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Sensors made from ‘electronic spider silk’ printed on human skin (c) Huang Lab, Cambridge
27.05.2024

Sensors made from ‘electronic spider silk’ printed on human skin

Researchers have developed a method to make adaptive and eco-friendly sensors that can be directly and imperceptibly printed onto a wide range of biological surfaces, whether that’s a finger or a flower petal.

The method, developed by researchers from the University of Cambridge, takes its inspiration from spider silk, which can conform and stick to a range of surfaces. These ‘spider silks’ also incorporate bioelectronics, so that different sensing capabilities can be added to the ‘web’.

The fibres, at least 50 times smaller than a human hair, are so lightweight that the researchers printed them directly onto the fluffy seedhead of a dandelion without collapsing its structure. When printed on human skin, the fibre sensors conform to the skin and expose the sweat pores, so the wearer doesn’t detect their presence. Tests of the fibres printed onto a human finger suggest they could be used as continuous health monitors.

Researchers have developed a method to make adaptive and eco-friendly sensors that can be directly and imperceptibly printed onto a wide range of biological surfaces, whether that’s a finger or a flower petal.

The method, developed by researchers from the University of Cambridge, takes its inspiration from spider silk, which can conform and stick to a range of surfaces. These ‘spider silks’ also incorporate bioelectronics, so that different sensing capabilities can be added to the ‘web’.

The fibres, at least 50 times smaller than a human hair, are so lightweight that the researchers printed them directly onto the fluffy seedhead of a dandelion without collapsing its structure. When printed on human skin, the fibre sensors conform to the skin and expose the sweat pores, so the wearer doesn’t detect their presence. Tests of the fibres printed onto a human finger suggest they could be used as continuous health monitors.

This low-waste and low-emission method for augmenting living structures could be used in a range of fields, from healthcare and virtual reality, to electronic textiles and environmental monitoring. The results are reported in the journal Nature Electronics.

Although human skin is remarkably sensitive, augmenting it with electronic sensors could fundamentally change how we interact with the world around us. For example, sensors printed directly onto the skin could be used for continuous health monitoring, for understanding skin sensations, or could improve the sensation of ‘reality’ in gaming or virtual reality application.

While wearable technologies with embedded sensors, such as smartwatches, are widely available, these devices can be uncomfortable, obtrusive and can inhibit the skin’s intrinsic sensations.

Last year, some of the same researchers showed that if the fibres used in smart textiles were coated with materials that can withstand stretching, they could be compatible with conventional weaving processes. Using this technique, they produced a 46-inch woven demonstrator display.

“If you want to accurately sense anything on a biological surface like skin or a leaf, the interface between the device and the surface is vital,” said Professor Yan Yan Shery Huang from Cambridge’s Department of Engineering, who led the research. “We also want bioelectronics that are completely imperceptible to the user, so they don’t in any way interfere with how the user interacts with the world, and we want them to be sustainable and low waste.”

There are multiple methods for making wearable sensors, but these all have drawbacks. Flexible electronics, for example, are normally printed on plastic films that don’t allow gas or moisture to pass through, so it would be like wrapping your skin in cling film. Other researchers have recently developed flexible electronics that are gas-permeable, like artificial skins, but these still interfere with normal sensation, and rely on energy- and waste-intensive manufacturing techniques.

3D printing is another potential route for bioelectronics since it is less wasteful than other production methods, but leads to thicker devices that can interfere with normal behaviour. Spinning electronic fibres results in devices that are imperceptible to the user, but don't have a high degree of sensitivity or sophistication, and they’re difficult to transfer onto the object in question.

Now, the Cambridge-led team has developed a new way of making high-performance bioelectronics that can be customised to a wide range of biological surfaces, from a fingertip to the fluffy seedhead of a dandelion, by printing them directly onto that surface. Their technique takes its inspiration in part from spiders, who create sophisticated and strong web structures adapted to their environment, using minimal material.

The researchers spun their bioelectronic ‘spider silk’ from PEDOT:PSS (a biocompatible conducting polymer), hyaluronic acid and polyethylene oxide. The high-performance fibres were produced from water-based solution at room temperature, which enabled the researchers to control the ‘spinnability’ of the fibres. The researchers then designed an orbital spinning approach to allow the fibres to morph to living surfaces, even down to microstructures such as fingerprints.

Tests of the bioelectronic fibres, on surfaces including human fingers and dandelion seedheads, showed that they provided high-quality sensor performance while being imperceptible to the host.

