Hall elements as mass production magnetic sensors are new application area for thin film technology such as vacuum deposition and MB E. Highly sensitive InSb thin film Hall elements formed by vacuum deposition are often applied as magnetic sensors for DC brushless motors used in electronic equipment. InAs Hall elements developed and produced by MBE have high sensitivity and stability over a wide temperature range and have potential for the present and future applications required by many electronic systems. Here, we review the recent status of application, production and the good characteristics of thin film Hall elements for use as magnetic sensors.

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We have developed a novel rotational vibrating disk gyroscope using a silicon bulk micromachining technique. The vibrating disk is driven in the rotational direction by electrostatic force using comb finger actuator and is supported by four notched springs. The chip has the size of 8mm×8mm square, which includes the disk shaped vibrating mass with a diameter of 2mm and a thickness of 55μm. Additionally, we adapted the ASIC by using Multi-Chip Service (MICS/MCS) for signal processing. We finally obtained the sensitivity of 28μV/(deg/sec).

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The design and the driving characteristics of a micro conveyance actuator based on superconducting magnetic levitation are reported. This actuator consists of three parts; a superconductor (Y-Ba-Cu-O), a stator layer made by patterned copper electrodes on the poly-imide film and a slider with four permanent magnets (the size of one magnet is 1mm cube). This conveyance actuator is free from particle generation, because there is no contact between moving and stationary parts by the magnetic levitation. The position of the slider is controlled by the current in patterned electrodes. In this paper, we discuss the driving characteristics of the linear and rotary motion by using the micro-step actuation. We have obtained the quick conveyance with the speed of 280μm/s in the range of 2.8mm and the precise positioning with the accuracy of 40μm by combining the step actuation in the entire area and the micro-step actuation in the local area near the target position.

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A novel optically addressed spatial light modulator for optical information processing is proposed. The modulator is integrated with micromirror, on which magnetic material is electroplated, photodiode and electric coil. A phtotocurrent will flow in the electric coil and the mirror supported by four cantilevers is actuated by the generated magnetic forces. This movable mirror is placed parallel to another fixed mirror, which structure is called a Fabry-Perot interferometer configuration. Theoretical analysis is performed to estimate the electromagnetic forces acting on the mirror and the displacement of the mirror. Numerical simulations by three-dimensional coupled magneto-structural finite element analysis are also performed, resulting in good agreement with theoretical results. In addition, it is shown that the proposed modulator is effective for pattern recognition.

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The transient responses of quartz crystal microbalance (QCM) odor sensors coated with tert-butyl-calix [6] arene (calixarene) were analyzed. Calixarene is known as a molecule with a particular pot-like shape and large size. The sensor sensitivity is high because of its sensing film porous structure due to the large molecular size. The transient response, as generated by the application of a step variation in the concentration of the odor vapor, possesses useful information about the structure of the sensing film. The transient response can be modeled supposing a sum of two exponential decays with different time constants. The objective of this work is to study the relationship between the transient responses to the vapors and the sensing film structure. Calixarene was deposited as sensing film on a QCM by the Langmuir-Blodgett (LB) method at various deposition surface pressures. The deposition surface pressure modified the film structure and the transient responses. The results showed that the transient sensor response of calixarene film offers useful information for the separation and classification of odor/ gas samples.

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We propose a novel method for individual immobilization of biomaterial for biosensor application. Various kinds of biomaterial were first immobilized on certain supports such as glass beads or microfabricated metal particles of which size is almost the same as the size of transducer element. Then the suspension mixture of the various support was arranged on the transducer array by the fluidic self-assembly method at random. Glass beads immobilized with glucose oxidase and/or peroxidase were successfully arranged by this method using gravity, as a short-range force required in self-assembly. The beads gave chemiluminescence with the addition of luminol and its substrate. The metal particles consisted of nickel and/or gold layers formed by electroplating and evaporation on a photolithographically patterned chip. The coin-shaped particles were arranged on a nickel dot array by magnetic force interaction as the short-range force. The direction of binding of the particles were also controllable using the multilayer structure.

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