Indian Journal of Engineering & Materials Sciences Vol. 15, April 2008, pp. 99-103 Design and simulation of optimum piezoelectric MEMS microactuator for smart control applications Soma Dutta* Materials Science Division, National Aerospace Laboratories, Bangalore 560 017, India Received November 2006; accepted 28 February 2008 This paper presents the design and finite element simulation of a novel piezoelectric microactuator. The optimaly designed cantilever type piezoelectric microactuator deflects at its tip by converse piezoelectric effect. It consists of a thin film PZT layer, intimately attached with a variable thickness SOI elastic layer and electrically connected with top and bottom electrodes by contact pads. The goal of this coupled piezoelectric actuator design is to multiply the force by adding a support beam, placed closer to the fixed end and by varying the width of the active layer. Structural simulation employed commercial software tool ANSYS/COVENTORWARE and the results include free tip deflection, blocked force and mechanical stresses while subjecting the actuator to a prescribed input voltage. MEMS, a new branch of microelectronics is proving to be of vital importance in designing of micro devices, which act both as sensors and actuators. MEMS is an outgrowth of VLSI technology, extending its power to third dimension to design and fabricate dynamic structures, like micro motors, micro gears, micro sensors etc, all in micro meter scales. MEMS have an additive advantage of integrating the required signal conditioning circuits on the same silicon wafer that is used to fabricate the MEMS device. This enables the complete stand-alone device to be fabricated and packaged. Sensing and active control of aeroeleastic vibrations has been a challenging research area in avionics based vibration damping of flexible structures. In modern active control application for smart structures, a piezoelectric transducer is used as an actuator bonded to, or embedded in a base structure to minimize the unwanted vibration of the base structure enhancing aero vehicles to operate beyond the traditional flutter boundaries, improve ride qualities, and minimize vibration fatigue damage. Piezoelectric ceramics, PZT (lead zirconate titanate) based actuators and sensors are widely explored/investigated because of their high electromechanical coupling coefficient, scalable architectures (thin, thick, and bulk), light weight, wide operating temperature range, large useful bandwidth, tunable piezoelectric properties and flexible operating frequency range. This PZT material has also been integrated as a thin film into MEMS and found very promising for micro sensor and actuators in MEMS applications. Combining micro-machined silicon membranes with piezoelectric (or ferroelectric) thin/thick films has resulted in novel micro-devices such as motorsP 1 P, accelerometersP 2 P, pressure sensorsP 3 P, micro pumpsP 4 P, actuatorsP 5 P or acoustic resonatorsP 6 P. Stresses of up to 100 MPa and strains of up 0.1% have been obtainedP 7 P. MEMS devices are designed, realised and used in various fields. Numerous structures and models were studied and are extensively used for MEMS devices, like diaphragms, valves, pumps, channels, gears and beams. Micro cantilever beams are of these structures that are commonly used for both sensing and actuation purposes. Various actuators and actuation principles can be adapted and realised using cantilever beams. The focus in this paper is on the design of a MEMS based PZT cantilever for application in active suppression of structural vibrations in micro air vehicles with a long-term goal of development and demonstration. In this structure, the 1 µm PZT film is sandwiched between two electrodes on a SiOB 2 B layer (Fig. 1). Structural simulation has been done in ANSYS as well as in COVENTOR to predict the free tip deflection and the blocked force while subjecting the actuator to a prescribed input voltage. The bimorph actuator is 145 µm long and 10 µm wide. The evolution of the resonant frequency with the cantilever length has been studied. ___________ *E-mail: dutta_som@yahoo.co.in