Textination Newsline

Imagine a sweater that powers electronics to monitor your health or charge your mobile phone while running. This development faces challenges because of the lack of materials that both conduct electricity stably and are well suited for textiles. Now a research group, led by Chalmers University of Technology in Sweden, presents an ordinary silk thread, coated with a conductive plastic material, that shows promising properties for turning textiles into electricity generators.

Thermoelectric textiles convert temperature differences, for example between our bodies and the surrounding air, into an electrical potential. This technology can be of great benefit in our everyday lives and in society. Connected to a sensor, the textiles can power these devices without the need for batteries. These sensors can be used to monitor our movements or measure our heartbeat.

Since the textiles must be worn close to the body, the materials used in them must meet high demands on safety and flexibility. The silk thread that the researchers tested has a coating made of a conducting polymer. It is a plastic material with a chemical structure that makes the material electrically conductive and well adapted to textiles.

“The polymers that we use are bendable, lightweight and are easy to use in both liquid and solid form. They are also non-toxic," says Mariavittoria Craighero, who is a doctoral student at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology, and first author of a recently published study.

Enhanced stability and conductivity
The method used to make the electrically conductive thread is the same as used in previous studies within the same research project.  Previously, the thread contained metals to maintain its stability in contact with air. Since then, advances have been made to manufacture the thread with only organic (carbon-based) polymers. In the current study, the researchers have developed a new type of thread with enhanced electrical conductivity and stability.

“We found the missing piece of the puzzle to make an optimal thread – a type of polymer that had recently been discovered. It has outstanding performance stability in contact with air, while at the same time having a very good ability to conduct electricity. By using polymers, we don't need any rare earth metals, which are common in electronics," says Mariavittoria Craighero.

To show how the new thread can be used in practice, the researchers manufactured two thermoelectric generators – a button sewn with the thread, and a piece of textile with sewn-in threads. When they placed the thermoelectric textiles between a hot and a cold surface, they could observe how the voltage increased on the measuring instrument. The effect depended on the temperature difference and the amount of conductive material in the textile.  As an example, the larger piece of fabric showed about 6 millivolts at a temperature difference of 30 degrees Celsius. In combination with a voltage converter, it could theoretically be used to charge portable electronics via a USB connector.  The researchers have also been able to show that the thread’s performance is maintained for at least a year. It is also machine washable.

"After seven washes, the thread retained two-thirds of its conducting properties. This is a very good result, although it needs to be improved significantly before it becomes commercially interesting," says Mariavittoria Craighero.

Can meet functions that these textiles require
The thermoelectric fabric and button cannot be produced efficiently outside the lab environment today. The material must be made and sewn in by hand, which is time-consuming. Just sewing it into the demonstrated fabric required four days of needlework. But the researchers see that the new thread has great potential and that it would be possible to develop an automated process and scale up.
 
“We have now shown that it is possible to produce conductive organic materials that can meet the functions and properties that these textiles require. This is an important step forward. There are fantastic opportunities in thermoelectric textiles and this research can be of great benefit to society," says Christian Müller, Professor at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology and research leader of the study.
 
More about the study
The scientific Article Poly(benzodifurandione) Coated Silk Yarn for Thermoelectric Textiles is published in Advanced Science. Authors are Mariavittoria Craighero, Qifan Li, Zijin Zeng, Chunghyeon Choi, Youngseok Kim, Hyungsub Yoon, Tiefeng Liu, Przemysław Sowiński, Shuichi Haraguchi,  Byungil Hwang, Besira Mihiretia, Simone Fabiano and Christian Müller. The researchers are active at Chalmers University of Technology, Linköping University and Chung-Ang University in Seoul, South Korea. The research has been funded by the EU's Horizon 2020 research and innovation programme, through the Marie Skłodowska-Curie project HORATES, the Knut and Alice Wallenberg Foundation, the European Research Council (ERC), the Swedish Research Council and Linköping University.

Introducing the fashion of the future: a T-shirt you can wear a few times, then, when you get bored with it, dissolve and recycle to make a new shirt.

Researchers at the ATLAS Institute at the CU Boulder are now one step closer to that goal. In a new study, the team of engineers and designers developed a DIY machine that spins textile fibers made of materials like sustainably sourced gelatin. The group’s “biofibers” feel a bit like flax fiber and dissolve in hot water in minutes to an hour.

The team, led by Eldy Lázaro Vásquez, a doctoral student in the ATLAS Institute, presented its findings in May at the CHI Conference on Human Factors in Computing Systems in Honolulu.

“When you don’t want these textiles anymore, you can dissolve them and recycle the gelatin to make more fibers,” said Michael Rivera, a co-author of the new research and assistant professor in the ATLAS Institute and Department of Computer Science.

