How Smart Is Your Shirt?

Defining Standards for a New Generation of Smart Textiles
Jack Maxwell

The use of the word “smart” as shorthand for a product or device that exceeds the normal functions of its less intelligent peers is well established in the modern lexicon. Less well established, however, is just exactly what it means.

There are smart cars in development that someday, we are told, will be able to drive autonomously. There are smartphones in our pockets and purses that provide a portal to the vast riches of the internet.
And a relatively new category of intelligent products is now gaining steam: smart textiles. This evolving industry encompasses everything from clothing that protects medical workers against airborne contaminants, to a soldier’s uniform that can charge her electronic devices in the field, to bedsheets that may someday be able to monitor a hospital patient’s vital signs.

But defining what constitutes a smart textile has been almost as challenging as creating one. Fortunately, ASTM has a long history of helping researchers, manufacturers, consumers, and others involved with new technologies to establish a consensus on terminology and standards. The latest example: the recently established Subcommittee on Smart Textiles (D13.50), which is under the aegis of the ASTM Committee on Textiles (D13). Smart textiles are a fast-growing field, and a robust set of standards can help the industry reach its full potential.

Degrees of Intelligence

One of the key issues facing anyone trying to get a handle on smart textile technology is differentiating among the broad range of products that reside under this large umbrella.

Jesse Jur, Ph.D., is an assistant professor of textile engineering, chemistry and science in the College of Textiles at North Carolina State University. “A smart textile is most easily defined as a textile that is responsive,” Jur explains. “From this perspective, smart textiles can be a very broad term. It can involve either textiles that have a specialty coating that changes in response to external stimuli, or one that is electrically connected via sensors to provide feedback to the user. The latter is of growing interest and is most often regarded as textile electronics.”

Fitness-oriented people may be familiar with t-shirts that wick sweat away from the body to keep a runner or cyclist cool and dry. But new innovations from manufacturers like Schoeller and outdoor apparel makers like Columbia take the concept to the next level through the use of phase-change fabrics that actually adjust their permeability as the wearer’s body temperature fluctuates. When the heat is on, the fabric pores enlarge to cool it down; in cooler conditions, the pores close up to help the wearer retain warmth.

Phase-change fabrics could make a nice complement to advancements in textile electronics. Athletic wear manufacturers have been in the forefront when it comes to incorporating electronics into their latest designs.

Joshua Teitelbaum, a U.S. Department of Commerce official, provides three examples: “In the U.S., Under Armour currently offers a smart shoe with the ability to track a user’s runs and fitness data. Google and Levi’s have partnered through Project Jacquard to produce smart denim, including a new jacket for cyclists that allows the wearer to tap or swipe across its surface to interact with his phone — for example, asking Google Maps for directions or answering calls. Internationally, Adidas has developed a smart shirt, worn under players’ uniforms, that collects biometric data from each athlete and shares it with coaches in real time, allowing them to develop targeted workouts on the field or identify fatigued players.”

Jur points out that the market for these products is still maturing. “Many of the major athletic apparel companies have activity in the textile electronics space,” Jur says, “and though some products are still not able to be mass produced or have a cost that puts the product out of reach for a larger consumer base, we expect that situation to change quickly.”

Smart Military Clothing

While everyone from hardcore athletes to weekend warriors can benefit from gear that tracks their workouts, Teitelbaum notes that “fitness is just one possible application for smart fabrics. We’ve seen growth in military, medical, transportation, and industrial sectors too.”

One of the most interesting initiatives in the area of military applications focuses on lightening the foot soldier’s load. Studies conducted by the U.S. Army indicate that a fully equipped soldier carries between 50 and 120 pounds [22 and 55 kg] of equipment, including chargers and batteries for devices like GPS units and cell phones. Research into ways to reduce this burden with textile electronics shows real promise.

“We are exploring the use of these textiles to turn the combat uniform into a power and data bus,” says Carole Winterhalter, chief technology officer of the Revolutionary Fibers and Textiles Manufacturing Innovation Institute, who works at the U.S. Army Natick Soldier Research, Development, and Engineering Center. “Right now, combat clothing is passive. It doesn’t ‘do’ anything. But by integrating a conductive network within the fabric, cutting pattern pieces, sewing them into a garment, and joining the conductive elements, we can create conductive pathways that are used to transport power and data from one device to another. Just like a vehicular bus transports people, a clothing bus transports power.”

