Textination Newsline

Embroidering power-generating yarns onto fabric allowed researchers to embed a self-powered, numerical touch-pad and movement sensors into clothing. The technique offers a low-cost, scalable potential method for making wearable devices.

“Our technique uses embroidery, which is pretty simple – you can stitch our yarns directly on the fabric,” said the study’s lead author Rong Yin, assistant professor of textile engineering, chemistry and science at North Carolina State University. “During fabric production, you don’t need to consider anything about the wearable devices. You can integrate the power-generating yarns after the clothing item has been made.”

In the study published in Nano Energy, researchers tested multiple designs for power-generating yarns. To make them durable enough to withstand the tension and bending of the embroidery stitching process, they ultimately used five commercially available copper wires, which had a thin polyurethane coating, together. Then, they stitched them onto cotton fabric with another material called PTFE.

“This is a low-cost method for making wearable electronics using commercially available products,” Yin said. “The electrical properties of our prototypes were comparable to other designs that relied on the same power generation mechanism.”

The researchers relied on a method of generating electricity called the “triboelectric effect,” which involves harnessing electrons exchanged by two different materials, like static electricity. They found the PTFE fabric had the best performance in terms of voltage and current when in contact with the polyurethane-coated copper wires, as compared to other types of fabric that they tested, including cotton and silk. They also tested coating the embroidery samples in plasma to increase the effect.

“In our design, you have two layers – one is your conductive, polyurethane-coated copper wires, and the other is PTFE, and they have a gap between them,” Yin said. “When the two non-conductive materials come into contact with each other, one material will lose some electrons, and some will get some electrons. When you link them together, there will be a current.”
Researchers tested their yarns as motion sensors by embroidering them with the PTFE fabric on denim. They placed the embroidery patches on the palm, under the arm, at the elbow and at the knee to track electrical signals generated as a person moves. They also attached fabric with their embroidery on the insole of a shoe to test its use as a pedometer, finding their electrical signals varied depending on whether the person was walking, running or jumping.

Lastly, they tested their yarns in a textile-based numeric keypad on the arm, which they made by embroidering numbers on a piece of cotton fabric, and attaching them to a piece of PTFE fabric. Depending on the number that the person pushed on the keypad, they saw different electrical signals generated for each number.

“You can embroider our yarns onto clothes, and when you move, it generates an electrical signal, and those signals can be used as a sensor,” Yin said. “When we put the embroidery in a shoe, if you are running, it generates a higher voltage than if you were just walking. When we stitched numbers onto fabric, and press them, it generates a different voltage for each number. It could be used as an interface.”

Since textile products will inevitably be washed, they tested the durability of their embroidery design in a series of washing and rubbing tests. After hand washing and rinsing the embroidery with detergent, and drying it in an oven, they found no difference or a slight increase in voltage. For the prototype coated in plasma, they found weakened but still superior performance compared with the original sample. After an abrasion test, they found that there was no significant change in electrical output performance of their designs after 10,000 rubbing cycles.

In future work, they plan to integrate their sensors with other devices to add more functions.
“The next step is to integrate these sensors into a wearable system,” Yin said.

The study, “Flexible, durable and washable triboelectric yarn and embroidery for self-powered sensing and human-machine interaction,” was published online in Nano Energy. Co-authors included Yu Chen, Erdong Chen, Zihao Wang, Yali Ling, Rosie Fisher, Mengjiao Li, Jacob Hart, Weilei Mu, Wei Gao, Xiaoming Tao and Bao Yang. Funding was provided by North Carolina State University through the NC State Faculty Research & Professional Development Fund and the NC State Summer REU program.

Interview with Henning Wehland & Robert Kapferer, Circularity Germany

I'm a very curious guy by nature. That's why I offered to help out at a well-known hot dog station in Münster (Germany) this year, to draw attention to the shortage of staff in the gastronomy. I wrote an article about it on LinkedIn, which was in turn reacted to by Ines Chucholowius.
From her profile, I could see that she is a consultant for strategic marketing and communication in the textile industry. Not entirely serious, she offered me a job in her office. Like pushing a button, the pictures in my mind set in: Textile industry, exciting! Merchandising, contacts in the industry, collaborations, and I agreed to a short chat, at the end of which we spoke on the phone and arranged to meet.
 
She told me about her website TEXTINATION.de. And we were already involved in an exciting, heated exchange about perception and truth in the textile industry. Without further ado, we left it at that and I went home with a chunk of new information about an exciting field. Our dialogue on social media continued and eventually Ines offered me the chance to feed my die-hard curiosity with the support of TEXTINATION.de. I could write a blog on the site, about people, products, service providers, producers, startups or trends that interest me, to add to my half-knowledge about the textile industry.

