Autonomous self-healing wearable flexible heaters enabled by innovative MXene/polycaprolactone composite fibrous networks and silver nanowires

For flexible devices to be effectively integrated into long-lasting wearable systems, self-healing properties that can repair the damage are crucial. Although numerous studies have reported on the fabrication of self-healing devices, most still rely on external energy sources, such as heat or light, to initiate the intrinsic healing mechanisms. In this study, we successfully developed a spontaneously self-healing heater (SHH) that eliminates the need for any additional processes. To fabricate the SHH, we employed electrospun polycaprolactone (PCL) fibers, which have a melting point of 60 °C, as the core material. We coated the PCL fibers with Ti₃C₂T _X MXene nanosheets and silver nanowires (AgNWs) to form electrode layers. Although PCL is unsuitable for heaters due to its low melting point, introducing MXene nanosheets as shape-retention barriers enabled the development of a thermally stable MXene/PCL composite that exhibits self-healing capabilities. The AgNW-coated MXene/PCL fibers demonstrated excellent electrical conductivity, with the heater’s temperature increasing proportionally to the applied voltage. The optimized heater achieved excellent flexibility, reaching temperatures above PCL’s melting point with a voltage of only 1–2 V. We repeatedly induced a crack on the heater’s surface and applied a voltage of 1.6 V, resulting in a temperature increase to 61 °C. Remarkably, the crack was autonomously repaired. Even in more severe damage scenarios with a complete cut the sample, the heater successfully rejoined the severed portions without any deterioration. This flexible heater’s inherent autonomous self-healing characteristics liberate users from the burden of trivial component repairs, ultimately enhancing the longevity of wearable devices. Graphical Abstract: This study presents a flexible heater that demonstrates spontaneous self-healing capabilities during heat generation, eliminating the necessity for additional processes.[Figure not available: see fulltext.]