Microgrids power small geographic areas using a network of distributed energy sources. Microgrids that serve municipalities, college campuses, and hospital complexes draw and store power from various sources, including solar, wind, water, and other renewable energy systems. A team of nanoengineers at the University of California San Diego took inspiration from full-scale microgrids when designing a new wearable microgrid that harvests and stores electricity from sources within the human body.

The UCSD team used screen-printing to create a shirt with components placed at specific locations on the chest. Flexible technology printed on the shirt includes biofuel cells powered by sweat and triboelectric generators harvesting energy from movement. The shirt also contains supercapacitors that store the bio-generated energy, releasing it when needed to power a small electronic device.

Silver connectors printed on the shirt connect the three separate operations. The engineers found that bending, crumpling, folding, and washing in soap-free water did not reduce any of the printed components’ performance. 

As soon as the wearer starts moving, the shirt can provide power. Triboelectric generators on the waist and forearms harvest energy from walking and running movements. Once the exercise results in perspiration, biofuel cells placed at the chest draw power from sweat. When movement pauses, the biofuel cells can still provide energy. 

Like a community microgrid, the shirt provides continuous power because it doesn’t rely on a single source. And just as a community microgrid is more sustainable and reliable than a traditional, single-source power grid, the UCSD shirt offers a reliable, renewable alternative battery power for wearables and other small electronics.

The nanoengineers have published a paper on their findings in the journal nature communications. The current wearable microgrid could power devices during exercise or physical therapy. The UCSD team intends to continue developing wearable microgrids that harvest energy from other body functions, which could eventually provide power during rest. That means wearable microgrids have the potential for widespread application.