Piezoelectric MEMS Devices Research Articles

ACTIVE DAMPING OF A PIEZOELECTRIC MEMS ACOUSTIC SENSOR

ABSTRACT This paper presents the fabrication process and active damping strategy of piezoelectric MEMS acoustic sensor by combining two functions of sensing and actuation of the PZT film in one device. The electric characteristics of PZT film were determined by measurement. Simulation of self-sensing control law, and control circuit are introduced. Important issues of the implementation of closed loop damping control are discussed. Experiment results show that the self-sensing damping of piezoelectric MEMS acoustic sensor is implemented successfully. This technology is more promising in improving the dynamic performance of piezoelectric MEMS devices because very low driven voltage and power consuming are sufficient.

Modelling and analysis of a MEMS approach to dc voltage step-up conversion

This paper studies the principle of a novel voltage step-up converter based on a micromachined variable parallel-plate capacitor in combination with an electrostatic actuator. Electrical equivalent circuit and system-level SIMULINK models have been developed. Based on these models, an analysis of design parameters and expected device performance has been performed to serve as a starting point for a prototype implementation. Possible areas of application are self-powered, stand-alone sensing systems, aerospace applications and any kind of electrostatic or piezoelectric MEMS devices in general.

파이렉스 #7740 유리박막을 이용한 MEMS용 MLCA와 Si기판의 양극접합 특성

본 논문은 파이렉스 #7740 유리 박막을 이용한 MEMS용 MLCA (Multi Layer Ceramic Actuator)와 Si기판의 양극접합 특성에 관한 것이다. 최적의 RF 마그네트론 스피터링 조건 (Ar 100%, input power <TEX>$1\;W/cm^2$</TEX>)하에서 MLCA기판위에 파이렉스 #7740 유리의 특성을 갖는 박막을 증착하였다. <TEX>$450^{\circ}C$</TEX>에서 1시간 열처리한 다음, -760 mmHg, 600V 그리고 <TEX>$400^{\circ}C$</TEX>에서 1시간동안 양극접합했다. 그 다음에 Si 다이어프램을 제조한 후, MLCA/Si 접합계면과 MLCA 구동을 통한 Si 다이어프램 변위특성을 분석 및 평가하였다. 다이어프램 형상에 따라 정밀한 변위 세어가 가능했으며 0.05-0.08 %FS의 우수한 선형성을 나타내었다. 또한, 측정동안 접합계면 균열이나 계면분리가 일어나지 않았다. 따라서, MLCA/Si기판 양각접합기술은 고성능 압전 MEMS 소자 제작공정에 유용하게 사용가능할 것이다. This paper describes anodic bonding characteristics of MLCA (Multi Layer Ceramic Actuator) to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with same properties were deposited on MLCA under optimum RF magneto conditions(Ar 100%, input power <TEX>$1\;W/cm^2$</TEX>). After annealing in <TEX>$450^{\circ}C$</TEX> for 1 hr, the anodic bonding of MLCA and Si-wafer was successfully performed at 600 V, <TEX>$400^{\circ}C$</TEX> in - 760 mmHg. Then, the MLCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity is 0.05-0.08 %FS. Moreover, any damages or separation of MLCA/Si bonded interfaces do not occur during actuation test. Therefore, it is expected that anodic bonding technology of MLCA/Si wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.

Electro-Mechanical Coupling and Power Generation in a Pzt Micro-Engine

AbstractA piezoelectric thin film MEMS device for generating power from a novel heat engine which approaches a Carnot cycle has been developed. The structure of the underlying electrode and PZT thin film generator has been optimized for increased adhesion. Atomic force microscopy was used to track electrode grain size and roughness; generating grain sizes of approximately 100 and 200 nm in diameter and a roughness of about 14-20 nm provide substantial improvements in film adhesion over systems with smaller grains and smoother surfaces. This has led to the ability to operate the engine at frequencies between 10 and 1500 Hz. The system of interest (a fluid filled cavity sealed by a micromachined silicon membrane and the PZT film) shows increased deflections for a given pressure applied to the membrane at frequencies where the system resonates. By operating the system dynamically, it is possible to generate more than 2 V from a single generator structure.