藤田 孝之

Previously, we developed a flexible and biocompatible wiring that has excellent performance to tension and good inflectional characteristics. Using this technique, we prepared the flexible strain sensor and we successfully achieved to measure the strain level. © 2012 The Institute of Electrical Engineers of Japan.

Continuous human monitoring is substantially useful to realize a high QoL (quality of life) society. In the previous work, we fabricated a prototype system for monitoring an electrocardiograph (ECG), heart rate (HR), 3 axes human body acceleration, temperature for human body and human circumstances, simultaneously. These data are transmitted to the host PC and used for analyzing the human activities and conditions such as a heart rate variability (HRV). The HRV that calculated from HR is valuable for recognizing a mental or physical stress of human subjects. In this study, we demonstrate a fuzzy logic HR extraction algorithm on the prototype system to realize an autonomous HRV monitoring system. On-board fuzzy algorithm will reduce the communication traffic and improve an accuracy of the HR extraction. From the implementation result, the error ratio of the HR extraction is improved from 0.9 % to 0.4 %.

In this paper, we demonstrate for the first time ring laser oscillation using a set of silicon (111) mirrors fabricated by microelectromechanical systems (MEMS) technology with a semiconductor optical amplifier (SOA) as an optical amplifier medium. Four (111) mirrors were fabricated perpendicular to a (110) silicon wafer surface to form an optical loop. The (111) mirrors were fabricated by a combination of deep reactive-ion etching (DRIE) and anisotropic wet etching, followed by electroplating with a highly reflective Au film. Adjusting the mirror alignment for the oscillation was not required because the mirrors were already precisely positioned with the accuracy of the crystal orientation. In experiments, oscillation began at an injection current of more than 110 mA into the SOA. We confirmed that both forward and backward propagating lasers oscillated simultaneously in a single mode. Our results will especially be useful for realization of next-generation optical MEMS ring laser gyroscopes.

The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-mu m-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Usingasiliconmoldingtechniquecomplementedbyalift-offprocess, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 mu m are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T. (C) 2011 Elsevier B.V. All rights reserved.

The mechanical properties of low-stress cantilevered Nd2Fe14B/Ta multilayered microstructures are characterized. The cantilevered microstructures are fabricated using silicon molding technique and XeF2 gas-phase silicon etching process. The magnetic microcantilevers show relatively high quality factors varying from 75 to 135. The Young's modulus of the Nd2Fe14B/Ta multilayered film is evaluated by fitting the resonance response of the microcantilevers, which is smaller than those of bulk Nd2Fe14B magnets due to the texture effect. The good mechanical properties of the microcantilevers indicate that Nd2Fe14B/Ta multilayered films can be used as a structural material for microsystem applications. In addition, the electromagnetic driving of the Nd2Fe14B/Ta magnetic microcantilever is also demonstrated. (C) 2011 The Japan Society of Applied Physics

This paper describes the fabrication of MEMS-based electromagnetic energy harvesters for scavenging energy from the ambient vibration. The novel energy harvester is fabricated by bonding a vibrator with embedded micro-magnets and a stator with integrated microcoils. The micro-magnets are formed by using sputtering deposition of NdFeB/Ta multilayered magnetic films with a thickness of 10 mu m and silicon molding techniques. High-aspect-ratio silicon micro-springs are fabricated using deep reactive ion etching to achieve large vibration amplitude. The microcoils fabricated by electroplating processes are serially connected for multiplication of the output voltages from individual magnet-coil units. The energy harvester is successfully fabricated and wire-bonded for characterization. The maximum voltage output of the energy harvester at 115 Hz is approximately 2 mV, which corresponds to a power density of 1.2 nW cm(-3). The performance of the energy harvester could be greatly improved by protecting the micro-magnets from oxidation and decreasing the spacing between the vibrator layer and the stator layer.

To evaluate the ship-handling skills and kansei of professionals and students, we studied physical performance and mental workload using a simulator and an actual ship. We demonstrated the effects of physiological indices based on professional performance and features as seen from their mental workload with heart rate variability, nasal temperature, and salivary amylase activity, and considered new practical education using professional kansei.

