Mechanical Response of Silicon MEMS Diaphragms to Applied Pressure

The response of silicon-based MEMS diaphragms to applied pressure was studied to determine their ability to effectively measure the extent of blast overpressure. Different pressures (0-100 psi) were applied to silicon diaphragms of different diameters (1200, 1500, and 2200 μm) to study their mechanical response under both static and dynamic conditions using experimental and finite element analysis. A laser triangulation sensor was used to determine the diaphragm displacement as a function of blast pressure. High speed camera images were obtained to understand the response of the diaphragm at an applied blast pressure. Results show consistent behavior for deflections (10, 14, and 26 μm, respectively, at 40 psi) under dynamic conditions. Finite element analysis indicates that the dynamic deflection is larger than the corresponding static deflection for the same applied pressures. Burst strengths were not consistent, although the diaphragms fractured at their circumferential edges and showed a small degree of plastic deformation. It also appears that the diaphragm manifests a hemispherical as well as a conical deflection depending on applied blast pressures.