Fabrication of highly sensitive capacitive pressure sensors with porous PDMS dielectric layer via microwave treatment

This work aims to present a flexible, highly sensitive, capacitive pressure sensor based on an elastomeric dielectric layer with uniformly distributed micro-pores. The porous dielectric layer was simply produced by microwave treatment of polydimethylsiloxane (PDMS) mixed with a sacrificial solvent within a few minutes. The pressure sensor using a porous PDMS dielectric layer fabricated with 40 wt% sacrificial solvent had a sensitivity of 0.813 kPa−1, which is 11 times higher than that of the sensor using a non-porous dielectric layer. To further improve the sensitivity, low-cost commercial glass was used as a mold to form microstructures on the surface of the porous dielectric layer. Due to the enhanced deformability, high sensitivity of 1.43 kPa−1 and a fast response time of 70 ms was achieved. The performances of a sensor array as well as finger sensors were also demonstrated by placing light-weight objects on the array and holding a plastic cup. It would be expected that the proposed sensors could be utilized in the application of artificial skins or soft robotics.