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, ultralow 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, or as 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–1) in the pressure range 0–6 kPa, with a limit of detection of 50 Pa. 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.

Organic thin film transistors, employing diverse device architectures, materials and form factors, have been demonstrated as effective sensors of a variety of analytes, including ions. In many such devices, it...

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.

A porous and conductive gate electrode of PEDOT:PSS and sulphonated mesoporous silica nanoparticles is investigated for organic thin film transistor sensors.