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sportswear Stocksnap, Pixabay
30.08.2023

Detecting exhaustion with smart sportswear

Researchers at ETH Zurich have developed an electronic yarn capable of precisely measuring how a person’s body moves. Integrated directly into sportswear or work clothing, the textile sensor predicts the wearer’s exhaustion level during physical exertion.

Exhaustion makes us more prone to injury when we’re exercising or performing physical tasks. A group of ETH Zurich researchers led by Professor Carlo Menon, Head of the Biomedical and Mobile Health Technology Lab, have now developed a textile sensor that produces real-time measurements of how exhausted a person gets during physical exertion. To test their new sensor, they integrated it into a pair of athletic leggings. Simply by glancing at their smartphone, testers were able to see when they were reaching their limit and if they ought to take a break.

Researchers at ETH Zurich have developed an electronic yarn capable of precisely measuring how a person’s body moves. Integrated directly into sportswear or work clothing, the textile sensor predicts the wearer’s exhaustion level during physical exertion.

Exhaustion makes us more prone to injury when we’re exercising or performing physical tasks. A group of ETH Zurich researchers led by Professor Carlo Menon, Head of the Biomedical and Mobile Health Technology Lab, have now developed a textile sensor that produces real-time measurements of how exhausted a person gets during physical exertion. To test their new sensor, they integrated it into a pair of athletic leggings. Simply by glancing at their smartphone, testers were able to see when they were reaching their limit and if they ought to take a break.

This invention, for which ETH Zurich has filed a patent, could pave the way for a new generation of smart clothing: many of the products currently on the market have electronic components such as sensors, batteries or chips retrofitted to them. In addition to pushing up prices, this makes these articles difficult to manufacture and maintain.

By way of contrast, the ETH researchers’ stretchable sensor can be integrated directly into the material fibres of stretchy, close-fitting sportswear or work clothing. This makes large-scale production both easier and cheaper. Menon highlights another benefit: “Since the sensor is located so close to the body, we can capture body movements very precisely without the wearer even noticing.”

An extraordinary yarn
When people get tired, they move differently – and running is no exception: strides shorten and become less regular. Using their new sensor, which is made of a special type of yarn, the ETH researchers can measure this effect. It’s all thanks to the yarn’s structure: the inner fibre is made of a conductive, elastic rubber. The researchers wrapped a rigid wire, which is clad in a thin layer of plastic, into a spiral around this inner fibre. “These two fibres act as electrodes and create an electric field. Together, they form a capacitor that can hold an electric charge,” says Tyler Cuthbert, a postdoc in Menon’s group, who was instrumental in the research and development that led to the invention.

Smart running leggings
Stitching this yarn into the thigh section of a pair of stretchy running leggings means that it will stretch and slacken at a certain rhythm as the wearer runs. Each movement alters the gap between the two fibres, and thus also the electric field and the capacitor’s charge.

Under normal circumstances, these charge fluctuations would be much too small to help measure the body’s movements. However, the properties of this yarn are anything but normal: “Unlike most other materials, ours actually becomes thicker when stretched,” Cuthbert says. As a result, the yarn is considerably more sensitive to minimal movements. Stretching it even a little produces distinctly measurable fluctuations in the sensor’s charge. This makes it possible to measure and analyse even subtle changes in running form.

But how can this be used to determine a person’s exhaustion level? In previous research, Cuthbert and Menon observed a series of testers, who ran while wearing athletic leggings equipped with a similar sensor. They recorded how the electric signals changed as the runners got more and more tired. Their next step was to turn this pattern into a model capable of predicting runners’ exhaustion which can now be used for their novel textile sensor.  But ensuring that the model can make accurate predictions outside the lab will require a lot of additional tests and masses of gait pattern data.

