Apropos K

Electronics that stick to the skin

It looks like a tattoo, but it isn’t one. It does, however, conduct electricity – wirelessly! Welcome to the future, welcome to polymer electronics.

This is a sandwich of printed circuits and SBS elastomer is just 750 nm thick, for extremely high flexibility and comfort. Credit: Waseda University

It can be assumed that the era of thick and heavy watches on our wrists that are crammed with high-tech equipment will soon be over. Pulse and heart rate monitors: instead of being strapped on, such monitors will simply be stuck on the skin in future and will send a host of medically relevant parameters to stationary receivers. Secret services are already delighted about the tremendous new opportunities that are opening up for monitoring and tapping operations. The incredible thing is that you don’t realise that you are “wired” – because you aren’t. The secret is the use of ultrathin conductive polymer films. 

It is perhaps something of an exaggeration, but there is a danger that what we will be wearing on our skin in the near future is smarter than we are. Because the electronics which we are talking about here and in the development of which scientists all over the world are investing a great deal of time and energy are described as smart. What are involved here are conductive polymers, which can be produced anywhere with the simplest of inkjet printers and with which surfaces can be coated. Fast progress is being made in the development of conductive polymers. Research scientists at Waseda University in Tokyo, Japan, only recently came up with a new process, with which not only ultrathin electrically conductive SBS films (SBS: polystyrene-polybutadiene-polystyrene) can be manufactured with complex circuits and functions but which can also simply be stuck to the skin and be connected to further components easily – without wires and without plugs. 

The conductive “wiring” is also produced by inkjet printing. It appears that chips and LEDs can be integrated extremely easily - with an adhesive that is located between two polymer layers. The entire sandwich structure is, however, only 750 nanometres thick and is therefore far thinner than a hair! Chemists, polymer scientists, biomechanics and many other scientific disciplines are working hand-in-hand on this development project, in order to get the best out of the polymer material and in order to find applications where such thin and powerful polymer electronics are crucial, so that existing technical limitations can be overcome. It remains to be seen when conductive polymers will establish themselves on a large scale and replace existing conventional technology, e.g. in medicine, healthcare, sport or the industrial environment. Experts are convinced that conductive polymers will establish themselves. The only question is: when? GD

Reference

Marin Okamoto, Mizuho Kurotobi, Shinji Takeoka, Junki Sugano, Eiji Iwase, Hiroyasu Iwata and Toshinori Fujie, Sandwich fixation of electronic elements using free-standing elastomeric nanosheets for low-temperature device processes, J. Mater. Chem. C, 5 (2017) 1321-1327, DOI: 10.1039/c6tc04469g