Characteristic analysis of a capacitive pressure-sensitive structure with dual movable electrode plates

In conventional microelectromechanical systems capacitive pressure-sensitive structures, the upper electrode plate functions as a movable diaphragm, while the lower electrode plate is part of the bulk silicon substrate. To enhance the measurement resolution of barometric altimeters, this paper proposes a capacitive pressure-sensitive structure with dual movable electrode plates (DMCPSS), in which both the upper and lower electrode plates serve as movable diaphragms. Under external pressure, the synchronous deformation of the two movable diaphragms increases the electrode plate spacing variation, thereby amplifying the capacitance change and improving pressure sensitivity and measurement resolution. Finite element analysis results demonstrate that, over a pressure range of 0-130 kPa, the proposed structure achieves a 50% higher relative sensitivity than a conventional structure with a single movable electrode plate. Furthermore, the DMCPSS exhibits a temperature coefficient of capacitance of 935 ppm/°C at 101 kPa over a temperature range of -40 to 120 °C.