This paper describes the micro-patterning of thick NdFeB magnetic films using a high-power plasma etching method. The effects of RF bias power and gas composition on the selectivity and etching rate are experimentally studied. A maximum etching rate of 60 nm min(-1) is achieved with an inductively coupled plasma power of 500 W and a RF bias power of 200 W. A maximum selectivity of 0.26 between hard baked AZP4903 photoresist and NdFeB magnetic films is achieved when volumetric Cl-2 concentration is 2.5%. NdFeB micro-magnets as thick as 4.2 mu m are achieved by using AZP4903 photoresist. Magnetic film as thick as 10 mu m can be patterned by using SU-8 photoresist with a thickness of 100 mu m as the mask. The magnetic property of patterned microstructures is characterized using a vibrating sample magnetometer and the magnetic field distribution is measured using a Hall effect sensor IC. The characterization results indicate that the patterned magnetic microstructures have a high magnetic remanance of 1.0 T, which is comparable to that of the non-patterned NdFeB films.

In this paper, we describe a novel type of ring laser gyroscope (RLG) using the winking phenomenon. Conventional sensing methods of gyroscopes are categorized into vibrating-type gyroscopes using the Coriolis force and optical-type gyroscopes using the Sagnac effect. The novel type of gyroscope presented here utilizes the winking phenomenon. The winking phenomenon is intensity changes of circulatory counter propagating lasers with an applied angular velocity. The advantage is that the intensity change caused by the winking phenomenon is more than 100 times larger than the capacitance change of conventional gyroscopes in micro-electromechanical systems (MEMS) technology. The detecting circuits for the winking phenomenon become simple compared with the vibrating M EMS gyroscope, because the circuits of the MEMS gyroscopes should detect a capacitance change of 1.5x10(-4)%/deg/s, which corresponds to 0.7 aF/deg/s. The novel RLG using the winking phenomenon does not have a dead-band because the intensity changes are linearly observed at a small to middle angular velocity. Thus; a mechanical dither is not required like in a conventional RLG using a He-Ne laser. En the experiments, an RLG including a semiconductor optical amplifier (SOA), mirrors, and beam splitters is assembled to observe the winking phenomenon. The basic characteristics of laser intensity vs. injection current and wavelength spectra were confirmed and the winking phenomenon was observed when an angular velocity was applied to the RLG. We observed that the change in laser intensity is 1.9x10(-2)%/deg/s.

Thick silicon dioxide with good heat insulation properties can reduce the parasitic capacitance and heat conductivity in sensors and actuators. This research focuses on the evaluation of the mechanical properties of the silicon dioxide microstructure fabricated by using trench etching and oxidation process in order to use it for movable elements. in MEMS devices. The elastic modulus is estimated from the resonant frequency of fabricated cantilevers. It revealed comparable values to that of bulk SiO2. Non-linear characteristics such as hardening and softening spring effects are observed dependent on the patterning direction of trench etching. (C) 2011 Published by Elsevier Ltd.

The data of human activities and circumstances are important factor for the system-of-systems engineering (SoSE) with human centered systems. A small device that can collect a lot of data of the human conditions and circumstances by using various MEMS (Micro Electro Mechanical Systems) sensors is very useful device to monitor the human accidents or troubles. This study demonstrates a prototype development of a multipurpose human-data acquisition system that can measure various time-based data e.g. 3-axis acceleration, humidity, pressure, temperature, ECG, and microphone, simultaneously. The measured data are stored in a micro SD card memory or transmitted from the Bluetooth RF module via an onboard microcontroller, which will be help for data analysis. The detailed configurations of the prototype device and some experimental results are also shown. © 2011 IEEE.

