Powering Batteries With Sweat
AMAY BANDODKAR — ELECTRICAL AND COMPUTER ENGINEERING PROFESSOR AT NORTH CAROLINA STATE UNIVERSITY
Tiny computers can do wonderful things when strapped to your body— think smartwatches, fitness trackers and other wearables—but how to comfortably, easily and consistently power these devices without a bulky battery and the need for constant recharging is a challenge. Bandodkar has come up with a novel idea: Use sweat.
Typically 90 percent of the size of a wearable device is taken up by the power source, usually a battery. Bandodkar got the idea to save space by using the wearer’s own sweat as the battery’s electrolyte—the solution that supplies the electrical current. He built a sensor that is four times smaller and 20 times lighter than other models that run on conventional batteries.
“By using a person’s own sweat as the battery’s electrolyte, I was able to develop a thin, flexible, battery cell which has an energy capacity similar to that of a coin cell battery [the kind used in watches] but without the latter’s use of toxic chemicals and rigid, metallic housing,” he says. Bandodkar has begun testing the sensor and battery but cautions that it will take several years to develop the technology for consumer products such as wearable devices. Eventually, he hopes the technology will prove useful for implantable medical devices, such as pacemakers or as heating patches on the skin that can increase blood
flow and expedite healing.