The global e-textiles market is promising and e-textile products are being explored in numerous exciting areas, from thermal radiation control, body parameter measurement to disease prevention, and many more. Leading industry players and researchers are utilizing the many ways that fabrics can exploit electronics, as demonstrated by a range of projects and partnerships.

The next revolution in the industry involves the combination of electronics and textiles to form "smart" textile products. The e-textiles market is expected to be worth over US$1.4 billion by 2030, according to a recent report by IDTechEx Research.

The snapshot of the e-textile application readiness levels shows a robust pipeline. Applications such as elite sports biometric (chest straps or apparel), heated clothing, illuminated apparel, high-fashion e-textile apparel, carpet pressure sensors and similar extend from the early commercial sales to full market penetration. There are also many applications at early development phases, rendering the pipeline deep and robust.

Despite all these, there are many challenges. The supply chain is immature, although efficiency is improving with co-located manufacturing. Challenges around reliability, cross-compatibility & standards, equipment suitability, materials availability and overheads costs have previously been prohibitive to commercial development of many different product types.

However, thanks to significant investments and partnerships, some of these barriers are being lowered, with more players able to make more advanced e-textile products as less prohibitive prices. These developments improve the chances that emerging e-textile products have against incumbent options in each of the markets they target, and a range of formulations now exist to address varying needs.

Wireless charging, washable garments with printed circuits

In May 2020, Liquid X, a manufacturer of functional metallic inks with prototype-to-production design and manufacturing capabilities, and Powercast Corporation, a supplier in radio-frequency (RF)-based long-range over-the-air wireless power technology, have announced a printed electronics venture to enable garment manufacturers to easily integrate wireless power functionality into durable, flexible, high performance and washable e-textiles.

Utilizing Liquid X’s proprietary, particle-free ink technology, manufacturers can print circuitry directly onto a garment, add Powercast’s wireless power technology and a battery, and seal this all into the garment during the manufacturing process.

The two companies’ goal is to enable cost-effective manufacturing of durable e-textiles, with battery-powered features such as health and wellness, movement monitoring, or LED-based illumination embedded directly into garments, that consumers can conveniently recharge over the air, and wash, without having to remove a battery pack.

Today’s smart garments often snap electronics onto the garment along with battery packs that users must detach before washing. With the combined technologies of Liquid X and Powercast, now manufacturers can integrate the electronics directly into the garment.

First, circuitry is printed on the fabric using Liquid X’s proprietary ink, including Powercast’s RF wireless receiving antenna. Through additive manufacturing techniques, Liquid X’s particle-free ink is deposited directly onto the fabric, conformally coating the fibers of the fabric to create highly conductive traces, enabling cost-effective, durable solutions for textile-based products while maintaining the integrity of the base fabric material.

Next, Powercast’s Powerharvester RF wireless power receiver chip, a battery, and other components are mounted onto the printed traces. Finally, an encapsulant provides a high strength waterproof bond to seal in all of the electronics.

To recharge the battery, consumers simply place a Powercast RF transmitter in the closet or drawer where they store their smart wearable. It transmits RF energy over the air to the RF receiver embedded in the wearable, which then converts it to direct current (DC) to charge the battery.

The two Pennsylvania-based companies showcased at CES in January 2020 a wirelessly rechargeable smart athletic shirt prototype that illuminates using printed electronics, embedded power harvesting technology, and LEDs powered over the air up to 10 feet away from the wireless transmitter.

3D-printed functional textiles powered by novel polymer nanocomposites

Researchers at the University of Borås, Sweden, have developed a new method for printing on textiles which cuts short the resource intensive production process. What is currently printed with screen or inkjet technology can now be done by printing directly on textiles with a 3D printer. This is important in producing smart and functional textiles.

Doctoral student Razieh Hashemi Sanatgar has in her research project developed a new polymeric material with electrically conductive properties used as a feeding material in the 3D printer.

It is a nanocomposite, a mixture of a polymer into which she mixed electrically conductive nanofillers, including carbon nanotubes and carbon black. A systematic study of how different mixtures of these nanocomposites attach to the textile and what properties are achieved has been done.

