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26.02.2024

Cooling down with Nanodiamonds

Researchers from RMIT University are using nanodiamonds to create smart textiles that can cool people down faster.

The study found fabric made from cotton coated with nanodiamonds, using a method called electrospinning, showed a reduction of 2-3 degrees Celsius during the cooling down process compared to untreated cotton. They do this by drawing out body heat and releasing it from the fabric – a result of the incredible thermal conductivity of nanodiamonds.

Published in Polymers for Advanced Technologies, project lead and Senior Lecturer, Dr Shadi Houshyar, said there was a big opportunity to use these insights to create new textiles for sportswear and even personal protective clothing, such as underlayers to keep fire fighters cool.

The study also found nanodiamonds increased the UV protection of cotton, making it ideal for outdoor summer clothing.

Researchers from RMIT University are using nanodiamonds to create smart textiles that can cool people down faster.

The study found fabric made from cotton coated with nanodiamonds, using a method called electrospinning, showed a reduction of 2-3 degrees Celsius during the cooling down process compared to untreated cotton. They do this by drawing out body heat and releasing it from the fabric – a result of the incredible thermal conductivity of nanodiamonds.

Published in Polymers for Advanced Technologies, project lead and Senior Lecturer, Dr Shadi Houshyar, said there was a big opportunity to use these insights to create new textiles for sportswear and even personal protective clothing, such as underlayers to keep fire fighters cool.

The study also found nanodiamonds increased the UV protection of cotton, making it ideal for outdoor summer clothing.

“While 2 or 3 degrees may not seem like much of a change, it does make a difference in comfort and health impacts over extended periods and in practical terms, could be the difference between keeping your air conditioner off or turning it on,” Houshyar said. “There’s also potential to explore how nanodiamonds can be used to protect buildings from overheating, which can lead to environmental benefits.”

The use of this fabric in clothing was projected to lead to a 20-30% energy saving due to lower use of air conditioning.

Based in the Centre for Materials Innovation and Future Fashion (CMIFF), the research team is made up of RMIT engineers and textile researchers who have strong expertise in developing next-generation smart textiles, as well as working with industry to develop realistic solutions.

Contrary to popular belief, nanodiamonds are not the same as the diamonds that adorn jewellery, said Houshyar. “They’re actually cheap to make — cheaper than graphene oxide and other types of carbon materials,” she said. “While they have a carbon lattice structure, they are much smaller in size. They’re also easy to make using methods like detonation or from waste materials.”

How it works
Cotton material was first coated with an adhesive, then electrospun with a polymer solution made from nanodiamonds, polyurethane and solvent.

This process creates a web of nanofibres on the cotton fibres, which are then cured to bond the two.

Lead researcher and research assistant, Dr Aisha Rehman, said the coating with nanodiamonds was deliberately applied to only one side of the fabric to restrict heat in the atmosphere from transferring back to the body.  

“The side of the fabric with the nanodiamond coating is what touches the skin. The nanodiamonds then transfer heat from the body into the air,” said Rehman, who worked on the study as part of her PhD. “Because nanodiamonds are such good thermal conductors, it does it faster than untreated fabric.”

Nanodiamonds were chosen for this study because of their strong thermal conductivity properties, said Rehman. Often used in IT, nanodiamonds can also help improve thermal properties of liquids and gels, as well as increase corrosive resistance in metals.

“Nanodiamonds are also biocompatible, so they’re safe for the human body. Therefore, it has great potential not just in textiles, but also in the biomedical field,” Rehman said.

While the research was still preliminary, Houshyar said this method of coating nanofibres onto textiles had strong commercial potential.
 
“This electrospinning approach is straightforward and can significantly reduce the variety of manufacturing steps compared to previously tested methods, which feature lengthy processes and wastage of nanodiamonds,” Houshyar said.

Further research will study the durability of the nanofibres, especially during the washing process.

