Stepping up efforts to develop battery-free sensors, U.S. researchers have created a graphene-based device that harvests energy from ambient radiation to provide the electricity needed to operate an ultra-low-power temperature sensor.

The technology lets the sensor operate for at least 24 hours during a power outage.

The latest prototype is the team’s second self-powered sensor, following an earlier graphene-based solar-powered sensor. Together, the two devices are part of a wider effort to create autonomous sensors that draw energy from multiple sources in their surroundings instead of relying on conventional batteries.

The research, carried out by physicists and materials scientists at the University of Arkansas and the University of Michigan, is aimed at meeting three key requirements for next-generation sensors.

According to the team, the devices must harvest energy locally, consume only nanowatts of power, and operate unattended for years, potentially decades. The researchers said the latest ambient radiation-powered sensor satisfies all three criteria.

As opposed to traditional wireless sensors that depend on batteries, the new device captures energy already present in everyday environments.

Paul Thibado, a physics professor at the University of Arizona who began studying the properties of Graphene nearly a decade ago, said ambient electromagnetic radiation exists throughout modern homes because of electrical wiring.

The sensor uses a graphene inductor to harvest energy from the magnetic fields surrounding power lines. That energy is then sent through a circuit, converted into usable electricity, and stored in capacitors that power the temperature sensor, he added.

Thibado further explained that because the capacitors are replenished faster than they are discharged, the sensor can continue operating even if power is interrupted.

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