Thermospun Conductive Composites with a Wide Strain Range, Excellent Fatigue Resistance, and High Linearity for Fibrous Strain Sensors

The development of a fibrous conductive elastomer with the ability to withstand large deformations and exhibit linear stretching sensitivity is significant and challenging for wearable strain sensors. Herein, a continuous thermospinning strategy is presented to fabricate a fibrous strain sensor (MCPF sensor) that offers a wide sensing range, excellent fatigue resistance, high linearity, and good mechanical properties. The MCPF consists of CNTs modified by a silane coupling agent (KH570-CNT) and polydimethylsiloxane (PDMS) as the conductive substances and elastic substrates, respectively. The interface between KH570-CNT and PDMS is enhanced, resulting in superior mechanical properties of the MCPF sensor. The MCPF exhibits a wide strain range (0–100%), good stretch repeatability for 1000 cycles of 50% strain, and excellent conductivity. Additionally, the MCPF can be knitted onto a stretchable fabric, enabling excellent flexibility. The fibrous sensor assembled with the MCPF demonstrates high linearity, minimal response time (<120 ms), high cyclic stability (>70,000 s), and stable responses under various strain ranges and cyclic frequencies. In practical applications, the MCPF sensor can simulate the monitoring of large and facet joint movements, indicating its wearability, wide detection range, extremely high sensitivity, and timely responsiveness. Through modification with a silane coupling agent, the aggregation between CNTs is effectively reduced, and CNTs can be uniformly dispersed in the PDMS substrate. This control over aggregation improves the dispersion of CNTs in PDMS, resulting in the excellent mechanical, electrical, and sensing properties observed in the prepared MCPF. Therefore, the fibrous conductive elastomer fabricated using the continuous thermospinning strategy holds promise for producing high-performance wearable strain sensors.