Textile antenna for wireless data transfer  
To enable the textile sensor to send electrical signals wirelessly to a smartphone, the researchers equipped it with a loop antenna made of conducting yarn, which was also sewn directly onto the leggings. “Together, the sensor and antenna form an electrical circuit that is fully integrated into the item of clothing,” says Valeria Galli, a doctoral student in Menon’s group.

The electrical signal travels from the stretchable sensor to the antenna, which transmits it at a certain frequency capable of being read by a smartphone. The wearer runs and the sensor moves, creating a signal pattern with a continuously fluctuating frequency, which a smartphone app then records and evaluates in real time. But the researchers still have quite a bit of development work to do to make this happen.

Applications include sport and workplace
At the moment, the researchers are working on turning their prototype into a market-ready product. To this end, they are applying for one of ETH Zurich’s sought-after Pioneer Fellowships. “Our goal is to make the manufacture of smart clothing cost-effective and thus make it available to a broader public,” Menon says. He sees the potential applications stretching beyond sport to the workplace – to prevent exhaustion-related injuries – as well as to rehabilitation medicine.

Thread-like pumps can be woven into clothes (c) LMTS EPFL
27.06.2023

Thread-like pumps can be woven into clothes

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.

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.

More information:
EPFL Fibers exoskeleton wearables
Source:

Celia Luterbacher, School of Engineering | STI

(c) Fraunhofer IBMT
10.05.2023

Using textile electrodes to stop muscle tremor

Scientists at the Fraunhofer Institute for Biomedical Engineering IBMT have been working with international partners to develop a technology platform to help relieve the symptoms of muscle tremors. Tiny biocompatible electrodes in the muscles, combined with external electrodes and controllers, form an intelligent network of sensors and actuators to detect muscle signals and provide electrical stimuli as needed. Together with exoskeletons, the technology could also help people with spinal cord injuries.

Scientists at the Fraunhofer Institute for Biomedical Engineering IBMT have been working with international partners to develop a technology platform to help relieve the symptoms of muscle tremors. Tiny biocompatible electrodes in the muscles, combined with external electrodes and controllers, form an intelligent network of sensors and actuators to detect muscle signals and provide electrical stimuli as needed. Together with exoskeletons, the technology could also help people with spinal cord injuries.

A compact controller on a belt or under a jacket, a couple of discreet textile electrodes on the arms and legs, and electrodes three centimeters long and barely a millimeter thin in the muscle are all it will take to help people with tremor disorders in the future. Whenever muscle tremors start, the system sends electrical stimuli to the muscles; these stimuli are registered by the nervous system. The nervous system then stops sending interfering signals to the muscles, which settle down again. That is the basic idea behind the technology that scientists from Fraunhofer IBMT have been working on together with project partners by developing, manufacturing, integrating and experimentally testing a set of intramuscular and external electrodes and associated controllers.

The scientists have already made some concrete achievements. “We have managed to reduce muscle tremors significantly in trials with patients,” explains Andreas Schneider-Ickert, project manager for active implants and innovation manager.

The system is part of the EU-funded joint project “EXTEND.” A total of nine project partners from five different countries are working together to develop a versatile platform of distributed neural interfaces. The technology will be able to help people with neuromuscular disorders, such as tremors, or symptoms of paralysis. Even people with spinal cord injuries could benefit from this. The technology uses external controllers to link the implanted electrodes into an intelligent network. The components communicate with each other wirelessly, exchange data, detect muscle signals and send targeted stimuli into the muscles. Implanted systems are already being used medically to provide stimulation, but the current methods require complex surgical operations that are considerably stressful for patients.

Implants for the human-machine interface
A key element of EXTEND is the implants, which are made from biocompatible platinum-iridium and silicone and are injected into the muscle through a catheter. Just three centimeters long and barely a millimeter in diameter, the tiny implant has an electrode at each end that functions as either a sensor or an actuator. External electrodes sewn into a textile ribbon supply the module with energy. This sends pulsed alternating current through the muscle tissue to the implant. “What’s innovative about this is not only the intelligent interplay between control electronics, sensors and actuators, but also the principle of modulating the alternating current to transmit data,” explains Schneider-Ickert.

