Off-the-shelf, power-generating clothes are almost here

A lightweight, comfortable jacket that can generate the power to light up a jogger at night may sound futuristic, but materials scientist Trisha Andrew at the University of Massachusetts Amherst could make one today. In a new paper this month, she and colleagues outline how they have invented a way to apply breathable, pliable, metal-free electrodes to fabric and off-the-shelf clothing so it feels good to the touch and also transports enough electricity to power small electronics.

She says, “Our lab works on textile electronics. We aim to build up the materials science so you can give us any garment you want, any fabric, any weave type, and turn it into a conductor. Such conducting textiles can then be built up into sophisticated electronics. One such application is to harvest body motion energy and convert it into electricity in such a way that every time you move, it generates power.” Powering advanced fabrics that can monitor health data remotely are important to the military and increasingly valued by the health care industry, she notes.

Generating small electric currents through relative movement of layers is called triboelectric charging, explains Andrew, who trained as a polymer chemist and electrical engineer. Materials can become electrically charged as they create friction by moving against a different material, like rubbing a comb on a sweater. “By sandwiching layers of differently materials between two conducting electrodes, a few microwatts of power can be generated when we move,” she adds.

In the current early online edition of Advanced Functional Materials, she and postdoctoral researcher Lu Shuai Zhang in her lab describe the vapor deposition method they use to coat fabrics with a conducting polymer, poly(3,4-ethylenedioxytiophene) also known as PEDOT, to make plain-woven, conducting fabrics that are resistant to stretching and wear and remain stable after washing and ironing. The thickest coating they put down is about 500 nanometers, or about 1/10 the diameter of a human hair, which retains a fabric’s hand feel.

The authors report results of testing electrical conductivity, fabric stability, chemical and mechanical stability of PEDOT films and textile parameter effects on conductivity for 14 fabrics, including five cottons with different weaves, linen and silk from a craft store.

“Our article describes the materials science needed to make these robust conductors,” Andrew says. “We show them to be stable to washing, rubbing, human sweat and a lot of wear and tear.” PEDOT coating did not change the feel of any fabric as determined by touch with bare hands before and after coating. Coating did not increase fabric weight by more than 2 percent. The work was supported by the Air Force Office of Scientific Research.

Until recently, she and Zhang point out, textile scientists have tended not to use vapor deposition because of technical difficulties and high cost of scaling up from the laboratory. But over the last 10 years, industries such as carpet manufacturers and mechanical component makers have shown that the technology can be scaled up and remain cost-effective. The researchers say their invention also overcomes the obstacle of power-generating electronics mounted on plastic or cladded, veneer-like fibers that make garments heavier and/or less flexible than off-the-shelf clothing “no matter how thin or flexible these device arrays are.”

“There is strong motivation to use something that is already familiar, such as cotton/silk thread, fabrics and clothes, and imperceptibly adapting it to a new technological application.” Andrew adds, “This is a huge leap for consumer products, if you don’t have to convince people to wear something different than what they are already wearing.”

Test results were sometimes a surprise, Andrew notes. “You’d be amazed how much stress your clothes go through until you try to make a coating that will survive a shirt being pulled over the head. The stress can be huge, up to a thousand newtons of force. For comparison, one footstep is equal to about 10 newtons, so it’s yanking hard. If your coating is not stable, a single pull like that will flake it all off. That’s why we had to show that we could bend it, rub it and torture it. That is a very powerful requirement to move forward.”

Andrew is director of wearable electronics at the Center for Personalized Health Monitoring in UMass Amherst’s Institute of Applied Life Sciences (IALS). Since the basic work reported this month was completed, her lab has also made a wearable heart rate monitor with an off-the-shelf fitness bra to which they added eight monitoring electrodes. They will soon test it with volunteers on a treadmill at the IALS human movement facility.

She explains that a hospital heart rate monitor has 12 electrodes, while the wrist-worn fitness devices popular today have one, which makes them prone to false positives. They will be testing a bra with eight electrodes, alone and worn with leggings that add four more, against a control to see if sensors can match the accuracy and sensitivity of what a hospital can do. As the authors note in their paper, flexible, body-worn electronics represent a frontier of human interface devices that make advanced physiological and performance monitoring possible.