The study tackles a growing problem around the world: In 2018 alone, people in the United States added more than 11 million tons of textiles to landfills, according to the Environmental Protection Agency—nearly 8% of all municipal solid waste produced that year.

The researchers envision a different path for fashion.

Their machine is small enough to fit on a desk and cost just $560 to build. Lázaro Vásquez hopes the device will help designers around the world experiment with making their own biofibers.

“You could customize fibers with the strength and elasticity you want, the color you want,” she said. “With this kind of prototyping machine, anyone can make fibers. You don’t need the big machines that are only in university chemistry departments.”

Spinning threads
The study arrives as fashionistas, roboticists and more are embracing a trend known as “smart textiles.” Levi’s Trucker Jacket with Jacquard by Google, for example, looks like a denim coat but includes sensors that can connect to your smartphone.

But such clothing of the future comes with a downside, Rivera said:

“That jacket isn't really recyclable. It's difficult to separate the denim from the copper yarns and the electronics.”

To imagine a new way of making clothes, the team started with gelatin. This springy protein is common in the bones of many animals, including pigs and cows. Every year, meat producers throw away large volumes of gelatin that doesn’t meet requirements for cosmetics or food products like Jell-O. (Lázaro Vásquez bought her own gelatin, which comes as a powder, from a local butcher shop.)

She and her colleagues decided to turn that waste into wearable treasure.

The group’s machine uses a plastic syringe to heat up and squeeze out droplets of a liquid gelatin mixture. Two sets of rollers in the machine then tug on the gelatin, stretching it out into long, skinny fibers—not unlike a spider spinning a web from silk. In the process, the fibers also pass through liquid baths where the researchers can introduce bio-based dyes or other additives to the material. Adding a little bit of genipin, an extract from fruit, for example, makes the fibers stronger.

Other co-authors of the research included Mirela Alistar and Laura Devendorf, both assistant professors in ATLAS.

Dissolving duds
Lázaro Vásquez said designers may be able to do anything they can imagine with these sorts of textiles.

As a proof of concept, the researchers made small textile sensors out of gelatin fibers and cotton and conductive yarns, similar to the makeup of a Jacquard jacket. The team then submerged these patches in warm water. The gelatin dissolved, releasing the yarns for easy recycling and reuse.

Designers could tweak the chemistry of the fibers to make them a little more resilient, Lázaro Vásquez said—you wouldn’t want your jacket to disappear in the rain. They could also play around with spinning similar fibers from other natural ingredients. Those materials include chitin, a component of crab shells, or agar-agar, which comes from algae.

“We’re trying to think about the whole lifecycle of our textiles,” Lázaro Vásquez said. “That begins with where the material is coming from. Can we get it from something that normally goes to waste?”

Automotive industry is a major driver of printed electronics growth. Application areas cover an extensive range either in powertrain (e.g., battery management and thermal interfaces) or interior design (e.g., HMI technologies, interior warmers, displays, 3D smart interfaces with integrated light and decorative elements) and even car exteriors (e.g., integrated antennas, photovoltaics, lights and displays).

Experts suggest that a significant focus on differentiation within the automotive industry is now directed toward developments occurring in interior design and features. Motivations such as cost efficiency, size and weight reduction, lower energy requirements, design freedom and enhanced aesthetics fuel the progress of printed electronics.

HMI and interior sensing solutions
A primary market for printed and hybrid electronics in automotive industry is the development of Human-Machine Interfaces (HMI) with seamless design. Stretchable electronics and sensor solutions are integrated in plastic, textile or leather parts turning them into smart surfaces that enhance user experiences. Lightweight, flexible and stretchable HMI solutions with customizable form factors replace mechanical buttons and complex wiring systems.

Flexible printed sensors allow for the development of beautifully functional HMI systems with any desired sensing layouts that serve to control and adjust motions, climate, volume, lighting and similar functions at users’ fingertips. The combination of functionality and aesthetics is attained through the integration of touch-sensitive technology with lighting and other decorative elements.

Saral Inks© portfolio for these applications ranges from stretchable conductive inks, printed sensor inks and conductive adhesive inks for LED and SMD attachment and interconnection of several printed electronics layers together; all easily screen-printable.

Embedded sensing solutions within steering wheels, seats and seatbelts are few examples of established practices aimed at enhancing safety and comfort in automotive interiors. Advanced flexible printed pressure and capacitive sensitive electronics facilitate the detection and classification of vehicle occupants.

Heating and thermal management
Printed temperature sensing and heating elements for interior comfort, EV motor drives or battery thermal management constitute other trending application areas of printed electronics in the automotive context.

Printed battery safety sensors ensure the early detection of critical situations in the battery packs in a non-complex and very efficient way. These flexible and thin printed electronics on polymer foils with heating or sensing function facilitate easy handling and integration among individual cells within the battery module. They secure equal distribution of charge, prevent over-charging and improve battery lifetime.