Once it has been implanted and started, the sensors register the first signs of muscle tremors and pass the information on to the external components. The controller evaluates the data and sends signals through the textile electrodes to stimulate the muscle. This closes a control circuit of intelligently networked sensor and actuator components that counteracts the tremor.

The stimulus signal is not strong enough to trigger a muscle contraction directly. It is the nervous system that plays the decisive role here. This registers the stimulation in the muscle tissue and responds by stopping the commands that trigger the muscle tremor. At least that is the theory — the finer details of the relationship between tremors and signals from the nervous system are yet to be researched. “In clinical trials, however, our method is working astonishingly well. Initial trials have shown that providing the patient with stimuli for one or two hours is enough to reduce tremor symptoms for a longer period of time,” says Schneider-Ickert.

Since tremors often occur in both arms and both legs, implants can be injected and external textile electrodes placed in all the affected muscle groups. This creates a distributed sensor network. The controllers can keep track of all the implanted and external electrodes at the same time and control them in coordination with each other. All this happens in real time, with the person experiencing no delay at all.

The technology being developed in the EXTEND joint project is just as functional as conventional implant systems, but minimally invasive and therefore easier to accept and better for everyday use. The basic concept originates from a Spanish project partner. Based in this concept, the researchers at Fraunhofer IBMT designed the electrodes and implantable components and produced and integrated them in the in-house cleanroom. The scientists have 25 years of expertise in neuroprosthetics and active implants.

Exoskeletons to prevent paraplegia
For tremor patients, EXTEND brings them the hope that their symptoms can be alleviated considerably. However, the technology platform could also help people with spinal cord injuries thanks to motorized exoskeletons. This is a possible because, in cases of paralysis, the nerve fibers are often not completely cut off. They can still transmit stimuli from the brain, albeit very weakly. The sensors register the activity and transmit it to the controller, which analyzes all the signals, works out what movement the person wants to perform and activates exactly the right prostheses to support the muscles in executing the movement.

Following initial successful tests, the concepts and technologies used in EXTEND have been steadily developed, miniaturized, optimized and subjected to further implementation studies. As a result, the project has now been completed with a successful proof of concept of the miniaturized full system in humans. Fraunhofer IBMT will use the knowledge gained from EXTEND to further develop its expertise in the field of neuromuscular and neural interfaces.

Source:

Fraunhofer Institute for Biomedical Engineering IBMT

Vadim Zharkov: https://youtu.be/x9gCrhIPaPM
28.02.2023

‘Smart’ Coating Could Make Fabrics into Protective Gear

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.

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.

Source:

Dartmouth / Textination

Photo: Marlies Thurnheer
25.10.2022

Textile Electrodes for Medtech Applications

  • Successful financing round for Empa spin-off Nahtlos

Nahtlos, an Empa spin-off, has received 1 million Swiss francs in a first round of financing from a network of business angels from Switzerland and Liechtenstein and from the Startfeld Foundation. With this funding, Nahtlos aims to drive the market entry of its newly developed textile-based electrode for medical applications.

  • Successful financing round for Empa spin-off Nahtlos

Nahtlos, an Empa spin-off, has received 1 million Swiss francs in a first round of financing from a network of business angels from Switzerland and Liechtenstein and from the Startfeld Foundation. With this funding, Nahtlos aims to drive the market entry of its newly developed textile-based electrode for medical applications.

Over the past two years, Nahtlos, an Empa spin-off, has developed novel textile-based electrodes for recording heart activity (electrocardiogram, ECG) – for example, to detect atrial fibrillation – and for electrostimulation therapies, for example, to preserve the muscle mass in paralyzed patients. Textile-based electrodes enable gentle and skin-friendly application, even if the electrodes have to be worn for several days or even weeks. The textile electrode is thus the first alternative to the gel electrode, which was developed 60 years ago and is still considered the standard for medical applications today.

