Weft-Knitted Fabric for a Highly Stretchable and Low-Voltage Wearable Heater

Wearable heaters have attracted broad attention due to their applications in personal heating systems and healthcare management, such as heat preservation in textile/clothing and thermotherapy. Protecting heating performance against deterioration under large deformation is is important for the application of wearable heaters. Here, a highly stretchable electrically driven heater based on electrically conductive weft-knitted fabrics is reported, which can be transformed from traditional fabrics through a facile heat treatment process. As an example, a heater made from Modal shows a heating temperature higher than 100 degrees C at a driving voltage as low as 3 V. The Joule heating performance of the heater does not deteriorate even under a large strain of 70%. Furthermore, according to theoretical analysis and experimental results, the output power and saturated temperature of the heater under a certain voltage can be easily tuned by tailoring the shape and size of the fabric to meet customized demands. The superior performance of the heater originates from the weft-knitted structural configuration. Finally, the application of the ultrastretchable heater in wearable thermal therapy devices is demonstrated, showing its great potential in wearable electronics.