Researchers from SANKEN (The Institute of Scientific and Industrial Research), at Osaka University design wood-derived electronic-skin substrates for electrophysiological monitoring that are functional, sustainable, and comfortable
Osaka, Japan – The idea of wirelessly gathering electrical information from the body through the skin is not new. However, the ideal electrode material must fulfill a significant list of criteria to be a realistic candidate for use on patients. Researchers from Osaka University have designed an electrode substrate derived from wood that appears to tick all the boxes and their findings have recently been published in Advanced Materials Interfaces.
The electrodes needed for on-skin electronics are supported by a substrate material that makes effective contact with the skin. Choosing a substrate requires the consideration of numerous factors: Is it flexible and comfortable to wear, but still durable? Can the substrate be sterilized so that it can be reused? Does it stick well to the skin and allow the skin to breathe? Is the substrate environmentally sustainable to produce and dispose of?
Finding a candidate is therefore tricky, but the Osaka researchers believe they have designed the most promising one to date. Their cellulose-based material is essentially paper made up of tiny nanofibers, giving it the name nanopaper e-skin, and it is the gaps between the fibers, whose size can be controlled, that give their substrate the edge.
“To get the best possible electrical signal it is important for a substrate to make good contact with the skin, which means it must be smooth. However, many examples of smooth materials are also very dense which severely reduces their breathability and results in user discomfort,” says study author Teppei Araki. “Because our nanopaper is a mesh of very fine fibers, it maintains good contact with the skin, but also has pores meaning that water vapor can pass through, reducing inflammation and making it comfortable to wear.” explains study first author Yintong Huang.
Once wet, the nanopaper could stick to skin because of the action of the water in the pores and was able to withstand 100 cycles of deformation on the forehead while maintaining function. The nanopaper could also be sterilized at high temperature.
“We believe that our nanopaper offers compatibility with both the body and the environment,” says senior author Hirotaka Koga. “The availability, flexibility, skin-conformability and -breathability, thermal stability, toughness, biocompatibility, and environmental sustainability of our substrate all combine to make it a highly promising candidate for electrophysiological monitoring that we expect to easily translate into the clinic for the measurement of data such as ECGs.” These results provide a very promising step forward in the field of on-skin electronics and may be the jump needed for explosive developments when we combine techniques of flexible and sustainable electronics that we have developed (See recent works below).
The article, “Skin-Adhesive, -Breathable, and -Compatible Nanopaper Electronics for Harmonious On-Skin Electrophysiological Monitoring,” was published in Advanced Materials Interfaces at DOI: https://doi.org/10.1002/admi.202202263
“Human Stress Monitoring” DOI: 10.1002/advs.202204746
“Imperceptible Electrophysiological Sensing” DOI: 10.1088/2058-8585/ac968c
“Nanopaper Semiconductor” DOI: 10.1021/acsnano.1c10728
“All-Cellulose-Derived Humidity Sensor” DOI: 10.1039/D1TC05339F
About Osaka University
Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world, being named Japan's most innovative university in 2015 (Reuters 2015 Top 100) and one of the most innovative institutions in the world in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.