Nahtlos founder and former Empa researcher Michel Schmid and co-founder and business economist José Näf have further developed the textile-based technology, which was developed and patented at Empa in various projects funded by Innosuisse, among others. The goal was to produce a product for long-term medical applications that reliably records ECG signals for up to several weeks, achieves a high level of patient acceptance and is cost-effective for the healthcare provider. Today, the patent for textile-based electrode technology is owned by Nahtlos after reaching a milestone.

Financing by business angels and Startfeld Foundation
Schmid and Näf were looking for investors to certify their product, set up production and develop the market – and recently found what they were looking for: In a seed financing round, the two young entrepreneurs were able to acquire 1 million Swiss francs from business angels from Switzerland and Liechtenstein as well as from the Startfeld Foundation. Nahtlos was supported in setting up its company by Startfeld, the start-up promotion arm of Switzerland Innovation Park Ost (SIP Ost), in the form of coaching, consulting and early-stage financing. Nahtlos is also based in the Innovation Park Ost, where innovations are initiated and accelerated through collaboration between start-ups, companies, universities and research institutions.

Together with Empa and Nahtlos, SIP Ost was present at OLMA this year. Visitors could learn live and on the spot about Empa's research activities in the field of Digital Health as well as about the Nahtlos technology and its textile electrodes for health monitoring.

Wireless Power Transmission for Technical Textiles Bild von Gerd Altmann auf Pixabay
27.08.2019

WIRELESS POWER TRANSMISSION FOR TECHNICAL TEXTILES

The trend towards the "Internet of Everything" is ongoing. Whether in industrial, medical or everyday applications, more and more electrical devices are connected to each other, record sensing values, exchange data and react to them. Due to smaller structures, new processing possibilities and new flexible materials, such systems are also being used more and more frequently in the textile sector. For example, medical measurements can be recorded directly on a garment, actuators such as EMS electrodes can be integrated directly into the textile or functions such as MP3 players, GPS receivers, fall detectors, heating structures and much more can be embedded simply and intuitively in textiles. Communication and data exchange usually take place wirelessly via WLAN, Bluetooth, RFID or, in the future, via the 5G network.

The trend towards the "Internet of Everything" is ongoing. Whether in industrial, medical or everyday applications, more and more electrical devices are connected to each other, record sensing values, exchange data and react to them. Due to smaller structures, new processing possibilities and new flexible materials, such systems are also being used more and more frequently in the textile sector. For example, medical measurements can be recorded directly on a garment, actuators such as EMS electrodes can be integrated directly into the textile or functions such as MP3 players, GPS receivers, fall detectors, heating structures and much more can be embedded simply and intuitively in textiles. Communication and data exchange usually take place wirelessly via WLAN, Bluetooth, RFID or, in the future, via the 5G network.

Electrical energy is required for such applications and functions. Despite the efforts to further minimize the energy demand of electronic circuits, it is not always possible to operate these systems completely energy autonomously. Therefore, energy storage devices such as batteries or rechargeable accumulators are necessary for operation. The big advantage of recharging is that smaller, more compact energy storage devices can be used to achieve the same or an increased service life running time. There are two basic concepts for recharging a battery with electrical energy. On the one hand wired and with connections like a micro-USB cable. On the other hand wireless via wireless power transmission. With wired solutions, contacts can wear out or be added by fuzz, especially in the textile sector. In addition, the connecting process is less flexible and uncomfortable.

Wireless concepts offer several advantages and are therefore better suited. For example, the electronics including energy storage can be completely encapsulated, since no galvanic contacts are required. Among other things, this makes the textile directly machine-washable, because the electronics are protected from water, detergents and sweat. This means that no components need to be removed from the textile when washing. A further purely practical advantage is the simplicity of charging. With the suitable concept, the textile can be hung on hangers, placed in laundry baskets or, ideally, simply placed in the washing machine and charged without any further action of the user. The result is an uncomplicated, charming way of operating smart textiles.

