Professor Genevieve Dion, Director of Drexel University's (Philadelphia, PA) Center for Functional Fabrics, is collaborating with other experts to coat yarn with the highly conductive, two-dimensional material MXene. They demonstrated that the yarn could be used with standard textile manufacturing techniques to create wearable conductive fabric.
Tech Briefs: What got you interested in wearable technology?
Professor Genevieve Dion: Doing research and creating new materials that could really change an industry is what I find really fascinating. I don’t just think about wearable technology these days, I think about textiles as devices. The idea that the textiles that surround us can potentially be transformed into smart devices is an incredible opportunity for the future. Before coming to Drexel University, I was a designer and created different textiles, experimenting with material processes, chemical changes, and so on. In many ways, functional fabrics is a continuum of this theme in my career with just a slight change in direction.
Tech Briefs: Do you have any ideas about the first applications for this?
Professor Dion: One of the things we have discovered is that although a lot of people talk about wearable technology or smart textiles, we don’t see that many on the market. At Drexel’s Center for Functional Fabrics, we think about the challenges that have to be overcome to make these products a reality. We’re thinking about how they’re going to scale and how they’re going to be meaningful. It’s difficult to give you a particular application because we have to first find out what customers want. A few of the smart textile products that have come out were too early and underdeveloped, while others were too gadgety and did not spark interest. I want our first applications to be in a place where we can make a meaningful contribution. The medical field is a great one: new devices that are not cumbersome can really make a difference in the medical world — I think those will be first on the market.
Tech Briefs: What sorts of medical applications do you foresee?
Professor Dion: It could be for monitoring vitals or for gradual dispensing of medication. Functional fabrics can be active or passive, if you were to design a new yarn with medicine embedded into it, you could incorporate a slow-release function that offers amazing benefits without being too intrusive.
Tech Briefs: Could you tell me about your work with MXene yarn?
Professor Dion: Yarns that incorporate MXene, a highly conductive two-dimensional material, are interesting and what we’ve done with them is important. Our PhD students do basic research with scalability in mind. While we are demonstrating the potential of the material, we want to also show that it will be mass manufacturable, something that is often overlooked. If you create a material that has all the right properties, but it can’t be scaled to tens of thousands of meters, you have to go back to the drawing board and redesign your entire process. For example, it takes about one mile of yarn to knit a shirt or a sweater. MXene yarns have great potential for use in functional fabrics due to their high electrical conductivity and electrochemical performance and the durability of their performance at lab scale.
Tech Briefs: Have you had any success in making it scalable?
Professor Dion: While Drexel is producing large quantities of MXene, we only have small quantities in the lab. Our PhD students designed a MXene ink to coat the fiber by using something similar to a dye vat, mimicking a process commonly used in the textile industry. We used a natural fiber—cotton—that we were able to successfully wash without losing any of MXene’s properties. Even though we only had 10 meters of the material, we were still able to demonstrate its durability. We were also able to knit the yarn on an industrial machine made for rapid fabric production. Although we haven’t made it at scale yet, we have used processes that can be scaled up.
Tech Briefs: If these fibers are all conductive, what prevents them from short circuiting?
Professor Dion: That goes into the design of the device you’re making; you leave enough space so they don’t short circuit, an inter-digitated supercapacitor. It’s one thing to have the material and another to design for the end application. For example, we have a capacitive touch sensor — when we touch it, we disrupt the current, which translates to a reading. Smart textiles are very complex systems and a large transdisciplinary team is essential to achieving our goals. You need someone who understands materials, someone who understands electricity, and someone who understands design and human factors to create these textile systems.
Tech Briefs: What is your specialty?
Professor Dion: I’m an industrial designer — we specialize in form factor and manufacturability. The MXene yarn you referred to was done in collaboration with a materials scientist here at Drexel University, Dr. Yury Gogotsi. We co-advise a PhD student, who invented the yarn and the coating, using the MXene from Dr. Gogotsi’s lab. Once she made the yarn, we worked together at our lab to create these future textiles.
