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Smart Fabric Converts Heat to Electricity

by ccadm


Imagine clothing that monitors your temperature, tracks your activity, or keeps you cozy all by itself without needing an external power source.

Well, all this and more is fast becoming a reality thanks to all the research and development happening at the intersection of tech and clothing. 

Technological advancement has been transforming our lives by making our phones and home appliances smarter. Now, even our clothes are becoming smart, unlocking possibilities that pave the way for an exciting and more sustainable future.

The global smart textile market is already valued at $4.1bln and is projected to rise to $24.5 bln by 2032. Interestingly, energy harvesting currently accounts for the largest share of this market, according to Markets and Markets.

Energy harvesting is converting ambient energy into electrical energy to power autonomous electronic devices. This energy can be harvested from various sources, including mechanical and thermal. To create energy-harvesting textiles, active materials are usually added to the textile’s surface or woven or embroidered into it. 

Such smart fabrics can potentially be utilized as an alternative to batteries, which require recharging or periodic replacement because they contain only a finite amount of energy. In wearable textile applications, batteries tend to be rigid, bulky items that must be removed before washing and hence need improvement.

While still at a relatively early stage, this sector is growing rapidly, driven by a combination of factors, including technology advances, design, consumer demand, miniaturization, and government policies.

Now, let’s take a look into the exciting innovations in the sector and the literal power of the clothes that we wear!

Smart Fabric to Convert Body Heat Into Electricity

One of the most recent and electrifying developments was made by researchers from the University of Waterloo in collaboration with a leading institution in textile science and engineering at Jiangnan University, who created a smart fabric that converts thermal energy from the body and sunlight into electrical power.

This smart fabric has the capability to generate power, observe health metrics, and track physical activity. These sensors allow the fabric to detect temperature changes and monitor pressure, stress, and chemical composition.

A promising application of this fabric is smart face masks that can track the temperature and rate of your breath as well as detect chemicals to help identify conditions like lung cancer and viruses. According to Yuning Li, director of the Printable Electronic Materials Lab at Waterloo and a professor in the Department of Chemical Engineering:

“We have developed a fabric material with multifunctional sensing capabilities and self-powering potential (that) brings us closer to practical applications for smart fabrics.”

The fabric designed by the team is flexible, MXene-based, thermoelectric, and can precisely determine strain stimuli and temperature. To achieve this, the team developed a layer of adhesive polydopamine (PDA) on the surface of the nylon fabric, which facilitated the MXene attachment through hydrogen bonding. 

MXene has been drawing a lot of attention for its rare combination of properties like layered structure, flexibility, large surface area, electric and metallic conductivity, biocompatibility, hydrophilicity, size tunability, and rich surface chemistry. The study noted:

“The resultant MXene-based thermoelectric fabric exhibits outstanding temperature detection capability and cyclic stability while also delivering excellent sensitivity, rapid responsiveness (60 ms), and remarkable durability in strain sensing (3200 cycles).”  

The novel fabric is not only more cost-effective, durable, and stable than other fabrics on the market, but unlike the current wearable devices that need frequent recharging, this one can operate without requiring an external source of power. This way, the research demonstrates the huge potential of integrating conductive polymers and MXene with modern fabric tech for the advancement of smart fabrics.

Noting the various progress made in tech, including AI, which is evolving rapidly to offer advanced signal processing for health monitoring and the preservation of food and pharmaceuticals, Li argued that all these advancements rely on ‘comprehensive data collection, which traditional sensors—often cumbersome, expensive, and unwieldy—are unable to achieve.’ This makes printed sensors, embedded in smart fabrics, ideal for continuous data collection and monitoring, Li added.

While this innovative fabric marks significant progress in making these applications feasible, the researchers will now focus on further improving the fabric’s capabilities and incorporating it with electronic systems. A smartphone app may also be part of this future development to track and transmit data from the fabric to healthcare professionals for real-time, non-invasive health monitoring.

Pioneering Fabrics of the Future

Advancements in smart clothing have been happening rapidly for some time now. In 2016, researchers from the Georgia Institute of Technology in Atlanta created a micro-cable power fabric that could harvest energy from sunlight and motion.

For this, the scientists weaved thread with thin, fiber-based solar cells and triboelectric nanogenerators. The resultant smart fabric had a 320 μm thick single layer and could be integrated into tents, curtains, and various clothes. The textile, as per the study, could directly charge a cell phone and continuously power an electronic watch.