“Our spinning approach allows the bioelectronic fibres to follow the anatomy of different shapes, at both the micro and macro scale, without the need for any image recognition,” said Andy Wang, the first author of the paper. “It opens up a whole different angle in terms of how sustainable electronics and sensors can be made. It’s a much easier way to produce large area sensors.”

Most high-resolution sensors are made in an industrial cleanroom and require the use of toxic chemicals in a multi-step and energy-intensive fabrication process. The Cambridge-developed sensors can be made anywhere and use a tiny fraction of the energy that regular sensors require.

The bioelectronic fibres, which are repairable, can be simply washed away when they have reached the end of their useful lifetime, and generate less than a single milligram of waste: by comparison, a typical single load of laundry produces between 600 and 1500 milligrams of fibre waste.

“Using our simple fabrication technique, we can put sensors almost anywhere and repair them where and when they need it, without needing a big printing machine or a centralised manufacturing facility,” said Huang. “These sensors can be made on-demand, right where they’re needed, and produce minimal waste and emissions.”

The research was supported in part by the European Research Council, Wellcome, the Royal Society, and the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation (UKRI).

Source:

Sarah Collins, University of Cambridge

A Passion for Paisley Photo The Great Tapestry of Scotland
21.05.2024

Edinburgh was weaving Paisley shawls 40 years before Paisley

Edinburgh was weaving what became known as Paisley shawls in the 1700s more than 40 years before the Renfrewshire town they were named after, a new exhibition will show.

Hosted by Heriot-Watt University and The Great Tapestry of Scotland in Galashiels, the exhibition will reveal that Edinburgh weavers were the first in Britain to create replicas of the Kashmir shawls brought back from India, the first recorded being in 1767.

It wasn’t until 1808 that Paisley’s weaving industry started making the shawls, and later gave the garment its iconic name.

The exhibition, called A Passion for Paisley, will feature a selection from the range of more than 100 shawls and shawl fragments that forms part of the University’s textile collection, housed in the Scottish Borders Campus in Galashiels.

Edinburgh was weaving what became known as Paisley shawls in the 1700s more than 40 years before the Renfrewshire town they were named after, a new exhibition will show.

Hosted by Heriot-Watt University and The Great Tapestry of Scotland in Galashiels, the exhibition will reveal that Edinburgh weavers were the first in Britain to create replicas of the Kashmir shawls brought back from India, the first recorded being in 1767.

It wasn’t until 1808 that Paisley’s weaving industry started making the shawls, and later gave the garment its iconic name.

The exhibition, called A Passion for Paisley, will feature a selection from the range of more than 100 shawls and shawl fragments that forms part of the University’s textile collection, housed in the Scottish Borders Campus in Galashiels.

Helen Taylor, Archivist at Heriot-Watt University, said: “Paisley design has stayed a very iconic motif and has remained a fixture even as fashions have changed.  Our collection in the Borders is a very good one and was really developed for teaching and research. You can't recreate the weaving, because the looms don’t exist anymore. But if you’re looking for design inspiration, Paisley shawls are a great example of East-West influence.”

Paisley shawls are richly patterned and often feature a distinctive Persian-style teardrop motif. This is inspired by the Babylonian Tree of Life, a magical tree from Mesopotamian mythology that grew in the centre of paradise.

Other motifs include floral and tendril designs, a striped zebra design and an oblong motif known as a ‘temple door’ design. Red was a recurring colour in Paisley shawls, alongside blues, greens, yellows and other colours, all created from natural plant dyes. Paisley shawls were hugely popular in the 18th and 19th centuries. Empress Josephine, Napoleon’s first wife, was known to own about 400 of the woollen shawls.

“When the British empire was expanding, people started bringing back Kashmir shawls as gifts,” Ms Taylor explained. “They were very expensive and were actually woven in cashmere. Weavers in Edinburgh started making reproduction shawls, and the first record of a reproduction Kashmir shawl being woven was in Edinburgh in 1767.”

Edinburgh in the 1700s already had a damask industry – when designs are woven into fabric rather than printed onto it – and it was these weavers who started making the reproduction Kashmir shawls. But when fashions evolved and the shawls got bigger, the Edinburgh weavers started outsourcing to Paisley, where weaving skills and technology were advancing and amongst the best in the world.

“In Edinburgh, shawl weaving was more of a cottage industry, with small looms being used around the city’s Old Town and shawls being woven in sections and sewn together,” Ms Taylor said. “In Paisley, they started using Jacquard looms, which used punch cards and allowed more complex design to be woven more easily.”