Continuous observation of human activities and circumstances are quite important to improve the QoL (Quality of Life). A small device that can collect a lot of data of the human conditions and circumstances by suing various MEMS (Micro Electro Mechanical Systems) sensors is very useful device to prevent the human accidents or troubles. The accidents especially happen to the professional driver or pilot e. g. the operator of the human centered transportation systems cause a serious accident. This study demonstrates a prototype development of an autonomous multi-environmental sensing device for human applications that can measure various time-based data, simultaneously. The measured data are stored in a micro SD card memory via an onboard microcontroller, which will be help for data analysis and preventing the accidents. The detailed configurations of the prototype device and some experimental results are also shown.

A pilotage is one of important factors in order to keep a safety and a security of main harbors in Japan; however, pilots' marine accidents sometime happen while they work. The pilots' accidents happen well for the transfer from vessel to pilot boat on the sea, and pilots and pilots' associations do their best for reducing the accidents under International Maritime Organization (IMO) convention. In other word, a safety measure for the transfer is the important subject for pilots. The purpose of this paper is to evaluate a pilot's physical performance while their work using large model sensors (acceleration sensors), and we read characteristics of performance for the transfer. This research is first challenge to evaluate the pilots' performance in real situation.

Human centered transportation systems assume a large role in our daily life. In order to improve the quality and safeness of the systems, an ultra-small wearable sensor network that monitors the human operator's activity is heavily demanded. The system is constituted by the fully batch fabricated MEMS (Micro electromechanical systems) sensors, MCU (Micro control unit), ICs (Integrated circuits), RF (Radio frequency) module and also energy harvester for power supply. The energy harvester is one of the small power generators that obtain the electrical energy from the ambient environment. This autonomous power supply provides the continuous monitoring system for long periods. This paper reports a vibratory type energy harvester by using electrostatic mechanism and its application for the human centered transportation system. © 2011 IEEE.

A wearable health monitoring system and its applications for long term monitoring are presented in this paper. The system, called a "button system," is attached over the chest for monitoring electrocardiogram (ECG), heart rate (HR), 3 axis acceleration, and temperature, as well as system battery voltage. The data is then sent to the host computer via a wireless transmitter. The button system is composed of three round substrates connected together. The substrate is 24 mm in diameter and 5-10 mm thick, making the system applicable for use in daily life. The several various types of sensors, microcontroller, programmable gain amplifier (PGA) and Bluetooth wireless transmitter are embedded in system. The Micro Processing Unit (MPU) samples ECG and acceleration at 125 Hz to calculate HR for transmission. The battery voltage and temperature are sampled at 0.2 Hz due to the slow variability. The current consumption during wireless telecommunications is about 40 mA, so it is possible to use it continuously for about two hours with Li-ion button battery (75 mAh). In this study, we measured data while sleeping (for about 6 hours) with a large capacity battery (2000 mAh) instead of Li-ion battery. Heart rate variability (HRV) was then used as a quantitative marker of automatic nervous system activity, and the temporal variation of HRV was estimated. © 2011 IEEE.

Continuous observation of human activities and circumstances are quite important for healthcare applications that collect a lot of data from the various MEMS (Micro Electromechanical Systems) sensors. This study demonstrates the multi-environmental sensing system for human applications that can measure the time-based three-axes acceleration (threeaxes shock), barometric pressure, temperature and relative humidity, simultaneously. The system has battery and large sized memory for autonomous sensing. The measured data are stored in a flashmemory via an onboard microcontroller. The detailed configurations of the prototype device and some experimental results are investigated.

This paper reports the observation of winking phenomenon in a ring laser gyroscope (RLG), in which the air is used as a laser path with a semiconductor optical amplifier (SOA) as a gain medium. The winking phenomenon is a significant characteristic of RLGs, which the light intensity varies with an applied angular velocity. The ring laser resonator using an SOA was assembled to observe the winking phenomenon and resonance characteristics were examined. As a result, the winking phenomenon was successfully observed and we found that the SOA can be used for the gain medium of the RLG.

