| In this paper, a permanent magnet bistable micro-relay was studied, it was designed based on the mechanism of metal contacts conduction of electromechanical relays. And it was fabricated using MEMS micro-machining techniques; the overall size of a single device was only 10mm×5mm×1mm (produced on silicon substrates ). The device consists of a pair of electrothermal actuators, a leveraged permalloy cantilever beam suspended by two supporting torsion flexures, and a bistable system. The switch of the circuit can be achieved by the driving force of the micro-actuator through the middle cross-shape torsion beam. And the steady-state can be held by the attraction of the magnetic circuit structure underground. In such way, the mechanism of low-power consumption and bistable state can be achieved.At first, TiNi-based SMA thin films were deposited on silicon substrate by sputtering TiNi target using RF magnetron sputtering method. Results from DSC(differential scanning calorimetry) revealed martensitic transformation and good shape memory effect upon heating and cooling.Based on the study of TiNi SMA films, a mico-actuaor with TiNi / Si bimorph structure and a mico-actuaor with TiNi/Si bimorph structure were produced respectively . It was revealed that the TiNi / Si bimorph cantilever was nearly flat at room temperature. The devices with TiNi / Si bimorph cantilever were fabricated and obtained with a deflection of under 2.0V pulse voltage and 1 ~ 6HZ operating frequency..Finally, the integrated manufacturing methods of the overall micro-relay were studied. The second method used glass substrate, Cu sacrificial layer, SMA actuators with TiNi / PI bimorph structure. Finally,a micro-relay with Ni/SU-8 bimorph structure was produced, and the surface morphology were tested using surface profile measuring instrument and SEM(scanning electron microscope).
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