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(c) NC State
07.08.2023

Wearable Connector Technology - Benefits to Military, Medicine and beyond

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.

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.

Source:

North Carolina State University, Sean Cudahy

(c) Fraunhofer WKI
19.04.2023

Sustainable natural-fiber reinforcement for textile-reinforced concrete components

Textile-reinforced concrete components with a sustainable natural-fiber reinforcement possess sufficient bond and tensile load-bearing behavior for the utilization in construction. This has been verified by researchers at the Fraunhofer WKI in collaboration with Biberach University of Applied Sciences and the industrial partner FABRINO. In the future, textile-reinforced components with natural-fiber reinforcement could therefore replace conventionally reinforced concrete components and improve the environmental balance in the construction industry.

Textile-reinforced concrete components with a sustainable natural-fiber reinforcement possess sufficient bond and tensile load-bearing behavior for the utilization in construction. This has been verified by researchers at the Fraunhofer WKI in collaboration with Biberach University of Applied Sciences and the industrial partner FABRINO. In the future, textile-reinforced components with natural-fiber reinforcement could therefore replace conventionally reinforced concrete components and improve the environmental balance in the construction industry.

Non-metallic reinforcements for concrete elements are currently often made from various synthetically produced fibers - for example from glass or carbon fibers. An ecological alternative to synthetic fibers is provided by flax or other natural fibers. These are widely available and are more sustainable, due, amongst other things, to their renewable raw-material basis, the advantages regarding recycling, and the lower energy requirements during production. This is where the researchers from the Fraunhofer WKI and Biberach University of Applied Sciences, in collaboration with an industrial partner, became active. Their goal was to demonstrate that reinforcements made from textile fibers are just as suitable for utilization in construction as synthetic fibers.

"At the Fraunhofer WKI, we have produced leno fabrics from flax-fiber yarn using a weaving machine. In order to enhance sustainability, we tested a treatment of the flax yarns for improving the tensile strength, durability and adhesion which is ecologically advantageous compared to petro-based treatments," explained Jana Winkelmann, Project Manager at the Fraunhofer WKI. In the coating process, a commonly used petro-based epoxy resin was successfully replaced by a partially bio-based impregnation. A large proportion (56%) of the molecular structure of the utilized epoxy resin consists of hydrocarbons of plant origin and can therefore improve the CO2 balance.

Textile reinforcements have a number of fundamental advantages. They exhibit, for example, significantly reduced corrodibility at the same or higher tensile strength than steel, with the result that the necessary nominal dimension of the concrete covering can be reduced. This often allows smaller cross-sections to be required for the same load-bearing capacity. Up to now, however, the load-bearing behavior of textile reinforcements made from natural fibers in concrete components has not been systematically investigated.

At Biberach University of Applied Sciences, researchers tested the bond and tensile load-bearing behavior as well as the uniaxial flexural load-bearing behavior of concrete components with textile reinforcement made from flax fibers. The scientists came to the conclusion that the natural-fiber-based textile-reinforced components with a bio-based impregnation are fundamentally suitable. The suitability was demonstrated by both a significant increase in the breaking load compared to non-reinforced and under-reinforced concrete components and in finely distributed crack patterns. The curves of the stress-strain diagrams could be divided into three ranges typical for reinforced expansion elements (State I - non-cracked, State IIa - initial cracking, and State IIb - final crack pattern). The delineation of the ranges becomes more pronounced as the degree of reinforcement increases.

As a whole, regionally or Europe-wide available, renewable natural fibers and a partially bio-based coating contribute towards an improvement of the CO2 footprint of the construction industry. As a result, a further opportunity is being opened up for the energy- and raw-material-intensive construction industry in terms of meeting increasingly stringent environmental and sustainability requirements. "Textile-reinforced concretes enable lighter and more slender structures and therefore offer architectural leeway. We would like to continue our research into the numerous application possibilities of natural-fiber-reinforced concretes," said Christina Haxter, a staff member at the Fraunhofer WKI.

The project, which ran from 9th December 2020 to 31st December 2022, was funded by the German Federal Environmental Foundation (DBU).   

Photo: pixabay
10.08.2021

Stand-up paddle board made from renewable lightweight mater

Stand-up paddling has become a popular sport. However, conventional surfboards are made of petroleum-based materials such as epoxy resin and polyurethane.

Researchers at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut, WKI, want to replace plastic boards with sustainable sports equipment: They are developing a stand-up paddle board that is made from one hundred percent renewable raw materials. The ecological lightweight material can be used in many ways, such as in the construction of buildings, cars and ships.

