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Researchers at the University of Colorado Boulder are developing a wearable electronic device that’s “really wearable” — a stretchy and fully-recyclable circuit board that’s inspired by, and sticks onto, human skin.
The team, led by Jianliang Xiao and Wei Zhang, describes its new “electronic skin” in a paper published today in the journal Science Advances. The device can heal itself, much like real skin. It also reliably performs a range of sensory tasks, from measuring the body temperature of users to tracking their daily step counts.
And it’s reconfigurable, meaning that the device can be shaped to fit anywhere on your body.
“If you want to wear this like a watch, you can put it around your wrist,” said Xiao, an associate professor in the Paul M. Rady Department of Mechanical Engineering at CU Boulder. “If you want to wear this like a necklace, you can put it on your neck.”
He and his colleagues are hoping that their creation will help to reimagine what wearable devices are capable of. The group said that, one day, such high-tech skin could allow people to collect accurate data about their bodies — all while cutting down on the world’s surging quantities of electronic waste.
“Smart watches are functionally nice, but they’re always a big chunk of metal on a band,” said Zhang, a professor in the Department of Chemistry. “If we want a truly wearable device, ideally it will be a thin film that can comfortably fit onto your body.”
Stretching out

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Those thin, comfortable films have long been a staple of science fiction. Picture skin peeling off the face of Arnold Schwarzenegger in the Terminator film franchise. “Our research is kind of going in that direction, but we still have a long way to go,” Zhang said.
His team’s goals, however, are both robot and human. The researchers previously described their design for electronic skin in 2018. But their latest version of the technology makes a lot of improvements on the concept — for a start, it’s far more elastic, not to mention functional.
To manufacture their bouncy product, Xiao and his colleagues use screen printing to create a network of liquid metal wires. They then sandwich those circuits in between two thin films made out of a highly flexible and self-healing material called polyimine.
The resulting device is a little thicker than a Band-Aid and can be applied to skin with heat. It can also stretch by 60% in any direction without disrupting the electronics inside, the team reports.
“It’s really stretchy, which enables a lot of possibilities that weren’t an option before,” Xiao said.

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The team’s electronic skin can do a lot of the same things that popular wearable fitness devices like Fitbits do: reliably measuring body temporary, heart rate, movement patterns and more.
Less waste
Arnold may want to take note: The team’s artificial epidermis is also remarkably resilient.
If you slice a patch of electronic skin, Zhang said, all you have to do is pinch the broken areas together. Within a few minutes, the bonds that hold together the polyimine material will begin to reform. Within 13 minutes, the damage will be almost entirely undetectable.
“Those bonds help to form a network across the cut. They then begin to grow together,” Zhang said. “It’s similar to skin healing, but we’re talking about covalent chemical bonds here.”
Xiao added that the project also represents a new approach to manufacturing electronics — one that could be much better for the planet. By 2021, estimates suggest that humans will have produced over 55 million tons of discarded smart phones, laptops and other electronics.
His team’s stretchy devices, however, are designed to skip the landfills. If you dunk one of these patches into a recycling solution, the polyimine will depolymerize, or separate into its component molecules, while the electronic components sink to the bottom. Both the electronics and the stretchy material can then be reused.
“Our solution to electronic waste is to start with how we make the device, not from the end point, or when it’s already been thrown away,” Xiao said. “We want a device that is easy to recycle.”
The team’s electronic skin is a long way away from being able to compete with the real thing. For now, these devices still need to be hooked up to an external source of power to work. But, Xiao said, his group’s research hints that cyborg skin could soon be the fashion fad of the future.
“We haven’t realized all of these complex functions yet,” he said. “But we are marching toward that device function.” More

Silicon has been the workhorse of electronics for decades because it is a common element, is easy to process, and has useful electronic properties. A limitation of silicon is that high temperatures damage it, which limits the operating speed of silicon-based electronics. Single-crystal diamond is a possible alternative to silicon. Researchers recently fabricated a single-crystal diamond wafer, but common methods of polishing the surface — a requirement for use in electronics — are a combination of slow and damaging.
In a study recently published in Scientific Reports, researchers from Osaka University and collaborating partners polished a single-crystal diamond wafer to be nearly atomically smooth. This procedure will be useful for helping diamond replace at least some of the silicon components of electronic devices.
Diamond is the hardest known substance and essentially does not react with chemicals. Polishing it with a similarly hard tool damages the surface and conventional polishing chemistry is slow. In this study, the researchers in essence first modified the quartz glass surface and then polished diamond with modified quartz glass tools.
“Plasma-assisted polishing is an ideal technique for single-crystal diamond,” explains lead author Nian Liu. “The plasma activates the carbon atoms on the diamond surface without destroying the crystal structure, which lets a quartz glass plate gently smooth away surface irregularities.”
The single-crystal diamond, before polishing, had many step-like features and was wavy overall, with an average root mean square roughness of 0.66 micrometers. After polishing, the topographical defects were gone, and the surface roughness was far less: 0.4 nanometers.
“Polishing decreased the surface roughness to near-atomic smoothness,” says senior author Kazuya Yamamura. “There were no scratches on the surface, as seen in scaife mechanical smoothing approaches.”
Furthermore, the researchers confirmed that the polished surface was unaltered chemically. For example, they detected no graphite — therefore, no damaged carbon. The only detected impurity was a very small amount of nitrogen from the original wafer preparation.
“Using Raman spectroscopy, the full width at half maximum of the diamond lines in the wafer were the same, and the peak positions were almost identical,” says Liu. “Other polishing techniques show clear deviations from pure diamond.”
With this research development, high-performance power devices and heat sinks based on single-crystal diamond are now attainable. Such technologies will dramatically lower the power use and carbon input, and improve the performance, of future electronic devices.

