Automobile emission control has been regulated severely for preserve earth environment. The role of the sensor used in the engine regulating system becomes increasingly important and high reliability and highly precision are demanded. Especially, the air flow sensor which measures air flux is important to perform precise combustion in engine.
First of all, the air flux measurement technologies of an automobile engine, and the subjects and countermeasures of a hot wire air flow sensor are described. Next, the development examples of an air flow sensor where utilized MEMS (Micro-Electro-Mechanical System) and DSP(digital-signal-processing) technology for improvements of measurement accuracy and reliability with the miniaturized design are described.

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Abstract - Automotive sensors are used for emission gas purification, energy conservation, car kinematic performance, safety and ITS (intelligent transportation system). The comparison of the sensor characteristics was made for their application area. Many kinds of the principles are applied for the sensors. There are two types of sensors, such as physical and chemical one. Many of the automotive sensors are physical type such as mechanical sensors. And a gas sensor is a chemical type. The sensors have been remarkably developed with the advancement of the MEMS (Micro Electro Mechanical Systems) technology. In this paper, gas, pressure, combustion pressure, acceleration, magnetic, and angular rate sensors for automotive use are explained with their features.
The sensors are key devices to control cars in the engine, power train, chassis and safety systems. The environment resistance, long term reliability, and low cost are required for the automotive sensors. They are very hard to be resolved. However, the sensor technology contributes greatly to improving global environment, energy conservation, and safety. The applications of automotive sensors will be expanded with the automobile developments.

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A high-speed thermoelectric infrared sensor has been fabricated by the CMOS process and micromachining. The time constant of the sensor has been reduced by means of a reduction of sensor size and a thin Si₃N₄ membrane structure. The sensitivity has been improved with a precisely patterned Au black infrared absorption layer formed by a PSG lift-off process. The characteristics of the sensor have been simulated using a thermal equivalent circuit model. A time constant of 270 μsec and sensitivity of 60 V/W at atmospheric pressure have been achieved. This time constant is smaller than any other reported value of thermopiles.

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A heat resistant micro heater consisting of a Pt thin film and a diaphragm was developed for automotive sensors and its reliability was evaluated from the mechanical and thermal points of view. The dominant failure modes for instant overheating and longtime heating were found to be de-lamination of the Pt film and electromigration of Pt, respectively. The life time was estimated to be over 10 years when the average heater temperature was 400°C (the peak temperature was over 600°C). As automotive sensors utilized this micro heater, the developed air flow meter and air quality sensor are described with features and evaluation methods unique to these sensors.

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This paper describes a vision-based algorithm for recognizing the vehicle model type from time-sequence road images. Many types of vehicle models are offered commercially, and some of them are resemble in shape. This prevents us to discriminate their model types from the others easily. To solve these problems, we proposes a hierarchical recognition method with training process, in which the resemble model groups are firstly generated and the effective features to discriminate the models in the each group are then selected using the subspace method in training. In the recognition process, a front area is firstly detected from each frame of the input time-sequence images, then a hierarchical recognition which consists of a group and a category discrimination is performed. Finally, the results of frame recognition are integrated to realize stable recognition. The experimental results using time-sequence road images show the proposed method is effective: the recognition rate for the registered model types is more than 99%, and the rejection rate for unregistered vehicle type is more than 92%.

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Lots of traffic accidents are related in physiological and psychological state of the driver. Therefore, physiological and/or psychological measurement of a driver is important for prevention of a traffic accident. The aim of this study is to quantitatively evaluate the amount of mental workloads by Facial Skin Thermal image (FST), which is thermal image of the human face. A measurement of physiological and psychological state of the driver who is under mentally workloaded during driving task was conducted. The evaluation method for physiological index, which were FST, Electroencephalogram (EEG), Electrocardiogram (ECG), based on the correlations among those indexes was considered. A result of present experiment, an efficiency of FST in evaluation of a mental working load of a driver was shown.

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It is necessary that the presenting information in the driver assistance system is a presentation method trusted by the driver. A conventional driver assistance system presented warning only in the state of the running environment of the vehicle like the headway distance with a vehicle forward etc. In this paper, authors proposed the method for presenting warning that considered the status and the individual difference (It is elderly people in this paper) of the consciousness of the driver in addition to the state of the running environment of the vehicle, and showed the effectiveness by the verification experiment.

