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Image: Udo Jandrey
22.03.2024

New model for sustainable structures of textile-reinforced concrete

By reinforcing concrete with textiles instead of steel, it is possible to use less material and create slender, lightweight structures with a significantly lower environmental impact. The technology to utilise carbon fibre textiles already exists, but it has been challenging, among other things, to produce a basis for reliable calculations for complex and vaulted structures. Researchers from Chalmers University of Technology, in Sweden, are now presenting a method that makes it easier to scale up analyses and thus facilitate the construction of more environmentally friendly bridges, tunnels and buildings.

By reinforcing concrete with textiles instead of steel, it is possible to use less material and create slender, lightweight structures with a significantly lower environmental impact. The technology to utilise carbon fibre textiles already exists, but it has been challenging, among other things, to produce a basis for reliable calculations for complex and vaulted structures. Researchers from Chalmers University of Technology, in Sweden, are now presenting a method that makes it easier to scale up analyses and thus facilitate the construction of more environmentally friendly bridges, tunnels and buildings.

"A great deal of the concrete we use today has the function to act as a protective layer to prevent the steel reinforcement from corroding. If we can use textile reinforcement instead, we can reduce cement consumption and also use less concrete − and thus reduce the climate impact," says Karin Lundgren, who is Professor in Concrete Structures at the Department of Architecture and Civil Engineering at Chalmers.

Cement is a binder in concrete and its production from limestone has a large impact on the climate. One of the problems is that large amounts of carbon dioxide that have been sequestered in the limestone are released during production. Every year, about 4.5 billion tonnes of cement are produced in the world and the cement industry accounts for about 8 percent of global carbon dioxide emissions. Intensive work is therefore underway to find alternative methods and materials for concrete structures.

Reduced carbon footprint with thinner constructions and alternative binders
By using alternative binders instead of cement, such as clay or volcanic ash, it is possible to further reduce carbon dioxide emissions. But so far, it is unclear how well such new binders can protect steel reinforcement in the long term.

"You could get away from the issue of corrosion protection, by using carbon-fibres as reinforcement material instead of steel, because it doesn't need to be protected in the same way. You can also gain even more by optimising thin shell structures with a lower climate impact," says Karin Lundgren.

In a recently published study in the journal Construction and Building Materials, Karin Lundgren and her colleagues describe a new modelling technique that was proved to be reliable in analyses describing how textile reinforcement interacts with concrete.

"What we have done is to develop a method that facilitates the calculation work of complex structures and reduces the need for testing of the load-bearing capacity," says Karin Lundgren.

One area where textile reinforcement technology could significantly reduce the environmental impact is in the construction of arched floors. Since the majority of a building’s climate impact during production comes from the floor structures, it is an effective way to build more sustainably. A previous research study from the University of Cambridge shows that textile reinforcement can reduce carbon dioxide emissions by up to 65 percent compared to traditional solid floors.

Method that facilitates calculations
A textile reinforcement mesh consists of yarns, where each yarn consists of thousands of thin filaments (long continuous fibres). The reinforcement mesh is cast into concrete, and when the textile-reinforced concrete is loaded, the filaments slip both against the concrete and against each other inside the yarn. A textile yarn in concrete does not behave as a unit, which is important when you want to understand the composite material's ability to carry loads. The modelling technique developed by the Chalmers researchers describes these effects.

"You could describe it as the yarn consisting of an inner and an outer core, which is affected to varying degrees when the concrete is loaded. We developed a test and calculation method that describes this interaction. In experiments, we were able to show that our way of calculating is reliable enough even for complex structures," says Karin Lundgren.

The work together with colleagues is now continuing to develop optimisation methods for larger structures.

"Given that the United Nations Environment Programme (UNEP) expects the total floor area in the world to double over the next 40 years due to increased prosperity and population growth, we must do everything we can to build as resource-efficiently as possible to meet the climate challenge," says Karin Lundgren.