The conventional printing processes, such as screen or inkjet technology, require large amounts of energy, water, and chemicals. The method that has now been developed opens up great flexibility in the production process.

The goal of the research is to develop an integrated and tailor-made production process for smart and functional textiles that simultaneously uses less water, energy, chemicals and makes less waste and thus leaves as little an imprint on the environment as possible, while at the same time being of benefit from a production point of view, as the method is both cost and resource efficient, according to Sanatgar.

Another benefit is that it is possible to get customized production with printing the nanocomposite directly on the textile material on the exact places needed.

One challenge in the project was to achieve and maintain the desired properties of electrically conductive 3D printer filaments evenly after the filament has passed through the 3D printer.

In the project, the scientists have succeeded in optimizing the properties of the nanocomposite before and after 3D printing, which is important to be able to control the properties and their changes after printing.

Another challenge was how well the polymers and nanocomposite adhere to different textile materials. The results from this part of the project fill an important gap in the research field. As 3D printing on textiles is a novel technology, the adhesion of polymers and nanocomposites on textiles has not been thoroughly explored.

What the scientists have now done is a systematic study where they have investigated the effect of different printing process parameters on the adhesion of polymers and nanocomposites on textiles.

The new process can be used in the production of smart bandages, VR gloves, garments with sensor and heat properties, rescue equipment, sports garments that sense body temperature, medical equipment, the automotive, aerospace and space industry, etc. - situations which need control of exactly where the conductive material should be placed on the textile material and how the conductive property should function.

Graphene textiles developed for heat adaptive clothing

Thanks to the thermal properties and flexibility of graphene, scientists at the University of Manchester have created smart adaptive clothing which can lower the body temperature in hot climates in June 2020.

They have created a prototype garment to show dynamic thermal radiation control in clothing. Graphene layers were used to control thermal radiation from textile.

The development also opens the door to new applications such as, interactive infrared displays and covert infrared communication on textiles.

The human body radiates energy in the form of electromagnetic waves in the infrared spectrum, known as blackbody radiation. In a hot climate it is desirable to make use of the full extent of the infrared radiation to lower the body temperature which can be achieved by using infrared-transparent textiles.

As for the opposite case, infrared-blocking covers are ideal to minimize the energy loss from the body. Emergency blankets are a common example used to deal with treating extreme cases of body temperature fluctuation.

The collaborative team of scientists demonstrated the dynamic transition between two opposite states by electrically tuning the infrared emissivity (the ability to radiate energy) of graphene layers integrated onto textiles.

One-atom thick graphene was first isolated and explored in 2004 at the University of Manchester. Its potential uses are vast and research has already led to leaps forward in commercial products including batteries, mobile phones, sporting goods and automotive.

The new research published in journal Nano Letters, demonstrates that the smart optical textile technology can change its thermal visibility. The technology uses graphene layers to control thermal radiation from textile surfaces.

Professor Coskun Kocabas, who led the research, pointed out that the ability to control the thermal radiation is a key necessity for several critical applications such as temperature management of the body in excessive temperature climates.

Thermal blankets are a common example used for this purpose. However, maintaining these functionalities as the surroundings heats up or cools down has been an outstanding challenge.

The successful demonstration of the modulation of optical properties on different forms of textile can leverage the ubiquitous use of fibrous architectures and enable new technologies operating in the infrared and other regions of the electromagnetic spectrum for applications including textile displays, communication, adaptive space suits, and fashion.

This study built on the same group’s previous research using graphene to create thermal camouflage which was able to fool infrared cameras. The new research can also be integrated into existing mass-manufacture textile materials such as cotton.

To demonstrate, the team developed a prototype product within a t-shirt allowing the wearer to project coded messages invisible to the naked eye but readable by infrared cameras.

Professor Coskun Kocabas added that the next step for this area of research is to address the need for dynamic thermal management of earth-orbiting satellites. Satellites in orbit experience excesses of temperature, when they face the sun and they freeze in the earth’s shadow.

The technology could enable dynamic thermal management of satellites by controlling the thermal radiation and regulate the satellite temperature on demand.

