IEEE PULSE presents

E-Textiles for Health Monitoring: Off to a Slow Start, but Coming Soon

Feature May/June 2020
Author: Leslie Mertz

Smart technology is in cellphones, televisions, cars, and home appliances, but smart textiles haven’t inundated the market yet. While engineers have been developing new and interesting ways to marry electronics and fabrics for several years now, the average person isn’t wearing e-tights to audit vital signs during a workout, switching to electronically enhanced bed sheets to track sleep patterns, or adding smart base layers to the everyday wardrobe. If the technology is moving forward as rapidly as it appears to be, why aren’t e-textiles flooding the market?

“There are many arguments out there as to why not,” said e-textiles expert James Hayward (Figure 1). “Earlier arguments centered around the lack of standards, the lack of a clear, efficient value chain, and the maturity of manufacturing of these products, but I increasingly think it’s more (about the) value proposition they have relative to their competitors.” Hayward is a principal analyst at IDTechEx, Cambridge, U.K., and lead author of “E-Textiles 2019–2029: Technologies, Markets, and Players,” a comprehensive review of this emerging field [1]. The report is one of many produced by IDTechEx and its 20-plus analysts, who closely follow various tech-industry trends, and provide consulting services for clients around the world.

The market is definitely an influencer, agrees e-textiles developer John L. Volakis, Ph.D. (Figure 2), who spent 14 years as director of the Ohio State University (OSU) ElectroScience Laboratory before becoming Dean of Florida International University’s College of Engineering & Computing in 2017. “Look at wearable watches, such as iWatches and Fitbits. They are popular. To go to the next level of technology—and e-textiles are the next level of technology—existing technologies need to stop making money,” he said. “It’s not that we cannot do it; it’s the market demand.”

Figure 1. James Hayward. (Photo courtesy of IDTechEx.)

Great idea, stiff competition

The e-textiles industry is working hard to promote the narrative that these products offer an ideal interface to the body for health-related monitoring, Hayward said. “Every single day we are in contact with textiles. It’s that’s ubiquity that the platform really brings. And because we’re so used to the ubiquity, the comfort, and the practicality of traditional textile products, the idea is we can take that ubiquity and those interface properties, and apply them alongside the extra functional advantages of electronics,” he remarked. Instead of a person having to attach sensors, which is required for most current health-monitoring technology, “you just pull on a T-shirt or garment in the morning and then all of the sensing or whatever else you need is already in place,” he described. “That’s the big-picture selling point of the whole e-textile movement at the moment.”

Figure 2. John L. Volakis, former director of the OSU ElectroScience Laboratory and now dean of Florida International University’s College of Engineering and Computing, considers e-textiles as “the next level of technology” beyond smart phones and other devices. (Photo courtesy of FIU.)

Translating that vision to products and sales is another matter. Hayward highlighted the 2015 to early 2017 emphasis on smart clothing for the sports and fitness arena, such as products to monitor respiration or heart rate while exercising. “There were a huge number of e-textile projects in development and lots of new players, both investigating the space and also entering the space, so there were younger start-ups, spinoffs from other large companies, and also development projects in a lot of the key apparel brands that exist,” he said. “But for individual reasons and big general reasons, a lot of those projects fell through and were canceled.” One of the biggest general hurdles was that other devices, including smart phone apps, traditional electrocardiogram (ECG) electrodes, and chest straps, already had a strong consumer presence.

That led to an overall e-textile industry shift away from the sports and fitness and toward the medical market, according to Hayward. “The product platform itself is pretty similar between the two cases, but the way that you deploy it and the way its regulated is different in the medical environment, so those companies that are still developing these products are now really focused quite heavily on the medical applications of e-textiles.” For instance, he said, a yoga mat initially designed with pressure sensors to help a person do exercises correctly might be repurposed as a bed mat to prevent pressure ulcers in hospitals; or a shirt to help a jogger assess heart- and respiration-rate variability throughout the course of a run might be revamped to monitor patients in a hospital or to assist in rehabilitative environments.

