Takayuki Fujita

Analysis of a highly sensitive silicon gyroscope with cantilever beam as vibrating mass

Abstract In this paper we investigate the behaviour of a silicon-based angular rate sensor which uses a cantilever beam for the vibrating mass. To this end, we examine how the mechanical quality factor influences both the sensitivity and stability of the sensor in the absence of any feedback control. By way of analysis, a simple physical model is presented that describes both the relationship between the tuned device and its sensitivity and, also, how the stability of the device is affected by the various modes of the beams vibration.

Disk-shaped bulk micromachined gyroscope with vacuum sealing

Abstract In this paper, we present the vacuum-sealed vibrating gyroscope using silicon bulk micromachining technology. The size of the device is 12×12×1.4 mm 3 . Two glass substrates hold the silicon sensing part. The sensing part is encircled with the silicon frame which forms hermetic seal with the glass substrates. From the results of initial testing, we obtain an angular rate detection sensitivity of approximately 8.9 μV/(° s −1 ), a nonlinearity of 1.25% FS and a detection resolution of approximately 0.2° s −1 at 1 Hz BW. Additionally, we show the detection characteristics of the two orthogonal components of the applied angular rates simultaneously.

Analysis And Design Concept Of Highly Sensitive Silicon Gyroscope

This paper deals with the silicon angular rate sensor which has a cantilever beam as a vibration mass. Under the open loop control of the mass movement, the mechanical qualityfactor influences the sensitivity and stability of the sensor. In this paper, the simple analysis, the tuned device with respect to the sensitivity, and mcdes of the vibration of the beam which influences the stability are described.

Dual-band GaAs FET power amplifier with two-frequency matching circuits

A dual-band GaAs FET power amplifier with the two-frequency lumped-element matching circuits is designed using the low-pass Chebyshev-form impedance transformer design method. An 800/1500MHz 1Watt-class GaAs FET amplifier is fabricated and the experimental results show the saturated output powers of 30.9dBm and 28.2dBm with the power added-efficiencies of 51.6% and 51.9% at 800MHz and 1500MHz, respectively. The fabricated circuit size is 24mm by 28mm. The presented design approach enables a simple dual-band power amplifier with superior performance and small size.

Application of Multi-Environmental Sensing System in MEMS Technology - Monitoring of Human Activity

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 bodys activity and environmental load quantitatively. In this paper, we detail the system configuration and characteristics, and provide the examples of measured data.

Two-dimensional micromachined gyroscope

In this study a novel cross-shaped micro-gyroscope which detects two orthogonal component of the applied rate is developed. Four nickel cantilever-plates are arranged in a cross that sits above a glass substrate with four fixed electrodes. Upon applying rotations, there result varying amounts of Coriolis acceleration in the vibrating plates which can be detected by corresponding capacitance changes that depend on the separation between the cantilever and fixed electrode. From the results of testing, we obtain an angular rate detection sensitivity of approximately 0.1 mV/(rad/sec) and detect the two orthogonal components of the applied angular rate simultaneously.

Design of two-dimensional micromachined gyroscope by using nickel electroplating

Abstract In this paper we present a prototype cross-shaped micro-gyroscope that detects two orthogonal components of the applied angular rates. From the results of initiai testing, we obtain an angular-rate detection sensitivity of approximately 0.1 mV (rad s −1 ) −1 and detect the two orthogonal components of the applied angular rates simultaneously. Additionally, we designed the ASIC that acts as an interface circuit for our gyroscope.

Zero temperature coefficient gas-sealed pressure sensor using mechanical temperature compensation

A novel gas sealed capacitive pressure sensor with a self-temperature compensated structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding in nitrogen with a pressure of 100 kPa and integrated with a platinum resistor based temperature sensor for human activity monitoring. A ring-shaped structure on the diaphragm of the pressure sensor is used for temperature compensation. The pressure sensor with the temperature compensation structure can mechanically suppress the thermal expansion effect of the sealed gas in cavity. Using the compensation structure, measured temperature coefficient was much reduced as compared to that of the pressure sensor without compensation. The sensitivities of the pressure sensor before and after compensation are almost same in a pressure range from 80 kPa to 100 kPa.

SOI-MEMS Sensor for Multi-Environmental Sensing-System

Miniaturized environmental sensor chips for data gathering are useful for various applications, such as anthropometric or body-motion measurement. In this study, 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 times 5 mm2 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.

Wireless MEMS Sensing System for Human Activity Monitoring

This study describes a human activity monitoring system that uses microelectromechanical systems (MEMS) sensors. The prototype system contains four sensors for ambient monitoring: 3-axis acceleration, barometric pressure, temperature, and relative humidity. The peripheral circuitry for each sensor is connected to a one-chip microprocessor. The measured data is stored in memory and transferred via a wireless transmitter. We measured a human subjects daily life activities, and using data mining, we were able to obtain a representation of that subjects life circumstances.