Saral Inks© solutions for comprehensive thermal management include functional inks for printed sensing and heating elements, suitable for battery monitoring, seat and floor warming, as well as defroster systems.

Smart surfaces with 3D geometries
Film insert molding and In-Mold Electronics (IME) stand as pioneering technologies for the integration of printed electronics into automotive parts; with IME emerging as the promising solution for making 3D smart surfaces where conductive inks play the central role.

At the core of IME lies the thermoforming process of printed electronics that involves high pressure and temperatures. Saral StretchSilver 800 conductive ink exhibits remarkable resilience when printed on Polycarbonate (PC) sheets and going through 3D thermoforming processes without sacrificing functionality.

The low-cost FibeRobo, which is compatible with existing textile manufacturing techniques, could be used in adaptive performance wear or compression garments.

Researchers from MIT and Northeastern University developed a liquid crystal elastomer fiber that can change its shape in response to thermal stimuli. The fiber, which is fully compatible with existing textile manufacturing machinery, could be used to make morphing textiles, like a jacket that becomes more insulating to keep the wearer warm when temperatures drop.

Instead of needing a coat for each season, imagine having a jacket that would dynamically change shape so it becomes more insulating to keep you warm as the temperature drops.
A programmable, actuating fiber developed by an interdisciplinary team of MIT researchers could someday make this vision a reality. Known as FibeRobo, the fiber contracts in response to an increase in temperature, then self-reverses when the temperature decreases, without any embedded sensors or other hard components.

The low-cost fiber is fully compatible with textile manufacturing techniques, including weaving looms, embroidery, and industrial knitting machines, and can be produced continuously by the kilometer. This could enable designers to easily incorporate actuation and sensing capabilities into a wide range of fabrics for myriad applications.

The fibers can also be combined with conductive thread, which acts as a heating element when electric current runs through it. In this way, the fibers actuate using electricity, which offers a user digital control over a textile’s form. For instance, a fabric could change shape based on any piece of digital information, such as readings from a heart rate sensor.

“We use textiles for everything. We make planes with fiber-reinforced composites, we cover the International Space Station with a radiation-shielding fabric, we use them for personal expression and performance wear. So much of our environment is adaptive and responsive, but the one thing that needs to be the most adaptive and responsive — textiles — is completely inert,” says Jack Forman, a graduate student in the Tangible Media Group of the MIT Media Lab, with a secondary affiliation at the Center for Bits and Atoms, and lead author of a paper on the actuating fiber.

He is joined on the paper by 11 other researchers at MIT and Northeastern University, including his advisors, Professor Neil Gershenfeld, who leads the Center for Bits and Atoms, and Hiroshi Ishii, the Jerome B. Wiesner Professor of Media Arts and Sciences and director of the Tangible Media Group. The research will be presented at the ACM Symposium on User Interface Software and Technology.

Morphing materials
The MIT researchers wanted a fiber that could actuate silently and change its shape dramatically, while being compatible with common textile manufacturing procedures. To achieve this, they used a material known as liquid crystal elastomer (LCE).

A liquid crystal is a series of molecules that can flow like liquid, but when they’re allowed to settle, they stack into a periodic crystal arrangement. The researchers incorporate these crystal structures into an elastomer network, which is stretchy like a rubber band.

As the LCE material heats up, the crystal molecules fall out of alignment and pull the elastomer network together, causing the fiber to contract. When the heat is removed, the molecules return to their original alignment, and the material to its original length, Forman explains.

By carefully mixing chemicals to synthesize the LCE, the researchers can control the final properties of the fiber, such as its thickness or the temperature at which it actuates.

They perfected a preparation technique that creates LCE fiber which can actuate at skin-safe temperatures, making it suitable for wearable fabrics.

“There are a lot of knobs we can turn. It was a lot of work to come up with this process from scratch, but ultimately it gives us a lot of freedom for the resulting fiber,” he adds.
However, the researchers discovered that making fiber from LCE resin is a finicky process. Existing techniques often result in a fused mass that is impossible to unspool.

Researchers are also exploring other ways to make functional fibers, such as by incorporating hundreds of microscale digital chips into a polymer, utilizing an activated fluidic system, or including piezoelectric material that can convert sound vibrations into electrical signals.

Fiber fabrication
Forman built a machine using 3D-printed and laser-cut parts and basic electronics to overcome the fabrication challenges. He initially built the machine as part of the graduate-level course MAS.865 (Rapid-Prototyping of Rapid-Prototyping Machines: How to Make Something that Makes [almost] Anything).

To begin, the thick and viscous LCE resin is heated, and then slowly squeezed through a nozzle like that of a glue gun. As the resin comes out, it is cured carefully using UV lights that shine on both sides of the slowly extruding fiber.

