Harmful volatile organic compounds (harmful VOCs), e.g., lacquer, thinner, solvent for paint, are used in a painting process in factories. Two kinds of organic thin films were deposited onto a quartz crystal by an r.f. sputtering with poly(tetrafluoroethylene) (PTFE) and poly(ethylene terephthalate) (PET) targets (sputtered PTFE thin film and sputtered PET film), and we evaluated detection sensitivities for the VOCs using quartz crystal microbalance (QCM) method. The frequency shift of the sputtered PTFE thin film due to the adsorption of the VOCs was larger than that of the sputtered PET thin film when acetaldehyde or toluene was used for the VOC. It suggests that the adsorption mass of these VOCs to the sputtered PTFE thin film was higher than that to the sputtered PET thin film. In addition, the adsorption masses of these VOCs decreased with increase of the environmental temperature at both of the sputtered thin films, which suggests that desorption velocities of these VOC molecules increase compared to the adsorption velocities at higher temperature. The adsorption amount of water of the sputtered PET thin film was higher than those of other VOCs, and response to the detection of water was excellent. Therefore, it is considered that the sputtered PET thin film can be used for reference sensor for water.

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We studied Cu-Cu direct bonding for the application of 3D integration. Thin Cu film deposited specimens are bonded under high vacuum by surface activated bonding method at room temperature. In the room-temperature direct bonding process, surface roughness has a strong influence on bonding. In general, metal bonding needs high bonding pressure. For successful bonding, it is important to reveal the influence of surface roughness and bonding pressure on the bonding properties. Therefore, we investigated the relationship between surface roughness and bonding strength with bonding pressure as the parameter. The specimen with smaller surface roughness than 1nm Ra was successfully bonded by bonding pressure of 10MPa, but for bigger roughness than 1nm Ra the successful bonding needed pressure of 50MPa.

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The MEMS gas sensor consisted of a poly-Si heater, a SnOx gas sensitive film and Pt/TiN/Ti electrodes was produced by all dry processes and the properties of this sensor were evaluated. 50 ppm ethanol gas was stably detected in smaller size and at lower-power consumption by the MEMS gas sensor than by the conventional bulk gas sensor.

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This paper presents a method for detecting the horizontal movement of a human body relative to a two-frequency CW microwave sensor device. It is difficult to detect a target that moves laterally in a system because the change in distance between the target and the sensor is too small. It is not possible to obtain sufficient gain because the Doppler frequency is smaller than the cut-off frequency of the amplifier. In our system, we employ two sensors using sequential lobing to measure horizontal speed of the target. Additionally, we use an approximated curve rather than approximated line to estimate the horizontal speed. We calculate the error rate relative to the actual horizontal speed, and we achieve a reduction in error rate of 40.7% compared to the conventional method, thus indicating the potential usefulness of this method for target detection.

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We have been developing a bus networked tactile sensor system using integrated devices with MEMS force sensors and signal processing LSIs (sensor nodes) to realize the whole body tactile sensation of humanoid robots. Although the MEMS-CMOS integration technology enables the MEMS sensor to have a digital serial communication function which can reduce the number of wires and transferred data, a channel capacity of the bus line is one of the factors to determine the scalability of the system and time resolution of the tactile data. High-speed data transmission of the whole system is a promising way to increase the channel capacity. We developed the 45MHz sensor nodes (previously 1.2MHz). In this paper, we report for the high channel capacity a high-speed asynchronous serial interface system and physical implementation. The interface was implemented on a generic Field Programmable Gate Array (FPGA) with an 800MHz oversampling based clock and data recovery, which uses a phase-shifted multi clocks (200MHz base clock and 4 phases of it). The developed system confirmed that at maximum 35Mbps bus channel capacity with about 550kHz sensor node packet generation rate can be realized, that means each of 255 sensor nodes on the bus can respond within 1ms on an average.

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Characteristics of 75mol%(Zn_1-xMg_x)Cr₂O₄-25mol%TiO₂ ceramics as a gas-sensing element were studied by aiming at the application to electronic nose systems for odor analysis and ethylene (C₂H₄) gas control in fruits ripening processes. These ceramics were prepared by sintering the powders of source compounds, and their sensitivities and response-times for the diluted gases of H₂, NH₄, C₃H₈, C₂H₄, CH₄, and CO in air were examined. It was revealed that these ceramics were p-type and possessed high sensitivities based on the redox reaction by the adsorption and desorption of these gases even at the low concentrations of less than 10 ppm. The dependence on Mg composition x was also reported in relation to the electrical properties.

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[in Japanese]

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