This is a sandwich of printed circuits and SBS elastomer is just 750 nm thick, for extremely high flexibility and comfort. (Image courtesy of Waseda University.)

A group of researchers at Waseda University has developed processes and materials for ultrathin stick-on electronic devices using an elastomeric "nanosheet"

film. The result is an easier production process that preserves high elasticity and flexibility 50 times better than previously reported polymer nanosheets, all at only 750 nm thick.

This research is published in the Journal of Materials Chemistry C online edition.

Smart electronics and wearable devices have several requirements for widespread adoption, especially ease of fabrication and wearing comfort. The materials and processes developed by the Waseda University team represent important strides forward on both counts.

Inkjet printing of circuitry and low-temperature fixing could allow the production of electronic devices which are durable and functional but also thin and flexible enough for use as a comfortable, skin-fitting appliance. These advances could help change the nature of wearable electronics from objects the size of wristwatches to items less noticeable than a band-aid.

The Waseda team also established a method of joining electronic components without soldering, allowing thinner and more flexible elastomer films. They created conductive "wiring" with inkjet printing, which can be done with a household type printer without the need for cleanroom conditions. Further, conductive lines and elements such as chips and LEDs can be connected by adhesive sandwiching between two elastomeric nanosheets, without using chemical bonding by soldering or special conductive adhesives.

According to the researchers, these simple, low-temperature processes gave the resulting ultrathin structures achieve better adhesion, without using adhesive matter such as tape or glue, better elasticity and comfort for skin-contact applications. The new system was proven functional for several days on an artificial skin model.

These results were achieved through collaboration among three specialties: Molecular assembly and biomaterials science; medical robotics and rehabilitation engineering; and micro-electromechanical systems.

Uses for these products are expected to include human-machine interfaces and sensors in the form of electronic tattoos, as radically improved tools for the fields of medicine, healthcare and sports training.

These applications are the subject of further investigation by the Waseda University Institute of Advanced Active Aging Research.

Source: Waseda University

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