High-performance strain sensor based on a 3D conductive structure for wearable electronics

Strain sensors have been widely used in various applications, such as wearable devices, robot arms, electronic skin, and human-machine interfaces. There is an increasing demand for flexible strain sensors as they have high sensitivity, a wide range, excellent flexibility, and good stability. Herein, we report a flexible strain sensor that utilizes reduced graphene oxide (rGO) decorated with Ag nanoparticles as the sensing material (Ag-rGO). Polydimethylsiloxane is used as the substrate and packing material to form a sandwich structure. The process of fabricating the strain sensor is simple and of low cost. The strain sensor exhibits high performance due to the unique 3D conductive structure. Ag nanoparticles function as connection points and adhere to the surface of graphene, which considerably improves the electrical conductivity of rGO, yielding a sensor with high sensitivity. The Ag-rGO strain sensor has a gauge factor (GF) up to 429 with a strain range of 200%; the minimal limit strain of the sensor is 0.2%, where the GF achieves 7.23. Additionally, we employed the strain sensor for applications involving the monitoring of human motions, such as facial expression recognition, vocal vibration tests, motion recognition, pulse, and breath monitoring. The strain sensor proposed in this study exhibits high sensitivity, wide range, and ultrashort response and recovery time. Moreover the sensor can be used to monitor human motions in real time. Therefore, the strain sensor possesses significant potential for use in wearable devices for healthcare, motion monitoring, speech recognition, and human interaction.