Textination Newsline

Indian Institute of Technology Guwahati researchers have developed a water-repellent, conductive textile that converts electricity and sunlight into heat. Designed to keep wearers warm in cold environments, this innovation addresses the serious health risks posed by prolonged exposure to very low temperatures, including hemoconcentration-based arterial blood clotting, breathing difficulties, and weakened immunity.
 
The findings of this research have been published in the journal, Nano-Micro-Small, in a paper co-authored by Prof. Uttam Manna, Department of Chemistry, IIT Guwahati, along with his research team, Ms. Debasmita Sarkar, Mr. Haydar Ali, Mr. Rajan Singh, Mr. Anirban Phukan, Mr. Chittaranjan Mishra, and Prof. Roy P. Paily from Department of Electronics and Electrical Engineering, IIT Guwahati.

Extreme cold temperatures can lead to health problems that can even be fatal. Studies indicate that deaths due to extreme cold outnumber those caused by extreme heat. Traditional solutions protect oneself from extreme cold, such as heaters or layered clothing are often bulky or require a constant power source. Conductive textiles offer a lightweight, flexible alternative, but existing versions often have limitations, such as poor durability, high power consumption, and vulnerability to water exposure.

To overcome these challenges, IIT Guwahati research team developed a novel approach by sprayed ultra-thin and clean silver nanowires onto cotton fabric to make it conductive. These nanowires are 100,000 times thinner than a human hair, allowing electricity to flow through the fabric, helping it generate heat while remaining soft and flexible. Due to its exceptional electrical conductivity and the ability to convert both electricity and sunlight into heat, silver nanowires were chosen for this experiment. The low electrical resistance of silver allows the electrothermal conversion at low applied voltage and eliminating the risk of electrocution.

One limitation with silver nanowires is that it can tarnish over time, affecting performance. To address this, researchers applied a water-repellent coating to the silver nanowires that protects against oxidation, water, and stains. The coating, inspired by lotus leaves, has a microscopic rough surface texture, which causes water to roll off instead of soaking in. This keeps the textile dry, ensuring long-lasting conductivity and effective heating, even in damp conditions. The water-repellent coating also prevents damage from sweat, rain, or accidental spills, making it reliable for outdoor and everyday applications.

The textile can convert electricity using a small rechargeable battery or solar energy into heat and can maintain a desired temperature between 40°C and 60°C for over 10 hours.

The researchers tested the textile in wearable knee and elbow bands, demonstrating its potential to provide sustained warmth for individuals working in cold environments and arthritis patients needing localized heat therapy. Additionally, the textile has broader applications, such as on-demand water heating and accelerating chemical reactions by wrapping it around the reaction vessels.

Speaking about the developed textile, Prof. Uttam Manna, said, “Our textile is self-cleanable, breathable, and flexible and can easily be scaled up. Its durability and long-lasting performance make it useful in a range of applications that require controlled heating."
The research team has filed an Indian patent on the innovation and is now working towards integrating the developed material with a miniaturised and appropriate electronic circuit to create viable products. Additionally, the team is seeking industry collaborations to bring the innovation to market for potential dry thermos-therapy applications in the near future.

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!”