If the light is too dim, the material will separate and drip out of the machine, but if it is too bright, clumps can form, which yields bumpy fibers.

Then the fiber is dipped in oil to give it a slippery coating and cured again, this time with UV lights turned up to full blast, creating a strong and smooth fiber. Finally, it is collected into a top spool and dipped in powder so it will slide easily into machines for textile manufacturing.
From chemical synthesis to finished spool, the process takes about a day and produces approximately a kilometer of ready-to-use fiber.

“At the end of the day, you don’t want a diva fiber. You want a fiber that, when you are working with it, falls into the ensemble of materials — one that you can work with just like any other fiber material, but then it has a lot of exciting new capabilities,” Forman says.

Creating such a fiber took a great deal of trial and error, as well as the collaboration of researchers with expertise in many disciplines, from chemistry to mechanical engineering to electronics to design.

The resulting fiber, called FibeRobo, can contract up to 40 percent without bending, actuate at skin-safe temperatures (the skin-safe version of the fiber contracts up to about 25 percent), and be produced with a low-cost setup for 20 cents per meter, which is about 60 times cheaper than commercially available shape-changing fibers.

The fiber can be incorporated into industrial sewing and knitting machines, as well as nonindustrial processes like hand looms or manual crocheting, without the need for any process modifications.
The MIT researchers used FibeRobo to demonstrate several applications, including an adaptive sports bra made by embroidery that tightens when the user begins exercising.

They also used an industrial knitting machine to create a compression jacket for Forman’s dog, whose name is Professor. The jacket would actuate and “hug” the dog based on a Bluetooth signal from Forman’s smartphone. Compression jackets are commonly used to alleviate the separation anxiety a dog can feel while its owner is away.

In the future, the researchers want to adjust the fiber’s chemical components so it can be recyclable or biodegradable. They also want to streamline the polymer synthesis process so users without wet lab expertise could make it on their own.

Forman is excited to see the FibeRobo applications other research groups identify as they build on these early results. In the long run, he hopes FibeRobo can become something a maker could buy in a craft store, just like a ball of yarn, and use to easily produce morphing fabrics.

“LCE fibers come to life when integrated into functional textiles. It is particularly fascinating to observe how the authors have explored creative textile designs using a variety of weaving and knitting patterns,” says Lining Yao, the Cooper-Siegel Associate Professor of Human Computer Interaction at Carnegie Mellon University, who was not involved with this work.

This research was supported, in part, by the William Asbjornsen Albert Memorial Fellowship, the Dr. Martin Luther King Jr. Visiting Professor Program, Toppan Printing Co., Honda Research, Chinese Scholarship Council, and Shima Seiki. The team included Ozgun Kilic Afsar, Sarah Nicita, Rosalie (Hsin-Ju) Lin, Liu Yang, Akshay Kothakonda, Zachary Gordon, and Cedric Honnet at MIT; and Megan Hofmann and Kristen Dorsey at Northeastern University.

What comes to mind when you think about “wearable technology?” In 2023, likely a lot, at a time when smartwatches and rings measure heart rates, track exercise and even receive text messages. Your mind might even drift to that “ugly” light-up sweater or costume you saw last Halloween or holiday season.

At the Wilson College of Textiles, though, researchers are hard at work optimizing a truly new-age form of wearable technology that can be proven useful in a wide range of settings, from fashion and sports to augmented reality, the military and medicine.

Currently in its final stages, this grant-funded project could help protect users in critical situations, such as soldiers on the battlefield and patients in hospitals, while simultaneously pushing the boundaries of what textiles research can accomplish.

“The goals set for this research are quite novel to any other literature that exists on wearable connectors” says Shourya Dhatri Lingampally, Wilson College of Textiles graduate student and research assistant involved in the project alongside Wilson College Associate Professor Minyoung Suh.

Ongoing since the fall of 2021, Suh and Lingampally’s work focuses on textile-integrated wearable connectors, a unique, high-tech sort of “bridge” between flexible textiles and external electronic devices. At its essence, the project aims to improve these connectors’ Technology Readiness Level — a key rating used by NASA and the Department of Defense used to assess a particular technology’s maturity.

To do this, Lingampally and her colleagues’ research examines problems that have, in the past, affected the performance of wearable devices.

Sure, these advances may benefit fashion, leading to eccentric shirts, jackets, or accessories — “to light up or change its color based on the wearer’s biometric data,” Lingampally offers — the research has roots in a much deeper mission.

Potential benefits to military, medicine and beyond
The project is funded through more than $200,000 in grant money from Advanced Functional Fabrics of America (AFFOA), a United States Manufacturing Innovation Institute (MII) located in Cambridge, Massachusetts. The mission of AFFOA is to support domestic manufacturing capability to support new technical textile products, such as textile-based wearable technologies.