For the future, Andrew says, “We’re working on taking any garment you give us and turning it into a solar cell so that as you are walking around the sunlight that hits your clothes can be stored in a battery or be plugged in to power a small electronic device.”

Zhang and Andrew believe their vapor coating is able to stick to fabrics by a process called surface grafting, which takes advantage of free bonds dangling on the surface chemically bonding to one end of the polymer coating, but they have yet to investigate this fully.

Wearable Devices Communicate Vital Brain Activity Information

What can we learn about emotions, the brain and behavior from a wristband? Plenty, according to a prominent MIT engineer and researcher in her plenary session address at the American Pain Society Annual Scientific Meeting.

Rosalind Picard, ScD, FIEEE and her team at MIT pioneered the use of wearable technology to recognize changes in human emotion. They have made several new discoveries, including that autonomic activity measured through a sweat response is not as general as previously thought, and carries more specific information related to different kinds of brain activity.

“The skin is purely innervated by the sympathetic branch of the autonomic nervous system,” said Picard. “We can observe increases in sympathetic brain activation by monitoring subtle electrical changes across the surface of the skin.”

Sympathetic activation occurs when experiencing excitement or stress, whether physical, emotional or cognitive. In some medical conditions, such as epilepsy, it shows significant increases related to certain areas of the brain being activated.

Wristwatch-like devices can employ sensors for continuous, real-time data gathering. Picard explained that changes in electrodermal activity occur as the result of atypical activation in deep regions of the brain. This discovery already has been commercialized for use in seizure monitoring.

Seizures occur when there are abnormal, excessive or synchronous neuronal activity, and can cause convulsions evidenced by violent shaking and loss of control and consciousness.

When someone has recurring seizures, the diagnosis usually is epilepsy. When some regions of the brain, such as those involved with anxiety, pain, stress and memory are activated during a seizure, they can elicit patterns of electrical changes in the skin.

Picard reported her group has built an automated machine learning method that can detect compulsive seizures by combining measures of electrodermal activity on the wrist with measures of motion. The wrist-worn detector is now more than 96 percent accurate for detecting convulsive seizures.

While they have not demonstrated detection of non-convulsive seizures, 42 percent to 86 percent of non-convulsive, complex partial seizures also have significant electrodermal responses.

Picard said other clinical applications for wristband electrodermal monitoring include anxiety, mood and stress monitoring and measuring analgesic responses. “We know that pain exacerbates anxiety and stress and we are doing more studies to determine how reductions in anxiety and stress could indicate an analgesic response activated by a pain management therapy, said Picard.

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3D-printed ‘bionic skin’ could give robots the sense of touch

Engineering researchers at the University of Minnesota have developed a revolutionary process for 3D printing stretchable electronic sensory devices that could give robots the ability to feel their environment. The discovery is also a major step forward in printing electronics on real human skin.

The research will be published in the next issue of Advanced Materials and is currently online.

“This stretchable electronic fabric we developed has many practical uses,” said Michael McAlpine, a University of Minnesota mechanical engineering associate professor and lead researcher on the study. “Putting this type of ‘bionic skin’ on surgical robots would give surgeons the ability to actually feel during minimally invasive surgeries, which would make surgery easier instead of just using cameras like they do now. These sensors could also make it easier for other robots to walk and interact with their environment.”

McAlpine, who gained international acclaim in 2013 for integrating electronics and novel 3D-printed nanomaterials to create a “bionic ear,” says this new discovery could also be used to print electronics on real human skin. This ultimate wearable technology could eventually be used for health monitoring or by soldiers in the field to detect dangerous chemicals or explosives.

“While we haven’t printed on human skin yet, we were able to print on the curved surface of a model hand using our technique,” McAlpine said. “We also interfaced a printed device with the skin and were surprised that the device was so sensitive that it could detect your pulse in real time.”

McAlpine and his team made the unique sensing fabric with a one-of-a kind 3D printer they built in the lab. The multifunctional printer has four nozzles to print the various specialized “inks” that make up the layers of the device — a base layer of silicone, top and bottom electrodes made of a conducting ink, a coil-shaped pressure sensor, and a sacrificial layer that holds the top layer in place while it sets. The supporting sacrificial layer is later washed away in the final manufacturing process.

