Study and Analysis of Hollow Bistable MEMS Switch

In this paper, we have investigated the switching voltage and latching mechanism of curved shape latched hollow beam subjected to electrostatic force. The switching voltage of solid bistable beams has been seen to scale with the beam thickness. Unlike Nano-sized beams, which can only be made using E-beam lithography, hollow beams utilizing 50–100 nm of sputtered thin films can be fabricated using conventional lithographic processes. The switching voltage analysis is based on reduced order model (ROM) analysis. The latching criteria for the beam is also derived. It is seen that hollow beams require higher initial elevation compared to solid beams of the same dimension to latch. However, despite this, hollow beams provide significant reduction in switching voltage. For the chosen test case of a 600 µm x 2 µm x 5 µm beam, a 4X reduction in switching voltage and stable equilibrium of beam deflection 15 µmis obtained.