Static behavior of bilayer microcantilevers under thermal actuation

This paper investigates the size-dependent static behavior of micro scale thermal actuators. The actuator is considered as a bilayer microcantilever and the modified couple stress theory is utilized to capture the size-dependency of the mechanical behavior of the device. Considering Euler–Bernoulli beam theory, the equations governing axial and lateral deformations of the microbeam are derived. Equivalent material properties including length scale parameter are defined for the bilayer microbeam and deflection of the actuator due to temperature change is calculated using these equivalent quantities. For numerical analysis, a bilayer microbeam made of aluminum and polysilicon is considered. For this microbeam, the lateral deflection due to temperature change is obtained based on the modified couple stress theory and compared to the results of the classical model and the influence of size-dependency on mechanical response of the microbeam is discussed. Finally, the effect of the thickness of layers on the lateral deflection of the device is investigated.