Flexible PDMS Pressure Sensor Based on Mutual Inductance Coil

The increasing use of pressure sensors has spurred the pursuit of highly sensitive sensor development. This paper proposes an inductive flexible pressure sensor that employs a hollow-shell flexible PDMS sponge skeleton. Three groups of hollow-shell flexible sponge shells with varying wall thicknesses were tested. The results demonstrate that thicker walls do not promote sensor sensitivity. Among the tested sensors with wall thicknesses of 4 mm, 5 mm, and 6 mm, the sensor with a 4 mm wall thickness exhibited the highest sensitivity of approximately 42.6 Mpa ^-1 in the high pressure range of 30–100 kPa. Additionally, this sensor achieved a minimum detectable pressure of 25 Pa. Its response time was rapid, with a loading time of approximately 233 ms and an unloading time of about 117 ms. Notably, the inductive pulse output from the sensor exhibited consistent amplitude and peak patterns over 1000 applied pressure cycles, demonstrating superior immunity to interference compared to a capacitive sensor of the same size under identical conditions. Subsequent application tests revealed the accurate sensing capability of the inductive flexible pressure sensor for pulse beats, thus further confirming its feasibility for practical applications.