There are several concepts and possibilities for wirelessly supplying a textile with energy. The most popular and at the same time most efficient method is the inductive power transmission [1]. Two coils are inductively coupled to each other and thus transmit energy wirelessly (Figure 2). Air, wood, plastic, but also liquids such as water or human tissue can be penetrated a few centimeters almost loss-free.  There are also various concepts for integrating electronics into textiles. From the production of the entire circuit on thin printed circuit boards to complete textile integration, a wide variety of mixtures are possible. The easiest concepts to develop are those in which all circuit parts are manufactured on printed circuit boards. Thin printed circuit boards can have substrate thicknesses of a few tenths of a millimeter (Figure 1). But flexible possibilities such as manufacturing on silicones are also conceivable. Among other things, the sensors and microcontrollers as well as the coil for inductive energy transfer to the substrate are manufactured. This complete printed circuit board then only has to be connected to the textile, whether by gluing, sewing or insertion.

Concepts in which the receiver coil is integrated into the textile go one step further. For example, ultra-fine wires or strands are woven or embroidered and the textile material thus becomes the substrate itself as a functionalized textile. The rest of the circuit, which is still integrated on a conventional substrate, is then connected to the coil and the textile. Since some of the spools can have diameters of a few centimeters, one can gain in flexibility because the textile spool can move almost freely. With a complete textile integration, the components are finally attached to the textile and the conductor paths are embroidered or woven in.

Consistently implemented and used, wireless power transmission as a simple and convenient charging method of textiles can thus contribute to sustainably strengthen the market for smart textiles improving handling and user experience.

Source:

Fraunhofer Institute for Electronic Nano Systems ENAS
Authors: Dominik Schröder, Dr. Christian Hedayat

Imagine a truck tarp that can harvest the energy of sunlight! Picture by Peter H. on Pixabay
20.08.2019

TEXTILE BASED SOLAR CELLS

Imagine a truck tarp that can harvest the energy of sunlight!

Imagine a truck tarp that can harvest the energy of sunlight!
With the help of new textile-based solar cells developed by Fraunhofer researchers, semitrailers could soon be producing the electricity needed to power cooling systems or other onboard equipment. In short, textile-based solar cells could soon be adding a whole new dimension to photovoltaics, complementing the use of conventional silicon-based solar cells. Solar panels on building roofs are a common enough sight today – as are large-scale solar parks. In the future, we may well see other surfaces being exploited for photovoltaic generation. Truck tarps, for example, could be used to produce the electricity consumed by the driver when underway or parked up for the night, or to power electronic systems used to locate trailers in shipping terminals. Similarly, conventional building facades could be covered with photovoltaic textiles in place of concrete render. Or the blinds used to provide shade in buildings with glass facades could be used to create hundreds of square meters of additional surface for producing power.

Glass-fiber fabric as a solar-cell substrate
At the heart of such visions are pliable, textile-based solar cells developed at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in collaboration with the Fraunhofer Institute for Electronic Nano Systems ENAS, Sächsisches Textilforschungsinstitut e.V and industrial partners erfal GmbH & Co. KG, PONGS Technical Textiles GmbH, Paul Rauschert GmbH & Co. KG and GILLES PLANEN GmbH. “There are a number of processes that enable solar cells to be incorporated in coatings applied to textiles,” explains Dr. Lars Rebenklau, group manager for system integration and electronic packaging at Fraunhofer IKTS. In other words, the substrate for the solar cells is a woven fabric rather than the glass or silicon conventionally used. “That might sound easy, but the machines in the textile industry are designed to handle huge rolls of fabric – five or six meters wide and up to 1000 meters in length,” explains Dr. Jonas Sundqvist, group manager for thin-film technology at Fraunhofer IKTS. “And during the coating process, the textiles have to withstand temperatures of around 200 °Celsius. Other factors play a key role too: the fabric must meet fire regulations, have a high tensile strength and be cheap to produce. “The consortium therefore opted for a glass-fiber fabric, which fulfills all of these specifications,” Rebenklau says.

