Design of flexible resistance sensor based on mesh convex microstructure

Abstract

To solve the problems of large volume and poor flexibility of the traditional pressure sensor prepared by rigid materials, a flexible pressure resistance sensor with mesh convex platform microstructure has been prepared by using polydimethylsiloxane (PDMS) as a substrate and graphene as a conductive functional layer. The preparation process of the graphene conductive layer of the flexible sensor and PDMS substrate are optimized. And the effect of the concentration of graphene on the sensitivity of the sensor is investigated. The experimental results show that the addition of polyurethane to graphene and the hydrophilic treatment of the PDMS can improve the stability of the sensitivity of the sensor. Excessive graphene blocks microstructural gaps, leading to enhanced microstructural resistance to deformation which will reduce sensitivity. The experimental results show that the thicker the PDMS, the smaller the microstructural deformation, resulting in lower sensitivity. Based on the theoretical basis of elastic mechanics, the calculated results show that the microstructural strain decreases with the thickness of PDMS, consistent with the experimental results. Finally, the performance of PDMS microstructure sensor with thickness of 0.2 mm has been tested. The sensor has a high linear sensitivity (0.152 kPa−1) and a wide linear dynamic response range (0–4 kPa), along with a fast response time of 83 ms and reliable stability. The sensor has been attached to the index finger joint for bending test and fixed to the left hand pulse detection beat, which shows the sensor is able to detect human physiological activity.