Novel Composite Structure Electro-Thermal Micro Actuator

Micro-actuator is an important part of Micro Electro Mechanical Systems, which used as the drive and executing unit. The function of micro-actuator includes of energy conversion, motion and force transmission and system message response. In this paper, A novel electro-thermal actuator has been researched including design, model building, performance analysis and experimental testing.Traditional electro-thermal actuators are mainly bimorph. Though bimorph electro-thermal actuator can produce relatively large displacement and force, its motion is out-of-plan and not rectilinear. Bent-beam electro-thermal actuator solves these problems. Its produce relatively large force, and its motion is in-plane and rectilinear. However, its disadvantages are energy-consuming and high operating temperature. In the integrated circuit, it will cause the change of devices in performance by change in temperature. What's more, its displacement is small.Using non-silicon surface machining, we prompt a novel design of micro-actuator based on the bent-beam electro-thermal actuator. The novel design adopts part of design of the bent-beam thermal actuator to ensure in-plane motion, and change single material into two material-polymer and metal. The imbedded metal uses the spring-like design, which can pass the electricity and also get the advantages of large CTE of polymer.Considering the limit of manufacturing and displacement, we get the optimal structural parameters; make analysis in operating temperature and driving displacement, prove the success of design and get the performance of this actuator. In follow, we make lots of research in manufacturing, including multiple photoresist sacrifice layer, Cu sacrifice layer, Cure of structural SU-8, successfully get a simple, reliable and integrated manufacturing process. Finally, we test the performance of samples.Under the 0.5v driving voltage, a novel electro-thermal actuator with 800μm long cantilevers can produce a driving displacement of 13.6μm, with power of 18mw. It gets better performances than the bent-beam electro-thermal actuator with the same size.