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

Abstract

A comprehensive thermal model for an electro-thermal-compliant (ETC) microactuator is presented in this paper. The model accounts for all modes of heat dissipation and the temperature dependence of thermophysical and heat transfer properties. The thermal modelling technique underlying the microactuator model is general and can be used for the virtual testing of any ETC device over a wide range of temperatures (300-1500 K). The influence of physical size and thermal boundary conditions at the anchors, where the device is connected to the substrate, on the behaviour of an ETC microactuator is studied by finite element simulations based on the comprehensive thermal model. Simulations show that the performance ratio of the microactuator increased 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 heat loss to the substrate via the device anchors increased the actuator stroke by 66% and its energy efficiency by 400%, on average, over the temperature range of 300-1500 K. An important observation made is that the size of the device and thermal boundary conditions at the device anchor primarily control the stroke, operating temperature and performance ratio of the microactuator for a given electrical conductivity.

Dimensional Analysis of a Hot-arm Actuator

“…Physical modelling of such devices poses many difficulties, one of the most significant being that the thermal, electrical, and mechanical domains are coupled with one another. Nonetheless, many researchers have produced models of varying complexity [4][5][6][7][8][9][10][11]. In order to accommodate the large spatial variations in properties, the use of finite element analysis (FEA) software packages in such models is common [10], as are highly elaborate analytical models that solve for spatially distributed parameters, resulting in a large number of simultaneous equations [8]- [9].…”

An improved in-plane thermal folded V-beam actuator for optical fibre alignment

“…Temperature dependent values of density and thermal conductivity of air are taken from Mills [12], as well as formulae for the convection coefficient for macro systems, which are extrapolated to the micro domain. For the radiation estimation, the structures are modelled as grey bodies with an emissivity of 0.7 [9,13].…”

Thermal Microactuators

“…Numerous research groups have developed numerical models of thermal microactuator performance Bergna et al, 2005;Enikov et al, 2005;Howell et al, 2007;Lott et al, 2002;Mankame and Ananthasuresh, 2001;Serrano et al, 2006;and Wong and Phinney, 2007). These models include electrical, thermal, and mechanical effects and are implemented through finite difference as well as finite element approaches.…”