NTU Singapore scientists also successfully developed a ‘fabric’ that turns body movement into electricity. To create this stretchable and waterproof fabric, the scientists used a polymer that converted mechanical force, such as pressing or squeezing, into electrical energy. The fabric has a base layer of stretchable spandex and is also integrated with a rubber-like material that makes it flexible, strong, and waterproof.

Stretchable and Waterproof Fabric

In an experiment, the team demonstrated that tapping on a small piece of this fabric produced electrical energy that could effectively light up a hundred LEDs. Also, washing, crumpling, or folding the fabric didn’t negatively affect the performance and could maintain stable electrical output for as much as five months.

“We think it could be woven into t-shirts or integrated into soles of shoes to collect energy from the body’s smallest movements, piping electricity to mobile devices.”

Study lead Lee Pooi See, Materials scientist, and NTU Associate Provost Professor

While smart fabrics are the subject of much research and development, their cost-effectiveness remains a big challenge. Their lack of practicality, at times, can also be an issue.

To address these issues, researchers have developed next-generation smart textiles that can be produced inexpensively by using the same machines as in conventional clothing. Researchers first demonstrated that coating fibers with materials that can withstand stretching can be compatible with conventional weaving processes. Now, smart textiles can also be made using automated processes, with no limits on their size or shape. 

This is just the beginning, as all this interest in smart textiles is leading to many other interesting innovations. For instance, this progress has also led to the development of a wearable device that can be embedded into fabric or worn as a jacket. It can camouflage its wearer from heat-detecting sensors, such as night vision goggles, no matter the weather. 

While the device’s surface heats up or cools down quickly to match ambient temperatures, hiding the wearer’s body heat, the inside remains at the same temperature as human skin.

Meanwhile, at the National University of Singapore, researchers developed a moisture-driven electricity generation (MEG) device using fabric, sea salt, carbon ink, and a special water-absorbing gel. By keeping one end of the fabric always wet and the other end dry, the carbon-coated fabric generated an electric current with the capacity to produce electricity for over 150 hours. Acting essentially as a battery, it provided higher electrical output than a conventional AA battery, showing the potential to power everyday electronics.

The MEG device’s concept is built upon the ability of different materials to generate electricity from the interaction with moisture in the air. This demonstrates its suitability for various practical uses, such as wearable electronics and information storage devices.

Engineers have also made transistors and electronic devices from thread. One such research involved weaving thin threads into fabric to create electronic devices that can be worn on the skin or implanted surgically for diagnostic monitoring. 

The first thread-based transistors (TBTs) were combined with thread-based sensors to enable the creation of completely flexible, multiplexed devices. The TBT here involved coating a linen thread with carbon nanotubes to create a semiconductor surface for electrons to travel and then attaching it to two thin gold wires, one of which was attached to an electrolyte-infused gel. 

According to the study author Sameer Sonkusale, professor of electrical and computer engineering at Tufts University School of Engineering:

“There are many medical applications in which real-time measurement of biomarkers can be important for treating disease and monitoring the health of patients. The ability to fully integrate a soft and pliable diagnostic monitoring device that the patient hardly notices could be quite powerful.”

Intelligent Fabrics for Adapting to Changing Temperatures 

Another dimension of smart textiles being explored is temperature-adaptive fabric, which enhances energy efficiency by reducing the need for powered heating or cooling systems.

In this context, new research from the Hong Kong Polytechnic University, published this week, introduces breathable and thermally-insulated soft robotic clothing that can automatically adapt to changing ambient temperatures, helping ensure worker safety in hot environments. 

Interesting research from the American Chemical Society a few years ago involved developing a material that cools its wearer without using electricity by transferring heat and allowing moisture to evaporate from the skin.

With air conditioning and other cooling methods responsible for a significant portion of electricity usage in the US, the researchers took a targeted approach, cooling off a person’s body instead of an entire room.

While clothing and textiles are already designed to do just that, most have high costs, poor cooling capacity, and large electricity consumption. So, the researchers made the new material by electrospinning a polymer, specifically a water-repelling polymer, and a thermally conductive filler into nanofibrous membranes. 

These membranes had large enough pores to allow sweat to evaporate from the skin and air to circulate while repelling water from the outside. The study noted that besides personal cooling, the membrane could also be useful for seawater desalination, solar energy collection, and thermal management of electronic devices.

