Comprehensive thermal modelling and characterization of an electro-thermal-compliant microactuator

A comprehensive thermal model for an electro-thermal-compliant (ETC) microa ctuator is presented in this paper. The model accounts for all modes of hea t dissipation and the temperature dependence of thermophysical and heat tra nsfer properties. The thermal modelling technique underlying the microactua tor model is general and can be used for the virtual testing of any ETC dev ice over a wide range of temperatures (300-1500 K). The influence of physic al size and thermal boundary conditions at the anchors, where the device is connected to the substrate, on the behaviour of an ETC microactuator is st udied by finite element simulations based on the comprehensive thermal mode l. Simulations show that the performance ratio of the microactuator increas ed by two orders of magnitude when the characteristic length of the device was increased by one order of magnitude from 0.22 to 2.2 mm. Restricting he at loss to the substrate via the device anchors increased the actuator stro ke by 66% and its energy efficiency by 400%, on average, over the temperatu re range of 300-1500 K. An important observation made is that the size of t he device and thermal boundary conditions at the device anchor primarily co ntrol the stroke, operating temperature and performance ratio of the microa ctuator for a given electrical conductivity.