Design and Evaluation of a MEMS Bimetallic Thermal Actuator for Viscosity Measurements

A non-cantilever-beam micro-electro-mechanical (MEMS) based viscosity sensor is proposed. This novel vibration viscometer device utilizes thermal actuation and piezoresistive sensing. As the actuation bias is kept constant, viscosity changes can be correlated to changes in the oscillation amplitude. This proposed solution is CMOS compatible, inexpensive and reliable. This paper investigates the vertical movement of thin silicon/aluminum bimetal diaphragms with varying bimetal areas and diaphragm thickness to better understand the thermo- mechanical behavior of the proposed actuator/sensor device. Proof of concept results are presented in which the oscillation amplitude of the bimetal actuator changes when the device is immersed in media of different viscosity.