A Wearable All‐Fabric Thermoelectric Generator

Abstract Wearable thermoelectric generators are a promising energy source for powering activity trackers and portable health monitors. However, known iterations of wearable generators have large form factors, contain expensive or toxic materials with low elemental abundance, and quickly reach thermal equilibrium with a human body, meaning that thermoelectric power can only be generated over a short period of wear. Here, an all‐fabric thermopile is created by vapor printing persistently p‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐Cl) onto commercial cotton and this thermopile is integrated into a specially designed, wearable band that generates thermovoltages >20 mV when worn on the hand. It is shown that the reactive vapor coating process creates mechanically rugged fabric thermopiles that yield notably high thermoelectric power factors at low temperature differentials, as compared to solution‐processed counterparts. Further, best practices for naturally integrating thermopiles into garments are described, which allow for significant temperature gradients to be maintained across the thermopile despite continuous wear.