Thermoelastic Actuation: Solution for Circular Composite Plates With Application in MEMS

This paper presents the dynamic analysis of a thermoelastically actuated circular composite diaphragm, for MEMS applications. The diaphragm is used as an acoustic transmitter, actuated at ultrasonic frequencies via a diffused surface heater at its center. The principle of operation of the thermal actuator is the generation of an oscillating temperature gradient across the diaphragm cross-section due to Joule heating of the diffused heater, creating a thermal moment that results in out-of-plane bending of the diaphragm. The mechanical analysis of the diaphragm, modeled as a composite plate, is based on the classical laminated plate theory. The time harmonic heat conduction resulting from the Joule heating of the diffused surface heater, modeled as a surface heat flux input, is analyzed using the Fourier heat conduction model. Analytical expressions have been obtained for the temperature distribution, and the resulting thermal moment, and plate deflection.