F. Alsaleem, M.H. Hasan
University of Nebraska - Lincoln,
Keywords: pressure sensor, MEMS, squeeze film damping
Summary:Pressure sensing is one of the earliest applications of Micro-Electro-Mechanical-Systems MEMS. Changing the pressure sensing element (such as capacitive and optical) size to the microscale has created opportunities to reduce power consumption and production costs of pressure sensors while increasing their sensitivity. However, current technology struggles with reducing the complexity of using pressure sensors in applications where measuring the amount of pressure is not as important as a threshold value for an action to occur. Examples of this complexity are the extra circuitry, controllers, and/or decision units that are needed to trigger an alarm in a car for low air-pressure in the tire, or to trip an HVAC compressor if the refrigerant pressure is lower than a threshold value. In this work, we propose a novel tunable smart threshold MEMS pressure sensor for such applications. The activation of subharmonic resonance (twice-natural frequency) for a cantilever-based MEMS due to AC and DC electrostatic excitation is used to trigger the sensor at a specific threshold pressure value. This sensor can be easily tuned to trigger at different threshold pressure values by simply adjusting the AC or DC voltage values.