Due to the need for regulatory approval, medical e-textile products can take years to get to market, but some are starting to become available today, and more are on the way. The early entries tend to address specific applications in ways that only e-textiles can, Hayward said. For instance, he pointed to LifeSense Group in the Netherlands, which has commercialized Carin, smart underwear and an associated app [2] that together sense and assess stress urinary incontinence, and provide targeted training exercises to alleviate it. He remarked, “That’s a perfect example of a specific product that pretty much has to be textile, because you’re not going to put any other kind of sensor into something as delicate as underwear. It has a very clear use case with a population that really needs it, and no other options exist.”

The “main opportunities” in e-textiles today are those products that are linked to a specific health need, and offer a clearly better way to provide support for that need, he said. “It’s really getting to the point where you can prove the value proposition that is incumbent.”

All washed up

On the technology side, one of the biggest reasons that e-textiles aren’t in everyone’s closets quite yet is washability, according to Christian Dalsgaard, co-founder of Denmark-based Ohmatex A/S, which has been developing smart textiles for about two decades. “A true e-textile product needs to be washed. A lot of the research has demonstrated some very nice (capabilities), however the washability is just a few wash cycles, and the ordinary consumer expects 30–50 washes,” he asserted. “Everything that is included as part of the fabric—the microelectrodes, and any pressure, physiological, capacitance, or temperature sensors—need to be washed, and that’s where there’s been a lack of research, but also where the commercialization opportunities are.”

Washability is a complicated matter. Conductive materials in the fabrics take a lot of abuse from the mechanical action of the washing machine, the water, and the soap chemistry, he said. A point of particular concern is strain relief, which is often the weakest point in electronics devices. This refers to the transition zone between something that is rigid and something that is not (for instance, the series of ridges at the point where a flexible computer cable links to plastic connector housing). With those considerations, he remarked, making e-textiles that are sturdy enough to survive repeated washings requires “a lot of experiments, trial and error, and good common sense, and then combining solutions that look most promising.”

This means that washability has to be a priority in the design process from the beginning, Dalsgaard contended. To make its products safe to wash, Ohmatex has developed electronics units that can either slide in or out, or be attached or detached with a snap connector, so it is a simple matter to remove them prior to washing and put them back in place afterward. The company also focuses on the washability of those materials that cannot be removed, such as the sensors. “In everything we do, from the very first second, we think about how this can be washed. In every concept, it is taken into account,” he said, noting that most of the sensors in its products are now able to survive 150 washes.

Another approach is to make the electronics washable too, so they would not need to be removed prior to cleaning the garment. Volakis and assistant professor Asimina Kiourti of the OSU ElectroScience Laboratory developed a method for sewing circuits right onto fabric that is similar to sewing a name onto a sports jersey or a logo onto a baseball cap [3]. They used standard embroidery machines to do the sewing, but replaced the normal thread with highly conductive silver thread, and sewed it into the intricate design of the circuit, he described, noting that the sewn-on circuits flex with the garment and can also be washed (Figure 3).

Figure 3. Volakis’ RF Communication Lab (RFCOM), including doctoral student Dieff Vital (shown here), is using a sewing machine and conductive threads to embroider electronic circuits directly onto clothing. The group is also sewing antennas onto textiles as a way to harvest unused and scattered wattage power from cell towers, and ultimately charge biosensors or other medical devices. (Photo courtesy of FIU.)

Volakis is pleased with the progress, but notes that embroidered circuits are prototypes and have a long way to go before they make their way into marketable products. “Moving it into the marketplace requires an influx of funding that is very substantial, because it also has to have a manufacturing process in place,” he said. “I have two paths: I can make that a 100-percent focus of my life to get funding to make and demonstrate these prototypes; or can slowly develop it with a little money and strong interest. And we’re doing the latter right now.”

Coming soon?

Hayward, Dalsgaard, and Volakis acknowledged that e-textile development has not been as speedy as most experts anticipated, but a growing collection of products are making their way into the medical arena and others will follow.

Ohmatex has been especially visible in the e-textile space. It has been working closely with the European Space Agency (ESA) to develop smart fabrics as a way to gather biometrics about astronauts living in the zero-gravity conditions present on the International Space Station (ISS) (Figure 4). Its first project for the ESA was a smart-sock system that tracked astronauts’ muscular activity, so exercise routines can be adjusted as needed to limit the muscle deterioration that occurs during extended, zero-gravity space travel.