Source:

Chalmers | Mia Halleröd Palmgren

Smart glove teaches new physical skills Image: Alex Shipps/MIT CSAIL
18.03.2024

Smart glove teaches new physical skills

Adaptive smart glove from MIT CSAIL researchers can send tactile feedback to teach users new skills, guide robots with more precise manipulation, and help train surgeons and pilots.

You’ve likely met someone who identifies as a visual or auditory learner, but others absorb knowledge through a different modality: touch. Being able to understand tactile interactions is especially important for tasks such as learning delicate surgeries and playing musical instruments, but unlike video and audio, touch is difficult to record and transfer.

Adaptive smart glove from MIT CSAIL researchers can send tactile feedback to teach users new skills, guide robots with more precise manipulation, and help train surgeons and pilots.

You’ve likely met someone who identifies as a visual or auditory learner, but others absorb knowledge through a different modality: touch. Being able to understand tactile interactions is especially important for tasks such as learning delicate surgeries and playing musical instruments, but unlike video and audio, touch is difficult to record and transfer.

To tap into this challenge, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and elsewhere developed an embroidered smart glove that can capture, reproduce, and relay touch-based instructions. To complement the wearable device, the team also developed a simple machine-learning agent that adapts to how different users react to tactile feedback, optimizing their experience. The new system could potentially help teach people physical skills, improve responsive robot teleoperation, and assist with training in virtual reality.

Will I be able to play the piano?
To create their smart glove, the researchers used a digital embroidery machine to seamlessly embed tactile sensors and haptic actuators (a device that provides touch-based feedback) into textiles. This technology is present in smartphones, where haptic responses are triggered by tapping on the touch screen. For example, if you press down on an iPhone app, you’ll feel a slight vibration coming from that specific part of your screen. In the same way, the new adaptive wearable sends feedback to different parts of your hand to indicate optimal motions to execute different skills.

The smart glove could teach users how to play the piano, for instance. In a demonstration, an expert was tasked with recording a simple tune over a section of keys, using the smart glove to capture the sequence by which they pressed their fingers to the keyboard. Then, a machine-learning agent converted that sequence into haptic feedback, which was then fed into the students’ gloves to follow as instructions. With their hands hovering over that same section, actuators vibrated on the fingers corresponding to the keys below. The pipeline optimizes these directions for each user, accounting for the subjective nature of touch interactions.

“Humans engage in a wide variety of tasks by constantly interacting with the world around them,” says Yiyue Luo MS ’20, lead author of the paper, PhD student in MIT’s Department of Electrical Engineering and Computer Science (EECS), and CSAIL affiliate. “We don’t usually share these physical interactions with others. Instead, we often learn by observing their movements, like with piano-playing and dance routines.

“The main challenge in relaying tactile interactions is that everyone perceives haptic feedback differently,” adds Luo. “This roadblock inspired us to develop a machine-learning agent that learns to generate adaptive haptics for individuals’ gloves, introducing them to a more hands-on approach to learning optimal motion.”

The wearable system is customized to fit the specifications of a user’s hand via a digital fabrication method. A computer produces a cutout based on individuals’ hand measurements, then an embroidery machine stitches the sensors and haptics in. Within 10 minutes, the soft, fabric-based wearable is ready to wear. Initially trained on 12 users’ haptic responses, its adaptive machine-learning model only needs 15 seconds of new user data to personalize feedback.

In two other experiments, tactile directions with time-sensitive feedback were transferred to users sporting the gloves while playing laptop games. In a rhythm game, the players learned to follow a narrow, winding path to bump into a goal area, and in a racing game, drivers collected coins and maintained the balance of their vehicle on their way to the finish line. Luo’s team found that participants earned the highest game scores through optimized haptics, as opposed to without haptics and with unoptimized haptics.

“This work is the first step to building personalized AI agents that continuously capture data about the user and the environment,” says senior author Wojciech Matusik, MIT professor of electrical engineering and computer science and head of the Computational Design and Fabrication Group within CSAIL. “These agents then assist them in performing complex tasks, learning new skills, and promoting better behaviors.”

