Constructing Ion-Bridging Structure with Controlled Cracks in Plasticized PVC with Graphene for Highly Sensitive Strain Sensor with a Wide Strain Range.

The gauge factor (GF) is a critical parameter for strain sensors, but it faces limitations in achieving high GF values across a wide strain range. This work proposes a novel approach to enhance resistance changes within strains through synergistically combining controlled-crack sizing and an ion-bridging structure. This ion-conductive bridge forms at the interface between graphene and polyvinyl chloride (PVC) gel. Precise management of the crack initiation and propagation on graphene is achieved by controlling adhesion force between graphene and PVC gel. The resulting PVC gel/graphene-based strain sensor featuring this synergistic design exhibits exceptional sensitivity. It achieves GFs of 635 (ε < 40%), 1.5 × 10 (40% < ε < 80%), and 7.8 × 10 (80% < ε < 100%) over a 100% stretching range. This innovative ion-bridging construction enables precise control over bridge connectivity at the interface, mitigating graphene's inherent stretchability limitations and enhancing the GF of PVC gel, thereby enhancing strain sensor performance. The sensor detects bending motions and monitors angles within higher strain ranges, making it suitable for wearable applications in human motion tracking. Furthermore, a PVC-based posture correction system distinguishes various motions, including shoulder band stretching, armband stretching, and even full squats, showcasing its practicality and versatility.