Electronic skins or 'e-skins' have recently emerged as a novel platform for electronics, taking on more important roles in health diagnostics, therapeutics, and monitoring. Stand-alone and self-sustained e-skins are essential to providing reliable, effective and sometimes life-saving functions. A stable power supply is the most critical factor in developing practical e-skins because the performance of their potential applications depends significantly on power availability. Thus, a realistic and accessible power source is urgently needed for a next-generation of smart, stand-alone, always-on e-skin systems. This is a challenge because human skin intimately integrated with e-skins is an extremely harsh environment for power generation. Skin is cool, dry, acidic and lacks potential energy sources. The overall objective of this proposal is to create the ability to generate an innovative, practical, and longstanding power from human sweat, which is one of the few available energy resources on the skin, by using the metabolisms of sweat-eating bacteria including human skin microorganisms or ammonia-oxidizing microorganisms. Given that the total non-human microbial cells inhabiting in and on our bodies outnumber the human cells by at least a factor of 10, the direct use of the microbial cells to produce power is conceivable for e-skins. Findings will first be disseminated within the discipline through local and international conferences and journal publications; then they will be distributed through educational venues maximizing the project's reach and impact. The project will train graduate students and outcomes will be integrated into post-secondary courses and K-12 outreach activities.
This project will establish an innovative strategy to revolutionize power generation on human skin, delivering on-chip energy to the next generation of e-skin paradigm. The proposed sweat-powered batteries will be based on microbial fuel cells (MFCs), exploiting sweat-eating bacteria including human skin-inhabiting or ammonia-oxidizing microorganisms as a biocatalyst to transform the chemical energy of sweat into electrical power through bacterial metabolism. A thin, soft, flexible MFC will be pre-inoculated with selected electrogenic (or electron-producing) sweat-eating bacteria and will operate with human sweat, delivered by an integrated battery-free skin-interfaced system. The two-fold central hypothesis is that (i) some sweat-eating bacteria are capable of extracellular electron transfer and act as a biocatalyst in the microbial fuel cell device to produce electrical power, and (ii) those microorganisms can feed off the human sweat including ammonia and other organic substances for constant and sustaining bioelectricity generation. The immediate potential benefits of the proposed research are that (a) the project will develop a skin-mountable bacteria-powered battery system and establish fundamental knowledge critical to increase its performance, (b) the work will promote and accelerate the discovery and characterization of electrogenically active sweat-eating microorganisms, and (c) it will also create a novel skin-interfaced microfluidic system for sweat collection, delivery and storage to drive the integrated bacteria-powered battery. (d) Finally, this project will allow the microbial fuel cell technology to find more realizable applications as "biopower-on-skin" enables an entirely new area of energy harvesting research.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