Bringing a lifelike experience to electronic settings
In robotic teleoperation, the researchers found that their gloves could transfer force sensations to robotic arms, helping them complete more delicate grasping tasks. “It’s kind of like trying to teach a robot to behave like a human,” says Luo. In one instance, the MIT team used human teleoperators to teach a robot how to secure different types of bread without deforming them. By teaching optimal grasping, humans could precisely control the robotic systems in environments like manufacturing, where these machines could collaborate more safely and effectively with their operators.

“The technology powering the embroidered smart glove is an important innovation for robots,” says Daniela Rus, the Andrew (1956) and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT, CSAIL director, and author on the paper. “With its ability to capture tactile interactions at high resolution, akin to human skin, this sensor enables robots to perceive the world through touch. The seamless integration of tactile sensors into textiles bridges the divide between physical actions and digital feedback, offering vast potential in responsive robot teleoperation and immersive virtual reality training.”

Likewise, the interface could create more immersive experiences in virtual reality. Wearing smart gloves would add tactile sensations to digital environments in video games, where gamers could feel around their surroundings to avoid obstacles. Additionally, the interface would provide a more personalized and touch-based experience in virtual training courses used by surgeons, firefighters, and pilots, where precision is paramount.

While these wearables could provide a more hands-on experience for users, Luo and her group believe they could extend their wearable technology beyond fingers. With stronger haptic feedback, the interfaces could guide feet, hips, and other body parts less sensitive than hands.

Luo also noted that with a more complex artificial intelligence agent, her team's technology could assist with more involved tasks, like manipulating clay or driving an airplane. Currently, the interface can only assist with simple motions like pressing a key or gripping an object. In the future, the MIT system could incorporate more user data and fabricate more conformal and tight wearables to better account for how hand movements impact haptic perceptions.

Luo, Matusik, and Rus authored the paper with EECS Microsystems Technology Laboratories Director and Professor Tomás Palacios; CSAIL members Chao Liu, Young Joong Lee, Joseph DelPreto, Michael Foshey, and professor and principal investigator Antonio Torralba; Kiu Wu of LightSpeed Studios; and Yunzhu Li of the University of Illinois at Urbana-Champaign.

The work was supported, in part, by an MIT Schwarzman College of Computing Fellowship via Google and a GIST-MIT Research Collaboration grant, with additional help from Wistron, Toyota Research Institute, and Ericsson.

Source:

Alex Shipps, MIT CSAIL

Empa researcher Simon Annaheim is working to develop a mattress for newborn babies. Image: Empa
11.03.2024

Medical textiles and sensors: Smart protection for delicate skin

Skin injuries caused by prolonged pressure often occur in people who are unable to change their position independently – such as sick newborns in hospitals or elderly people. Thanks to successful partnerships with industry and research, Empa scientists are now launching two smart solutions for pressure sores.

If too much pressure is applied to our skin over a long period of time, it becomes damaged. Populations at high risk of such pressure injuries include people in wheelchairs, newborns in intensive care units and the elderly. The consequences are wounds, infections and pain.

Skin injuries caused by prolonged pressure often occur in people who are unable to change their position independently – such as sick newborns in hospitals or elderly people. Thanks to successful partnerships with industry and research, Empa scientists are now launching two smart solutions for pressure sores.

If too much pressure is applied to our skin over a long period of time, it becomes damaged. Populations at high risk of such pressure injuries include people in wheelchairs, newborns in intensive care units and the elderly. The consequences are wounds, infections and pain.

Treatment is complex and expensive: Healthcare costs of around 300 million Swiss francs are incurred every year. "In addition, existing illnesses can be exacerbated by such pressure injuries," says Empa researcher Simon Annaheim from the Biomimetic Membranes and Textiles laboratory in St. Gallen. According to Annaheim, it would be more sustainable to prevent tissue damage from occurring in the first place. Two current research projects involving Empa researchers are now advancing solutions: A pressure-equalizing mattress for newborns in intensive care units and a textile sensor system for paraplegics and bedridden people are being developed.