In order to establish monitoring systems for home health in elderly people including the prevention of mental illness, we investigated the acceleration of teeth in utterance on the assumption that an acceleration sensor can be implanted into an artificial denture in the near future. In the experiment, an acceleration sensor was fixed in front of the central incisors on the lower jaw by using a denture adhesive, and female and male subjects spoke five Japanese vowels. We then measured the teeth accelerations in three (front-to-back, right-to-left and top-to-bottom) axes and conducted frequency analyses. The result showed that high power spectral densities of the teeth accelerations were observed at a low frequency range of 2-10Hz (both the female and the male) and at a high frequency range of 200-300Hz (the female) or 100-150 Hz (the male). The low and high frequency components indicate movements of the lower jaw and voice sounds by bone conduction, respectively. Especially in the top-to-bottom axis of the central incisor, the frequency component appeared to be significant. Therefore, we found that utterance can be efficiently detected using the acceleration in this axis. We also found that three conditions of normal speech, lip synchronizing and humming can be recognized by using frequency analysis of the acceleration in the top-to-bottom axis of the central incisor.

This study demonstrates the electret type inertial energy harvester for low-frequency vibrations such as human movements. Because a moving mass of the harvester is supported by the very soft spring, the mass collides easily with the frame structure. This collision induces the higher natural frequency vibration to the mass even at the applied vibration frequencies below the natural resonant frequency, which improves the efficiency of the power generation. The fabricated device generated the power of 1.8 nW(rms) for applied vibration of 20 Hz and 200 mu m(p-p) with the optimal load resistance of 32 MO. The packaged device size is 0.23 cm(3) and the weight of the moving mass is 122 mg. (C) 2011 Published by Elsevier Ltd.

Mental workload is useful for evaluating a performance of ship navigator- a captain, a duty officer, and a pilot. The heart rate variability (R-R interval), nasal temperature and salivary amylase predict well based on pre-experiments; however, most of research tests a professional skill. The evaluation does not test a cadet yet. Moreover, the teamwork evaluation is not yet also. In this paper, we measure cadets' R-R interval while they guide a ship from narrow channel to open sea in New York, and evaluate their teamwork based on R-R interval for simulator training. The experiment is carried out using a ship bridge simulator, not a real ship. We show R-R interval is a good index for evaluating the teamwork for simulator training in ship navigation. © 2011, TSI® Press Printed in the USA. All rights reserved.

This paper reports the observation of winking phenomenon in a ring laser gyroscope (RLG), in which the air is used as a laser path with a semiconductor optical amplifier (SOA) as a gain medium. The winking phenomenon is a significant characteristic of RLGs, which the light intensity varies with an applied angular velocity. The ring laser resonator using an SOA was assembled to observe the winking phenomenon and resonance characteristics were examined. As a result, the winking phenomenon was successfully observed and we found that the SOA can be used for the gain medium of the RLG. © 2011 The Institute of Electrical Engineers of Japan.

In order to establish monitoring systems for home health in elderly people including the prevention of mental illness, we investigated the acceleration of teeth in utterance on the assumption that an acceleration sensor can be implanted into an artificial denture in the near future. In the experiment, an acceleration sensor was fixed in front of the central incisors on the lower jaw by using a denture adhesive, and female and male subjects spoke five Japanese vowels. We then measured the teeth accelerations in three (front-to-back, right-to-left and top-to-bottom) axes and conducted frequency analyses. The result showed that high power spectral densities of the teeth accelerations were observed at a low frequency range of 2-10Hz (both the female and the male) and at a high frequency range of 200-300Hz (the female) or 100-150 Hz (the male). The low and high frequency components indicate movements of the lower jaw and voice sounds by bone conduction, respectively. Especially in the top-to-bottom axis of the central incisor, the frequency component appeared to be significant. Therefore, we found that utterance can be efficiently detected using the acceleration in this axis. We also found that three conditions of normal speech, lip synchronizing and humming can be recognized by using frequency analysis of the acceleration in the top-to-bottom axis of the central incisor. © 2011 The Institute of Electrical Engineers of Japan.