Source:

Shu Shu Zheng, RMIT University

wind energy Photo: Carlos / Saigon - Vietnam, Pixabay
21.02.2024

Composites' hopes are pinned on wind energy and aviation sectors

Composites Germany - Results of the 22nd Composites Market Survey

  • Critical assessment of the current business situation
  • Future expectations brighten
  • Investment climate remains subdued
  • Different expectations of application industries
  • Growth drivers with slight shifts
  • Composites index points in different directions

For the 22nd time, Composites Germany has collected current key figures on the market for fiber-reinforced plastics. All member companies of the supporting associations of Composites Germany: AVK and Composites United as well as the associated partner VDMA were surveyed.
In order to ensure that the different surveys can be compared without any problems, no fundamental changes were made to the survey. Once again, mainly qualitative data was collected in relation to current and future market developments.

Composites Germany - Results of the 22nd Composites Market Survey

  • Critical assessment of the current business situation
  • Future expectations brighten
  • Investment climate remains subdued
  • Different expectations of application industries
  • Growth drivers with slight shifts
  • Composites index points in different directions

For the 22nd time, Composites Germany has collected current key figures on the market for fiber-reinforced plastics. All member companies of the supporting associations of Composites Germany: AVK and Composites United as well as the associated partner VDMA were surveyed.
In order to ensure that the different surveys can be compared without any problems, no fundamental changes were made to the survey. Once again, mainly qualitative data was collected in relation to current and future market developments.

Critical assessment of the current business situation
After consistently positive trends were seen in the assessment of the current business situation in 2021, this has slipped since 2022. There is still no sign of a trend reversal in the current survey. The reasons for the negative sentiment are manifold and were already evident in the last survey.

At present, politicians do not seem to be able to create a more positive environment for the industry with appropriate measures. Overall, Germany in particular, but also Europe, is currently experiencing a very difficult market environment.

However, the main drivers of the current difficult situation are likely to be the persistently high energy and commodity/raw material prices. In addition, there are still problems in individual areas of the logistics chains, for example on the main trade/container routes, as well as a cautious consumer climate. A slowdown in global trade and uncertainties in the political arena are currently fueling the negative mood in the market.

Despite rising registration figures, the automotive industry, the most important application area for composites, has not yet returned to its former volume. The construction industry, the second most important key area of application, is currently in crisis. Although the order books are still well filled, new orders are often failing to materialize. High interest rates and material costs coupled with the high cost of living are having a particularly negative impact on private construction, but public construction is also currently unable to achieve the targets it has set itself. According to the ZDB (Zentralverband Deutsches Baugewerbe), the forecasts in this important sector remain gloomy: "The decline in the construction industry is continuing. Turnover will fall by 5.3% in real terms this year and we expect a further 3% drop next year. Residential construction remains responsible for the decline, which will slump by 11% in real terms this year and continue its downward trajectory at -13% in 2024."

It is not only the assessment of the general business situation that remains pessimistic. The situation of their own companies also continues to be viewed critically. The picture is particularly negative for Germany. Almost 50% of respondents are critical of the current business situation in Germany. The view of global business and Europe is somewhat more positive. Here, "only" 40% and 35% of respondents respectively assess the situation rather negatively.

Future expectations brighten
Despite the generally rather subdued assessment of the business situation, many of those surveyed appear to be convinced that the mood is improving, at least in Europe. When asked about their assessment of future general business development, the values for Europe and the world are more optimistic than in the last survey. The survey participants do not currently expect the situation in Germany to improve.

Respondents were more optimistic about their own company's future expectations for Europe and the global market.

The participants seem to be assuming a moderate short to medium-term recovery of the global economy. The forecasts are more optimistic than the assessment of the current situation. It is striking that the view of the German region is more critical in relation to Europe and the global economy. 28% of those surveyed expect the general market situation in Germany to develop negatively. Only 13% expect the current situation to improve. The figures for Europe and the world are better.

Investment climate remains subdued
The current rather cautious assessment of the economic situation continues to have an impact on the investment climate.

While 22% of participants in the last survey still assumed an increase in personnel capacity (survey 1/2023 = 40%), this figure is currently only 18%. In contrast, 18% even expect a decrease in personnel.

The proportion of respondents planning to invest in machinery is also declining. While 56% of respondents in the last survey still expected to make such investments, this figure has now fallen to 46%.

