Gradient Response Color‐Changing Joule Heating Fabric for Visual Temperature Detection

Abstract Smart heating textiles with high safety factors are urgently demanded when multitudinous intelligent heater products spring up in wearable electronics. We report a Joule heating fabric with gradient response discoloration for visual temperature detection. The Joule heating fabric exhibits high electrical conductivity, and the surface resistance is around 150 Ω (2 cm). The temperature of Joule heating fabric rapidly rises from room temperature (25.6 °C) to 42.6 °C at 8 V in 160 s and keeps an equilibrium with the environmental temperature based on the electrothermal conversion properties of graphene. Meanwhile, the Joule heating fabric exhibits gradient response discoloration and turns from amaranth (25.6 °C) to blue (33.0 °C) and white (38.0 °C) successively. Once the power is turned off, the Joule heating fabric turns back to the amaranth in 60 s, resulting from the disappearance of Joule heating. These results suggest the temperature change of Joule heating fabric can be visualized via the gradient response color‐changing behavior under the applied voltage. The Joule heating fabric maintains stable electrothermal performance after repeated mechanical deformations and presents favorable durability even undergone over 50 cycles. The Joule heating fabric displays potential in wearable electronics for protecting the human body against scald.