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An SOI (Silicon on Insulator) angular rate sensor with an open beam structure (OBS) has been designed and fabricated. To obtain good performance of the sensor, the FEM (Finite Element Method) analysis was carried out for several types of sensor structures to evaluate the vibration stability of the sensor. The stability of vibration modes was investigated by defining the independency between the excitation and detection vibration modes of the sensor structures. The FEM results showed the proposed OBS improved the independency by 60 times compared to the conventional structure.
The OBS also made it possible to wire from electrodes beside the mass of the sensor to exterior bonding electrodes by mono-layer silicon on the SOI. Due to the easy wiring, the process became simple and low cost. The size of the sensor element was 1mm × 1mm × 0.5mm, and good linearity within +/- 0.5 % of the sensor output was obtained. The experimental results showed that the OBS provided fine sensor features; good stability in wide temperature range, and high precision. Therefore, this sensor is suitable for automotive applications, and has attained to mass production.

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We developed a method for detecting driver's gaze direction. Most of traffic accidents are caused by driver's human errors, which often appear with driver's look a side behavior while driving. It is appropriate to provide the drivers warning information depending on their attention levels. We developed our method that detects the positions of both eyes in an image acquired by a camera built in a rear-view mirror for a driver assistance system. Assuming that driver's faces are projected correctly in the images, described in this paper, are the method that we detected the driver's gaze directions accurately.

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This paper proposes a method for evaluating driver stress using a motor-vehicle driving simulator and a biomarker as an index of stress. Software has been developed, which can deliberately control driving tasks, in addition to analyzing driving information, such as frequency of the use of accelerator and/or brakes and the degree of deviation from the driving course. Sympathetic nervous activity was noninvasively evaluated using a hand-held monitor of salivary amylase activity, which chemically measured a biomarker every few minutes. Using healthy 20 female adults, the appropriateness of the proposed method was evaluated in vivo. The experimental results showed that the driving stress might be caused to the drivers in only 20 minutes by adding more severe driving tasks than normally experienced by the subjects without endangering them. Furthermore, the result indicate that frequent measurements of sympathetic nervous activity were possible without putting the subjects under restraint by using salivary amylase activity as the index.

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Using Sn-doped single crystal InSb thin films of 1.0μm thickness grown on GaAs substrates by molecular beam epitaxy (MBE), we have developed new magneto-resistance (MR) elements with very small temperature dependence. These MR elements was used to form rotation detection sensors combined with bias magnet, and we can achieve the stable contactless detection of rotating gear teeth over a wide range of rotation speeds and a wide range of temperatures-20 to 140°C.

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Few researches have been so far investigated in applying lateral motional MEMS structure to a micro-switch. In this paper we report on the design and fabrication of a laterally-driven silicon RF micro-switch, which is based on a capacitive-type series switch. The isolation is greatly improved by using lateral motion in mutually opposite directions. In addition, this lateral movement is effective to alleviate the adhesion of a contact area. The cooperation of electrostatic lateral force with a spring force increases the release force by 28 %. The fabricated switch is expected to have the isolation of -47.6 dB at 2 GHz and the insertion loss of less than 0.2 dB. The silicon RF transmission line proposed here helps the process very easy because of keeping the overall structure simple.

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The detection of accidents on elderly person living alone and the communication between the elderly person and his/her family are very important. This paper describes a new method for tracking and fall detection of elderly person using omni-directional image sensor, and the Itawari-kan communication system that supports their communications and gives alarms for detected accidents on the elderly person. This system tracks the person's head position in real-time by image processing on images captured by some omni-directional image sensor. Then, the system transmits the information of the detected head position to another site. The computer of recipient site generates the computer graphics animation of the tracked person and displays the animation on a monitor. When the system detects an accident from the head position, the system gives an alarm. This method reduces traffic on network and keeps the privacy for the tracked person. We made a prototype system of the Itawari-kan communication system. Experiments on the system showed good feasibility of the proposed system.