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Materials provided by Osaka University. Note: Content may be edited for style and length. More

Rochester Institute of Technology scientists have developed new simulations of black holes with widely varying masses merging that could help power the next generation of gravitational wave detectors. RIT Professor Carlos Lousto and Research Associate James Healy from RIT’s School of Mathematical Sciences outline these record-breaking simulations in a new Physical Review Letters paper.
As scientists develop more advanced detectors, such as the Laser Interferometer Space Antenna (LISA), they will need more sophisticated simulations to compare the signals they receive with. The simulations calculate properties about the merged black holes including the final mass, spin, and recoil velocity, as well as peak frequency, amplitude, and luminosity of the gravitational waveforms the mergers produce.
“Right now, we can only observe black holes of comparable masses because they are bright and generate a lot of radiation,” said Lousto. “We know there should be black holes of very different masses that we don’t have access to now through current technology and we will need these third generational detectors to find them. In order for us to confirm that we are observing holes of these different masses, we need these theoretical predictions and that’s what we are providing with these simulations.”
The scientists from RIT’s Center for Computational Relativity and Gravitation created a series of simulations showing what happens when black holes of increasingly disparate masses — up to a record-breaking ratio of 128:1 — orbit 13 times and merge.
“From a computational point of view, it really is testing the limits of our method to solve Einstein’s general relativity equations on supercomputers,” said Lousto. “It pushes to the point that no other group in the world has been able to come close to. Technically, it’s very difficult to handle two different objects like two black holes, in this case one is 128 times larger than the other.”

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Materials provided by Rochester Institute of Technology. Original written by Luke Auburn. Note: Content may be edited for style and length. More

The properties of synthesised magnets can be changed and controlled by charge currents as suggested by a study and simulations conducted by physicists at Martin Luther University Halle-Wittenberg (MLU) and Central South University in China. In the journal Nature Communications, the team reports on how magnets and magnetic signals can be coupled more effectively and steered by electric fields. This could result in new, environmentally friendly concepts for efficient communication and data processing.
Magnets are used to store large amounts of data. They can also be employed in transmitting and processing signals, for example in spintronic devices. External magnetic fields are used to modify the data or the signals. This has few drawbacks. “Generating magnetic fields, for example with the help of a current-carrying coil, requires a lot of energy and is relatively slow,” says Professor Jamal Berakdar from the Institute for Physics at MLU. Electric fields could help. “However, magnets react very weakly — if at all — to electrical fields, which is why it is so hard to control magnetically based data using electrical voltage,” continues the researcher. Therefore, the team from Germany and China looked for a new way to enhance the response of magnetism to electrical fields. “We wanted to find out whether stacked magnetic layers reacted fundamentally differently to electrical fields,” explains Berakdar. The idea: The layers could serve as data channels for magnetically based signals. If a metal layer, for example platinum, is inserted between two magnetic layers, the current flowing in it attenuates the magnetic signal in one layer but amplifies it in the other. Through detailed analysis and simulations, the team was able to show that this mechanism can be precisely controlled by tuning the voltage. This drives the current and allows for a precise and efficient electrical control of the magnetic signals. In addition, it can be implemented on a nanoscale, making it interesting for nanoelectronic applications.
The researchers went one step further in their work. They were able to show that the newly designed structure also responds more strongly to light or, more generally, to electromagnetic waves. This is important if electromagnetic waves are to be guided through magnetic layers or if these waves are to be used to control magnetic signals. “Another feature of our new concept is that this mechanism works for many material classes, as simulations under realistic conditions show,” says Berakdar. The findings could thus help to develop energy-saving and efficient solutions for data transmission and processing.
The study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), the National Natural Science Foundation of China, and the Natural Science Foundation of Hunan Province in China.

