Its energy-harvesting capabilities come courtesy of a metamaterial, a synthetic material engineered with characteristics not found in nature, like the ability to bend light the wrong way or shrink when you stretch it. In this case, the microwave-harvesting metamaterial that acts kind of like a solar panel, converting microwaves into up to 7.3 volts of electricity, enough to charge small electronics. It can scavenge stray signals, like from appliances or satellites, to improve efficiency and make lost energy usable.