Surprisingly, all of the layers of “inks” used in the flexible sensors can set at room temperature. Conventional 3D printing using liquid plastic is too hot and too rigid to use on the skin. These flexible 3D printed sensors can stretch up to three times their original size.

“This is a completely new way to approach 3D printing of electronics,” McAlpine said. “We have a multifunctional printer that can print several layers to make these flexible sensory devices. This could take us into so many directions from health monitoring to energy harvesting to chemical sensing.”

Researchers say the best part of the discovery is that the manufacturing is built into the process.

“With most research, you discover something and then it needs to be scaled up. Sometimes it could be years before it ready for use,” McAlpine said. “This time, the manufacturing is built right into the process so it is ready to go now.”

The researchers say the next step is to move toward semiconductor inks and printing on a real body.

“The possibilities for the future are endless,” McAlpine said.

In addition to McAlpine, the research team includes University of Minnesota Department of Mechanical Engineering graduate students Shuang-Zhuang Guo, Kaiyan Qiu, Fanben Meng, and Sung Hyun Park.

The research was funded by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health (Award No. 1DP2EB020537). The researchers used facilities at the University of Minnesota Characterization Facility and Polymer Characterization Facility for testing.

Click-on arm prosthesis controlled by patient’s thoughts

Last Friday, the first patient in the Netherlands received his click-on robotic arm. By means of a new technique, this robotic arm is clicked directly onto the bone. A unique characteristic of this prosthesis is that it can be controlled by the patient’s own thoughts. Worldwide, there are only a handful of patients with such a prosthesis.

In April 2010, Johan Baggerman lost his arm in a serious accident. Seven years later, he is one of the first patients in the world with a click-on robotic arm. In the case of a click-on robotic arm, the arm prosthesis is connected directly to the arm stump. Through an opening in the skin, the patient “clicks” the prosthesis onto a metal rod in the bone. Because the prosthesis connects directly to the skeleton, a prosthesis socket is no longer necessary. This ensures that it does not slip off, avoids skin problems, and makes it very easy to put on and take off. This method has already been applied to the leg for a longer period and is now being applied for the first time in Netherlands to the arm. The main difference with the click-on leg prostheses is that the new arm prosthesis can communicate with the patient’s nerves, allowing the patient to control the prosthesis with their mind.

Range of motion

Surgeon Jan Paul Frölke and rehabilitation physician Henk van de Meent introduced the click-on prosthesis in the Netherlands. They have been applying the technique to help leg amputees since 2009. From now on it is also possible for patients with an arm amputation to receive a click-on prosthesis. “All movements can be made with the shoulder,” explains Henk van de Meent. “This gives the patients a larger range of motion. Another advantage is that the click-on prosthesis is attached easily and quickly.” Because the innovation is still so new, the prosthesis is not yet widely available and agreements still need to be set up with health insurance companies. Eligibility is determined on a patient-to-patient basis.

Surgeries

Three surgeries are needed for the click-on arm prosthesis. During the first surgery, the surgeon inserts a metal rod into the marrow cavity of the bone. The exterior of the rod has a rough surface. This rough side is recognized and accepted by the existing bone, whereby the bone growth maximally embeds the rod. Six to eight weeks later, the second, short intervention takes place. The surgeon makes a small hole in the skin and screws a connecting rod into the rod placed earlier. This connecting rod protrudes slightly so that the prosthesis can click onto it.

The third surgery is the Targeted Muscle Reinnervation (TMR) surgery and is performed by a specialized plastic surgeon. The nerves that controlled the muscles in the hand and the underarm before the amputation are meticulously attached to parts of the muscles in the upper arm stump. By connecting the nerves to the muscle, the muscle acts like an amplifier of the nerve signal.

Controlling muscles with thoughts

The surgeries are followed by a rehabilitation period, so that the patient can learn to contract the muscles in their upper arm by using their thoughts. If the patient imagines opening and closing their hand, the muscles in the upper arm contract. The muscle activity in the upper arm is measured by Myoband which are electrodes surrounding the upper arm like a bracelet. Once the nerves have sufficiently grown into the muscle, the muscle signal is strong enough to be detected by the sensor in the Myoband and the computer in the robot arm can be controlled via Bluetooth. This is what makes movement possible.

