Study Of A Bi-Stable Electromagnetic Actuator Used In MEMS Communication Relay

Micro relays as a kind of components are widely used and plays an essential role in the fields of aerospace, computer and communication. Communication relay is one of the main applications, its output value accounts for about a quarter of the entire relay industry, and it has more technical content and higher added value of relay products.A bi-stable electromagnetic actuator used in micro communication relay is studied. It is composed of a planar coil, a nickel elastic platform, and a silicon spacer. It uses double layers Cu coils and magnetized permalloy core to increase the driving force, uses polymide for isolation, and realizes the bi-stable mechanisms by permanent magnet.The magnetic circuit theory is introduced. We consider the following parameters: gap magnetic flux leakage, the distribution effect of induction potential and the nonlinear permeability for permalloy. Based on the distributed method, the magnetic circuit model is setup. Matlab program and Ansys simulation are used to calculate how these structure parameter such as cantilever thickness and gap width influence the device capacity. Cantilever thickness is the key factor. The optimal structure parameters are determined.The MEMS micro-actuator has been fabricated via micromaching technology. A polyimide insulation layer is used to fabricate the planar coil. Furthermore, the nickel elastic platform was fabricated via electroplating and silicon wet etching process. And the silicon supporter is fabricated via silicon wet etching process to rectify the working gap.The elasticity coefficient of the device is measured, So is the bi-stable characteristic of the MEMS micro-magnetic actuator. The results showed that the device had good performance of bi-stable actuation, and the response time was short (about 10ms),which prove the feasibility of this prototype structure.