Batteries are the bottleneck of any electronic system, says Dina El-Damak, a professor of electrical engineering at the University of Southern California. A device is only as good as its power source, and already the quest for more power and faster computing has led to dangerous situations like the Samsung Galaxy 7 explosions. One solution is creating self-powered devices that generate electricity from sources like motion and body heat with no internal battery needed.

Though it’ll be a while before we break up with our iPhone chargers, scientists around the country are working toward this goal, and companies are in on it, too.

There are many ways self-powered devices can work. One is piezoelectric energy, which is generated when you apply pressure to certain materials. Another method, more common in the public imagination, is harvesting movement. But while movement seems obvious, it’s not practical to have a device that only works when you’re in motion. So, for many researchers, the best source of energy is body heat, or thermoelectric generation.

Both Wang and Misra at ASSIST work with industry partners to try to bring the technology to market. Wang says that he thinks it’ll be three years before his device could come to market.

Until then, there’s the Matrix Watch, which uses body heat and starts shipping in September.