Reviewed by Lexie CornerJan 16 2025
Researchers at North Carolina State University have developed wearable technologies that generate electricity from human motion while enhancing user comfort. This advancement is based on a deeper understanding of materials that improve the tactile properties of textiles and produce electricity through friction with other surfaces.
Image Credit: Pedro Henrique Wink Reis, North Carolina State University
The key lies in molecules known as amphiphiles, which are commonly used in consumer products to reduce skin friction. For instance, amphiphiles are frequently added to diapers to minimize chafing.
We set out to develop a model that would give us a detailed fundamental understanding of how different amphiphiles affect the surface friction of different materials. The model helps us understand the molecular basis for friction reduction and can be used by engineers to tailor a material’s properties for different applications.
Lilian Hsiao, Study Corresponding Author and Associate Professor, Chemical and Biomolecular Engineering, North Carolina State University
“We then began a series of experiments to explore whether we could use amphiphiles to modify materials and incorporate them into haptic energy harvesters,” said Saad Khan.
Specifically, we wanted to know if we could create energy from friction in amphiphile-modified materials. It turns out we could not only generate electricity, but we could do so while also reducing the friction that people wearing these materials experience.
Saad Khan, Study Co-Corresponding Author and INVISTA Professor, Chemical and Biomolecular Engineering, North Carolina State University
The researchers demonstrated that wearable textiles could be engineered with smooth, skin-friendly surfaces using amphiphiles. They further discovered that certain amphiphiles possess electron-donating properties. By incorporating these electron-donating amphiphiles into the wearable materials, the team created textiles capable of generating electricity through friction when rubbed against other materials or human skin, while maintaining comfort.
“The technology for harvesting static energy is well established, but devices that can be worn for long periods of time are still missing. In our proof-of-concept testing, we found these amphiphile materials not only feel good on the skin but could generate up to 300 volts, which is remarkable for a small piece of material,” said Hsiao.
“An optimal balance between friction needed to generate power and maintaining the comfort of the wearer is paramount in designing haptic technologies, and amphiphile chemistry offers a facile way to do so. We’re interested in doing more to make use of these materials, such as exploring how they can be incorporated into existing haptic devices. And we’re open to working with industry partners on identifying new applications,” said Khan.
The study’s first author is Pallav Jani, an NC State Ph.D. graduate. Co-authors include Hilmar Koerner, head of the Polymer Matrix Composites Program at the Air Force Research Laboratory; Maryanne Derkaloustian and Charles Dhong of the University of Delaware; and Kushal Yadav, a Ph.D. candidate at NC State.
The research was supported by the National Science Foundation, the Dreyfus Foundation, the Sloan Research Fellowship, the Nonwovens Institute, the National Institutes of Health, and the National Eye Institute.
Journal Reference:
Jani, K, P., et al. (2024) Compressing slippery surface-assembled amphiphiles for tunable haptic energy harvesters. doi.org/10.1126/sciadv.adr4088