Abstract
An electro-thermal microactuator is investigated in the present study. The micromachined device is activated by thermal expansion of a V-shaped bent beam anchored at the two ends while an electric current is passed through the beam. Thermal stress caused by joule heating pushes the apex forward, generating large tip displacements and output forces. Finite element analysis is first applied to analyze the temperature field, strain distribution, tip displacements and output forces of the beam. Then, polysilicon surface-micromachining technique is used to fabricate the devices and experimental data are compared with the numerical results. In addition to a single V-shaped bent-beam structure, a cascaded bent-beam structure to amplify the tip displacement is also investigated. It is found that there exists an optimum inclined angle for single and cascaded bent beams to generate maximum tip displacements and output forces. The angle strongly depends on the bent beam geometry, The bent-beam actuators capable of generating large displacements (up to 60 μm) and output forces (up to several mN) show great potential in implementing in a variety of microsystems.