A passive perspiration biofuel cell: High energy return on investment

Summary Self-powered wearable systems that rely on bioenergy harvesters commonly require excessive energy inputs from the human body and are highly inefficient when accounting for the overall energy expenses. A harvester independent from the external environment for sedentary states has yet to be developed. Herein, we present a touch-based lactate biofuel cell that leverages the high passive perspiration rate of fingertips for bioenergy harvesting. Powered by finger contact, such a bioenergy-harvesting process can continuously collect hundreds of mJ of energy during sleep without movements, representing the most efficient approach compared to any reported on-body harvesters. To maximize the energy harvesting, complementary piezoelectric generators were integrated under the biofuel cell to further scavenge mechanical energy from the finger presses. The harvesters can rapidly and efficiently power sensors and electrochromic displays to enable independent self-powered sensing. The passive perspiration-based harvester establishes a practical example of remarkably high energy return on investment for future self-sustainable electronic systems.