Different expectations of application industries
The composites market is characterized by a high degree of heterogeneity in terms of both materials and applications. In the survey, the participants are asked to give their assessment of the market development of different core areas.

The expectations are extremely varied. The two most important application areas are the mobility and construction/infrastructure sectors. Both are currently undergoing major upheavals or are affected by declines, which is also clearly reflected in the survey. Growth is expected above all in the wind energy and aviation sectors.

Growth drivers with slight shifts
In terms of materials, there has been a change in the assessment of growth drivers. While the respondents in the last 9 surveys always named GRP as the material from which the main growth impetus for the composites sector is to be expected, the main impetus is now once again expected to come from CFRP or across all materials.

There is a slight regional shift. Germany is seen less strongly as a growth driver. In contrast, Europe (excluding Germany) and Asia are mentioned significantly more.

Composites index points in different directions
The numerous negative influences of recent times continue to be reflected in the overall Composites Index. This continues to fall, particularly when looking at the current business situation. On the other hand, there is a slight improvement in expectations for future market development, although this remains at a low level.

The total volume of processed composites in Europe in 2022 was already declining, and a further decline must also be expected for 2023. This is likely to be around 5% again.

It remains to be seen whether it will be possible to counteract the negative trend. Targeted intervention, including by political decision-makers, would be desirable here. However, this cannot succeed without industry/business. Only together will it be possible to maintain and strengthen Germany as a business/industry location. For composites as a material group in general, there are still very good opportunities to expand the market position in both new and existing markets due to the special portfolio of properties. However, the dependency on macroeconomic developments remains. It is now important to develop new market areas through innovation, to consistently exploit opportunities and to work together to further implement composites in existing markets. This can often be achieved better together than alone. With its excellent network, Composites Germany offers a wide range of opportunities.

The next composites market survey will be published in July 2024.

Source:

Composites Germany

Wearable Robots for Parkinson’s Disease Image: Tom Claes, unsplash
19.02.2024

Wearable Robots for Parkinson’s Disease

Freezing is one of the most common and debilitating symptoms of Parkinson’s disease, a neurodegenerative disorder that affects more than 9 million people worldwide. When individuals with Parkinson’s disease freeze, they suddenly lose the ability to move their feet, often mid-stride, resulting in a series of staccato stutter steps that get shorter until the person stops altogether. These episodes are one of the biggest contributors to falls among people living with Parkinson’s disease.

Today, freezing is treated with a range of pharmacological, surgical or behavioral therapies, none of which are particularly effective. What if there was a way to stop freezing altogether?

Freezing is one of the most common and debilitating symptoms of Parkinson’s disease, a neurodegenerative disorder that affects more than 9 million people worldwide. When individuals with Parkinson’s disease freeze, they suddenly lose the ability to move their feet, often mid-stride, resulting in a series of staccato stutter steps that get shorter until the person stops altogether. These episodes are one of the biggest contributors to falls among people living with Parkinson’s disease.

Today, freezing is treated with a range of pharmacological, surgical or behavioral therapies, none of which are particularly effective. What if there was a way to stop freezing altogether?

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Boston University Sargent College of Health & Rehabilitation Sciences have used a soft, wearable robot to help a person living with Parkinson’s walk without freezing. The robotic garment, worn around the hips and thighs, gives a gentle push to the hips as the leg swings, helping the patient achieve a longer stride.

The device completely eliminated the participant’s freezing while walking indoors, allowing them to walk faster and further than they could without the garment’s help.

“We found that just a small amount of mechanical assistance from our soft robotic apparel delivered instan-taneous effects and consistently improved walking across a range of conditions for the individual in our study,” said Conor Walsh, the Paul A. Maeder Professor of Engineering and Applied Sciences at SEAS and co-corresponding author of the study.

The research demonstrates the potential of soft robotics to treat this frustrating and potentially dangerous symptom of Parkinson’s disease and could allow people living with the disease to regain not only their mobility but their independence.

