MIT researchers have developed a battery-free, self-powered sensor that can harvest energy from its environment.

Because it requires no battery that must be recharged or replaced, and because it requires no special wiring, such a sensor could be embedded in a hard-to-reach place, like inside the inner workings of a ship's engine. There, it could automatically gather data on the machine's power consumption and operations for long periods of time.

The researchers built a temperature-sensing device that harvests energy from the magnetic field generated in the open air around a wire. One could simply clip the sensor around a wire that carries electricity -- perhaps the wire that powers a motor -- and it will automatically harvest and store energy which it uses to monitor the motor's temperature.

"This is ambient power -- energy that I don't have to make a specific, soldered connection to get. And that makes this sensor very easy to install," says Steve Leeb, the Emanuel E. Landsman Professor of Electrical Engineering and Computer Science (EECS) and professor of mechanical engineering, a member of the Research Laboratory of Electronics, and senior author of a paper on the energy-harvesting sensor.

In the paper, which appeared as the featured article in the January issue of the IEEE Sensors Journal, the researchers offer a design guide for an energy-harvesting sensor that lets an engineer balance the available energy in the environment with their sensing needs.

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