Textile waste into the front ... new T-shirt out the back
During this exchange and a long brainstorming session, certain terms kept tickling my attention:
Circular economy, recycling, recyclable material loops. Circular Economy, Recycling, Recyclables. Even though there are many different definitions and some even distinguishing between different aspects: the former thought from waste that flows back into production as a secondary raw material, a more modern approach avoiding waste already in production - the general consensus is really only that circular economy is a cycle in which waste is used as a source for something new.

Sounds like useful additions for all areas of the manufacturing real economy to me. Ines introduced me to Robert Kapferer: He runs a startup called Circularity Germany in Hamburg. His company, founded in 2021 and consisting of Robert and another partner, is an offshoot of the Dutch-based company Circularity B.V. Its founder Han Hamers, with a degree in child psychology and a professional background in the textile dyeing industry, had the idea five years ago for a production facility that spins new yarn exclusively from textile production waste and old textiles turning it into T-shirts, polo shirts and sweatshirts.
Whether this works, and if so, how, is what I wanted to find out, and Ines and I arranged to meet Robert for a 90-minute online conference.

Robert, originally an industrial engineer, comes from a less sustainable industry. He worked for 11 years as managing director for AVECO Material und Service GmbH, where he was responsible for the workwear of more than 50,000 employees.

At the beginning of our conversation, he emphasizes that a moment in January 2021 changed his life and from then on, he wanted to dedicate himself to the topic of circular economy with all his might. That was when he met Han Hamers, who inspired him to found Circularity Germany. His enthusiasm and passion for the subject sound credible, and he begins to describe the differences between chemical and mechanical recycling methods. In summary, the mechanical process of shredding and the subsequent spinning shortens the fibers and thus restricts their properties for further processing. The advantage lies primarily in the comparatively uncomplicated, fast and more cost-efficient process. In the chemical variant, chemical waste remains, but the processed materials are broken down again into their basic building blocks in such a way that they have almost all the same properties as a so-called virgin raw material. Circularity Germany stands for the mechanical process.

And then comes the sentence that gets all our attention: "We've advanced a spinning technology so much that it relies exclusively on waste-based raw materials."
This sentence almost doesn't stand out because Robert still talks - quite excitingly - about the fact that they are planning a production and manufacturing facility where everything from knitting yarn to relatively fine thread can be spun and then further processed into fabric. And here Ines and I ask intensively: Essential requirements for industrial production still seem to be unresolved, and necessary processes are still in the planning stage. For example, the question of whether to work with pre-consumer or post-consumer waste. Pre-consumer waste is cutting waste from the production of clothes, which corresponds to about 10% of the processed material. Post-consumer waste we know as used textiles.

As long as production still takes place in India, Circularity currently uses mainly pre-consumer waste. These come exclusively from sewing factories in the Tirupur region in the south of India. When using used textiles, which exist in large quantities in Germany (according to a study, 28-40% of all garments produced are thrown away unworn), Circularity produces blended yarns of cotton and polyester. The company does not offer pure cotton yarns.

Textiles are treated with chemicals to varying degrees - workwear in particular cannot do without them. The fact that Han Hemers is also collecting used textile stocks from the Dutch army in order to reintroduce them renewed into the consumer cycle is therefore not reassuring. Military clothing has to be finished with all kinds of additives.

Therefor I ask how he can dispel doubts in a consumer’s mind like mine, with a healthy half-knowledge of mask deals and greenwashing, that a well-intentioned vision will be followed by a dark awakening. This concern cannot yet be resolved after the conversation.

We limit ourselves to what is planned: Robert has the dream of reversing the globalized process of textile production. He wants to end the decoupling of cotton growing regions and far-flung production such as Asia with subsequent shipping of ready-made goods to Europe. In the future, existing used textiles and/or cutting wastes are to be collected on site, recycled and processed locally into new textiles.

I believe him in having this dream. However, some of my questions about sustainability remain unanswered - which is why I have my doubts about whether the idea is currently capable of performing and competing.
What are the reasons for this? For one thing, I think it's always difficult to do necessary pioneering work. Especially when listening to smart comments at the regulars' table that large companies are already working intensively on the principle of circular economy. But sometimes, apart from the term "circular economy" and a vague commitment to it, not much remains.

Circularity Germany is committed to developing a technology based exclusively on waste. The interview points out that this also includes making production more environmentally friendly and eliminating transport routes, which further reduces the burden on the environment. When all the requirements for realizing this dream have been met and a product that is competitive in terms of both quality and price can be launched on the market, it is up to the consumer to decide. Here one would have the credible argument of sustainability and a socially and environmentally fair process. Circularity would then not have to worry about PR.

It needs to be given time and, above all, attention. But perhaps the industry should get involved right here and now, and invest in startups like this and make sure that problems are cleared out of the way. Because one thing has become clear to us in this conversation:

It could all be so simple. Circular economy is achievable, but the road there is still costly and rocky. That's why we wish Robert and his team every success and, above all, perseverance. Thank you for the interview.

Short and sweet: the profile of the company in the attached factsheet for download.