For over a decade, Walsh’s Biodesign Lab at SEAS has been developing assistive and rehabilitative robotic technologies to improve mobility for individuals’ post-stroke and those living with ALS or other diseases that impact mobility. Some of that technology, specifically an exosuit for post-stroke gait retraining, received support from the Wyss Institute for Biologically Inspired Engineering, and Harvard’s Office of Technology Development coordinated a license agreement with ReWalk Robotics to commercialize the technology.

In 2022, SEAS and Sargent College received a grant from the Massachusetts Technology Collaborative to support the development and translation of next-generation robotics and wearable technologies. The research is centered at the Move Lab, whose mission is to support advances in human performance enhancement with the collaborative space, funding, R&D infrastructure, and experience necessary to turn promising research into mature technologies that can be translated through collaboration with industry partners. This research emerged from that partnership.

“Leveraging soft wearable robots to prevent freezing of gait in patients with Parkinson’s required a collaboration between engineers, rehabilitation scientists, physical therapists, biomechanists and apparel designers,” said Walsh, whose team collaborated closely with that of Terry Ellis,  Professor and Physical Therapy Department Chair and Director of the Center for Neurorehabilitation at Boston University.

Leveraging soft wearable robots to prevent freezing of gait in patients with Parkinson’s required a collaboration between engineers, rehabilitation scientists, physical therapists, biomechanists and apparel designers.

The team spent six months working with a 73-year-old man with Parkinson’s disease, who — despite using both surgical and pharmacologic treatments — endured substantial and incapacitating freezing episodes more than 10 times a day, causing him to fall frequently. These episodes prevented him from walking around his community and forced him to rely on a scooter to get around outside.

In previous research, Walsh and his team leveraged human-in-the-loop optimization to demonstrate that a soft, wearable device could be used to augment hip flexion and assist in swinging the leg forward to provide an efficient approach to reduce energy expenditure during walking in healthy individuals.

Here, the researchers used the same approach but to address freezing. The wearable device uses cable-driven actuators and sensors worn around the waist and thighs. Using motion data collected by the sensors, algorithms estimate the phase of the gait and generate assistive forces in tandem with muscle movement.

The effect was instantaneous. Without any special training, the patient was able to walk without any freezing indoors and with only occasional episodes outdoors. He was also able to walk and talk without freezing, a rarity without the device.

“Our team was really excited to see the impact of the technology on the participant’s walking,” said Jinsoo Kim, former PhD student at SEAS and co-lead author on the study.

During the study visits, the participant told researchers: “The suit helps me take longer steps and when it is not active, I notice I drag my feet much more. It has really helped me, and I feel it is a positive step forward. It could help me to walk longer and maintain the quality of my life.”

“Our study participants who volunteer their time are real partners,” said Walsh. “Because mobility is difficult, it was a real challenge for this individual to even come into the lab, but we benefited so much from his perspective and feedback.”

The device could also be used to better understand the mechanisms of gait freezing, which is poorly understood.

“Because we don’t really understand freezing, we don’t really know why this approach works so well,” said Ellis. “But this work suggests the potential benefits of a ’bottom-up’ rather than ’top-down’ solution to treating gait freezing. We see that restoring almost-normal biomechanics alters the peripheral dynamics of gait and may influence the central processing of gait control.”

The research was co-authored by Jinsoo Kim, Franchino Porciuncula, Hee Doo Yang, Nicholas Wendel, Teresa Baker and Andrew Chin. Asa Eckert-Erdheim and Dorothy Orzel also contributed to the design of the technology, as well as Ada Huang, and Sarah Sullivan managed the clinical research. It was supported by the National Science Foundation under grant CMMI-1925085; the National Institutes of Health under grant NIH U01 TR002775; and the Massachusetts Technology Collaborative, Collaborative Research and Development Matching Grant.

Source:

The research is published in Nature Medicine.
Source Leah Burrows
Harvard John A. Paulson. School of Engineering and Applied Sciences

Researchers led by Bernd Nowack have investigated the release of nanoparticles during the washing of polyester textiles. Image: Empa Image: Empa
14.02.2024

Release of oligomers from polyester textiles

When nanoplastics are not what they seem ... Textiles made of synthetic fibers release micro- and nanoplastics during washing. Empa researchers have now been able to show: Some of the supposed nanoplastics do not actually consist of plastic particles, but of water-insoluble oligomers. The effects they have on humans and the environment are not yet well-understood.

