Wearable E-Skin Microgrid with Battery-Based, Self-Regulated Bioenergy Module for Epidermal Sweat Sensing

Energy-autonomous wearable systems and wearable microgrids have been a focus of developing the next-generation wearable electronics due to their ability to harvest energy and to fully support the sustainable operation of wearable electronics. However, existing bioenergy harvesters require complex and low-efficiency voltage regulation circuitry and have not achieved reliable extended operation and energy storage. In this work, the first example of integrating sweat lactate biofuel cells with a rechargeable Zn-AgCl battery into a bioenergy module for regulation-free, high-efficiency, extended biochemical energy harvesting and storage is demonstrated. The integrated bioenergy module is able to operate at its best efficiency due to their matching operating potentials and is characterized by robust mechanical durability enduring over 1000 cycles of repeated tensile deformation, as well as the outstanding long-term autonomous operation that harvest 2.9 J of energy overnight from 20 min of exercise without measurable self-discharge. A fully integrated wearable electronic skin patch, powered by two such bioenergy modules, is developed to wirelessly perform continuous sweat pH, ascorbic acid, and lactate sensing. The presented bioenergy module, adapting the wearable microgrid design considerations, delivers a practical, high-efficiency, and reliable solution for next-generation wearable electronics that features compatible form factors, commensurate performance, and complementary characteristics.