Figure 4. The company Ohmatex A/S has been developing e-textiles for about two decades. They include smart fabrics—for the ESA—that gather biometrics about astronauts living in the zero gravity of the ISS. Before washing, electronics units can be easily removed from the fabric, as shown here. (Photo courtesy of Ohmatex A/S.)

In November 2019, the ESA signed a contract [4] for the development of new astronaut e-textiles: a full base-layer suit that incorporates electromyography (EMG), near infrared spectroscopy (NIRS), and dielectric electroactive polymer (DEAP) strain sensors. The EMG sensors detect muscle activity; the NIRS sensors track changes in oxygen content and therefore metabolism in targeted muscle groups; and the DEAP strain sensors measure changes in limb circumference and muscle volume. That combination of EMG, NIRS, and DEAP data can be used to optimize astronaut exercises further. ESA’s contract (for 1.04 million EUR) went to Ohmatex A/S, along with the Department of Biomedical Sciences at the University of Copenhagen, which will be validating the equipment on the ISS, and Danish Aerospace Company A/S, which will be handling the safety and space-qualification of the electronics. The suit could be in use by astronauts on the ISS as early as 2021.

Figure 5. Ohmatex also helped the company Palarum on its PUP smart socks. They use conductive yarns, textile-based pressure sensors underneath the foot, and a detachable housing that includes the batteries, Bluetooth module, and computer to detect both falls and the balance issues that can lead to falls. (Photo courtesy of Palarum.)

The technology going in the ISS suit also has potential commercial medical applications, Dalsgaard said, and Ohmatex A/S is working on a range of products with various companies. For example, it is developing a smart shirt with two European collaborators for patients with scoliosis. “This shirt maps the pressure that you have when you are putting the brace on, and it can help doctors to adjust the brace exactly,” he described. Ohmatex also helped the Lebanon-based company Palarum on its PUP smart socks [5], which are already on the market (Figure 5). Designed to detect falls as well as balance issues that can lead to falls, he said, the socks have conductive yarns that transfer readings from textile-based pressure sensors underneath the foot to a detachable housing that includes the batteries, Bluetooth module, and computer. Among other projects, he said, is a smart sleeve for Denmark-based PreCure [6] to measure muscle activation to monitor injury (so-called “mouse arm”) caused by extended computer use and the unnatural stress it puts on the arm (Figure 6).

Figure 6. Ohmatex is working on a number of projects with different companies, including this smart sleeve for the company PreCure. The sleeve measures muscle activation to monitor “mouse arm” injuries that can result from extended computer use. (Photo courtesy of Precure.)

Projects like these make Hayward confident that the e-textile field is poised for expansion. “It’s definitely coming,” he said. “It’s how quickly it’s coming, how much to invest, and how to invest that are the key questions that these companies face.”

Remarked Volakis, “There will be niche applications here and there, but eventually the market will come. There’s no question in my mind that the wearables will come.” One niche application is his group’s work on a vest that will have flexible radio-frequency identification (RFID) sensors to monitor a person’s vital signs, as well as an integrated antenna for distance communication via satellite or cellphone with medical staff. He added, “These are the kinds of things that are going to happen. It’s only a matter of time.”

References

  1. J. Hayward, “E-textiles 2019–2029: Technologies, markets and players: A comprehensive review of materials, processes, components, products and markets,” IDTechEx, Jul. 2019. Accessed: Feb. 2, 2020. [Online]. Available: https://www.idtechex.com/en/research-report/e-textiles-2019-2029-technologies-markets-and-players/671
  2. Carin. Accessed: Feb. 2, 2020. [Online]. Available: https://carinwear.com/what-is-carin/
  3. A. Kiourti, C. Lee, and J. L. Volakis, “Fabrication of textile antennas and circuits with 0.1 mm precision,” IEEE Antennas Wireless Propag. Lett., vol. 15, pp. 151–153, 2016.
  4. Ohmatex, “Smart textiles for the International Space Station,” Press release. Accessed: Feb. 2, 2020. [Online]. Available: https://www.ohmatex.dk/wp-content/uploads/2019/11/PRESS-RELEASE-SPACE-CONTRACT.pdf
  5. Palarum, “The PUP fall prevention system,” Accessed: Feb. 2, 2020. [Online]. Available: https://www.palarum.com/
  6. Accessed: Feb. 2, 2020. [Online]. Available: https://www.precure.dk/

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