This paper reports a novel micro gyroscope with improved resistance to acceleration or shock, which can measure 2-axis angular velocity with a single device. The novel device has a completely solid structure made of piezoelectric material, bulk-PZT, which is quite simple and unlike any conventional MEMS gyroscopes. When a longitudinal vibration is excited in PZT rectangular prism, a differential output voltage, generated by the Coriolis force, is obtained at the top and bottom surface electrodes, which is proportional to the applied angular velocity. The paper describes the operation principle, device design, and preliminary experimental results.

Monitoring of cardiorespiratory information such as the respiration and heartbeat is very important for public healthcare. Belt-type cardiorespiratory sensors using polyvinylidene fluoride (PVDF) as the sensing material have been studied by many research groups. In order to extract the respiration and heartbeat signals from the sensor output, very complicated low-frequency filtering circuits and analysis schemes are required. In this research, we propose a PVDF-based cardiorespiratory sensor with independently optimized sensitivity to heartbeat and respiration. The sensor comprises of a bending-sensitive unit and a bending-insensitive unit. The heartbeat signal can be optimized by using the bending-insensitive mode, and the respiration signal can be maximized by using the bending sensitive mode. This principle was experimentally verified using a prototype device. A batch fabrication process for the patch-type cardiorespiratory sensor made of flexible substrate, PVDF and flexible electrode was described. (C) 2009 Published by Elsevier Ltd.

Output-voltage operation on a sensor structure is proposed and a tri-axial accelerometer with low cross-axis sensitivities is designed. The output voltage between the electrodes sandwiching piezoelectric thin-films on a deforming structure is proportional to the in-plane stress of the piezoelectric thin-film. If the piezoelectric thin-film is processed to separated elements and the electrodes of the elements are connected in series, the output voltages from the series-connected piezoelectric elements are multiplied or canceled depending on the situations of the internal-stresses (i.e. compressive or tensile) of the elements. Proper design of the electrode connections by taking the deformation shape of structures into consideration can realize expected output-voltage operations on the device structure. The principle of structure-based output-voltage operation is applied to the design of a tri-axial accelerometer with low cross-axes sensitivities. Finite-element-method (FEM) simulations of the tri-axial accelerometer revealed the cross-axis sensitivity of less than 1.5 %. (C) 2010 Published by Elsevier Ltd.

A lot of energy harvesting devices using electret material has been developed. Since the power from the electret energy harvester is proportional to the surface charge concentration, i.e. charged voltage on the electret, frequency and dynamic range of the capacitance change. To fabricate the electret, the corona discharge is a very popular charging method that consists of a high voltage needle for corona ions generation, and a grid electrode applying a bias voltage that implants the electrons from corona ions to the electret material. In this study, we introduce a novel charging method with fine patterns using the buried grid-electrodes applied with a bias voltage. We also describe FEM analysis and experimental results. (C) 2010 Published by Elsevier Ltd.

4-Alkylidenehydrazino-1H-pyrazolo[3,4-d]pyrimidines, 4-arylmethylidenehydrazino-1H-pyrazolo[3,4-d]pyrimidines, and 2-substituted 7H-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]-pyrimidines as potential xanthine oxidase inhibitors were docked into the active site of the bovine milk xanthine dehydrogenase using two scoring functions involved in AutoDock 3.05 and the CAChe 6.1.10. The correlation coefficiency obtained between the AutoDock binding energy and IC(50) of the inhibitors was better than that obtained by the CAChe-PMF docking score. Many ligands exhibited one to four hydrogen bonds within the active site, where the detected hydrogen bonds by CAChe was identified quantitatively in the docked conformation by using MOPAC 2002. These ligands were docked into a long, narrow channel of the enzyme leading to the molybdopterin active moiety, with hydrogen bonding and electrostatic interaction between the planar aromatic moiety of the ligand and the enzyme. Furthermore, SAR among inhibitors was investigated, which revealed that the oxo group of pyrazolopyrimidine analogs is essential for its activity and the tricyclic derivatives are shown to be more potent than bicyclic ones. The mode of interaction of the docked inhibitors was described in details.

