A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires

TLDR

Next‑generation pressure sensors for e‑skin, wearables, robotics, and prosthetics require high sensing capability, yet existing surface patterning and special elastomeric interlayers are complex and costly, hindering large‑scale production. The authors employ a simple printing process to fabricate a sensor with an elastomeric composite interlayer filled with silver nanowires. This design yields a maximum sensitivity of 5.54 kPa⁻¹, maintains other performance attributes, remains flexible and stable over 200 bending cycles, reproduces without hysteresis, and can be integrated onto an adhesive bandage to detect both contact and non‑contact pressures such as human motion and airflow.

Abstract

The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1). The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.