Researchers Show New Strategy For Making E-Textiles With Inkjet Printing

In a new research study, North Carolina State University (NC State) scientists demonstrated they could print sheets of electrically conductive ink on polyester fabric to manufacture an e-textile that could be utilized in the design of future wearable devices.

When it comes to printing procedures, researchers are always trying to work on optimizing the process to achieve more efficiency. North Carolina State University scientists presented a new study in which they showed that they could print several layers of electrically conductive ink on polyester material to create an e-textile that could possibly be applied to map out future wearable products. How that works exactly? Find out in detail by reading on!

Starting Point and Challenges

The start is often simple. In this specific case, a FUJIFILM Dimatix inkjet printer was the base for it all. In the study, the researchers elaborate on how they created the e-textile and its characteristics with the printer and how it came to be a strong and flexible material. One of the challenges they faced was for the ink to not lose its ability to conduct electricity. It is very difficult to form scalable multi-layer electronic products with mixed materials interfaces on soft substrates, particularly on anisotropic and porous bases. To confront this issue, they had to find the perfect composition of materials, so the liquid ink would not trickle through the permeable ground level of the textile material. 

“Printing e-textiles has been a quite massive obstacle for the e-textile industry,” stated the study’s first creator Inhwan Kim, a former graduate student at NC State.  “We desired to make a construction layer by layer, which has not been accomplished on a textile layer with inkjet printing. It was a large battle for us to discover the appropriate content composition.”

They faced those challenges and had a successful result. The new findings could prolong techniques in the general digital marketplace to textile production. Due to the fact that the printing process can be conducted in regular atmospheric conditions and at a standard room temperature, the researchers have come to the conclusion that inkjet printing has the potential to offer a less difficult, more successful and more efficient method of creating digital textiles or “e-textiles” in comparison to current methods used.

“Inkjet printing is a rapidly advancing new technology that’s used in flexible electronics to make films used in cellphone displays and other devices,” said the study’s corresponding author Jesse Jur, professor of textile engineering, chemistry, and science at NC State. “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.”

How the E-Textile was Created

“We were able to coat the ink on the fabric in a multi-layer material that’s both durable and flexible,” Kim said. “The beauty of this is, we did everything with an inkjet printer – we didn’t use any lamination or other methodologies.”

As mentioned before a FUJIFILM Dimatix inkjet printer was used for the whole process and everything was printed on top of a polyethylene terephthalate (PET) textile, or in other words, a woven polyester cloth. To create the e-textile, two liquid components of urethane-acrylate, and poly(4-vinylphenol) were placed in the middle to perform as insulators and particle-free metalorganic decomposition (MOD) silver electrodes, in other words layers of electrically conductive silver ink, were printed around them, just like an Oreo or a sandwich.

The silver ink created an initial conductive layer by equally coating all of the individual fibers without hindering fiber gaps. After the printing process was completed, the surface of the material was examined via microscope. The findings led them to the conclusion that unique chemical interaction between materials was very significant to achieve their result. The chemical properties of the textile yarns, as well as the properties of the insulating materials, were essential to keep the ability of the liquid silver ink to conduct electricity intact and to prevent it from seeping through the porous polyester fabric.

“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.”

The Result and Further Goals

The electrical performance of the e-textile was tested and evaluated by bending the material. A lot. More than 100 rounds of testing were conducted, and the result was astonishing. The researchers found out that after all those cycles the material still did not lose its electrical performance. In comparison to facilities that need certain and special conditions and atmospheres to create such e-textiles, this method is much simpler and efficient. Thus, they want build on this foundation and enhance the electrical overall performance of the e-textile, as well as improve on the material’s breathability.

Printed electronics display distinctive shapes and flexibilities suited for various wearable products. The long-term goal of this is to generate and manufacture and e-textiles that could be utilized in wearable electronics such as, for example, in batteries to store power for electronic devices or biomedical gadgets that monitor and track heart rate.

Can you think of other electronic devices this e-textile could be used in? For example, something out of your everyday life? Tell us in the comments below if you have ideas!

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