From the American Chemical Society also came a new textile that not only keeps you cool in the summer but also warm in the winter, making it unique in this respect. While smart textiles have been known to warm or cool the wearer, fabric that can do both isn’t really that common. This strong yet comfortable fabric also requires no energy input.

To create this smart fabric, the scientists freeze-spun chitosan, which comes from a shellfish’s outer skeleton, and silk, into colored fibers with porous microstructures, which are then filled with a phase-changing polymer called polyethylene glycol (PEG). The thread was coated with polydimethylsiloxane so that liquid PEG, which absorbs and releases thermal energy, doesn’t leak out.

The researchers tested the fabric, which proved to be flexible, strong, and water-repellent, by weaving it into a piece of fabric that was then incorporated into a polyester glove. When worn by a person and placed in a hot chamber (122°F), the solid PEG absorbed the heat and melted into a liquid, cooling the skin. Conversely, when exposed to cold (50°F), the PEG solidified, releasing heat and warming the skin.

According to the researchers, the fabric can be scaled up for mass production because it is compatible with the existing textile industry.

Click here to learn about smart clothes for motion capture to change sports and physiotherapy.

Companies Involved in Energy-harvesting Smart Fabrics

Now, let’s take a look at companies that are innovating in the field of smart fabrics:

#1. Adidas

The company released the first pair of its smart shoes a decade ago. The shoes had a sensor, microprocessor, electric motor, and smart electronic textile material.

In 2021, Adidas unveiled its new textile innovation, STRUNG, which is described as an industry-first textile and creation process. This innovation allows Adidas to build and test different structures before sending the chosen design to the STRUNG robot. This product concept is entirely data-driven footwear for a specific runner profile.

Adidas has a market cap of $43 bln, and its shares are trading at $119.58, up 16.74% YTD. Its EPS (TTM) is -0.37, and its P/E (TTM) is -325, while the dividend yield paid is 0.32%, as per CNBC. For Q2 2024, the German sportswear company reported €5.82b in revenue, €196.0m in net income, and a 3.4% profit margin, which was up from 1.6% in 2Q23.

#2. DuPont De Nemours

In the world of smart clothing, DuPont has launched stretchable electronic links via  Intexar™. This smart clothing technology transforms ordinary fabrics into active and intelligent garments that provide critical biometric data such as heart rate, breathing rate, and muscle tension.

DuPont has a market cap of $33.47 bln, and its shares are trading at $80.19, up 4.22% YTD. It has an EPS (TTM) of 0.72 and P/E (TTM) of 111.16, while the dividend yield paid is 1.90%, as per CNBC. For Q2 2024, the company reported a 2% increase in net sales to $3.2bln and adjusted free cash flow increasing 53% to $425mln.

finviz dynamic chart for  DD

Other prominent names working on smart clothing include the UK-based Pireta, which has developed a unique additive process that adds conductivity to fabrics without impacting the garment’s performance or drape. Then there is Collebak’s Solar Charged jacket that absorbs light during the day and emits it at night. Xenoma’s e-skin, meanwhile, is a smart shirt embedded with sensors to monitor body movements and physiological data. OMSignal has bio-sensing apparel that uses energy-harvesting textiles to power sensors embedded in the fabric to monitor heart rate, breathing, and other vital signs.

Applied Materials, Nike, SolarEdge Technologies, Smartex, and Sensoria are also working in this field. 

In Europe, several companies have come together to launch the GRAPHERGIA project, aiming to transform the way energy is harnessed in textiles and battery systems. The project kicked off late last year to pioneer smart textiles that adapt to the body and charge themselves.

“We envision a world where your clothing does more than just look good—it powers your devices, acts as a sensor, and connects you seamlessly to the Internet of Things (IoT).”

– Prof. Spyros Yannopoulos, the project coordinator for GRAPHERGIA

Conclusion 

All these exciting innovations we talked about above have fashion now serving as a way not just to exude power in appearance but also literally gene­rate power. By integrating textiles with energy harvesters, we can also have environmentally friendly, pervasive, and sustainable wearable energy solutions. 

Energy-efficient fabrics are clearly emerging as the future of fashion, opening up a whole ne­w world of wearable tech. The only limit here is our imagination.

Click here to learn about the self-charging wearables.



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