The rehabilitation period after the TMR is very strenuous for the patient. Each day, the patients must “train” a practice hand with their mind. Once the real robotic arm is connected, this training becomes a lot easier because the movement of the hand in the patient’s mind is carried out immediately by the robotic arm. The intuitive link between brain and robotic arm gives the patient the feeling that they have the same control over the arm is as if it were their own. Even after the robotic arm is connected, there is an intensive rehabilitation period during which the patient must get used to their new arm.

Timeline:

April 28, 2010: Truck driver Johan Baggerman was involved in a serious truck accident. His arm was trapped and ultimately had to be amputated by the flight paramedic Michiel Vaneker.

October 21, 2013: Surgery 1 by surgeon Jan Paul Frölke: the metal rod is inserted.

January 13, 2014: Surgery 2 by surgeon Jan Paul Frölke: the connecting rod is fastened to the first rod.

April 8, 2016: TMR surgery by plastic surgeon Erik Walbeehm: the nerves are attached to the muscles in the upper arm.

2016: Start of training with the practice arm under guidance of the rehabilitation physician Henk de Meent. The patient learns to contract the muscles in his upper arm with his thoughts.

April 21, 2017: John Baggerman is the first patient in the Netherlands to receive a click-on robotic arm and starts the last part of his rehabilitation process.

Ultraviolet light sensor for wearable devices in the IoT era

Mass production technology for silicon based ultraviolet (UV) light sensors, suitable for smartphones and wearable devices in the Internet of Things (IoT) era, has been jointly developed by a research team at Tohoku University and SII Semiconductor Corporation, a semiconductor manufacturer at Seiko Instruments Group.

In recent years, there’s been growing interest within the healthcare community in the prevention of sunburns and skin blemishes. As such, easy measurement of UV light through the use of a smartphone or a wearable device could be of great benefit to healthcare and aesthetic medicine. In fact, the need to measure invisible UV light is also increasing in industrial fields, where equipment such as UV curing machines and printers using UV curable ink are being used more frequently now than ever before.

The new UV light sensor technology, developed by the research team led by Professor Shigetoshi Sugawa and Associate Professor Rihito Kuroda at Tohoku University’s Graduate School of Engineering, uses only silicon semiconductors to selectively detect and measure the light intensity of UV-A (315~400nm) and UV-B (280~315nm) light wavebands. These are the wavebands to which sunburns and skin blemishes are attributed. Versatile silicon semiconductor sensors are more adaptive to integrations with circuits and add more functions than compound semiconductor UV sensors.

Conventionally, silicon photodiode UV light sensors employ optical filters that cut off undesired visible light wavebands. By utilizing the differential spectral response of silicon photodiodes with high and low UV light sensitivities, the researchers were able to develop a sensor with UV range selective sensing capabilities without employing an optical filter.

The optical filter-less structure obtains a higher sensitivity by preventing a decrease of incident UV light intensity to the sensor.

Sugawa and Kuroda had previously developed a silicon photodiode technology providing 190~1100nm wide spectral response and high performance resistance against UV light irradiation. They did this through the JST SENTAN-project which ran from 2011 to 2013.

That silicon photodiode technology has now been applied to the mass production technology of the UV light sensors, which utilizes the newly introduced differential spectral response method. The developed UV light sensors are then loaded to small transparent resin packages with little constraints for assembly, which makes them suitable for use in smartphones and wearable devices. It is expected that anyone can detect and measure UV light using this newly developed technology.

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Physicists develop ultrathin superconducting film

Experimental physicists in the research group led by Professor Uwe Hartmann at Saarland University have developed a thin nanomaterial with superconducting properties. Below about -200 °C these materials conduct electricity without loss, levitate magnets and can screen magnetic fields. The particularly interesting aspect of this work is that the research team has succeeded in creating superconducting nanowires that can be woven into an ultra-thin film that is as flexible as cling film. As a result, novel coatings for applications ranging from aerospace to medical technology are becoming possible. The Volkswagen Foundation supported the research in it is initial stages; the work is currently receiving funding from the German Research Foundation (DFG)

The research team will be exhibiting their superconducting film at Hannover Messe from April 24th to April 28th (Hall 2, Stand B46) and are looking for commercial and industrial partners with whom they can develop their system for practical applications.

