Ultra-thin thermoplastic elastomer and printed conductive wiring come together in ‘electronic tattoos’

Advances in polymer materials science and processing techniques have led to the development of ultra-thin “electronic tattoos” that reportedly are 50 times more flexible and much easier to fabricate than existing technologies. The materials and processes developed by researchers at Waseda University (Shinjuku, Japan) are said to represent “huge strides forward” for smart electronics and wearable devices. The research is published in the Feb. 1 online edition of the Journal of Materials Chemistry.

By using an SBS elastomer and applying common ink-jet printing techniques to manufacture the circuitry, the researchers were able to produce an extremely flexible 750-nanometer-thick film that could fundamentally change the way we think of wearables.

The collaborative effort that brought together university experts in molecular assembly and biomaterials science, medical robotics and rehabilitation engineering, and micro-electro-mechanical systems established a solder-free method of joining electronic components. “The conductive wiring is created by inkjet printing, which can be done with a household-type printer without the need for cleanroom conditions,” explained the news release. “Further, conductive lines and elements such as chips and LEDs are connected by adhesive sandwiching between two elastomeric nanosheets, without using chemical bonding by soldering or special conductive adhesives.”

The low-temperature process produces ultra-thin structures that combine adhesion, elasticity and comfort in skin-contact applications.

Potential applications include human-machine interfaces and sensors via electronic tattoos in the medical and athletics spaces. Further research into these and other applications is now being conducted at the Waseda University Institute of Advanced Active Aging Research.