Smart wearable heaters with high durability, flexibility, water-repellent and shape memory characteristics

The electrical and thermal performance as well as the durability of the silver nanowire (AgNW)-based wearable heaters was assessed. Shape memory polymer (SMP, NOA 63), AgNW, and water repellent (WR) coatings were formed on fabrics by simple dip-and-dry coating and spray coating methods. The variation in temperature of the wearable heater with voltage and time was monitored. On applying voltage, the temperature initially increased with time and eventually converged to a steady-state value. Then, when the application of voltage was stopped, the temperature fell rapidly. Even when the fabrics were harshly deformed by bending, folding, rolling up, twisting, crumpling, grasping, rubbing, and scratching, the electrical and thermal performance remained almost consistent; after severely deformed the original flat shape could be restored by thermal stimulation. Moreover, in harsh environments with high humidity, the WR coating exhibited high performance and durability for protecting AgNW electrodes against corrosion. As a result, owing to the structural coating using materials that had functions such as shape memory (self-ironing or drip-dry) and water repellent property (self-cleaning), the enhanced smart wearable heaters had high electrical, thermal, and mechanical performance and the AgNW electrodes were highly durable.