Dr. Moonhyung Jang and Dr. Gang Wang

Dr. Moonhyung Jang, left, operates the generator to light an LED display as Dr. Gang Wang looks on in the Adaptive Structures Laboratory.

Michael Mercier / UAH

A bit of laboratory serendipity led University of Alabama in Huntsville (UAH) researchers to a simple mechanical way to generate electricity to operate electronic devices, says a paper they have published.

Triboelectric nanogenerators use multiple layers of different materials to generate electricity when pressed. While testing a triboelectric nanogenerator in the Adaptive Structures Laboratory of Dr. Gang Wang at UAH, a part of the University of Alabama System, postdoctoral research assistant Dr. Moonhyung Jang observed something unusual.

“During a finger-tapping test performed by Dr. Jang, a Scotch tape was introduced on the top to prevent electric shock,” says Dr. Wang, an associate professor of mechanical and aerospace engineering and the project’s principal investigator.

“An unexpected high voltage was observed. After a careful investigation, we figured out that the tape layer is the reason to cause this,” Dr. Wang says. “This led to our invention that introduces tacky materials to improve the performance of triboelectric generators.”

Consisting of a metalized polyester sheet that’s similar to shiny gift-wrap plastic material and a double-sided tape with an acrylic adhesive layer, the configuration is both simple and cost effective.

“A contact-and-separation motion is required for the current triboelectric generator design,” says Dr. Jang, who is the paper’s lead author. “In our recent paper, we demonstrated energy harvesting when someone is walking by using a shoe integrated with the current triboelectric generator. We can modify the design to meet other applications accordingly.”

Supported by Materials Sciences LLC via a U.S. Army Small Business Innovation Research (SBIR) phase 2 program, the goal of the project is to provide an energy harvesting solution that will power sensors and electronics to track flight times of aviation and missile structures. In the phase I effort, Dr. Wang and his team successfully demonstrated the galloping energy harvesting concept using piezoelectric materials.

Dr. Jang joined the group to support the SBIR phase 2 program on June 1, 2021. Alumnus Jacob Lee of Toney (B.S., Aerospace Engineering, May 2022) is a paper co-author. Lee is now an engineer at the U.S. Army Space and Missile Defense Command.

“We are grateful, as well, for the technical guidance from Dr. Simon Chung, vice president of research and development at Materials Sciences LLC,” Dr. Wang says. Dr. Chung is also a paper co-author.

“A simple idea was to try a triboelectric nanogenerator design by modifying the surface structure of a triboelectric layer using the atomic layer deposition technique,” says Dr. Wang. “This is why we invited Dr. Yu Lei to help us build such prototype in his lab by creating oxidized layers.”

Dr. Lei is the interim chair and an associate professor in the Department of Chemical and Material Engineering, and it was that prototype that Dr. Jang was testing when the unusual readings were noticed.

“Moreover, Dr. Lei also contributed to our current paper and provided lots of suggestions and comments from a material scientist’s perspective,” says Dr. Wang.

The investigators are exploring different concepts to improve the device’s performance. The scientists used an LED display to illustrate the concept, but they say it has much wider potential applications.

“The ultimate goal is to provide a power source for sensor and monitoring systems in different engineering applications,” says Dr. Jang. “We already conducted some tests to demonstrate a wearable sensor concept for the human body.”