Scientists have developed a tiny temperature sensor that harvests energy from magnetic fields near electrical wiring.

Electrical wiring produces weak electromagnetic fields that typically go unnoticed, but researchers have found a way to turn some of that energy into a power source for tiny electronic devices. Scientists at the University of Arkansas (U of A) and the University of Michigan have developed a graphene-based energy harvester capable of powering an ultra-low-power temperature sensor without a conventional battery.

The prototype operates using energy collected from its immediate surroundings, consuming power measured in nanowatts, or billionths of a watt. It represents another advance toward the team’s goal of developing autonomous sensors that could function unattended for decades.