Highly Sensitive Capacitive Low-Pressure Graphene Porous Foam Sensors

Abstract

Flexible pressure sensors are becoming increasingly popular due to their potential applications in multifunctional wearable devices. Among flexible pressure sensors, capacitive pressure sensors based on porous foams of poly(dimethylsiloxane) (PDMS) are widely investigated. In this work, we develop highly sensitive capacitive pressure sensors operating in a low-pressure range (<10 kPa) using graphene-coated PDMS foams with different ranges of pore sizes, obtained either by sugar templating or a combination of sugar templating and emulsion templating. Our analysis reveals that pressure sensors with the highest variation in pore sizes over a wide pore size range are the most sensitive and reach a high sensitivity of ∼3.7 kPa–1 (for a range of 2–6 kPa). These pressure sensors have a low limit of detection of ∼20 Pa and are able to detect small changes in pressure in many situations, demonstrating potential applications in wearable biomedical sensors. Our result shows future pathways for developing pressure sensors with higher sensitivities and, therefore, highly relevant for research in pressure sensors based on conductive foams.