A Compact Wireless Passive Pressure Sensor With High Sensitivity and Resolution Based on MEMS–FPCB Integration

The accurate monitoring of low-range pressure variations is crucial in many biomedical and wearable sensing applications, where abnormal pressure levels can indicate potential health risks. This brief presents a passive wireless inductor–capacitor (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i>) pressure sensor, developed using MEMS and flexible printed circuit board (FPCB) technologies for low-range pressure monitoring. The sensor comprises a 16.2-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m-thick MEMS layer with a 2-mm circular electrode, a bottom electrode with an integrated spiral inductor on the FPCB, and a 50-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m laser-cut polyimide (PI) intermediate layer forming the capacitive structure. Simulations and experimental evaluations in a controlled low-pressure water environment confirmed stable performance and close agreement between theoretical and measured responses over the 100–5000-Pa range. By accounting for parasitic capacitance effects from water environments and interlayer interactions, the sensor still achieves a high average sensitivity of 5.15 MHz/kPa, a fine resolution of 25 Pa, and a low-temperature coefficient of frequency (TCF) of 173 ppm/°C. With its compact, flexible, and wireless design, the proposed sensor holds strong potential for continuous physiological pressure monitoring.