Printable and Wearable Graphene-Based Strain Sensor With High Sensitivity for Human Motion Monitoring

Wearable strain sensors are appealing for monitoring human activities and evaluating human health. However, the development of wearable strain sensors with high sensitivity, large-scale manufacturing ability as well as the using of eco-friendly raw materials is still challenging. In this work, a simple and environmentally friendly high-performance strain sensor based on graphene/thermoplastic polyurethane (TPU) composite is reported. The green solvent dihydrolevoglucosenone (Cyrene) was used to dissolve and disperse TPU and graphene to make conductive ink, and the graphene/TPU composite film was embedded in the polydimethylsiloxane (PDMS) matrix by stencil printing and transfer process. The optimized sensor showed a very low detection limit (strain
$\sim ~0.1~\unicode{0x2030}$
), high sensitivity (GF >3905) and broad sensing range (0 - 82.4 %). Moreover, the sensor remains stable under 5,000 times of loading/unloading cycles, with outstanding fatigue resistance and long-term durability. Additionally, a series of human motion monitoring applications were demonstrated, indicating their great potential in practical applications.