Flexible Pressure Sensor Based on a Thermally Induced Wrinkled Graphene Sandwich Structure

Abstract

Flexible piezoresistive pressure sensors based on a graphene-elastomer composite have gained popularity as electronic wearable sensors due to their simplicity and promising practical application in health monitoring and wearable devices. There is an urgent need to develop pressure sensors that are simplistic in design with good sensitivity and equally capable of production in large volumes. Studies have shown that implementing micro/nanostructures improves the sensitivity of graphene-elastomer pressure sensors. Therefore, in this paper, we fabricated thick nano wrinkles on a graphene-elastomer sandwich structure through a rapid thermal annealing procedure. The wrinkled structure was fabricated by rapid thermal annealing of spin-coated PEDOT:PSS (PH1000) on graphene-PDMS composite to facilitate the generation of wrinkles and optimize the sensitivity of our pressure sensor. We performed analyses on our pressure sensor under various compressive loading ranges. The pressure sensor detected pressure applied at these various ranges within a reasonable response time of 160ms and demonstrated excellent repeatability without hysteresis. In addition, we observed satisfactory sensitivity under tensile strain exhibiting high stretchability. The sensor displayed good sensitivity of 2.83 kPa ⁻¹ from compressive loading in the low-pressure range 0 Pa −490 Pa, and from 490 Pa-10 kPa the sensitivity was 0.12k Pa ⁻¹ . The sensor demonstrated stretchability of up to 50% with a gauge factor of 20.1. We observed that it is highly responsive in the lower pressure range and capable of detecting subtle pressure. Furthermore, we demonstrated pressure detection in human motion monitoring. Overall, the pressure sensor displayed potential applications in human monitoring devices and wearable electronics.