New piezoelectric device harvests wasted energy from electronics

Piezoelectric generators that harness otherwise wasted energy from vibrations has been proposed for capturing energy in everything from shoes to roads. Now a new device made out of piezoelectric material by researchers at Louisiana Tech University could allow a wide range of electronic devices to harvest their own wasted operational energy, resulting in devices that are much more energy efficient. It even offers the potential to perpetually power micro and nano devices, such as biomedical devices or remotely located sensors and communication nodes.

The device, designed and fabricated by Dr. Long Que, assistant professor of electrical engineering at Louisiana Tech, uses a cantilever made out of material capable of converting distortions to itself into electrical energy. It is coated with a carbon nanotube film on one side that causes the cantilever to bend back and forth repeatedly when it absorbs light and/or heat. This causes the piezoelectric material to generate power for as long as the light and/or heat source is active.

“The greatest significance of this work is that it offers us a new option to continuously harvest both solar and thermal energy on a single chip, given the self-reciprocating characteristics of the device upon exposure to light and/or thermal radiation,” said Que. “This characteristic might enable us to make perpetual micro/nano devices and micro/nanosystems, and could significantly impact the wireless sensory network.”

The research team’s experiments showed that the device, called a CNF-PZT Cantilever, was able to generate enough power to operate some low-power microsensors and integrated sensors. One of the most impressive aspects of the system was its ability to “self-reciprocate” – perpetually produce energy without needing to draw power from an external energy source.

The researchers say that this self-reciprocation occurs from the cantilever’s constant absorption of photons and its high electrical conduction and rapid thermal dissipation into the environment. The team says it has routinely observed this self-reciprocation phenomenon, not only in the lab, but also in the field under sunlight.

“It is truly a hybrid energy-harvesting technology,” Que said. “My lab has been optimizing and making great progress on this technology in an effort to enhance its efficiency and overall performance, indicating great promise for this technology.”