Most of Heriot-Watt’s Paisley shawls were collected by a ceramics curator called Janet Paterson who collected Paisley shawls in the 1940s and 50s. The collection was given to the University by her son, Alan, along with his tartan collection.

A Passion for Paisley runs from 26 March to 12 July 2024 at The Great Tapestry of Scotland, 14-20 High St, Galashiels TD1 1SD. There is an entrance fee of £5.

Heriot-Watt School of Textiles and Design dates back to 1883, when classes in weaving, dyeing and chemistry were introduced to train workers for the local textiles industry.

The School is a centre of excellence in design, with Honorary Graduates including British fashion icon Dame Vivienne Westwood. It is based on Heriot-Watt’s Scottish Borders Campus, which is built around a historic mill in Galashiels, at the heart of Scotland's luxury textile industry.

The Great Tapestry of Scotland visitor centre was purpose-built to house The Great Tapestry of Scotland, one of the world’s largest community arts projects. The Tapestry was hand-stitched by a team of 1,000 stitchers from across Scotland and charts 420 million years of Scotland's history, heritage, innovations and culture through 160 panels.

Source:

Heriot-Watt University

NC State Research: Machine Learning to Create a Fabric-Based Touch Sensor (c) NC State University
13.05.2024

Machine Learning to Create a Fabric-Based Touch Sensor

A new study from NC State University combines three-dimensional embroidery techniques with machine learning to create a fabric-based sensor that can control electronic devices through touch.

As the field of wearable electronics gains more interest and new functions are added to clothing, an embroidery-based sensor or “button” capable of controlling those functions becomes increasingly important. Integrated into the fabric of a piece of clothing, the sensor can activate and control electronic devices like mobile apps entirely by touch.  

A new study from NC State University combines three-dimensional embroidery techniques with machine learning to create a fabric-based sensor that can control electronic devices through touch.

As the field of wearable electronics gains more interest and new functions are added to clothing, an embroidery-based sensor or “button” capable of controlling those functions becomes increasingly important. Integrated into the fabric of a piece of clothing, the sensor can activate and control electronic devices like mobile apps entirely by touch.  

The device is made up of two parts; the embroidered pressure sensor itself and a microchip which processes and distributes the data collected by that sensor. The sensor is triboelectric, which means that it powers itself using the electric charge generated from the friction between its multiple layers. It is made from yarns consisting of two triboelectric materials, one with a positive electric charge and the other with a negative charge, which were integrated into conventional textile fabrics using embroidery machines.

Rong Yin, corresponding author of the study, said that the three-dimensional structure of the sensor was important to get right.

“Because the pressure sensor is triboelectric, it needed to have two layers with a gap in between them. That gap was one of the difficult parts in the process, because we are using embroidery which is usually two-dimensional. It’s a technique for decorating fabric,” he said. “It’s challenging to make a three-dimensional structure that way. By using a spacer, we were able to control the gap between the two layers which lets us control the sensor’s output.”

Data from the pressure sensor is then sent to the microchip, which is responsible for turning that raw input into specific instructions for any connected devices. Machine learning algorithms are key to making sure this runs smoothly, Yin said. The device needs to be able to tell the difference between gestures assigned to different functions, as well to disregard any unintentional inputs that might come from the cloth’s normal movement.

“Sometimes the data that the sensor acquires is not very accurate, and this can happen for all kinds of reasons,” Yin said. “Sometimes the data will be affected by environmental factors like temperature or humidity, or the sensor touches something by mistake. By using machine learning, we can train the device to recognize those kinds of things.

“Machine learning also allows this very small device to achieve many different tasks, because it can recognize different kinds of inputs.”

The researchers demonstrated this input recognition by developing a simple music playing mobile app which connected to the sensor via Bluetooth. They designed six functions for the app: play/pause, next song, last song, volume up, volume down and mute, each controlled by a different gesture on the sensor. Researchers were able to use the device for several other functions, including setting and inputting passwords and controlling video games.

The idea is still in its early stages, Yin said, as existing embroidery technology is not capable of easily handling the types of materials used in the creation of the sensor. Still, the new sensor represents another piece of the developing wearable electronics puzzle, which is sure to continue picking up interest in the near future.

The paper, “A clickable embroidered triboelectric sensor for smart fabric,” is published in Device.

