Power is just a heartbeat away

Even our footsteps can generate power, by driving a salty liquid through microscopic pores in a shoe sole to deliver up to two watts per leg, using a “reverse electrowetting” device developed by Professor Tom Krupenkin at the University of Wisconsin, Madison. “This is more than sufficient to power such common devices as smartphones and tablets,” he says. “We expect the first product prototype to be available in one to two years.”