Plastic household items and clothing made of synthetic fibers release microplastics: particles less than five millimetres in size that can enter the environment unnoticed. A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size – but, as of today, little is known about their potential toxicity.

When nanoplastics are not what they seem ... Textiles made of synthetic fibers release micro- and nanoplastics during washing. Empa researchers have now been able to show: Some of the supposed nanoplastics do not actually consist of plastic particles, but of water-insoluble oligomers. The effects they have on humans and the environment are not yet well-understood.

Plastic household items and clothing made of synthetic fibers release microplastics: particles less than five millimetres in size that can enter the environment unnoticed. A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size – but, as of today, little is known about their potential toxicity.

Empa researchers from Bernd Nowack's group in the Technology and Society laboratory have now joined forces with colleagues from China to take a closer look at nanoparticles released from textiles. Tong Yang, first author of the study, carried out the investigations during his doctorate at Empa. In earlier studies, Empa researchers were already able to demonstrate that both micro- and nanoplastics are released when polyester is washed. A detailed examination of the released nanoparticles released has now shown that not everything that appears to be nanoplastic at first glance actually is nanoplastic.

To a considerable extent, the released particles were in fact not nanoplastics, but clumps of so-called oligomers, i.e. small to medium-sized molecules that represent an intermediate stage between the long-chained polymers and their individual building blocks, the monomers. These molecules are even smaller than nanoplastic particles, and hardly anything is known about their toxicity either. The researchers published their findings in the journal Nature Water.

For the study, the researchers examined twelve different polyester fabrics, including microfiber, satin and jersey. The fabric samples were washed up to four times and the nanoparticles released in the process were analyzed and characterized. Not an easy task, says Bernd Nowack. "Plastic, especially nanoplastics, is everywhere, including on our devices and utensils," says the scientist. "When measuring nanoplastics, we have to take this 'background noise' into account."

Large proportion of soluble particles
The researchers used an ethanol bath to distinguish nanoplastics from clumps of oligomers. Plastic pieces, no matter how small, do not dissolve in ethanol, but aggregations of oligomers do. The result: Around a third to almost 90 percent of the nanoparticles released during washing could be dissolved in ethanol. "This allowed us to show that not everything that looks like nanoplastics at first glance is in fact nanoplastics," says Nowack.

It is not yet clear whether the release of so-called nanoparticulate oligomers during the washing of textiles has negative effects on humans and the environment. "With other plastics, studies have already shown that nanoparticulate oligomers are more toxic than nanoplastics," says Nowack. "This is an indication that this should be investigated more closely." However, the researchers were able to establish that the nature of the textile and the cutting method – scissors or laser – have no major influence on the quantity of particles released.

The mechanism of release has not been clarified yet either – neither for nanoplastics nor for the oligomer particles. The good news is that the amount of particles released decreases significantly with repeated washes. It is conceivable that the oligomer particles are created during the manufacturing of the textile or split off from the fibers through chemical processes during storage. Further studies are also required in this area.

Nowack and his team are focusing on larger particles for the time being: In their next project, they want to investigate which fibers are released during washing of textiles made from renewable raw materials and whether these could be harmful to the environment and health. "Semi-synthetic textiles such as viscose or lyocell are being touted as a replacement for polyester," says Nowack. "But we don't yet know whether they are really better when it comes to releasing fibers."

Source:

Empa

Bacteria, eating Plastic and producing Multipurpose Spider Silk Photo: Kareni, Pixabay
05.02.2024

Bacteria, eating Plastic and producing Multipurpose Spider Silk

For the first time, researchers have used bacteria to “upcycle” waste polyethylene: Move over Spider-Man: Researchers at Rensselaer Polytechnic Institute have developed a strain of bacteria that can turn plastic waste into a biodegradable spider silk with multiple uses.

Their new study marks the first time scientists have used bacteria to transform polyethylene plastic — the kind used in many single-use items — into a high-value protein product.