Tech Briefs: How do you make the different circuits, touch sensors or circuits that convert Wi-Fi radiation to DC? How do you get these active functions?
Professor Dion: For the capacitive touch sensor, we knit carbon-infused nylon yarn into a specific pattern in the fabric. We then connect the fabric to a device using only two connectors. A microprocessor measures the signal, and once that’s done, you are able to read what is happening: a touch on the right button, on the left button, and so on. Even for a simple capacitive touch sensor, we’ve worked with computer scientists, electrical engineers, and mechanical engineers.
Tech Briefs: Is the microprocessor knit into the yarn?
Professor Dion: No, although there are people trying to create a microprocessor in the fiber itself, we normally put it outside of the textile or keep it well-hidden within it. When we make our textiles, we think about the grand challenges we have in order to create reliable devices of the future. One of the main concerns in the development of the capacitive touch sensor had to do with the fabric being woven, as opposed to knit. Because a woven textile needs hundreds of connection threads to the microprocessor, it would be a fabrication nightmare — the product is very difficult to assemble since yarn and threads don’t like glue or soldering. It also creates a very fragile and expensive textile. What we did to address that challenge was to translate to a knitted fabric, which allowed us to reduce the number of connections to two.
Tech Briefs: How do you connect?
Professor Dion: For now, we have little metal snaps. We are starting to address how we will connect in a scalable manner, depending on the end application. If you put it inside furniture, you don’t need to worry about the connectorization because it can be covered up. If you put it on the body, you need much stronger, more robust, and subtle connectors because of wear and tear and the movement of the body.
Tech Briefs: I’m curious about creating supercapacitors and converting Wi-Fi radiation to electricity — it’s seems a little far out.
Professor Dion: It is a little far out, but we’re making slow progress. One of the great challenges for any wearable device is power. We are now able to make very small fabric supercapacitor devices that can provide a certain amount of power. As our devices are becoming increasingly capable of generating more power, the power requirements for microprocessors are also diminishing, so we will meet somewhere in the middle. It’s always important to try to raise the bar on multiple fronts, while collaborating and understanding what everyone is doing. In the case of Wi-Fi energy harvesting, we worked with Dr. Gogotsi, an expert on supercapacitors, and Dr. Kapil Dandekar from Electrical and Computer Engineering, an expert on antennas. Since ambient Wi-Fi is energy that’s lost, the thinking was: “Could we have an antenna to harvest power from all the signals that are floating out there and transfer it to a supercapacitor?”
Tech Briefs: It seems to me that you’d need active circuitry in between the antenna and the capacitor.
Professor Dion: Yes, you do need something that could transfer it from one to the other, so we were looking into a microprocessor to create a matching network that could send the harvested power to the capacitor. The concept is doable, but we’re not there yet.
Tech Briefs: What excites you most about this project?
Professor Dion: There are several things I’m really excited about. Now that we have the new Center for Functional Fabrics in Philadelphia, it’s really exciting to think about bringing manufacturing back to this country and also seeing my young employees and students get so excited about innovation. At the Center, we have the opportunity to train and bring together people from all different disciplines. Watching them work in teams to address complex systems in a very transdisciplinary way has become the most exciting part for me. The potential to create meaningful products that could really help people is also extremely exciting. One of our ongoing projects is an exoskin wearable that could help with stroke rehabilitation, while being unobtrusive.
Tech Briefs: I like the idea of the different disciplines working together — I’ve always thought that’s the best way to achieve progress.
Professor Dion: I agree. When I started this 12 years ago, I instinctively knew it, but it’s since become even more apparent. As this is a new industry, there are not so many smart textile products out there. Being at the university has allowed me to ask, “why not?”
Every time we solve a problem, we encounter a thousand new ones, so one discipline alone cannot do it. If you want to be good at something, you need to have focus and discipline. Some people are generalists and that’s okay too, but if you understand that your knowledge is limited to the boundaries of a certain discipline, you know you need to have someone who has a solid foundation in other relevant disciplines. Learning to work together and speak a similar language, to communicate and innovate, is really exciting.
An edited version of this interview appeared in the February Issue of Tech Briefs.