Electronic fibers with transmission lines to measure body parameters

At the Swiss Federal Institute of Technology Lausanne (EPFL), researchers have developed electronic fibers which can be embedded in textiles to collect information about body parameters.

The fibers help measure subtle and complex fabrics deformations, and through that information about one’s body. The technology uses transmission line theory and can have several applications, such as in health care and robotics.

The research has been carried out by Professor Fabien Sorin and doctoral assistant Andreas Leber, at the Laboratory of Photonic Materials and Fiber Devices (FIMAP) in EPFL's School of Engineering. The technology can be used to detect body's movements - and many other factors.

Imagine clothing or hospital bed sheets capable of monitoring wearer’s breathing and other vital movements, or AI-powered textiles that allow robots to interact more safely and intuitively with humans - the soft transmission lines that have been developed open the door to all of these, according to Leber.

The researchers invented a single sensor that can detect different kinds of fabric deformation like stretching, pressure and torque at the same time. As introduced, finding a method for calculating all that was the biggest challenge, because it is difficult for sensors to measure several movements simultaneously.

Leber added that conventional sensors have several drawbacks. First, they are fragile and break easily. Second, a lot of them are needed to cover a large area, which eliminates many of the advantages of fabrics. And third, each type of conventional sensor can detect only one kind of deformation.

But by incorporating concepts from reflectometry, Sorin and Leber were able to create flexible fiber-shaped sensors that open up new doors for smart textiles. According to Leber, the technology works similar to a radar, but it sends out electrical impulses instead of electromagnetic waves.

The fiber sensors operate like transmission lines for high-frequency communication. The system measures the time between when a signal is sent out and when it's received, and uses that to determine the exact location, type and intensity of deformation.

This kind of detection technology has never before been used in applications requiring high mechanical flexibility and powerful electronic performance, which are two key features for distortion identification.

Creating the fibers is a complex task involving liquid metal, which serves as the conductor, and an optical fiber fabrication process. The structure is just a few micrometers thick and has to be perfect, otherwise it will not work.

With these fibers, the entire surface of a fabric becomes one large sensor. The trick was to create transmission lines made entirely of flexible materials, using a simple method that can be scaled up easily.

The team's research drew on a variety of disciplines including electrical engineering, mechanical engineering, materials science and process engineering. The next step will be to make the technology more portable by shrinking the electronic component.

Smart socks embedded with micro-sensors for diabetes patients

Siren, a San Francisco-based health technology company, has launched its first Neurofabric –powered product, the Siren Diabetic Sock and Foot Monitoring System.

Neurofabric is a kind of textile with micro-sensors embedded directly into the fabric, making its sensors completely seamless and virtually invisible to the user.

Siren Diabetic Socks continuously monitor foot temperature so people can detect signs of inflammation, the precursor to diabetic foot ulcers. The onset of diabetic foot ulcers represents a dangerous condition that, when left unchecked, can lead to serious complications, including amputation.

Monitoring foot temperature is clinically proven to be the most effective way of catching foot injuries, and is up to 87% more effective at preventing diabetic foot ulcers than standard diabetic foot care.

Current solutions for diabetic foot monitoring rely on non-continuous and manual measurement. People who want to monitor foot temperature have to go to the doctor and get six spots on each foot manually measured for temperature, a time-consuming and inefficient process.

Siren's solution enables real-time detection and early intervention, which can prevent the serious complications that result in over 100,000 lower limb amputations every year and cost the US healthcare system over US$43 billion annually.

For people with diabetic neuropathy, Siren’s socks look and feel just like a regular pair of socks and blend seamlessly into their daily lives. Comfortable and discreet, they provide continuous, clinical-grade temperature monitoring and health tracking over time. All they have to do is put on their socks like they would any other day.

Should signs of inflammation be detected, the patient and the doctor will receive notifications via the Siren companion app and/or text message.

Siren’s Foot Monitoring System includes a variety of patented technologies, enabling the standard manufacturing of integrated sensors, and simultaneous pairing of multiple devices, both of which were previously unsolved.