But where does this power come from? Winterhalter cites technologies like “wearable energy harvesters,” which include photovoltaic panels on helmets and backpacks that harness solar energy, and kinetic energy produced by the movement of a backpack and even the wearer’s knees. These new tools let soldiers generate power on the move — and eliminate the weight of extra batteries and chargers.

In terms of data, uniform shirts that monitor and report on a soldier’s physiological status — similar to wearable fitness trackers — are another potential military application. “We’re also looking at ways to eliminate the need to carry stiff, rigid antennas by incorporating flexible versions into the uniform,” Winterhalter says.

Healthcare Applications

Aging populations mean more and more people will be visiting hospitals, moving to nursing homes and other assisted living facilities, and relying on doctors, nurses, and other healthcare professionals. Data show that these workers have some of the highest rates of illness and injury of any occupation — and smart textile companies that target medical applications are developing products that address hazards inherent to the job.

For example, VESTEX — described by manufacturer Vestagen as an “active barrier” fabric — incorporates a highly repellent fluid barrier and a durable antimicrobial treatment. Garments made with VESTEX resist bacterial colonization caused by the transfer of harmful microorganisms contained in body fluid splatters and spills, providing enhanced protection to healthcare workers, according to Uncas “Ben” Favret, III, Vestagen’s founder and president.

Favret says, “Active barrier technologies like those found in VESTEX are applicable to any job where the wearer can be exposed to contaminants. And these technologies can be combined with electronic monitoring. For example, a bedsheet with special properties that limit friction against the skin to reduce the incidence of pressure sores could also incorporate a monitoring function that tracks a patient’s temperature and signals hospital staff when he’s spiking a fever.”

Jur is also excited about the potential for smart textiles in medical applications. “Health monitoring is the single biggest game-changing opportunity toward revolutionizing how we think of preventative healthcare,” he says. For example, he says, “Shirts that are able to bring the doctor’s office home with you, and provide feedback in ways relevant to you, have the opportunity to make a big impact.”

Defining Terms, Developing Standards

Committee D13 encompasses over 30 subcommittees covering everything from cotton fibers to pile floor coverings to body measurements for apparel sizing. The new subcommittee on smart textiles falls under D13’s purview.

“Electronic textile innovators and manufacturers are already facing challenges in combining two very different industries — electronics and textiles,” notes D13 staff manager Jennifer Rodgers. “Standards, and standards organizations like ASTM International, bring all stakeholders together to discuss these issues and determine test methods, specifications, best practices — even terminology and language.”

Favret understands how important it is to have “a common language and definitions everyone agrees on. In fact, the very definition of the phrase ‘smart textile’ itself is still in flux — what does this term really mean?” Winterhalter also raises this question. “From a military perspective, there’s a need for agreement on what is and what is not a smart textile,” she says. “It’s also vital to develop test methods that cover both systems as a whole and individual components.”

Teitelbaum agrees that consensus test methods for smart textile performance are necessary in such areas as home laundering and washability; electrical safety and electromagnetic compatibility (to ensure smart fabric products do not interfere with a wearer’s pacemaker, for instance); and mitigation of corrosion of embedded electronics caused by dyes, finishes, perfume, and sweat, among others.

The subcommittee will draw upon the expertise within D13, as well as the many experts in ASTM Committees F23 on Personal Protective Clothing and Equipment, E56 on Nanotechnology, F42 on Additive Manufacturing Technologies, F04 on Medical and Surgical Materials and Devices, and F15 on Consumer Products, to name a few.

“We’ll also coordinate work with our industry partners,” says Rodgers, “such as the American Association of Textile Chemists and Colorists and the Industrial Fabrics Association International. And we’ll look to establish new relationships in textiles with organizations that may hold expertise on the electronics supply side. We want to give everyone the opportunity to be involved in the creation of a standard and in defining its final content. The ultimate effectiveness of a standard is dependent on its relevance to the market, and we strongly encourage every interested person to join D13.50 and get involved in this effort.”

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