The research work is a collaborative effort involving the team led by Professor Uwe Hartmann at Saarland University and Professor Volker Presser of the Leibniz Institute for New Materials (INM), who also holds the Chair of Energy Materials at Saarland University. The results have been published in a number of scientific journals.

A team of experimental physicists at Saarland University have developed something that — it has to be said — seems pretty unremarkable at first sight. It looks like nothing more than a charred black piece of paper. But appearances can be deceiving. This unassuming object is a superconductor. The term ‘superconductor’ is given to a material that (usually at a very low temperatures) has zero electrical resistance and can therefore conduct an electric current without loss. Put simply, the electrons in the material can flow unrestricted through the cold immobilized atomic lattice. In the absence of electrical resistance, if a magnet is brought up close to a cold superconductor, the magnet effectively ‘sees’ a mirror image of itself in the superconducting material. So if a superconductor and a magnet are placed in close proximity to one another and cooled with liquid nitrogen they will repel each another and the magnet levitates above the superconductor. The term ‘levitation’ comes from the Latin word levitas meaning lightness. It’s a bit like a low-temperature version of the hoverboard from the ‘Back to the Future’ films. If the temperature is too high, however, frictionless sliding is just not going to happen.

Many of the common superconducting materials available today are rigid, brittle and dense, which makes them heavy. The Saarbrücken physicists have now succeeded in packing superconducting properties into a thin flexible film. The material is a essentially a woven fabric of plastic fibres and high-temperature superconducting nanowires. ‘That makes the material very pliable and adaptable — like cling film (or ‘plastic wrap’ as it’s also known). Theoretically, the material can be made to any size. And we need fewer resources than are typically required to make superconducting ceramics, so our superconducting mesh is also cheaper to fabricate,’ explains Uwe Hartmann, Professor of Nanostructure Research and Nanotechnology at Saarland University.

The low weight of the film is particularly advantageous. ‘With a density of only 0.05 grams per cubic centimetre, the material is very light, weighing about a hundred times less than a conventional superconductor. This makes the material very promising for all those applications where weight is an issue, such as in space technology. There are also potential applications in medical technology,’ explains Hartmann. The material could be used as a novel coating to provide low-temperature screening from electromagnetic fields, or it could be used in flexible cables or to facilitate friction-free motion.

In order to be able to weave this new material, the experimental physicists made use of a technique known as electrospinning, which is usually used in the manufacture of polymeric fibres. ‘We force a liquid material through a very fine nozzle known as a spinneret to which a high electrical voltage has been applied. This produces nanowire filaments that are a thousand times thinner than the diameter of a human hair, typically about 300 nanometres or less. We then heat the mesh of fibres so that superconductors of the right composition are created. The superconducting material itself is typically an yttrium-barium-copper-oxide or similar compound,’ explains Dr. Michael Koblischka, one of the research scientists in Hartmann’s group.

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A novel method for the fabrication of active-matrix 3-D pressure sensors

A recent study, affiliated with UNIST has created a three-dimensional, tactile sensor that could detect wide pressure ranges from human body weight to a finger touch. This new sensor with transparent features is capable of generating an electrical signal based on the sensed touch actions, also, consumes far less electricity than conventional pressure sensors.

The breakthrough comes from a research, conducted by Professor Jang-Ung Park of Materials Science and Engineering and his research team at UNIST. In the study, the research team presented a novel method of fabricating a transistor-type active-matrix pressure sensor using foldable substrates and air-dielectric layers.

Today, most transistors are created with silicon channel and silicon oxide-based dielectrics. However, these transistors have been found to be either lacking transparency or inflexible, which may hinder their utility in fabricating highly-integrated pressure sensor arrays and transparent pressure sensors.

