Comprehensive Thermal Modeling of ElectroThermoElastic Microstructures

Abstract

Bent and folded beam configurations have been popularly used in electrothermoelastic (E-T) actuation. This paper introduces new designs of thermal end-effector with micro-grasping and micro-heating capabilities. We obtained analytical models for all possible steady state temperature responses of suspended and overhanging microstructures that constitute bent beam, folded beam, and combined actuators. Generally, the thermal response of E-T microstructures is sensitive to the boundary conditions, particularly for high power input. Thermal models have predicted the failure due to melting, which is the most common reason for failure of E-T devices, and it often occurs in the longest and the thinnest microstructure.

Scanning and Actuation Techniques for Cantilever-Based Fiber Optic Endoscopic Scanners—A Review

“…A correction factor can be included in the equation to consider this approximation. The nonlinear partial differential equation describing the temperature variation ( T ) in space and time can be obtained using the conservation of energy [ 108 ]. In the case of a rectangular section bar (with width w , and height h ), the partial differential equation (PDE) describing the heat transfer along the length x becomes: with ρ , c p , ρ r , k p being the density, specific heat, resistivity, and the thermal conductivity of the material characterizing the actuator, respectively.…”

“…J is the current density along the actuator given by the current passing through it per unit section of the actuator material. S is the shape factor and is a function of total heat flux defined as: where t v is the air gap between the actuator material and the substrate [ 108 , 109 ].…”

“…In electrothermal actuators, the operable temperature is limited to avoid damage to the material. Thus, the corresponding terms in Equation (21) can be neglected [ 108 , 110 ]. Therefore, Equation (21) can be simplified to: …”

An experimentally verified model for thermal microactuators including nonlinear material properties, vacuum, and intra-device heat conduction

“…In an attempt to improve the efficiency of the flexure actuator design, modifications have been made to incorporate two hot arms, eliminating current flow in the cold arm [2]. Arrangements of both flexure actuators and bent-beam actuators have also been established to create more intricate devices, including microgrippers [3,4] and 6-axis positioners [5]. Unidirectional [6] and bidirectional [7,8] out-of-plane actuation has been achieved by offsetting the hot and cold arms in the out-of-plane direction, and bistable two way out-of-plane actuation has also been demonstrated using multilayered thermal micro-bridges [9,10].…”