In this study, we developed a precise 2D MEMS (Micro ElectroMechanical Systems) mirror control system. The system comprises a two-sided mirror and rectangularshaped springs that fabricated on a silicon-on-insulator (SOI) wafer. The mirror movement is detected by a specialized holed position sensitive device (H-PSD), and is proportional-integralderivative (PID) controlled by a microcontroller (MCU). We also discuss an application of an optical laser projector that can depict an arbitral figures on the screen. © 2010 IEEE.

In order to maintain human health care, it is important to record daily activity. For recording daily human activity, monitoring system which consists of multiple microelectromechanical systems (MEMS) has been developed. Using the MEMS based monitoring system, numerical data of subject's activity can be stored into a database. For example, when subject's activity on a single day is recorded, a huge volume of data is saved. To estimate the subject's activity condition from such a huge volume data, a fuzzy rule based approach is used in our study. Our proposed method consists of two steps of abstraction. First, action primitives are defined. In the first-step abstraction, sensor data is expressed as a sequence of actions by using the defined action primitives. Next, a fuzzy rule which maps a sequence of actions to a behavior is defined for each behavior. In the second-step abstraction, each sequence of actions is expressed as a behavior. From the results of abstraction, we can estimate the subject's state. © 2010 IEEE.

For the multiplication of sensor output voltage, series-connected PZT elements are proposed. The series-connected PZT device is successfully fabricated using dry-etching process of PZT. To validate the multiplication, the output voltages are measured when the device is vibrated. The output voltage of eight series-connected PZT elements roughly corresponds to the sum of the output voltage obtained from each single element. Using circuit simulator, SPICE, the influence of the parasitic capacitances is investigated. The calculated output voltages are in excellent agreement with the measured ones. Reducing the parasitic capacitances properly, the output voltage is linearly multiplied with the number of series-connection.

This paper describes a wireless cardiography monitoring system for human healthcare. The system consists of a cardiography sensor module and a radio frequency (RF) module for data communication. And the P, Q, R, S, T signals was acquired by using the prototype cardiography sensor. Real-time cardiography monitoring was demonstrated with a RF base station which was located 10 m away from the sensing object. ©2010 The Institute of Electrical Engineers of Japan.

For the multiplication of sensor output voltage, series-connected PZT elements are proposed. The series-connected PZT device is successfully fabricated using dry-etching process of PZT. To validate the multiplication, the output voltages are measured when the device is vibrated. The output voltage of eight series-connected PZT elements roughly corresponds to the sum of the output voltage obtained from each single element. Using circuit simulator, SPICE, the influence of the parasitic capacitances is investigated. The calculated output voltages are in excellent agreement with the measured ones. Reducing the parasitic capacitances properly, the output voltage is linearly multiplied with the number of series-connection. ©2010 The Institute of Electrical Engineers of Japan.

This paper provides MEMS (micro-electromechanical systems) vibratory beam accelerometer (VBA) for human movement measurements, which have a digital control system. The device structure with size of 5 x 5 mm2includes a frame, heavy mass, thick suspension beams, and thin vibrating beams made of silicon single crystal. The VBA measures acceleration using the resonant frequency change of the vibrating beams, which are designed to provide little resistance to movement along the sensitive axis and stiff resistance on the off-axis. This provides low off-axis sensitivity and high shock survivability. In this study, we designed a fully digital PLL (phase-locked loop) circuitry in a FGPA (field programmable gate array) based hardware controller. By Allan deviation, we proved that our system shows an extremely high resolution of 34 μG Hz−1/2and wide dynamic range of 90 dB in a device operation at 1 mTorr ambient pressure. © 2009, TSI® Press Printed in the USA.

This paper presents series-connected PZT elements that yield high output voltage, and also shows complete establishment in the fabrication process. Series-connected PZT elements are realized by connecting the upper electrode of a PZT element with the lower electrode of another PZT element. Sputtered PZT thin-film has perovskite crystalline structure and piezoelectric coefficients up to 40 pC/N. To avoid troublesome wet etching, the PZT films, the electrodes, and insulation layers are dry-etched. The all dry-etching process performs multilayer wiring of the electrodes. Evaluations for the PZT elements validates that the output voltage is the sum output voltage of each single element.

