Toward high-performance multifunctional electronics: Knitted fabric-based composite with electrically conductive anisotropy and self-healing capacity

Abstract

Textile-based electronics characterizing easy integration into textile garments and good wearability have received considerable attentions. However, it is still a huge challenge to integrate multiple functions into single electronic device, especially for those having different even opposite requirements in electrical properties. In this work, an anisotropic electrically conductive composite was prepared by encapsulating conductive knitted fabric (CKF) into polyurethane (PU). Based on anisotropic electrical conductivity, i.e., extremely low and stable resistivity in the coursewise direction and significant variation of resistivity in the walewise direction during tensile strains, the composite could efficiently integrate the electro-heating and strain-sensing functions that required opposite electrical properties. When applied for electro-heating applications in the coursewise direction, the CKF/PU composite exhibited fast thermal response, ultrahigh electric-thermal conversion (140 °C at 4 V), and stable electrothermal performance under a large strain (40%) or after long-term use (>1000 stretching cycles). When applied for strain-sensing applications in the walewise direction, the composite showed good sensing performances, including high sensitivity (GF of −8.1 at a 5% strain), low hysteresis, good reproducibility and stability (>1000 cycles), which enabled the device as a wearable sensor to accurately detect human joint movements and subtle motions. Furthermore, the self-healing function was exploited for the CKF/PU electronic device, by which the abnormal sensing property could be fully repaired at human body temperature. This work may shed new light on the future development of high-performance multifunctional wearable electronics with the anisotropic conducting feature.