In this regard, Professor Park’s team decided to use highly-conductive and transparent graphene transistors with air-dielectric layers. The sensor can detect different types of touch-including swiping and tapping..

“Using air as the dielectric layer in graphene field-effect transistors (FETs) can significantly improve transistor performance due to the clean interface between graphene channel and air,” says Professor Park. “The thickness of the air-dielectric layers is determined by the applied pressure. With that technology, it would be possible to detect pressure changes far more effectively.”

A convantional touch panel, which may be included in a display device, reacts to the static electrical when pressure is applied to the monitor screen. With this method, the position on screen contacted by a finger, stylus, or other object can be easily detected using changes in pressure, but can not provide the intensity of pressure.

The research team placed graphene channel, metal nanowire electrodes, as well as an elastic body capable of trapping air on one side of the foldable substrate. Then they covered the other side of the substrate, like a lid and kept the air. In this transistor, the force pressing the elastic body is transferred to the air-dielectric layer and alters its thickness. Such changes in the thickness of the air-dielectric layer is converted into an electrical signal and transmitted via metal nanowires and the graphene channel, expressing both the position and the intensity of the pressure.

This is regarded as a promising technology as it enables the successful implementation of active-matrix pressure sensors. Moreover, when compared with the passive-matrix type, it consumes less power and has a faster response time.

It is possible to send and receive signals only by flowing electricity to the place where pressure is generated. The change in the thickness of the air dielectric layer is converted into an electrical signal to represent the position and intensity of the pressure. In addition, since all the substrates, channels, and electrode materials used in this process are all transparent, they can also be manufactured with invisible pressure sensors.

“This sensor is capable of simultaneously measuring anything from lower pressure (less than 10 kPa), such as gentle tapping to high pressure (above 2 MPa), such as human body weight,” says Sangyoon Ji (Combined M.S./Ph.D. student of Materials Science and Engineering), the first co-author of the study. “It can be also applied to 3D touchscreen panels or smart running shoes that can analyze life patterns of people by measuring their weight distribution.”

“This study not only solves the limitations of conventional pressure sensors, but also suggests the possibility to apply them to various fields by combining pressure sensor with other electronic devices such as display.” says Professor Park.

Upcycling ‘fast fashion’ to reduce waste and pollution

Pollution created by making and dyeing clothes has pitted the fashion industry and environmentalists against each other. Now, the advent of “fast fashion” — trendy clothing affordable enough to be disposable — has strained that relationship even more. But what if we could recycle clothes like we recycle paper, or even upcycle them? Scientists report today new progress toward that goal.

The team will present the work at the 253rd National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 14,000 presentations on a wide range of science topics.

“People don’t want to spend much money on textiles anymore, but poor-quality garments don’t last,” Simone Haslinger explains. “A small amount might be recycled as cleaning rags, but the rest ends up in landfills, where it degrades and releases carbon dioxide, a major greenhouse gas. Also, there isn’t much arable land anymore for cotton fields, as we also have to produce food for a growing population.”

All these reasons amount to a big incentive to recycle clothing, and some efforts are already underway, such as take-back programs. But even industry representatives admit in news reports that only a small percentage gets recycled. Other initiatives shred used clothing and incorporate the fibers into carpets or other products. But Haslinger, a doctoral candidate at Aalto University in Finland, notes that this approach isn’t ideal since the carpets will ultimately end up in landfills, too.

A better strategy, says Herbert Sixta, Ph.D., who heads the biorefineries research group at Aalto University, is to upcycle worn-out garments: “We want to not only recycle garments, but we want to really produce the best possible textiles, so that recycled fibers are even better than native fibers.” But achieving this goal isn’t simple. Cotton and other fibers are often blended with polyester in fabrics such as “cotton-polyester blends,” which complicates processing.

Previous research showed that many ionic liquids can dissolve cellulose. But the resulting material couldn’t then be re-used to make new fibers. Then about five years ago, Sixta’s team found an ionic liquid — 1,5-diazabicyclo[4.3.0]non-5-ene acetate — that could dissolve cellulose from wood pulp, producing a material that could be spun into fibers. Later testing showed that these fibers are stronger than commercially available viscose and feel similar to lyocell. Lyocell is also known by the brand name Tencel, which is a fiber favored by eco-conscious designers because it’s made of wood pulp.