An emphasis on standard processes
Researchers also faced the challenge of how to apply the wafer-thin layers that make up a solar cell – the bottom electrode, the photovoltaic layer and the top electrode – to the fabric. These layers are between one and ten microns in thickness. By comparison, the surface of the fabric is like a mountain range. The solution was first to apply a layer that levels out the peaks and troughs on the surface of the fabric. For this purpose, researchers opted for a standard process from the textile industry: transfer printing, which is also used to rubberize fabrics. All the other processes have been adapted in such a way that they can be easily incorporated in standard production methods used in the textile industry. For example, the two electrodes – which are made of electrically conductive polyester – and the photovoltaic layer are applied by means of the common roll-to-roll method. The solar cells are also laminated with an additional protective layer in order to make them more robust.

Fabric-based solar cells ready for market launch in around five years
The research team has already produced an initial prototype. “This has demonstrated the basic functionality of our textile-based solar cells,” Rebenklau says. “Right now, they have an efficiency of between 0.1 and 0.3 percent.” In a follow-up project, he and the team are seeking to push this over the five percent mark, at which point the textile-based solar cells would prove commercially viable. Silicon-based solar cells are significantly more efficient, at between ten and 20 percent. However, this new form of solar cell is not intended to replace the conventional type, merely offer an alternative for specific applications. In the coming months, the team will be investigating ways of enhancing the service life of the fabric-based solar cells. If all goes according to plan, the first textile-based solar cells could be ready for commercialization in around five years. This would fulfill the original goal of the PhotoTex project: to provide new stimulus for Germany’s textile industry and improve its competitiveness.

Ariane5 © ESA_Stephane Corvaja 2016
09.05.2017

BAGS PACKED FOR SPACE: TEXTILES NEEDED FOR A MISSION TO MARS

  • Techtextil and Texprocess present ‘Living in Space’ in cooperation with ESA and DLR 
  • Nutrition, mobility, fashion and living: technical textiles make settlements in space possible

Beam me up, Scotty: a large amount of material has to be transported for a journey into space – and technical textiles account for a large proportion of them. Examples of the parts and products in which they are to be found will be on show at the ‘Living in Space’ exhibition during this year’s Techtextil und Texprocess (9 to 12 May 2017), which has been organised by Messe Frankfurt in cooperation with the European Space Agency (ESA) and the German Aerospace Centre (DLR). Among the exhibits to be seen are materials and technologies from Techtextil and Texprocess exhibitors in a ‘Material Gallery’, architecture for space by Ben van Berkel, space-inspired fashions and an original Mars Rover.

  • Techtextil and Texprocess present ‘Living in Space’ in cooperation with ESA and DLR 
  • Nutrition, mobility, fashion and living: technical textiles make settlements in space possible

Beam me up, Scotty: a large amount of material has to be transported for a journey into space – and technical textiles account for a large proportion of them. Examples of the parts and products in which they are to be found will be on show at the ‘Living in Space’ exhibition during this year’s Techtextil und Texprocess (9 to 12 May 2017), which has been organised by Messe Frankfurt in cooperation with the European Space Agency (ESA) and the German Aerospace Centre (DLR). Among the exhibits to be seen are materials and technologies from Techtextil and Texprocess exhibitors in a ‘Material Gallery’, architecture for space by Ben van Berkel, space-inspired fashions and an original Mars Rover. And – even without having completed a dizzying astronaut training programme – visitors can take a journey through space to Mars via virtual-reality glasses.