In this paper, we present the concept of a microelectromechanical systems ring laser gyroscope (MEMS-RLG) and its optical components. MEMS-RLG has a semiconductor optical amplifier (SOA) enclosed with mirrors that form an optical loop for an external laser oscillator in free space. To confirm the feasibility of MEMS-RLGs, we constructed an experimental device with commercially available SOA and mirrors for external oscillation. We also show the fabrication and characteristics of optical components such as movable mirrors and a lens-positioning device, which are required for a miniaturized MEMS-RLG.

Observation of daily human activity and status is important from the viewpoints of maintaining health and preventive medical care. In this study, we describe a system for monitoring human activities and conditions that uses microelectromechanical systems (MEMS) sensors. The system contains four MEMS sensors for environmental monitoring-3-axis acceleration, barometric pressure, temperature, and relative humidity -as well as the peripheral circuitry for each sensor. Measured human activity data are stored in a memory via an on-board microprocessor. We measured environmental data for a subject's daily life. To estimate the subject's activity and his condition from a huge volume of data, we applied a soft computing technique to machine learning for the automatic extraction of human-activity classification.

This report describes an examination of mechanical properties of multi-layer thin-film beam for a MEMS (micro-electromechanical systems) vibratory beam accelerometer (VBA). The target accelerometer has a frame, heavy mass, thick suspension beams and thin vibrating beams made of silicon or some MEMS materials with the size of 2 × 2 mm^2. The VBA measures the acceleration by using resonant frequency change of supporting beams. Since the beam property heavily depends on the performance of VBA, the stress examination method that uses resonance frequency of both-end-support beams with different lengths was used. Finally, the vibratory beam for the miniaturized VBA that contains layers of compressive-TEOS/tensile-TEOS/Pt-Ti/SiN/SiO_2 with suitable tensile stress of 7 MPa and low deflection of 0.75 μm was obtained.

This report provides a MEMS (micro-electromechanical systems) vibratory beam accelerometer (VBA) having a digital control system. The device structure with size of 5 x 5 mm(2) includes a frame, heavy mass, thick suspension beams, and thin vibrating beams made of silicon. The VBA measures acceleration using the resonant frequency change of the supporting beams, which are designed to provide little resistance to movement along the sensitive axis and stiff resistance on the off-axis. This provides low off-axis sensitivity and high shock survivability. In this study, we designed a fully digital PLL (phase-locked loop) circuitry in a FGPA (field programmable gate array) based hardware controller. By Allan deviation, we proved that our system has a resolution of 34 mu G Hz(-1/2) for a device operating at 1 mTorr.

This paper presents a development and characterization of a novel technology for seedlayer-less gold electroplating. This method allows that a gold film grows directly and selectively on a silicon surface. In the MEMS field, the gold film is increasingly drawing attention for its low electrical resistivity, high physicochemical stability, high biocompatibility and high reflectivity to the infrared ray. Due to low adhesion of the gold, it had been considered that it is difficult to obtain the direct electroplating film on a silicon surface. The two-step gold electroplating method presented here, which contains the first thin electroplating of 0.2 mu m with low current density of 0.75 mA/cm(2) and following annealing process at 250 degrees C for 30 min, achieves increasing adhesion and realizes practical gold film on a silicon. (C) 2006 Elsevier B.V. All rights reserved.

The intermodulation distortion characteristics of a microwave Si MOSFET power amplifier are improved by realization of a true second harmonic short-circuit termination of the drain. By the use of a circuit configuration taking account of the parasitic inductance of the FET drain, second harmonic short-circuiting of the drain is realized. First, a two-variable Taylor series expansion model of the drain current with respect to the gate voltage and the drain voltage is used and an approximate analysis by the perturbation method, including the low frequency (signal difference frequency) and second harmonic load dependence of the third-order intermodulation distortion, is used for an analysis of the intermodUlation distortion and its asymmetry. Next, a 1-GHz Si MOSFET power amplifier is fabricated. Reduction of the intermodUlation distortion and its asymmetry is realized by introducing a true second harmonic short circuit for the drain. (C) 2007 Wiley Periodicals, Inc.

