(Nanowerk News) The idea of wirelessly collecting electrical information from the body through the skin is not new. However, the ideal electrode material must meet a list of significant criteria to be a realistic candidate for use in patients. Researchers from Osaka University have designed a wood-derived electrode substrate that seems to tick all the boxes and their findings were recently published Advanced Material Interface (“Skin-Adhesive, -Breathable, and -Compatible Nanopaper Electronics for Harmonious Electrophysiological Monitoring of Skin”).
The electrodes required for in-skin electronics are supported by a substrate material that makes effective contact with the skin. Choosing a substrate requires considering a number of factors: Is it flexible and comfortable to wear, yet durable? Can the substrate be sterilized for reuse? Does it stick well to the skin and let the skin breathe? Is the substrate environmentally friendly to produce and dispose of?
Therefore, finding a candidate is tricky, but the Osaka researchers believe they have devised the most promising candidate to date. Their cellulose-based material is basically a paper made of tiny nanofibres, giving it the name nanopaper e-skin, and it is the gaps between the fibers, whose size can be controlled, that give the substrate an edge.
“To get the best electrical signal, it is important for the substrate to make good contact with the skin, which means it must be smooth. However, many examples of fine materials are also very dense which greatly reduces their breathability and results in user discomfort,” said study author Teppei Araki. “Because our nanopaper is a very fine fiber mesh, it maintains good contact with the skin, but is also porous which means moisture can pass through, reducing inflammation and making it comfortable to wear.” describes the study of the first author Yintong Huang.
Once wet, the nanopaper sticks to the skin due to the action of water in the pores and is able to withstand 100 cycles of deformation on the forehead while maintaining its function. Nanopaper can also be sterilized at high temperatures.
“We believe that our nanopaper offers compatibility with both the body and the environment,” said senior author Hirotaka Koga. “The availability, flexibility, skin suitability and breathability, thermal stability, toughness, biocompatibility and environmental sustainability of our substrates all combine to make them very promising candidates for electrophysiological monitoring which we hope to easily translate into the clinic for measurement. data such as ECG.
These results provide a very promising step forward in the field of in-skin electronics and may be a necessary leap for explosive development as we incorporate the flexible and sustainable electronics techniques we have developed (See recent work below).