Researchers Show Off a Flexible, Robust E-Textile for Wearables — Made on an Inkjet Printer

Researchers at the North Carolina State University have shown off a new method of creating e-textile wearable devices, starting with capacitors, using simple inkjet printing — borrowing a trick from the factories making smartphone displays.

“Inkjet printing is a rapidly advancing new technology that’s used in flexible electronics to make films used in cellphone displays and other devices,” explains the study’s corresponding author Professor Jesse S. Jur. "We think this printing method, which uses materials and processes that are common in both the electronics and textiles industries, also shows promise for making e-textiles for wearable devices."

Using an off-the-shelf Fujifilm Dimatix printer, the team were able to create an e-textile material for wearable electronics which proved both durable and flexible. The trick: Printing in layers, creating a "sandwich" of silver ink and insulative ink which are applied to the top of a woven polyester fabric.

"Printing e-textiles has been a very big challenge for the e-textile industry," writes first author Inhwan Kim, a former graduate student at NC State. "We wanted to build a structure layer by layer, which has not been done on a textile layer with inkjet printing. It was a big struggle for us to find the right material composition.

"We wanted a robust insulation layer in the middle, but we wanted to keep it as thin as possible to have the entire structure thin, and have the electric performance as high as possible. Also, if they are too bulky, people will not want to wear them. We were able to coat the ink on the fabric in a multi-layer material that’s both durable and flexible. The beauty of this is, we did everything with an inkjet printer — we didn’t use any lamination or other methodologies."

The resulting fabric was treated to a 100-cycle bend test, during which it didn't lose any of its electrical performance. There's work still to be done, however, with the team explaining that they want to boost the electrical performance to levels achieved with more esoteric production methods and improve the finished fabric's breathability.

The team has already come up with some sample use cases for the fabric, too, suggesting it could be applied to biomedical devices like heart-rate monitors or as a wearable battery for personal electronics.

The paper has been published under closed-access terms in the journal Applied Materials and Interfaces.