Optimally nestled at the start of life
The demands of our skin are completely different depending on age: In adults, the friction of the skin on the lying surface, physical shear forces in the tissue and the lack of breathability of textiles are the main risk factors. In contrast, the skin of newborns receiving intensive care is extremely sensitive per se, and any loss of fluid and heat through the skin can become a problem. "While these particularly vulnerable babies are being nursed back to health, the lying situation should not cause any additional complications," says Annaheim. He thinks conventional mattresses are not appropriate for newborns with very different weights and various illnesses. Annaheim's team is therefore working with researchers from ETH Zurich, the Zurich University of Applied Sciences (ZHAW) and the University Children's Hospital Zurich to find an optimal lying surface for babies' delicate skin. This mattress should be able to adapt individually to the body in order to help children with a difficult start in life.

In order to do this, the researchers first determined the pressure conditions in the various regions of the newborn's body. "Our pressure sensors showed that the head, shoulders and lower spine are the areas with the greatest risk of pressure sores," says Annaheim. These findings were incorporated into the development of a special kind of air-filled mattress: With the help of pressure sensors and a microprocessor, its three chambers can be filled precisely via an electronic pump so that the pressure in the respective areas is minimized. An infrared laser process developed at Empa made it possible to produce the mattress from a flexible, multi-layered polymer membrane that is gentle on the skin and has no irritating seams.

After a multi-stage development process in the laboratory, the first small patients were allowed to lie on the prototype mattress. The effect was immediately noticeable when the researchers filled the mattress with air to varying degrees depending on the individual needs of the babies: Compared to a conventional foam mattress, the prototype reduced the pressure on the vulnerable parts of the body by up to 40 percent.

Following this successful pilot study, the prototype is now being optimized in the Empa labs. Simon Annaheim and doctoral student Tino Jucker will soon be starting a larger-scale study with the new mattress with the Department of Intensive Care Medicine & Neonatology at University Children's Hospital Zurich.

Intelligent sensors prevent injuries
In another project, Empa researchers are working on preventing so-called pressure ulcer tissue damage in adults. This involves converting the risk factors of pressure and circulatory disorders into helpful warning signals.

If you lie in the same position for a long time, pressure and circulatory problems lead to an undersupply of oxygen to the tissue. While the lack of oxygen triggers a reflex to move in healthy people, this neurological feedback loop can be disrupted in people with paraplegia or coma patients, for example. Here, smart sensors can help to provide early warning of the risk of tissue damage.

In the ProTex project, a team of researchers from Empa, the University of Bern, the OST University of Applied Sciences and Bischoff Textil AG in St. Gallen has developed a sensor system made of smart textiles with associated data analysis in real time. "The skin-compatible textile sensors contain two different functional polymer fibers," says Luciano Boesel from Empa's Biomimetic Membranes and Textiles laboratory in St. Gallen. In addition to pressure-sensitive fibers, the researchers integrated light-conducting polymer fibers (POFs), which are used to measure oxygen. "As soon as the oxygen content in the skin drops, the highly sensitive sensor system signals an increasing risk of tissue damage," explains Boesel. The data is then transmitted directly to the patient or to the nursing staff. This means, for instance, that a lying person can be repositioned in good time before the tissue is damaged.

Patented technology
The technology behind this also includes a novel microfluidic wet spinning process developed at Empa for the production of POFs. It allows precise control of the polymer components in the micrometer range and smoother, more environmentally friendly processing of the fibers. The microfluidic process is one of three patents that have emerged from the ProTex project to date.

Another product is a breathable textile sensor that is worn directly on the skin. The spin-off Sensawear in Bern, which emerged from the project in 2023, is currently pushing ahead with the market launch. Empa researcher Boesel is also convinced: "The findings and technologies from ProTex will enable further applications in the field of wearable sensor technology and smart clothing in the future."