Stand-up paddling has become a popular sport. However, conventional surfboards are made of petroleum-based materials such as epoxy resin and polyurethane.

Researchers at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut, WKI, want to replace plastic boards with sustainable sports equipment: They are developing a stand-up paddle board that is made from one hundred percent renewable raw materials. The ecological lightweight material can be used in many ways, such as in the construction of buildings, cars and ships.

Stand-up paddling (SUP) is a sport that is close to nature, but the plastic boards are anything but environmentally friendly. As a rule, petroleum-based materials such as epoxy resin, polyester resin, polyurethane and expanded or extruded polystyrene are used in combination with fiberglass and carbon fiber fabrics to produce the sports equipment. In many parts of the world, these plastics are not recycled, let alone disposed of correctly. Large quantities of plastic end up in the sea and collect in huge ocean eddies. For Christoph Pöhler, a scientist at Fraunhofer WKI and an avid stand-up paddler, this prompted him to think about a sustainable alternative. In the ecoSUP project, he is driving the development of a stand-up paddle board that is made from 100 percent renewable raw materials and which is also particularly strong and durable. The project is funded by the German Federal Ministry of Education and Research (BMBF). The Fraunhofer Center for International Management and Knowledge Economy IMW is accompanying the research work, with TU Braunschweig acting as project partner.

Recovering balsa wood from rotor blades
“In standard boards, a polystyrene core, which we know as styrofoam, is reinforced with fiberglass and sealed with an epoxy resin. We, instead, use bio-based lightweight material,” says the civil engineer. Pöhler and his colleagues use recycled balsa wood for the core. This has a very low density, i.e. it is light yet mechanically stressable. Balsa wood grows mainly in Papua New Guinea and Ecuador, where it has been used in large quantities in wind turbines for many years – up to six cubic meters of the material can be found in a rotor blade. Many of the systems are currently being disconnected from the grid. In 2020 alone, 6000 were dismantled. A large proportion of this is burnt. It would make more sense to recover the material from the rotor blade and recycle it in accordance with the circular economy. “This was exactly our thinking. The valuable wood is too good to burn,” says Pöhler.

Since the entire sandwich material used in conventional boards is to be completely replaced, the shell of the ecological board is also made from one hundred percent bio-based polymer. It is reinforced with flax fibers grown in Europe, which are characterized by very good mechanical properties. To pull the shell over the balsa wood core, Pöhler and his team use the hand lay-up and vacuum infusion processes. Feasibility studies are still underway to determine the optimal method. The first demonstrator of the ecological board should be available by the end of 2022. “In the interests of environmental protection and resource conservation, we want to use natural fibers and bio-based polymers wherever it is technically possible. In many places, GFRP is used even though a bio-based counterpart could do the same,” Pöhler sums up.

Patented technology for the production of wood foam
But how is it possible to recover the balsa wood from the rotor blade — after all, it is firmly bonded to the glass-fiber reinforced plastic (GFRP) of the outer shell? First, the wood is separated from the composite material in an impact mill. The density differences can be used to split the mixed-material structures into their individual components using a wind sifter. The balsa wood fibers, which are available as chips and fragments, are then finely ground. “We need this very fine starting material to produce wood foam. Fraunhofer WKI has a patented technology for this,” explains the researcher. In this process, the wood particles are suspended to form a kind of cake batter and processed into a light yet firm wood foam that holds together thanks to the wood’s own binding forces. The addition of adhesive is not required. The density and strength of the foam can be adjusted. “This is important because the density should not be too high. Otherwise, the stand-up paddle board would be too heavy to transport.”

Initially, the researchers are focusing on stand-up paddle boards. However, the hybrid material is also suitable for all other boards, such as skateboards. The future range of applications is broad: For example, it could be used as a facade element in the thermal insulation of buildings. The technology can also be used in the construction of vehicles, ships and trains.

The Fraunhofer WKI double-rapier weaving machine with the Jacquard attachment in the upper of the photo.  © Fraunhofer WKI | Melina Ruhr. The Fraunhofer WKI double-rapier weaving machine with the Jacquard attachment in the upper of the photo.
02.06.2020

Fraunhofer WKI: Climate-friendly hybrid-fiber materials on the basis of renewable natural fibers

As a result of the new combination possibilities for bio-based hybrid-fiber materials achieved at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, the industrial application possibilities for renewable raw materials, for example in the automotive industry or for everyday objects such as helmets or skis, can be expanded.

