of the sensor are SF_z = 0.83 μV/^o/s, SF_x = SF_y = 3.10 μV/^o/s. In measurement application, the 3DOF gyro eliminates the sensor-to-sensor misalignment, and therefore provides accurate measurement with small cross-sensitivity. The sensor also has high shock resistance since no proof mass is used.

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Pd-based metallic glassy alloys have been investigated as materials for the hydrogen sensors. We prepared thin films of Pd-Cu-Si alloy known as typical metallic glassy alloys by r. f. magnetron sputtering method. And then, we examined their sensitivity to hydrogen by measuring the change of electric resistance of thin films when they were exposed to hydrogen gases of various concentrations at 50°C and 100°C. As a result, Pd-Cu-Si metallic glassy alloys showed excellent property as materials for the hydrogen sensors.

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This paper mainly presents the design and fabrication of a TDMA (time division multiple access) passive wireless pressure sensor using 2.45 GHz surface acoustic wave (SAW) delay lines. The SAW pressure sensor consists of two LiNbO₃ substrates. The first layer is a pressure-detective thin substrate, on which an interdigital transducer (IDT) and reflectors are fabricated. The second layer is a support substrate, in which a reference pressure cavity is etched. These two substrates are directly bonded. The pressure measurement was successfully demonstrated in a pressure range of 20∼280 kPa with good repeatability. In addition, the influence of a tire on the wireless interrogation of the sensor was investigated. Automobile tires have little negative influence on wireless communication, at least if they do not rotate.

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This paper describes the design, simulation and fabrication of a 3-DOF (degree of freedom) micro accelerometer with wireless readout system. The fabricated accelerometer has dimensions of 1000μm×1000μm×500μm (Length×Width×Thickness) and can detect three components of linear acceleration simultaneously. The sensitivities to X-axis, Y-axis and Z-axis are 30μV/g, 30μV/g and 23μV/g, respectively. A three input-channels wireless transceiver system has been developed and integrated with the sensing element to form a sensor node. The antenna has been designed to transmit the signal from sensor node to a server at a communication frequency of 2.4GHz over a distance of 20m. Three output signals, i.e. X-axis, Y-axis and Z-axis, from the accelerometer are transmitted to the server by time division multiplexing protocol. This allows our wireless sensor system to detect three components of acceleration independently.

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In this study, a new method for suppressing the background odor effect is proposed. Since odor sensors response to background odors in addition to a target odor, it is difficult to detect the target odor information. In the conventional odor sensing systems, the effect of the background odors are compensated by subtracting the response to the background odors (the baseline response). Although this simple subtraction method is effective for constant background odors, it fails in the compensation for time-varying background odors. The proposed method for the background suppression is effective even for the time-varying background odors.

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In the human skin, four kinds of tactile receptors are distributed three dimensionally, i.e., not only on the skin surface but also in the four corresponding depths of the skin. Imitating this, a tactile sensor having four stories is proposed, inside each story of which capacitive force sensing elements are distributed in an array. The recognition method of contact state using neural networks is proposed. The stress distribution of a sensor sheet is obtained, and the outputs of the sensing elements are simulated by FEM. By applying the outputs to neural networks, it is confirmed that the contact shape recognition is possible, and the sensor having four stories achieves higher recognition rate compared with that having one story. The MEMS fabrication method of an arrayed capacitive tactile sensor made of PDMS is proposed, in which Parylene is used as an anti-stiction layer for the purpose of peeling off the PDMS sheet easily from the substrate. By stacking this sensor one by one, fabrication of a sensor having four stories is possible. A sensor having one story is preliminarily fabricated. The basic performance of one force sensing element and that of an arrayed sensor composed of 3×3 elements are characterized, which shows the potential of the proposed sensor for tactile sensing.

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In this study, we investigate improvements in silicon nanotweezers used to handle DNA molecules. We analyzed the deformation and frequency properties of the nanotweezers by finite element method (FEM) analysis. From this analysis, we determined the appropriate operation area of the nanotweezers.

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