A key purpose of the research centers around improving the functionality of wearable monitoring devices with which soldiers are sometimes outfitted to monitor the health and safety of their troops remotely.

Similar devices allow doctors and other medical personnel to remotely monitor the health of patients even while away from the bedside.

Though such technology has existed for years, it’s too often required running wires and an overall logistically-unfriendly design. That could soon change.

“We have consolidated the electronic components into a small snap or buckle, making the circuits less obtrusive to the wearer,” Lingampally says, explaining the team’s innovations, which include 3D printing the connector prototypes using stereolithography technology.

“We are trying to optimize the design parameters in order to enhance the electrical and mechanical performance of these connectors,” she adds.

To accomplish their goals, the group collaborated with NC State Department of Electrical and Computer Engineering Assistant Research Professor James Dieffenderfer. The team routed a variety of electrical connections and interconnects like conductive thread, epoxy and solder through textile materials equipped with rigid electronic devices.

They also tested the components for compatibility with standard digital device connections like USB 2.0 and I2C.

Ultimately, Lingampally hopes their work will make wearable technology not only easier and more comfortable to use, but available at a lower price, too.

“I would like to see them scaled, to be mass manufactured, so they can be cost efficient for any industry to use,” she explains.

In a bigger-picture sense, though, her team’s work is reinforcing the far-reaching boundaries of what smart textile research can accomplish; a purpose that stretches far beyond fashion or comfort.

Pushing the boundaries of textiles research
Suh and Lingampally’s work is just the latest breakthrough research originating from the Wilson College of Textiles that’s aimed at solving critical problems in the textile industry and beyond.

“The constant advancements in technology and materials present immense potential for the textile industry to drive positive change across a range of fields from fashion to healthcare and beyond,” Lingampally, a graduate student in the M.S. Textiles program, says, noting the encouragement she feels in her program to pursue innovation and creativity in selecting and advancing her research.

Additionally, in the fiber and polymer science doctoral program, which Suh does research with, candidates focus their research on a seemingly endless array of STEM topics, ranging from forensics to medical textiles, nanotechnology and, indeed, smart wearable technology (just to name a few).

In this case, Suh says, the research lent itself to “unexpected challenges” that required intriguing adaptations “at every corner.” But, ultimately, it led to breakthroughs not previously seen in the wearable technology industry, attracting interest from other researchers outside the university, and private companies, too.

“This project was quite exploratory by nature as there hasn’t been any prior research aiming to the same objectives,” Suh says.

Meanwhile, the team has completed durability and reliability testing on its textile-integrated wearable connectors. Eventually, the group would like to increase the sample size for testing to strengthen and validate the findings. The team also hopes to evaluate new, innovative interconnective techniques, as well as other 3D printing techniques and materials as they work to further advance wearable technologies.

Ecole Polytechnique Fédérale de Lausanne (EPFL) researchers have developed fiber-like pumps that allow high-pressure fluidic circuits to be woven into textiles without an external pump. Soft supportive exoskeletons, thermoregulatory clothing, and immersive haptics can therefore be powered from pumps sewn into the fabric of the devices themselves.

Many fluid-based wearable assistive technologies today require a large and noisy pump that is impractical – if not impossible – to integrate into clothing. This leads to a contradiction: wearable devices are routinely tethered to unearable pumps. Now, researchers at the Soft Transducers Laboratory (LMTS) in the School of Engineering have developed an elegantly simple solution to this dilemma.

“We present the world’s first pump in the form of a fiber; in essence, tubing that generates its own pressure and flow rate,” says LMTS head Herbert Shea. “Now, we can sew our fiber pumps directly into textiles and clothing, leaving conventional pumps behind.” The research has been published in the journal Science.

Lightweight, powerful…and washable
Shea’s lab has a history of forward-thinking fluidics. In 2019, they produced the world’s first stretchable pump.

“This work builds on our previous generation of soft pump,” says Michael Smith, an LMTS post-doctoral researcher and lead author of the study. “The fiber format allows us to make lighter, more powerful pumps that are inherently more compat-ible with wearable technology.”

The LMTS fiber pumps use a principle called charge injection electrohydrodynamics (EHD) to generate a fluid flow without any moving parts. Two helical electrodes embedded in the pump wall ionize and accelerate molecules of a special non-conductive liquid. The ion movement and electrode shape generate a net forward fluid flow, resulting in silent, vibration-free operation, and requiring just a palm-sized power supply and battery.

To achieve the pump’s unique structure, the researchers developed a novel fabrication technique that involves twisting copper wires and polyurethane threads together around a steel rod, and then fusing them with heat. After the rod is removed, the 2 mm fibers can be integrated into textiles using standard weaving and sewing techniques.