Monitoring daily activity and load of human activity is important for maintaining health and preventing life-style related diseases or sudden death from overwork. We can evaluate quantitative activity and load with multiple sensors attached to the human body. In this study, we created a prototype system for measuring environmental conditions, including ambient temperature, pressure, humidity, and three-dimensional acceleration (shock) sensing devices, using MEMS technology. The prototype can continually monitor and record environmental conditions and provide the history of the body's activity and environmental load quantitatively. In this paper, we detail the system configuration and characteristics, and provide the examples of measured data.

Miniaturized environmental sensor chips for data gathering are useful for various applications, such as anthropometric or body-motion measurement. In this stud, we propose a microelectromechanical system MEMS) multi-sensor for environmental sensing. The system includes a sensor and peripheral interface circuitry chips. The sensor chip has a 3-axis accelerometer, with a pressure sensor and a humidity sensor. All sensors are built on a 10 x 5 mm(2) silicon-on-insulator SOI) wafer by the bulk MEMS process using deep reactive-ion etching RIE). The interface circuitry for each sensor is produced on a semi-custom Bi-CMOS application specific integrated circuit ASIC) chip by a Japanese IC foundry service of MICS.

Nowadays, home-delivery services of packages are imperative in everyday life. These service industries are trying to provide cheaper, faster and safer service. However, package condition and handling during transportation are not disclosed to a customer. In this study, we realized a prototype system by MEMS technology for measuring the environmental conditions around a package for home-delivery service. The system includes barometric pressure, temperature, relative humidity and three dimensional acceleration (shock) sensing devices, as well as an interface circuitry. The system is a size of 115 × 54 × 10 mm3 and a weight of 50 g. We measured the package conditions during the transportation by three Japanese domestic home-delivery services, and using data mining, we were able to obtain a representation of the package's circumstances. © 2007 The Institute of Electrical Engineers of Japan.

マイクロ波Si MOSFET電力増幅器の相互変調ひずみ特性を真のドレーン二次高調波短絡を実現することにより改善した.FETドレーンの寄生インダクタンスを考慮した回路構成の採用によりドレーン二次高調波短絡を実現した.まず,ドレーン電流のゲート電圧及びドレーン電圧による2変数テイラー級数展開モデルを用いて,三次相互変調ひずみの低周波(信号差周波数)及び二次高調波負荷依存性を取り入れた摂動法による近似解析理論を適用し,相互変調ひずみ及びその非対称性を検討した.次に,1GHz帯Si MOSFET電力増幅器を製作して,ドレーンの寄生インダクタを考慮した真のドレーンニ次高調波短絡回路を導入することにより,相互変調ひずみ及びその非対称性の低減を実現した.

This paper reports a novel structure for improving resistance to acceleration or shock in micro-gyro scopes. The novel device reported here is completely "solid", which is quite unlike any conventional micromachined-gyroscope. It has extremely simple structure and fabrication steps. When a longitudinal vibration is excited in PZT rectangular prism as a reference vibration, differential output voltage by the Coriolis force can be obtained on the PZT surface. The paper shows the operation principle, results from FEM analysis, and preliminary experimental results by the test device.

In order to deal with a variety of wireless communication systems, multichannel capabilities are being introduced into cellular phones. In the future, in order to attempt reduction in size and weight by using multichannel capabilities of various wireless devices, it will be necessary to realize multichannel operation of passive circuit elements, mixers, and amplifiers. This paper presents the current status of multichannel operations of active circuits, especially amplifiers, for which multichannel capabilities are difficult to provide. In addition, the status and challenges of the microwave dual-frequency matched dual-band GaAs FET power amplifiers being developed by the authors' group on the basis of the low-pass Chebyshev impedance transformers are discussed. (c) 2006 Wiley Periodicals, Inc.