Source:

Dr. Andrea Six, Empa

Feathers from waterfowl (c) Daunen- und Federnverbände Mainz
05.03.2024

Adhesives: Feathers replace petroleum

Adhesives are almost always based on fossil raw materials such as petroleum. Researchers at Fraunhofer have recently developed a process that allows to utilize keratin for this purpose. This highly versatile protein compound can be found, for instance, in chicken feathers. Not only can it be used to manufacture a host of different adhesives for a variety of applications, but the processes and end products are also sustainable and follow the basic principles underlying a bioinspired circular economy. The project, developed together with Henkel AG & Co. KGaA, addresses a billion-dollar market.

Adhesives are almost always based on fossil raw materials such as petroleum. Researchers at Fraunhofer have recently developed a process that allows to utilize keratin for this purpose. This highly versatile protein compound can be found, for instance, in chicken feathers. Not only can it be used to manufacture a host of different adhesives for a variety of applications, but the processes and end products are also sustainable and follow the basic principles underlying a bioinspired circular economy. The project, developed together with Henkel AG & Co. KGaA, addresses a billion-dollar market.

Adhesives are found nearly everywhere: in sports shoes, smartphones, floor coverings, furniture, textiles or packaging. Even auto windshields are glued into place using adhesives. Experts recognize more than 1,000 different types of adhesives. These can bond almost every imaginable material to another. Adhesives weigh very little and so lend themselves to lightweight design. Surfaces bonded with adhesive do not warp because, unlike with screw fastenings, the load is distributed evenly. Adhesives do not rust, and seal out moisture. Surfaces bonded with adhesive are also less susceptible to vibration. Added to which, adhesives are inexpensive and relatively easy to work with.

Feathers from poultry meat production
Traditionally, adhesives have almost always been made from fossil raw materials such as petroleum. The Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB has recently adopted a different approach. Researchers there have been using feathers as a base material instead of petroleum. Feathers are a by-product of poultry meat production. They are destroyed or mixed into animal feed. But feathers are far too valuable to go to waste because they contain the structural protein keratin. This biopolymer is found in animals and makes up talons, claws, hooves or feathers. Its fibrous structure is extremely strong.

Why keratin is perfect for manufacturing adhesives
Keratin is a biodegradable and thus eco-friendly material whose structure has specific properties that make it particularly suitable for the manufacture of adhesives. Keratin's polymer structure, i.e., its very long-chain molecules, as well as its ability to undergo cross-linking reactions predestine it for the manufacture of various adhesives. “The properties required for adhesives are to some extent already inherent in the base material and only need to be unlocked, modified and activated,” explains project manager Dr. Michael Richter.

Platform chemical and specialty adhesives
Over the past three years, Fraunhofer IGB has been working with Henkel AG & Co. KGaA on the KERAbond project: “Specialty chemicals from customized functional keratin proteins” — Kera being short for keratin, combined with the English word bond. Henkel is a global market leader in the adhesives sector.

The partners in the project have recently developed and refined a new process. In the first stage, feathers received from the slaughterhouse are sterilized, washed and mechanically shredded. Next, an enzyme process splits the long-chain biopolymers or protein chains into short-chain polymers by means of hydrolysis.

The output product is a platform chemical that can serve as a base material for further development of specially formulated adhesives. “We use the process      and the platform chemical as a “toolbox” to integrate bio-enhanced properties into the end product,” says Richter. This means parameters can be specified for the target special adhesive such as curing time, elasticity, thermal properties or strength. Also, it’s not just adhesives that are easy to manufacture but also related substances such as hardeners, coatings or primers.

In the next stage, the Fraunhofer team set about converting the feathers on a large scale. Ramping up the process fell to the Fraunhofer Center for Chemical-Biotechnological Processes CBP in Leuna. The aim was to prove that the keratin-based platform chemicals can also be manufactured cost-efficiently on an industrial scale. This involved processing several kilograms of chicken feathers, with the material produced being used for promising initial material trials at Fraunhofer IGB and Henkel.

