Analytical modeling and optimization for a laterally-driven polysilicon thermal actuator

Abstract

An electro-thermally and laterally driven microactuator is analytically examined which is based on the asymmetrical thermal expansion of the microstructure with different lengths of two beams. Deflection of the microactuator is modeled by the structural analysis. Analytical results are compared with the finite element model (FEM) results, and show a reasonable agreement. The magnitude of the deflection depends strongly on the geometry of the microactuator. The analytical model allows one to optimize efficiently the laterally driven thermal actuators.

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“…The laterally-driven polysilicon microactuator considered as a case study is the one studied in [26], where an analytical model of displacement and temperature is calculated. The microactuator is composed of two arms exhibiting different length; due to an applied voltage, a current flows in the series-connected arms.…”

“…In turn, the maximum temperature depends, from the geometrical viewpoint, on height hh and width d. The dependencies on other parameters like e.g. the thermal conductivity are shown in [26]. The parameter values used in this paper are shown in Table 1.…”

“…The parameter values used in this paper are shown in Table 1. The parameter ξ is used to take into account the difference of thermal conductivity and nonuniform heat generation between the top and the bottom layer [26]. The applied voltage is 5 V.…”

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“…These actuators, which are based on thermal expansion of heated members, offer significant advantages over electrostatic actuators, including lower operating voltages and improved force and displacement characteristics [43]. There are two general types of electrothermal actuators: the bent-beam or linear design, and the U-shaped or flexure design [4,34,35,[44][45][46][47][48][49]. In general, these actuators amplify the motion resulting from the thermal expansion of structural members as they are Joule-heated by a current flowing through the device.…”

“…In general, these actuators amplify the motion resulting from the thermal expansion of structural members as they are Joule-heated by a current flowing through the device. The versatility and usefulness of these devices has prompted the development of numerous models to predict and assess the actuator performance [37,48,49]. Because the devices operate using thermal expansion, their performance is invariably linked to the temperature profile produced during Joule heating, which, until recently, has not been experimentally verified [40].…”