A new, ultrathin energy harvesting system has the potential to harvest electricity from human motion. Based on battery technology and made from layers of black phosphorus that are only a few atoms thick, the new device generates small amounts of electricity when it is bent or pressed even at the extremely low frequencies characteristic of human motion.

The energy harvesting device is so thin it can be embedded in fabric.
(Credit: John Russell/Vanderbilt)

Because the basic building blocks of the harvester are about 1/5000th the thickness of a human hair, the engineers can make their devices as thin or as thick as needed for specific applications. They have found that bending their prototype devices produces as much as 40 µW per square foot and can sustain current generation over the full duration of movements as slow as 0.01 Hz, one cycle every 100 seconds.

The researchers acknowledge that one of the challenges they face is the relatively low voltage that their device produces. It’s in the millivolt range. However, they are applying their fundamental insights of the process to step up the voltage.