The pump’s simple design has a number of advantages. The materials required are cheap and readily available, and the manufacturing process can be easily scaled up. Because the amount of pressure generated by the pump is directly linked to its length, the tubes can be cut to match the application, optimizing performance while minimizing weight. The robust design can also be washed with conventional detergents.

From exoskeletons to virtual reality
The authors have already demonstrated how these fiber pumps can be used in new and exciting wearable technologies. For example, they can circulate hot and cold fluid through garments for those working in extreme temperature environments or in a therapeutic setting to help manage inflammation; and even for those looking to optimize athletic performance.

“These applications require long lengths of tubing anyway, and in our case, the tubing is the pump. This means we can make very simple and lightweight fluidic circuits that are convenient and comfortable to wear,” Smith says.

The study also describes artificial muscles made from fabric and embedded fiber pumps, which could be used to power soft exoskeletons to help patients move and walk.

The pump could even bring a new dimension to the world of virtual reality by simulating the sensation of temperature. In this case, users wear a glove with pumps filled with hot or cold liquid, allowing them to feel temperature changes in response to contact with a virtual object.

Pumped up for the future
The researchers are already looking to improve the performance of their device. “The pumps already perform well, and we’re confident that with more work, we can continue to make improvements in areas like efficiency and lifetime,” says Smith. Work has already started on scaling up the production of the fiber pumps, and the LMTS also has plans to embed them into more complex wearable devices.

“We believe that this innovation is a game-changer for wearable technology,” Shea says.

Researchers have developed next-generation smart textiles – incorporating LEDs, sensors, energy harvesting, and storage – that can be produced inexpensively, in any shape or size, using conventional industrial looms used to make the clothing worn every day.
 
An international team, led by the University of Cambridge, have previously demonstrated that woven displays can be made at large sizes, but these earlier examples were made using specialised manual laboratory equipment. Other smart textiles can be manufactured in specialised microelectronic fabrication facilities, but these are highly expensive and produce large volumes of waste.

However, the team found that flexible displays and smart fabrics can be made much more cheaply, and more sustainably, by weaving electronic, optoelectronic, sensing and energy fibre components on the same industrial looms used to make conventional textiles. Their results, reported in the journal Science Advances, demonstrate how smart textiles could be an alternative to larger electronics in sectors including automotive, electronics, fashion and construction.

Despite recent progress in the development of smart textiles, their functionality, dimensions and shapes have been limited by current manufacturing processes.
“We could make these textiles in specialised microelectronics facilities, but these require billions of pounds of investment,” said Dr Sanghyo Lee from Cambridge’s Department of Engineering, the paper’s first author. “In addition, manufacturing smart textiles in this way is highly limited, since everything has to be made on the same rigid wafers used to make integrated circuits, so the maximum size we can get is about 30 centimetres in diameter.”

“Smart textiles have also been limited by their lack of practicality,” said Dr Luigi Occhipinti, also from the Department of Engineering, who co-led the research. “You think of the sort of bending, stretching and folding that normal fabrics have to withstand, and it’s been a challenge to incorporate that same durability into smart textiles.”
Last year, some of the same researchers showed that if the fibres used in smart textiles were coated with materials that can withstand stretching, they could be compatible with conventional weaving processes. Using this technique, they produced a 46-inch woven demonstrator display.

Now, the researchers have shown that smart textiles can be made using automated processes, with no limits on their size or shape. Multiple types of fibre devices, including energy storage devices, light-emitting diodes, and transistors were fabricated, encapsulated, and mixed with conventional fibres, either synthetic or natural, to build smart textiles by automated weaving. The fibre devices were interconnected by an automated laser welding method with electrically conductive adhesive.
 
The processes were all optimised to minimise damage to the electronic components, which in turn made the smart textiles durable enough to withstand the stretching of an industrial weaving machine. The encapsulation method was developed to consider the functionality of the fibre devices, and the mechanical force and thermal energy were investigated systematically to achieve automated weaving and laser-based interconnection, respectively.

The research team, working in partnership with textile manufacturers, were able to produce test patches of smart textiles of roughly 50x50 centimetres, although this can be scaled up to larger dimensions and produced in large volumes.
 
“These companies have well-established manufacturing lines with high throughput fibre extruders and large weaving machines that can weave a metre square of textiles automatically,” said Lee. “So when we introduce the smart fibres to the process, the result is basically an electronic system that is manufactured exactly the same way other textiles are manufactured.”
The researchers say it could be possible for large, flexible displays and monitors to be made on industrial looms, rather than in specialised electronics manufacturing facilities, which would make them far cheaper to produce. Further optimisation of the process is needed, however.

