MEMS Microvalve for Harsh Environment

There is a need for small valves which control flow at high temperature and pressure for a number of commercial and military applications. However, traditional solenoid actuated valves are typically expensive, heavy and subject to undesirable electrical and mechanical failure modes. Micromachining techniques, commonly used in the electronics industry, are finding more and more applications for Micro Electro Mechanical Systems (MEMS). Most of the previous work in the area of MEMS valves has been limited to low pressure/low temperature flows at ambient conditions. In this presentation, the development and testing of a two stage MEMS diaphragm valve that is capable of operating at high temperature and pressure gas flows is presented. Valve requirements, tolerances and thermal management are considered in the design. Valve fabrication processes, such as Reactive Ion Etching (RIE) and laser ablation, are discussed in detail. Issues related to the actuation of the microvalve are also discussed, including two approaches based on shape memory alloy and piezoelectric materials. Modeling and test results are presented throughout to identify successes and lessons learned.