Batteries are the one part of your wearable device that still seem old school. Although we’ve seen improvements in size and endurance, the chemistry and physics of batteries are just plain hard. A lot of scientists are investigating the alternative of energy harvesting or scavenging; that is, producing usable energy from natural sources, such wind, sun, or human activity.
Researchers at North Carolina State University, for example, are looking into nanotechnology to produce a way to harvest and use the ambient energy generated by body heat to power electronic devices. There’s similar work going on at MIT, where Sangtae Kim is working stamp-sized device to harvest energy released by the user’s motion.
The elusive goal, of course, is to generate enough energy to actually run something. Enter the new flexible thermocell developed by researchers at the Huazhong University of Science and Technology in China. It uses two electrodes at different temperatures in an electrolyte gel. The different temperatures create a difference in energy potential; by exploiting that, the battery produces enough current to run a basic, text-only e-book reader: roughly 0.3 µW of power at 0.7 V. The prototype uses two kinds of cells in a checkerboard configuration and mounted in a glove.
Researchers foresee using the possibility of using this technology in clothing that can keep you warm or cool—like a wireless electric blanket—and powering wearable devices.