“The flexibility of these textiles is absolutely amazing,” said Occhipinti. “Not just in terms of their mechanical flexibility, but the flexibility of the approach, and to deploy sustainable and eco-friendly electronics manufacturing platforms that contribute to the reduction of carbon emissions and enable real applications of smart textiles in buildings, car interiors and clothing. Our approach is quite unique in that way.”

The research was supported in part by the European Union and UK Research and Innovation.

Precisely applied metal-organic technology detects and captures toxic gases in air.

A durable copper-based coating developed by Dartmouth researchers can be precisely integrated into fabric to create responsive and reusable materials such as protective equipment, environmental sensors, and smart filters, according to a recent study.
 
The coating responds to the presence of toxic gases in the air by converting them into less toxic substances that become trapped in the fabric, the team reports in Journal of the American Chemical Society.

The findings hinge on a conductive metal-organic technology, or framework, developed in the laboratory of corresponding author Katherine Mirica, an associate professor of chemistry. First reported in JACS in 2017, the framework was a simple coating that could be layered onto cotton and polyester to create smart fabrics the researchers named SOFT—Self-Organized Framework on Textiles. Their paper demonstrated that SOFT smart fabrics could detect and capture toxic substances in the surrounding environment.

For the newest study, the researchers found that—instead of the simple coating reported in 2017—they can precisely embed the framework into fabrics using a copper precursor that allows them to create specific patterns and more effectively fill in the tiny gaps and holes between threads.

The researchers found that the framework technology effectively converted the toxin nitric oxide into nitrite and nitrate, and transformed the poisonous, flammable gas hydrogen sulfide into copper sulfide. They also report that the framework’s ability to capture and convert toxic materials withstood wear and tear, as well as standard washing.
 
The versatility and durability the new method provides would allow the framework to be applied for specific uses and in more precise locations, such as a sensor on protective clothing, or as a filter in a particular environment, Mirica said.

“This new method of deposition means that the electronic textiles could potentially interface with a broader range of systems because they’re so robust,” she said. “This technological advance paves the way for other applications of the framework’s combined filtration and sensing abilities that could be valuable in biomedical settings and environmental remediation.”
The technique also could eventually be a low-cost alternative to technologies that are cost prohibitive and limited in where they can be deployed by needing an energy source, or—such as catalytic converters in automobiles—rare metals, Mirica said.
 
“Here we’re relying on an Earth-abundant matter to detoxify toxic chemicals, and we’re doing it without any input of outside energy, so we don’t need high temperature or electric current to achieve that function,” Mirica said.

Co-first author Michael Ko, initially observed the new process in 2018 as he attempted to deposit the metal-organic framework onto thin-film copper-based electrodes, Mirica said. But the copper electrodes would be replaced by the framework.

“He wanted it on top of the electrodes, not to replace them,” Mirica said. “It took us four years to figure out what was happening and how it was beneficial. It’s a very straightforward process, but the chemistry behind it is not and it took us some time and additional involvement of students and collaborators to understand that.”

The team discovered that the metal-organic framework “grows” over copper, replacing it with a material with the ability to filter and convert toxic gases, Mirica said. Ko and co-author Lukasz Mendecki, a postdoctoral scholar in the Mirica Group from 2017-18, investigated methods for applying the framework material to fabric in specific designs and patterns.

Co-first author Aileen Eagleton, who is also in the Mirica Group, finalized the technique by optimizing the process for imprinting the metal-organic framework onto fabric, as well as identifying how its structure and properties are influenced by chemical exposure and reaction conditions.

Future work will focus on developing new multifunctional framework materials and scaling up the process of embedding the metal-organic coatings into fabric, Mirica said.

Stylish sensors to wear 
With sensors that measure health parameters and can be worn on the body, we do let technology get very close to us. A collaboration between Empa and designer Laura Deschl, sponsored by the Textile and Design Alliance (TaDA) of Eastern Switzerland, shows that medical monitoring of respiratory activity, for example, can also be very stylish – as a shirt.
 
With sensors that measure health parameters and can be worn on the body, we do let technology get very close to us. A collaboration between Empa and designer Laura Deschl, sponsored by the Textile and Design Alliance (TaDA) of Eastern Switzerland, shows that medical monitoring of respiratory activity, for example, can also be very stylish – as a shirt.

The desire for a healthy lifestyle has triggered a trend towards self-tracking. Vital signs should be available at all times, for example to consistently measure training effects. At the same time, among the continuously growing group of people over 65, the desire to maintain performance into old age is stronger than ever. Preventive, health-maintaining measures must be monitored if they are to achieve the desired results. The search for measurement systems that reliably determine the corresponding health parameters is in full swing. In addition to the leisure sector, medicine needs suitable and reliable measurement systems that enable efficient and effective care for an increasing number of people in hospital and at home. After all, the increase in lifestyle diseases such as diabetes, cardiovascular problems or respiratory diseases is putting a strain on the healthcare system.