Building on this process, the researchers wanted to see if they could apply the same ionic liquid to cotton-polyester blends. In this case, the different properties of polyester and cellulose worked in their favor, Haslinger says. They were able to dissolve the cotton into a cellulose solution without affecting the polyester.

“I could filter the polyester out after the cotton had dissolved,” Haslinger says. “Then it was possible without any more processing steps to spin fibers out of the cellulose solution, which could then be used to make clothes.”

To move their method closer to commercialization, Sixta’s team is testing whether the recovered polyester can also be spun back into usable fibers. In addition, the researchers are working to scale up the whole process and are investigating how to reuse dyes from discarded clothing.

But, Sixta notes, after a certain point, commercializing the process doesn’t just require chemical know-how. “We can handle the science, but we might not know what dye was used, for example, because it’s not labeled,” he says. “You can’t just feed all the material into the same process. Industry and policymakers have to work on the logistics. With all the rubbish piling up, it is in everyone’s best interest to find a solution.”

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Lab-on-a-glove could bring nerve-agent detection to a wearer’s fingertips

There’s a reason why farmers wear protective gear when applying organophosphate pesticides. The substances are very effective at getting rid of unwanted bugs, but they can also make people sick. Related compounds — organophosphate nerve agents — can be used as deadly weapons. Now researchers have developed a fast way to detect the presence of such compounds in the field using a disposable “lab-on-a-glove.” The report on the glove appears in the journal ACS Sensors.

Organophosphate nerve agents, including sarin and VX, are highly toxic and can prevent the nervous system from working properly. Organophosphate pesticides are far less potent but work in a similar way and can cause illness in people who are exposed to them, according to the U.S. Centers for Disease Control and Prevention. Detecting either type of these sets of compounds accurately and quickly could help improve both defense and food security measures. So, Joseph Wang and colleagues set out to develop a wearable sensor that could meet the requirements of field detection.

The new wearable, flexible glove biosensor carries out the sampling and electrochemical biosensing steps on different fingers, with the thumb finger used for collecting the nerve-agent residues and an enzyme immobilized on the index finger. The researchers created stretchable inks to print the collection and sensing elements on these fingers. Detection of the collected residues is performed when the thumb touches the printed enzyme-based organophosphate biosensor on the glove index finger. So, a user would swipe the thumb of the glove on a surface for testing, then touch the thumb and index fingers together for the electrochemical analysis. For real-time results, the voltammetric data are sent via a reusable Bluetooth device on the back of the glove to a user’s mobile device. Testing showed that the glove could detect organophosphate pesticides methyl parathion and methyl paraoxon on various surfaces — including glass, wood and plastic — and on produce. The researchers say the sensor could be used in both security and food safety settings.

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New flexible sensor holds potential for foldable touch screens

Picture a tablet that you can fold into the size of a phone and put away in your pocket, or an artificial skin that can sense your body’s movements and vital signs. A new, inexpensive sensor developed at the University of British Columbia could help make advanced devices like these a reality.

The sensor uses a highly conductive gel sandwiched between layers of silicone that can detect different types of touch, including swiping and tapping, even when it is stretched, folded or bent. This feature makes it suited for foldable devices of the future.

“There are sensors that can detect pressure, such as the iPhone’s 3D Touch, and some that can detect a hovering finger, like Samsung’s AirView. There are also sensors that are foldable, transparent and stretchable. Our contribution is a device that combines all those functions in one compact package,” said researcher Mirza Saquib Sarwar, a PhD student in electrical and computer engineering at UBC.

The prototype, described in a recent paper in Science Advances, measures 5 cm x 5 cm but could be easily scaled up as it uses inexpensive, widely available materials, including the gel and silicone.

“It’s entirely possible to make a room-sized version of this sensor for just dollars per square metre, and then put sensors on the wall, on the floor, or over the surface of the body — almost anything that requires a transparent, stretchable touch screen,” said Sarwar. “And because it’s cheap to manufacture, it could be embedded cost-effectively in disposable wearables like health monitors.”

