Quick Thermal Response‐Transparent‐Wearable Heater Based on Copper Mesh/Poly(Vinyl Alcohol) Film

High‐performance, transparent, wearable heaters with fast thermal response are developed. To accomplish this, highly conductive and transparent copper (Cu) mesh films are transfer printed onto flexible poly(vinyl alcohol) (PVA) substrates of different thicknesses. The thermal response characteristics of the heaters, with different PVA substrate thicknesses, are analyzed and results are recorded. The Cu mesh/PVA film heater shows a favorable figure of merit value of 228.4 and outstanding durability in response to mechanical stress tests for bending, crumpling, and detaching. Through the test results, it is concluded that the thermal response time of the heater is directly related to the thickness of the PVA substrate. The optimized Cu mesh/PVA film heater, with a substrate thickness of ≈60 μm and input voltage of 3 V (DC), exhibits a fast Joule heating effect with a response time of ≈12 s and a ramping rate of ≈7.5 °C s −1 . These are excellent results, compared with the previously reported studies with other metal‐based flexible transparent heaters. A flexible transparent heater with low applied voltage and fast response time is expected to have innovative electrothermal applications, such as transparent soft actuators, wearable heaters, and medical thermotherapy pads.