Study Of Bistable Electrothermal Micro Actuator Technology Based On Flexible Mechanism

Micro actuator is an important part of micro electro mechanical system (MEMS). It is the driving and executing unit of MEMS which can be used for movement and force transfer, energy conversion and response to system information. And bistable mechanism means a mechanism which has two stable positions within its movement range. This mechanism stores energy in parts of moving process, and releases energy when transforming during two stable positions. It remains its one of stable positions when outside has a small disturbance, so it needs no energy input to stay the stable positions. Based on the compliant mechanism and MEMS non-silicon processing, this article joins actuator and bistable mechanism together, and lays a solid foundation to realize the micro relay which is distinct to traditional relay that depends on the electromagnet force to make and break. This type of micro relay remains stable state without any energy input, and has advantages of small size, low fabricating cost, and reliable processing.Polymer becomes to a good driving material of micro electrothermal actuator since its large coefficient of thermal expansion. An actuator in which metal was embedded in the Su-8 polymer and this composite is used as structural material can make full use of the advantages of polymer and metal. Based on these, the article optimized the fabrication and the device structure parameters. The test results show that the optimizing improves the actuator's performance. Meanwhile, the article demonstrates a standard Zn sacrificial layer technology which can be used in MEMS field.As the lock, the structure is calculated by analytic method in this article to insure the realization of working when integrated with actuator. The results show that the designed structure could be droved by actuator, and could accomplish the transform between two stable states. The article developed a processing to fabricate the micro gemel according to the structure. It broke the limit of fabricating accuracy in non-silicon processing field, and realized to fabricate micro gaps (0.5~3μm). The test results show that our bistable structure could accomplish the transform between two stable states.