Fabrication and Fatigue Testing of an Electrostatically Driven Microcantilever Beam

The reliability of a microelectromechanical system is an essential issue before the microdevice can be applied in practice. It is indispensable to investigate the mechanical properties of a microstructure to meet the requirements for longer lifetime and reliable performance. This paper studies the fabrication and the fatigue characteristics of a microcantilever beam, which is among the most widely employed microstructures in sensors and actuators. A pad is fabricated at the free end of the beam for larger effective external electrostatic load on the specimen. In fatigue tests, the specimen is actuated by the electrical voltage of 150 and 200 V at 100 Hz. The deflection of the beam is measured by the laser Doppler vibrometer. Based on the experimental results and ANSYS calculation, the displacement of the free end of the beam increases with the beam length and the applied load, and ranges from 61 to 600 nm. The fatigue life lies between 6.1 × 10⁶ and 1.4 × 10⁸ cycles. These results are consistent with the reference of a microcantilever beam subject to magnetic load.