Flexible capacitive pressure sensor array using acoustic-assisted fabrication of microstructures as surface and dielectric layers

Flexible pressure sensors have attracted considerable interests in the fields of intelligent robotics, human-machine interfaces and health monitoring for their portability, flexibility and real-time sensing performance. The microstructures of dielectric layer significantly affect the sensing performance of capacitive pressure sensors, but the common methods to fabricate microstructures always need physical and/or chemical molds, thus may not suit for low-cost fabrication of sensors. The wavy-shaped microstructures on the surface of fluid can be generated with the excitation of standing surface acoustic waves (SSAWs), which is suitable to be used as dielectric layers. Here, we developed a 6 × 6 flexible capacitive pressure sensor array with fingerprint-like surface cover layer and latticed dielectric layer. Both two layers were fabricated through the novel and rapid acoustic-assisted process. The fabricated capacitive sensor array exhibits high sensitivity of 28.8%/N for normal force loading, with spatial resolution of 1.5 mm. It has been successfully used to monitor the vibration of the Adam’s apple during swallowing and detecting the wrist activities in cycles. These studies demonstrate the great potential of the pressure sensor array with acoustically fabricated microstructures in wearable electronics for health monitoring.