Researchers led by Simon Annaheim from Empa's Biomimetic Membranes and Textiles laboratory in St. Gallen are therefore developing sensors for monitoring health status, for example for a diagnostic belt based on flexible sensors with electrically conductive or light-conducting fibers. However, other, less technical properties can be decisive for the acceptance of continuous medical monitoring by patients. For example, the sensors must be comfortable to wear and easy to handle – and ideally also look good.

This aspect is addressed by a cooperation between the Textile and Design Alliance, or TaDA for short, in eastern Switzerland and Empa. The project showed how textile sensors can be integrated into garments. In addition to technical reliability and a high level of comfort, another focus was on the design of the garments. The interdisciplinary TaDA designer Laura Deschl worked electrically conductive fibers into a shirt that change their resistance depending on how much they are stretched. This allows the shirt to monitor how much the subjects' chest and abdomen rise and fall while they breathe, allowing conclusions to be drawn about breathing activity. Continuous monitoring of respiratory activity is of particular interest for patients during the recovery phase after surgery and for patients who are being treated with painkillers. Such a shirt could also be helpful for patients with breathing problems such as sleep apnea or asthma. Moreover, Deschl embroidered electrically conductive fibers from Empa into the shirt, which are needed to connect to the measuring device and were visually integrated into the shirt's design pattern.

The Textile and Design Alliance is a pilot program of the cultural promotion of the cantons of Appenzell Ausserrhoden, St.Gallen and Thurgau to promote cooperation between creative artists from all over the world and the textile industry. Through international calls for proposals, cultural workers from all disciplines are invited to spend three months working in the textile industry in eastern Switzerland. The TaDA network comprises 13 cooperation partners – textile companies, cultural, research and educational institutions – and thus offers the creative artists direct access to highly specialized know-how and technical means of production in order to work, research and experiment on their textile projects on site. This artistic creativity is in turn made available to the partners as innovative potential.

Neo-ecology through innovative paper technology

To reduce the CO2 footprint, the Fraunhofer Institute for Casting, Composite and Processing Technology IGCV Augsburg research with a state-of-the-art wetlaid nonwoven machine for recycling carbon fibers. The production processes are similar to those of a paper manufacturing machine. The crucial difference: we turn not paper fibers into the paper but recycled carbon fibers into nonwoven roll fabrics. The carbon fiber thus gets a second life and finds an environmentally friendly way in nonwovens, such as door panels, engine bonnets, roof structures, underbody protection (automotive), and heat shields (helicopter tail boom), as well as in aircraft interiors.

“Wetlaid technology for processing technical fibers is currently experiencing a revolution following centuries of papermaking tradition.”
Michael Sauer, Researcher at Fraunhofer IGCV

The wetlaid technology used is one of the oldest nonwoven forming processes (around 140 BC - 100 AD). As an essential industry sector with diverse fields of application, wetlaid nonwovens are no longer only found in the classic paper. Instead, the application areas extend, for example, from adhesive carrier films, and packaging material, to banknotes and their process-integrated watermarks and security features. In the future, particularly sustainable technology fields will be added around battery components, fuel cell elements, filtration layers, and even function-integrated material solutions, e.g., EMI shielding function.

Fraunhofer IGCV wetlaid nonwovens line is specifically designed as a pilot line. In principle, very different fiber materials such as natural, regenerated, and synthetic fibers can be processed, mainly recycled and technical fibers. The system offers the highest possible flexibility regarding material variants and process parameters. In addition, sufficiently high productivity is ensured to allow subsequent scaled processing trials (e.g., demonstrator production).

The main operating range of the wetlaid line relates to the following parameters:

• Processing speed: up to 30 m/min
• Role width: 610 mm
• Grammage: approx. 20–300 gsm
• Overall machinery is ≥ IP65 standard for processing, e.g., conductive fiber materials
• Machine design based on an angled wire configuration with high dewatering capacity, e.g., for processing highly diluted fiber suspensions or for material variants with high water retention capacity.
• Machine modular system design with maximum flexibility for a quick change of material variants or a quick change of process parameters. The setup allows short-term hardware adaptations as well as project-specific modifications.

Research focus: carbon recycling at the end of the life cycle
The research focus of Fraunhofer IGCV is primarily in the field of technical staple fibers. The processing of recycled carbon fibers is a particular focus. Current research topics in this context include, for example, the research, optimization, and further development of binder systems, different fiber lengths and fiber length distributions, nonwoven homogeneity, and fiber orientation. In addition, the focus is on the integration of digital as well as AI-supported methods within the framework of online process monitoring. Further research topics, such as the production of gas diffusion layers for fuel cell components, the further development of battery elements, and filtration applications, are currently being developed.