Mems thermal film sensors for unsteady flow measurement

Deposited on a flexible skin, self-made MEMS (Micro Electronically-Mechanical Systems) thermal film sensors were applied to a contoured wall surface for sensing unsteady flow behaviors. The sensors, each featuring a platinum sensing element 0.1 μm in thickness on a polyimide substrate 20 μm thick, were about 150-200 ohm at room temperature. The frequency response of the sensors could be up to 30 kHz when operating in constant temperature mode. In studying the unsteady flow behaviors, the flow information of interest was mainly the frequency contents of the real-time signals measured. In this paper, the three presented cases illustrate how the signals of the MEMS sensors could be used to explore the instantaneous behaviors of the unsteady flows.