That product, which the researchers call “bio-inspired spider silk” because of its similarity to the silk spiders use to spin their webs, has applications in textiles, cosmetics, and even medicine.

For the first time, researchers have used bacteria to “upcycle” waste polyethylene: Move over Spider-Man: Researchers at Rensselaer Polytechnic Institute have developed a strain of bacteria that can turn plastic waste into a biodegradable spider silk with multiple uses.

Their new study marks the first time scientists have used bacteria to transform polyethylene plastic — the kind used in many single-use items — into a high-value protein product.

That product, which the researchers call “bio-inspired spider silk” because of its similarity to the silk spiders use to spin their webs, has applications in textiles, cosmetics, and even medicine.

“Spider silk is nature’s Kevlar,” said Helen Zha, Ph.D., an assistant professor of chemical and biological engineering and one of the RPI researchers leading the project. “It can be nearly as strong as steel under tension. However, it’s six times less dense than steel, so it’s very lightweight. As a bioplastic, it’s stretchy, tough, nontoxic, and biodegradable.”

All those attributes make it a great material for a future where renewable resources and avoidance of persistent plastic pollution are the norm, Zha said.

Polyethylene plastic, found in products such as plastic bags, water bottles, and food packaging, is the biggest contributor to plastic pollution globally and can take upward of 1,000 years to degrade naturally. Only a small portion of polyethylene plastic is recycled, so the bacteria used in the study could help “upcycle” some of the remaining waste.

Pseudomonas aeruginosa, the bacteria used in the study, can naturally consume polyethylene as a food source. The RPI team tackled the challenge of engineering this bacteria to convert the carbon atoms of polyethylene into a genetically encoded silk protein. Surprisingly, they found that their newly developed bacteria could make the silk protein at a yield rivaling some bacteria strains that are more conventionally used in biomanufacturing.

The underlying biological process behind this innovation is something people have employed for millennia.

“Essentially, the bacteria are fermenting the plastic. Fermentation is used to make and preserve all sorts of foods, like cheese, bread, and wine, and in biochemical industries it’s used to make antibiotics, amino acids, and organic acids,” said Mattheos Koffas, Ph.D., Dorothy and Fred Chau ʼ71 Career Development Constellation Professor in Biocatalysis and Metabolic Engineering, and the other researcher leading the project, and who, along with Zha, is a member of the Center for Biotechnology and Interdisciplinary Studies at Rensselaer.

To get bacteria to ferment polyethylene, the plastic is first “predigested,” Zha said. Just like humans need to cut and chew our food into smaller pieces before our bodies can use it, the bacteria has difficulty eating the long molecule chains, or polymers, that comprise polyethylene.

In the study, Zha and Koffas collaborated with researchers at Argonne National Laboratory, who depolymerized the plastic by heating it under pressure, producing a soft, waxy substance. Next, the team put a layer of the plastic-derived wax on the bottoms of flasks, which served as the nutrient source for the bacteria culture. This contrasts with typical fermentation, which uses sugars as the nutrient source.

“It’s as if, instead of feeding the bacteria cake, we’re feeding it the candles on the cake,” Zha said.

Then, as a warming plate gently swirled the flasks’ contents, the bacteria went to work. After 72 hours, the scientists strained out the bacteria from the liquid culture, purified the silk protein, and freeze dried it. At that stage, the protein, which resembled torn up cotton balls, could potentially be spun into thread or made into other useful forms.

“What’s really exciting about this process is that, unlike the way plastics are produced today, our process is low energy and doesn’t require the use of toxic chemicals,” Zha said. “The best chemists in the world could not convert polyethylene into spider silk, but these bacteria can. We’re really harnessing what nature has developed to do manufacturing for us.”

However, before upcycled spider silk products become a reality, the researchers will first need to find ways to make the silk protein more efficiently.

“This study establishes that we can use these bacteria to convert plastic to spider silk. Our future work will investigate whether tweaking the bacteria or other aspects of the process will allow us to scale up production,” Koffas said.