By increasing the proportion of flax fiber in hybrid-fiber materials to up to 50 percent, the scientists have demonstrated that it is possible to significantly increase the biogenic proportion in composite materials. The special aspect of the tested methods: The fabrics can be individually composed with the help of a weaving machine. In this way, process steps in industrial production, in which materials first have to be merged together, can be omitted. This will achieve reductions in energy and CO2 throughout the entire production process.

As a result of the new combination possibilities for bio-based hybrid-fiber materials achieved at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, the industrial application possibilities for renewable raw materials, for example in the automotive industry or for everyday objects such as helmets or skis, can be expanded.

By increasing the proportion of flax fiber in hybrid-fiber materials to up to 50 percent, the scientists have demonstrated that it is possible to significantly increase the biogenic proportion in composite materials. The special aspect of the tested methods: The fabrics can be individually composed with the help of a weaving machine. In this way, process steps in industrial production, in which materials first have to be merged together, can be omitted. This will achieve reductions in energy and CO2 throughout the entire production process.

Successfully woven: Different hybrid fabrics
In view of the increased demands being placed upon environmental and climate protection, science and industry are seeking sustainable alternatives to conventional materials in all branches of production. As a material, natural fibers offer a sustainable solution. Due to their low density and simultaneous high stability, natural fibers can be used to produce highly resilient light-weight-construction materials which are easy to recycle. In the “ProBio” project, scientists from the Fraunhofer WKI have therefore addressed the question as to how the proportion of natural fibers in bio-based hybrid-fiber materials can be increased as significantly as possible. A double-rapier weaving machine with Jacquard attachment was thereby utilized in order to produce the bio-based hybrid-fiber materials.

The researchers thereby focused specifically on bio-based hybrid-fiber composites (Bio-HFC). Bio-HFC consist of a combination of cellulose-based fibers, such as flax fibers, and synthetic high-performance fibers, such as carbon or glass fibers, for reinforcement. Bio-HFC can be utilized in, for example, vehicle construction. As an innovation in the “ProBio” project, the researchers interwove differing fiber-material combinations, reinforcing fibers and matrix fibers with the aid of the double-rapier weaving machine. This procedure differs from the process in which finished fabrics are layered on top of one another.

“We have combined the advantageous properties of the fiber materials within a composite material in such a way that we have been able to compensate for weak points in individual components, thereby achieving new properties in some cases. In addition, we have succeeded in increasing the proportion of bio-based fibers to up to 50 percent flax fibers, which we have combined with 50 percent reinforcing fibers,” says project team member Jana Winkelmann, describing the procedure. The bio-hybrid textiles, each consisting of 50 percent by weight carbon and flax fabric, are introduced into a bio-based plastic matrix. The composite material possesses a flexural strength which is more than twice as high as that of the corresponding composite material made from flax-reinforced epoxy resin. This mechanical performance capability can significantly expand the application range of renewable raw materials for technical applications.

With the weaving machine, the scientists have successfully combined innovative light-weight-construction composite materials with complex application-specific fabric structures and integrated functions. Reinforcing fibers, such as carbon and natural fibers, as well as multilayer fabrics and three-dimensional structures, can be woven together in a single work step. This offers advantages for industrial production, as production steps in which materials first have to be merged together can be omitted. “We have succeeded, for example, in utilizing conductive yarns or wires as sensors or conductor paths directly in the weaving process, thereby producing fabrics with integrated functions. The introduction of synthetic fibers as weft threads enables the production of bio-hybrid composites with isotropic mechanical properties,” explains Ms. Winkelmann.

Weaving technology makes it possible to create new products with a high proportion of bio-based components on a pilot scale. The project results provide an insight into the diverse combination possibilities of natural and reinforcing fibers and demonstrate opportunities for utilization not only in vehicle construction but also for everyday objects such as helmets or skis. The results will be presented within the framework of the 4th International Conference on Natural Fibers, ICNF, July 2019 in Porto, Portugal. The “ProBio” project, which ran from 1st July 2014 to 30th June 2019, was funded by the Lower Saxony Ministry of Science and Culture (MWK).

Background
Sustainability through the utilization of renewable raw materials has formed the focus at the Fraunhofer WKI for more than 70 years. The institute, with locations in Braunschweig, Hanover and Wolfsburg, specializes in process engineering, natural-fiber composites, wood and emission protection, quality assurance of wood products, material and product testing, recycling procedures and the utilization of organic building materials and wood in construction. Virtually all the procedures and materials resulting from the research activities are applied industrially.

Source:

Fraunhofer Institute for Wood Research WKI