The sensor could also be integrated in robotic “skins” to make human-robot interactions safer, added John Madden, Sarwar’s supervisor and a professor in UBC’s faculty of applied science.

“Currently, machines are kept separate from humans in the workplace because of the possibility that they could injure humans. If a robot could detect our presence and be ‘soft’ enough that they don’t damage us during an interaction, we can safely exchange tools with them, they can pick up objects without damaging them, and they can safely probe their environment,” said Madden.

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Simulation tool for efficient production of non-woven fabrics

Non-woven fabrics are indispensable to everyday life. A Fraunhofer Institute has developed software that makes the production of non-woven products much more efficient and flexible. With the tool FIDYST, it has been possible for the first time to simulate the movement of fibers in turbulent air currents. A real innovation — and the breakthrough in a theory that is over a hundred years old.

Non-woven materials are usually well hidden and are therefore not visible. However, if you are looking for them, you can find them everywhere: as a lining in winter jackets, as a padding in sofas, as a soundproofing mat in cars, as insulation in house walls, as a filter in kitchen exhaust hoods, as a cosmetic pad in bathrooms or as a separating layer in electric cables. Highly absorbent non-woven can even be found in the diapers of our little children. It is an extremely versatile and high-performance material which is indispensable in our everyday lives. Accordingly, textile manufacturers and mechanical engineers are interested in keeping its production as efficient and flexible as possible.

The Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern has developed special software called the FIDYST tool (Fiber Dynamics Simulation Tool). It simulates the movement of fibers in turbulent air flows. In the production of non-woven materials, the fibers or threads are each stretched with the aid of air and deposited onto a conveyor belt. Depending on the speed and temperature of the air stream, a non-woven product with the desired structure, density and strength results. One widely used application is random web, in which the individual fibers display a diverse orientation, thereby forming a random web which is simultaneously voluminous and firm.

How precisely the fibers move in the airflow and in which orientation they land on the conveyor belt is computed by the simulation software FIDYST which the researchers have developed. After simulating the airflow, the user only has to enter the material properties of the fibers in the software. The software then simulates the dynamic behavior of thousands of fibers. Even fiber mixtures can be simulated with the software. The result can be visualized in a three-dimensional representation.

Equipped with this data, the manufacturer can then, for example, improve the air flow in a targeted manner. This results in a non-woven fabric with the desired specification while at the same time reducing energy and raw material consumption. The software simulation can calculate that by changing the configuration of the machine, fewer fibers are needed to produce a non-woven fabric with the desired structure and strength.

The Fraunhofer tool not only benefits the textile manufacturers who want to precisely configure their machines for every desired non-woven product. “Mechanical engineers can also use it to create machines that are as efficient and flexible as possible,” explains Dr. Simone Gramsch, FIDYST Project Manager at ITWM.

Despite the complex computing operations, FIDYST does not rely on expensive, high-performance computers or data centers; the tool is content with standard PCs of the upper performance class and runs on both Windows and Linux.

Unique feature of Fraunhofer

After the calculation, the data can be exported in the “EnSight Gold Case” format and then visualized and analyzed. The format is standard in applications that deal with the visualization and analysis of flow dynamics of all kinds, such as in aircraft or automotive engineering, but also in sports or medicine.

Behind FIDYST is a real world premier. For the first time, it has been possible to precisely simulate and predict fiber dynamics in air currents. “The development is the result of several years of research as well as a few doctoral theses. It has been worth it, though; with FIDYST, we have a unique feature,” says project manager Simone Gramsch. The ITWM licenses the software to mechanical engineers or textile manufacturers. “If necessary, we also offer FIDYST as a service; then, all the simulations are executed on our computers according to the specifications of the customer,” says Gramsch. This is useful when it comes to particularly complex and, therefore, computer-intensive projects.

Mathematics lovers might be interested in the topic for another reason. More than 100 years ago, the French mathematicians Eugène and François Cosserat worked on equations to describe the behavior of elastic materials. The theory of Cosserat-Rods, named after them, ultimately formed the basis for the Fraunhofer researchers.

The Fraunhofer researchers will present a demo of FIDYST at the INDEX non-woven trade fair in Geneva (April 4 — 7, 2017).