“At the ‘Living in Space’ exhibition, Techtextil and Texprocess visitors can see examples of textile materials and processing technologies in an application-oriented setting. In cooperation with our partners and exhibitors, we have created an informative and entertaining area, the like of which has never been seen before at Techtextil and Texprocess”, explains Michael Jänecke, Brand Manager, Technical Textiles and Textile Processing, Messe Frankfurt. Given that technical textiles are to be found in almost every sphere of human life, the materials and processing technologies shown are oriented towards the ‘Architecture’, ‘Civilization’, ‘Clothing’ and ‘Mobility’ areas of application.

Ideal homes in space

Visitors can get an idea of how building in space could function at the ‘Architecture’ area curated by Stylepark architecture magazine. Lightweight construction and canopy specialist MDT-tex joined forces with star architect Ben van Berkel of the international UNStudio firm of architects to create a ‘Space Habitat’ especially for Techtextil. Comprising 60 individual modules, each of which is double twisted and under tension, the lightweight pavilion has an area of 40 square metres and consists of specially designed aluminium profiles covered with PTFE sheets. MDT-tex designed the fabric especially for the pavilion in an extremely light grammage without sacrificing its high-temperature resistance and technical properties.

Ultra-lightweight materials play a leading role in space travel because the lighter the space capsule’s load, the cheaper the transport. Reclining in comfortable seats, visitors to the Space Habitat can also travel to Mars using virtual-realist glasses and, at the same time, find out more about technical textiles and their processing in space.

Hightech-Fashion in orbit

No one likes to be too hot or too cold. Space-wear should not only protect the wearer from extreme temperatures but also regulate their body temperature, drain off moisture and be durable and easy to clean. All the better, then, if it also looks good, as shown by the designs in the ‘Clothing’ segment of the exhibition. The ESMOD Fashion School from Berlin presents outfits made by students within the framework of the ‘Couture in Orbit’ project (2015/2016), which was organised by ESA and the London Science Museum. Additionally, the POLI.design centre of the Politecnico di Milano (Milan University) presents outfits from the followup project, ‘Fashion in Orbit’ under the scientific supervision of Annalisa Dominoni and the technical supervision of Benedetto Quaquaro in cooperation with ESA and garment manufacturer Colmar.

The Hohenstein Textile Institutes present two models from the Spacetex research project, within the framework of which astronaut Alexander Gerst tested the interaction of body, apparel and climate under conditions of weightlessness during the ‘Blue Dot’ mission. In this connection, the model, ‘Nostalgia’ by Linda Pfanzler (Lower Rhine University) reminds the wearer of the earth with an integrated library of fragrances. The suits of the ‘Dynamic Space’ collection by Rachel Kowalski (Pforzheim University) contain electrodes that stimulate important muscle groups under conditions of weightlessness. The outfits by Leyla Yalcin and Sena Isikal (AMD Düsseldorf) come from the ‘Lift off’ collection created in cooperation with Bremen-based silver-yarn manufacturer Statex. They include a sleeping bag for astronauts made from silver-coated textiles, which can also be used as an overall and protects the wearer from electro-magnetic radiation. Thanks to the silver threads, another garment, a raincoat reflects light and stores the wearer’s body heat.

Material Gallery: fibers for space

In addition to the exhibits at the special exhibition, around 40 Techtextil and Texprocess exhibitors offer ideas for fibre-based materials and processing technology suitable for use in space in a ‘Material Gallery’. For the ‘Civilization’ segment, they include spacer fabrics for growing vegetables, for ‘Mobility’ a carbon yarn, which was used to make a fairing for the solid-fuel booster rocket of the Ariane 6. The Material Gallery also shows fibre-composite structures made of carbon fibres, such as a robot arm, a whole-body suit that transmits the wearer’s movements to a 3D model in real-time, functional apparel textiles with flame-retardant, anti-bacterial and temperature-regulating properties, and membrane systems for ventilating aircraft.

Exhibits from ESA, DLR and Speyer Museum of Technology, including an original Mars Rover and space suits, make the exhibition an extraordinary experience. The exhibits are supplemented by impulse lectures by ESA experts for technology transfer throughout the fair.