Foundations of a bioinspired economy
This bioinspired process is of particular significance for the Fraunhofer-Gesellschaft. Biotechnology is in fact one of the main fields of research for the Fraunhofer-Gesellschaft: “We draw our inspiration from functionality or properties that already exist in nature or in natural raw materials. And we attempt to translate these properties into products through innovative manufacturing methods. This generates a bioinspired cycle for valuable raw materials, Richter explains.

The project carries some economic weight. According to Statista, around one million tons of adhesives were manufactured in Germany alone in 2019. Total value is around 1.87 billion euros.

A patent application has been filed for the new process and an article published in a scientific journal. Two PhD students who have conducted extensive research on the project at Henkel and Fraunhofer are expected to complete their theses in the first quarter of 2024. This new keratin-based technology will allow a host of platform chemicals to be produced in a sustainable, bioinspired way.

The KERAbond project has been funded and supported over the past three years by Fachagentur Nachwachsende Rohstoffe (FNR) in Gülzow on behalf of the Federal Ministry of Food and Agriculture (BMEL) under the Renewable Resources Funding funding program (grant number 22014218).

Source:

Fraunhofer IBG

Photo: guentherlig, Pixabay
01.03.2024

The most tasteful kind of coating

Tiny external structures in the wax coating of blueberries give them their blue colour, researchers at the University of Bristol can reveal. This applies to lots of fruits that are the same colour including damsons, sloes and juniper berries.

In the study, published in Science Advances, researchers show why blueberries are blue despite the dark red colour of the pigments in the fruit skin. Their blue colour is instead provided by a layer of wax that surrounds the fruit which is made up of miniature structures that scatter blue and UV light. This gives blueberries their blue appearance to humans and blue-UV to birds. The chromatic blue-UV reflectance arises from the interaction of the randomly arranged crystal structures of the epicuticular wax with light.

Tiny external structures in the wax coating of blueberries give them their blue colour, researchers at the University of Bristol can reveal. This applies to lots of fruits that are the same colour including damsons, sloes and juniper berries.

In the study, published in Science Advances, researchers show why blueberries are blue despite the dark red colour of the pigments in the fruit skin. Their blue colour is instead provided by a layer of wax that surrounds the fruit which is made up of miniature structures that scatter blue and UV light. This gives blueberries their blue appearance to humans and blue-UV to birds. The chromatic blue-UV reflectance arises from the interaction of the randomly arranged crystal structures of the epicuticular wax with light.

Rox Middleton, Research Fellow at Bristol’s School of Biological Sciences, explained: “The blue of blueberries can’t be ‘extracted’ by squishing – because it isn’t located in the pigmented juice that can be squeezed from the fruit. That was why we knew that there must be something strange about the colour.

“So we removed the wax and re-crystallised it on card and in doing so we were able to create a brand new blue-UV coating.”

The ultra-thin colourant is around two microns thick, and although less reflective, it’s visibly blue and reflects UV well, possibly paving the way for new colorant methods.

“It shows that nature has evolved to use a really neat trick, an ultrathin layer for an important colorant," added Rox.

Most plants are coated in a thin layer of wax which has multiple functions, many of them that scientists still don’t understand. They know that it can be very effective as a hydrophobic, self-cleaning coating.

However until now, researchers did not know how important the structure was for visible colouration.

Now the team plan to look at easier ways of recreating the coating and applying it. This could lead to a more sustainable, biocompatible and even edible UV and blue-reflective paint.

Furthermore these coatings could have the same multiple functions as natural biological ones that protect plants.

Rox added: “It was really interesting to find that there was an unknown coloration mechanism right under our noses, on popular fruits that we grow and eat all the time.

“It was even more exciting to be able to reproduce that colour by harvesting the wax to make a new blue coating that no-one’s seen before.

“Building all that functionality of this natural wax into artificially engineered materials is the dream!”

Source:

Bristol University

Paper: ‘Self-assembled, Disordered Structural Colour from Fruit Wax Bloom’ by Rox Middleton et al in Science Advances.