Highly Stretchable, Knittable, Wearable Fiberform Hydrovoltaic Generators Driven by Water Transpiration for Portable Self‐Power Supply and Self‐Powered Strain Sensor

Abstract The development of excellently stretchable, highly mobile, and sustainable power supplies is of great importance for self‐power wearable electronics. Transpiration‐driven hydrovoltaic power generator (HPG) has been demonstrated to be a promising energy harvesting strategy with the advantages of negative heat and zero‐carbon emissions. Herein, this work demonstrates a fiber‐based stretchable HPG with the advantages of high output, portability, knittability, and sustainable power generation. Based on the functionalized micro‐nano water diffusion channels constructed by the discarded mask straps (MSs) and oxidation‐treated carbon nanomaterials, the applied water can continuously produce electricity during the spontaneous flow and diffusion. Experimentally, when a tiny 0.1 mL of water encounters one end of the proposed HPG, the centimeter‐length device can yield a peak voltage of 0.43 V, peak current of 29.5 µA, and energy density of 5.833 mW h cm −3 . By efficiently integrating multiple power generation units, sufficient output power can be provided to drive commercial electronic devices even in the stretched state. Furthermore, due to the reversibility of the electrical output during dynamic stretching‐releasing, it can passively convert physiological activities and motion behaviors into quantifiable and processable current signals, opening up HPG's application in the field of self‐powered wearable sensing.