“Professors Zha and Koffas represent the new generation of chemical and biological engineers merging biological engineering with materials science to manufacture ecofriendly products. Their work is a novel approach to protecting the environment and reducing our reliance on nonrenewable resources,” said Shekhar Garde, Ph.D., dean of RPI’s School of Engineering.

The study, which was conducted by first author Alexander Connor, who earned his doctorate from RPI in 2023, and co-authors Jessica Lamb and Massimiliano Delferro with Argonne National Laboratory, is published in the journal “Microbial Cell Factories.”

Source:

Samantha Murray, Rensselaer

Photo: TheDigitalArtist, Pixabay
31.01.2024

“Smart nanocomposites” for wearable electronics, vehicles, and buildings

  • Small, lightweight, stretchable, cost-efficient thermoelectric devices signify a breakthrough in sustainable energy development and waste heat recovery.
  • Next-gen flexible energy harvesting systems will owe their efficiency to the integration of graphene nanotubes. They offer easy processability, stable thermoelectric performance, flexibility, and robust mechanical properties.
  • Nanocomposites have high market potential in manufacturing generators for medical and smart wearables, vehicles sensors, and efficient building management.

Around half of the world’s useful energy is wasted as heat due to the limited efficiency of energy conversion devices. For example, one-third of a vehicle’s energy dissipates as waste heat in exhaust gases. At the same time, vehicles contain more and more electronic devices requiring electrical energy.

  • Small, lightweight, stretchable, cost-efficient thermoelectric devices signify a breakthrough in sustainable energy development and waste heat recovery.
  • Next-gen flexible energy harvesting systems will owe their efficiency to the integration of graphene nanotubes. They offer easy processability, stable thermoelectric performance, flexibility, and robust mechanical properties.
  • Nanocomposites have high market potential in manufacturing generators for medical and smart wearables, vehicles sensors, and efficient building management.

Around half of the world’s useful energy is wasted as heat due to the limited efficiency of energy conversion devices. For example, one-third of a vehicle’s energy dissipates as waste heat in exhaust gases. At the same time, vehicles contain more and more electronic devices requiring electrical energy. As another example, lightweight wearable sensors for health and environmental monitoring are also becoming increasingly demanding. The potential to convert waste heat or solar energy into useful electrical power has emerged as an opportunity for more sustainable energy management. Convenient thermoelectric generators (TEGs) currently have only low effectiveness and a relatively large size and weight. Based on expensive or corrosion-vulnerable materials, they are rigid and often contain toxic elements.
 
Recently developed, easy-to-process, self-supporting and flexible nonwoven nanocomposite sheets demonstrate excellent thermoelectric properties combined with good mechanical robustness. A recent paper in ACS Applied Nano Materials described how researches combined a thermoplastic polyurethane (TPU) with TUBALLTM graphene nanotubes to fabricate a nanocomposite material capable of harvesting electrical energy from sources of waste heat.

Thanks to their high aspect ratio and specific surface area, graphene nanotubes provide TPU with electrical conductivity, making it possible to achieve high thermoelectrical performance while maintaining or improving mechanical properties. “Stiffness, strength, and tensile toughness were improved by 7, 25, and 250 times compared to buckypapers, respectively. Nanocomposite sheet shows low electrical resistivity of 7.5*10-3 Ohm×cm, high Young’s modulus of 1.8 GPa, failure strength of 80 MPa, and elongation at break of 41%,” said Dr. Beate Krause, Group Leader, Leibniz-Institut für Polymerforschung Dresden e. V.

Graphene nanotubes, being a fundamentally new material, provide an opportunity to replace current TEG materials with more environmentally friendly ones. The sensors powered by such thermoelectric generators could act as a “smart skin” for vehicles and buildings, providing sensoring capabilities to monitor performance and prevent potential issues before they lead to breakdowns, ensuring optimal operational efficiency. In aircraft, no-wire nanocomposites could serve as stand-alone sensors for monitoring deicing systems, eliminating the need for an extensive network of electrical cables. The high flexibility, strength, and reliability of graphene nanotube-enabled thermoelectric materials also extend their applications into the realm of smart wearable and medical devices.

Source:

Leibniz-Institut für Polymerforschung Dresden e. V. / OCSiAl