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We have developed a high-sensitivity in-situ measurement technology that uses photons with an infrared wavelength band, as well as a systemization technology that demonstrates this measurement technology. More specifically, this measurement technology builds on a wavelength control technology and a wide-band photodetection technology whereby photons can be scanned over a broader wavelength range. With these technologies, gas concentrations can be measured with 1 ppb or higher sensitivity using absorption spectroscopy based on light-source wavelength based scanning in an infrared region.

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We propose a highly reliable thin film temperature sensor of 3x8x0.1mm, for which Nickel foil with a thickness of approx. 0.003mm is bonded onto a Zirconia baseboard of 0.05mm thickness using epoxy resin. The baseboard is then affixed to a ceramic reinforcing board of 0.40mm thickness with polyimide tape, and the fine resistance patterns in the nickel foil are fabricated using photo-etching technology. The resulting resistance patterns are then covered with another Zirconia baseboard using epoxy resin to protect from damage, moisture and acid in the air. Some of the key performance characteristics are a response time of about 6s in air and an accuracy drift of only ±0.01°C/year. As a result this temperature sensor will be applied to the precision manufacturing, semiconductor, and other industries where high accuracy and high reliability are demanded.

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LIDAR(LIght Detection And Ranging) that measures distance by the laser pulse is a necessary sensor of navigation for a deep space explorer that doses a planetary exploration. Two dimension of LIDAR scanning is required from both sides of the navigation control and the science observation in order to make a 3D map of surface efficiently. This paper proposes a novel method on the beam scanning mechanism for a receiver telescope with big aperture by using MEMS technology. In addition, it reports on the result of executing the basic function experiment of the beam scanning mechanism. The scanning optics system is composed of a telecentric telescope, and a micro shutter array. This optical system has achieved a narrow viewing angle corresponding to aperture of the shutter by limiting the view of the telescope that has a wide viewing angle with the shutter. We experimented by using the shutter array of 6mm×6mm size. As a result, it succeeded that the scanning angle in the achievement of azimuth angle 8.8deg, elevation angle 8.1deg, and the field of view angle of azimuth angle 1.8deg and elevation angle 0.6deg.

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In this paper, an optical and electric integrated sensor as a new non-contact sensor for the distance detection and material discrimination is proposed. The proposed sensor uses a pair of CdS cells as the electrodes of the plane type capacitance sensor and measures capacitance at several conditions of light emitting. Several coupling capacitance values are obtained by a pair of CdS cells because resistance of CdS changes by the quantity of light. Accordingly, the electrical and optical properties of the object are obtained from capacitance values. In this experiment, discrimination of seven kinds of sample materials and detection of the distance between the sensor and the material were demonstrated by the optical and electrical integrated sensor. As a result, it was suggested that discrimination of seven kinds of materials and detection of the distance between 1mm and 5mm were possible by the proposed sensor.

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Enzyme-linked Immunosorbent Assay (ELISA) process is widely used for diagnosis, measurement of environmental materials, foods and so on, because of its extreme sensitivity for antigen-antibody reaction. This process, however, requires a long reaction time. We were able to shorten the reaction time required to less than 1 hour, which originally took several to more-than-ten hours, by widely enlarging the reaction area / volume with fabricating fine pillar arrays. Our process will show the possibility for instant diagnosis and instant medical treatment.
Moreover, ELISA process also requires dilution or enrichment of samples beforehand when the concentration of samples is unpredictable because the measurable concentration range is narrow. By changing the reaction area from a vessel to a channel, our device had a larger measurable area which made it possible to detect drastically a wider range of sample concentrations.

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Simultaneous surface modifications of SnO₂ powder with Pt-loading and mesoporous SnO₂ (m-SnO₂) layer-coating have been conducted. The sensors fabricated with the powders prepared with the Pt-loading and subsequent modification with the m-SnO₂ layer showed higher H₂ response than the sensors fabricated with the reverse procedure sequence. Similar synergistic effects in sensing properties to CH₄ and C₂H₅OH were also observed at higher operating temperatures. However, such a synergistic effect was not observed when CO was employed as a sample gas. Thus, strict control of mesoporous structure and loading state of Pt microparticles on the surface of SnO₂ powder was found to be effective technique, which improves the gas-response properties of SnO₂-based sensors.

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