Researchers have been developing various ways to power wearable technology and clothing without the need for bulky batteries that make these devices and materials less user friendly. In a new approach, researchers at the Georgia Institute of Technology have developed fabric that can simultaneously harvest energy from both sunshine and motion, providing a potentially continuous power source for wearable technology and clothing.
Indeed, the aim of the research was to develop “a wearable, flexible uninterruptible power source, which could be better integrated with our clothes and could work day and night,” Zhong Lin Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering and leader of the team that created the fabric, told Design News.
“Energies associated with a human are mostly solar and mechanical,” Wang said. “Here, a micro-cable-structured textile was presented to simultaneously harvest energy from ambient sunshine and natural human biomechanical movement for portable electronics, which could sustainably drive an electronic watch and directly charge a cell phone [while they are being worn].”
Other benefits of the material is that it is highly breathable, flexible, and can adapt to human surface curves and biomechanical movement.
Researchers at the Georgia Institute of Technology have developed a fabric that can harvest energy from both the sun and motion.
To make the fabric, the team used commonly used materials and methods that can easily be reproduced and scaled for broader use in garments or even curtains or tents, Wang said.
“The whole textile is assembled on lightweight, cheap, and flexible polymer fibers via a low-temperature wet process with earth-abundant, low-cost materials,” he said. “The backbone of the textile is made from commonly used polymer materials. Similar devices could also be fabricated based on other flexible materials. Furthermore, the fabrication process of the electrode is a low-temperature wet process, which is energy-saving and compatible with possible large-scale manufacturing.”
Using a commercial textile machine, researchers weaved together solar cells constructed from lightweight polymer fibers with fiber-based triboelectric nanogenerators. These type of nanogenerators use a combination of the triboelectric effect and electrostatic induction to generate electricity from mechanical motion such as rotation, sliding, or vibration. This movement could include materials rubbing together before being separated, Wang said.
“In its simplest form, the triboelectric generator uses two parts of dissimilar materials, one an electron donor, the other an electron acceptor,” he explained. "When the materials are in contact, electrons flow from one material to the other. If the sheets are then separated, one sheet holds an electrical charge isolated by the gap between them. If an electrical load is then connected to two electrodes placed at the outer edges of the two surfaces, a small current will flow to equalize the charges. By continuously repeating the process, an alternating current can be produced.”
The fabric, which is 320 micrometers thick, also can be integrated easily with other functional fibers or electronic devices “to form a flexible self-powered system,” he said
“Fabricated mostly with lightweight polymer fibers on a commercial knitting machine via a shuttle-flying process, solar cells are fabricated into micro cables, which can be a component for fabricating fiber-based triboelectric nanogenerators,” Wang said. “Colorful and flexible textile modules with arbitrary size and various knitting patterns were demonstrated as a wearable power source for portable and flexible electronics.
The team has conducted early tests that have shown the fabric can endure repeated and rigorous use, but next steps include long-term durability tests, Wang said. Researchers also plan to optimize the fabric further for industrial uses, including the development of appropriate encapsulation to protect the electrical components from rain and moisture, he said.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.