Source:

North Carolina State University, Joey Pitchford

Photo: 政徳 吉田, Pixabay
03.05.2024

Vehicle underbodies made from natural fibers and recycled plastics

In collaboration with industrial partners, researchers at the Fraunhofer WKI have developed a vehicle underbody made from natural fibers and recycled plastics for automotive construction. The focus at the Fraunhofer WKI was directed at the development of the materials for injection molding as well as the hydrophobization of flax and hemp fibers for natural-fiber-reinforced mixed-fiber non-wovens.

The component fulfills the stringent technical requirements in the underbody area and could replace conventional lightweight vehicle underbodies in the future. With this development, the climate and environmental balance is optimized throughout the entire product life cycle.

In collaboration with industrial partners, researchers at the Fraunhofer WKI have developed a vehicle underbody made from natural fibers and recycled plastics for automotive construction. The focus at the Fraunhofer WKI was directed at the development of the materials for injection molding as well as the hydrophobization of flax and hemp fibers for natural-fiber-reinforced mixed-fiber non-wovens.

The component fulfills the stringent technical requirements in the underbody area and could replace conventional lightweight vehicle underbodies in the future. With this development, the climate and environmental balance is optimized throughout the entire product life cycle.

The project partners Fraunhofer WKI, Thuringian Institute for Textile and Plastics Research (TITK), Röchling Automotive SE & Co. KG, BBP Kunststoffwerk Marbach Baier GmbH and Audi AG have succeeded in developing a sustainable overall concept for vehicle underbodies. The researchers have thereby taken a challenging component group with a high plastic content and made it accessible for the utilization of natural materials. Until now, natural-fiber-reinforced plastics have predominantly been used in cars for trim parts without significant mechanical functions. Structural components such as vehicle underbodies are, however, exposed to enormous loads and place high demands on the bending and crash behavior of the material. In modern lightweight vehicle concepts, high-performance materials made from glass-fiber-reinforced plastics are therefore utilized.

The project team was able to replace the glass fibers with natural materials such as flax, hemp and cellulose fibers and to produce underbody components with a natural-fiber content of up to 45%. In the area of polymers, virgin polypropylene was completely dispensed with and solely recyclates were utilized. All the challenges associated with this material changeover – both the lower initial mechanical properties of the materials and the temporally restricted processing windows – were solved by means of skillful compound combinations.

At the Fraunhofer WKI, materials for injection molding were developed. “Natural-fiber injection-molded compounds have so far been known primarily for their increased strength and stiffness compared to non-reinforced polymers. In the development of the vehicle underbody, we have furthermore succeeded in fulfilling the stringent requirements for low-temperature impact strength through an innovative combination of selected post-consumer recyclates (PCR) as a matrix and natural fibers of varying degrees of purity - without forfeiting the required stiffness and strength,” explained Moritz Micke-Camuz, Project Manager at the Fraunhofer WKI.

Within the framework of the development, fiber-composite components made from natural-fiber-reinforced mixed-fiber non-wovens (lightweight-reinforced thermoplastic, LWRT) were realized for the first time at the TITK and at Röchling. The developed product not only fulfills the mechanical requirements: It also withstands in particular the challenges posed by the humid environment in which it is used. For the hydrophobization of flax and hemp fibers for LWRT components, a continuous furfurylation process was developed at the Fraunhofer WKI. Through furfurylation, moisture absorption can be reduced by up to 35 percent without impairment of the bending strength of the subsequent components. The furfurylated fiber material can also be easily processed on a non-woven production line.

The prototype components produced were subsequently extensively tested both at component level and in road tests. Amongst others, the vehicles from the VW Group’s new “Premium Platform Electric” (PPE) were used for this purpose. Long-term experience has already been gathered within the framework of the series testing. The gratifying result of these tests: The newly developed biocomposites fulfill all standard requirements for underbody components and have proven to be suitable for series production. Neither the use of natural fibers nor of (post-consumer) recyclates leads to a significant impairment of the properties.

One major advantage of the innovation is the significantly improved carbon footprint: Compared to series production, 10.5 kilograms of virgin material (PP/glass fiber) can be replaced by 4.2 kilograms of natural fibers and 6.3 kilograms of post-consumer recyclate. As a result, CO2 emissions during production, use and product life have been reduced by up to 40 percent.

Within the scope of the development project, an innovative, holistic overall concept for vehicle underbodies, including recycling with cascading re-use of the components, was developed. From a technical point of view, vehicle underbodies can be manufactured entirely from the new, high-performance lightweight bio construction material in the future.

The project was funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) via the project management organization TÜV Rheinland.

Source:

Fraunhofer-Institut für Holzforschung, Wilhelm-Klauditz-Institut WKI