Researchers at MIT have developed a device and software that could figure out exactly how much power is being used by every appliance, lighting fixture, and device in a home. (Bryce Vickmark)

New postage-stamp-sized sensors developed at MIT measure exactly how much power is being used by every device in a household. No wires need to be disconnected, and the placement of the sensors over the incoming power line does not require any particular precision. The sensors pick up so much information about spikes and patterns in the voltage and current, that the system can tell the difference between every different kind of light, motor, and other device, and show exactly which ones go on and off at what times.

The system uses an array of five sensors, each slightly offset from the others, and a calibration system that tracks the readings from each sensor and figures out which one is positioned to give the strongest signal.