Graphene porous foams for capacitive pressure sensing

TL;DR

This paper presents the development of highly sensitive, durable graphene-based porous foam capacitive pressure sensors suitable for biomedical and wearable applications, with low detection limits and customizable conductive structures.

Contribution

The study introduces a systematic analysis of graphene-coated and embedded porous foams, demonstrating their superior sensitivity and detection limits for flexible pressure sensing.

Findings

Porous graphene foams exhibit high sensitivity (~0.137/kPa) in 0-6 kPa range.

Achieved a very low detection limit of 0.14 Pa.

Demonstrated detection of weak physiological signals.

Abstract

Flexible pressure sensors are an attractive area of research due to their potential applications in biomedical sensing and wearable devices. Among flexible and wearable pressure sensors, capacitive pressure sensors show significant advantages, owing to their potential low cost, ultra-low power consumption, tolerance to temperature variations, high sensitivity, and low hysteresis. In this work, we develop capacitive flexible pressure sensors using graphene based conductive foams. In these soft and porous conductive foams, graphene is present either as a coating of the pores in the foam, inside the structure of the foam itself, or a combination of both. We demonstrate that they are durable and sensitive at low pressure ranges (<10 kPa). Systematic analysis of the different pressure sensors revealed that the porous foams with graphene coated pores are the most sensitive (~ 0.137/kPa) in the pressure range 0-6kPa. Additionally, we achieved very low limit of detection of 0.14 Pa, which is one of the lowest values reported. Further, we demonstrated the potential applications of our pressure sensors by showing detection of weak physiological signals of the body. Our work is highly relevant for research in flexible pressure sensors based on conductive foams as it shows the impact of different ways of incorporating conductive material on performance of pressure sensors.