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Materials provided by Martin-Luther-Universität Halle-Wittenberg. Note: Content may be edited for style and length. More

Nature has inspired engineers at UNSW Sydney to develop a soft fabric robotic gripper which behaves like an elephant’s trunk to grasp, pick up and release objects without breaking them.
The researchers say the versatile technology could be widely applied in sectors where fragile objects are handled, such as agriculture, food and the scientific and resource exploration industries — even for human rescue operations or personal assistive devices.
Dr Thanh Nho Do, Scientia Lecturer and UNSW Medical Robotics Lab director, said the gripper could be commercially available in the next 12 to 16 months, if his team secured an industry partner.
He is the senior author of a study featuring the invention, published in Advanced Materials Technologies this month.
Dr Do worked with the study’s lead author and PhD candidate Trung Thien Hoang, Phuoc Thien Phan, Mai Thanh Thai and his collaborator Scientia Professor Nigel Lovell, Head of the Graduate School of Biomedical Engineering.
“Our new soft fabric gripper is thin, flat, lightweight and can grip and retrieve various objects — even from confined hollow spaces — for example, a pen inside a tube,” Dr Do said.

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“This device also has an enhanced real-time force sensor which is 15 times more sensitive than conventional designs and detects the grip strength required to prevent damage to objects it’s handling.
“There is also a thermally-activated mechanism that can change the gripper body from flexible to stiff and vice versa, enabling it to grasp and hold objects of various shapes and weights — up to 220 times heavier than the gripper’s mass.”
Nature-inspired robotics
Dr Do said the researchers found inspiration in nature when designing their soft fabric gripper.
“Animals such as an elephant, python or octopus use the soft, continuum structures of their bodies to coil their grip around objects while increasing contact and stability — it’s easy for them to explore, grasp and manipulate objects,” he said.

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“These animals can do this because of a combination of highly sensitive organs, sense of touch and the strength of thousands of muscles without rigid bone — for example, an elephant’s trunk has up to 40,000 muscles.
“So, we wanted to mimic these gripping capabilities — holding and manipulating objects are essential motor skills for many robots.”
Improvement on existing grippers
Dr Do said the researchers’ new soft gripper was an improvement on existing designs which had disadvantages that limited their application.
“Many soft grippers are based on claws or human hand-like structures with multiple inward-bending fingers, but this makes them unsuitable to grip objects that are oddly shaped, heavy or bulky, or objects smaller or larger than the gripper’s opening,” he said.
“Many existing soft grippers also lack sensory feedback and adjustable stiffness capabilities, which means you can’t use them with fragile objects or in confined environments.
“Our technology can grip long, slender objects and retrieve them from confined, narrow spaces, as well as hook through holes in objects to pick them up — for example, a mug handle.”
Lead author Trung Thien Hoang said the researchers’ fabrication method was also simple and scalable, which allowed the gripper to be easily produced at different sizes and volumes — for example, a one-metre long gripper could handle objects at least 300 millimetres in diameter.
During testing, a gripper prototype weighing 8.2 grams could lift an object of 1.8 kilograms — more than 220 times the gripper’s mass — while a prototype 13 centimetres long could wrap around an object with a diameter of 30 mm.
Prof. Nigel Lovell said: “We used a manufacturing process involving computerised apparel engineering and applied newly designed, highly sensitive liquid metal-based tactile sensors for detecting the grip force required.
“The gripper’s flat continuum also gives it superior contact with surfaces as it wraps around an object, while increasing the holding force.
“What’s more, the total heating and cooling cycle for the gripper to change structure from flexible to rigid takes less than half a minute, which is among the fastest reported so far.”
Integrating robotic arms and the sense of touch
Dr Do has filed a provisional patent for the new gripper, having successfully tested and validated the technology as a complete device.
He expects the gripper to be commercially available in the next 12 to 16 months, if he finds an industry partner.
“We now aim to optimise the integrated materials, develop a closed-loop control algorithm, and integrate the gripper into the ends of robotic arms for gripping and manipulating objects autonomously,” Dr Do said.
“If we can achieve these next steps, there will be no need to manually lift the gripper which will help for handling very large, heavy objects.
“We are also working on combining the gripper with our recently announced wearable haptic glove device, which would enable the user to remotely control the gripper while experiencing what an object feels like at the same time.”
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Researchers from Western University and University of Houston published a new paper in the Journal of Marketing that examines whether spoiler movie reviews harm box office revenue.
The study, forthcoming in the Journal of Marketing, is titled “Do Spoilers Really Spoil? Using Topic Modeling to Measure the Effect of Spoiler Reviews on Box Office Revenue” and is authored by Jun Hyun (Joseph) Ryoo, Xin (Shane) Wang and Shijie Lu.
“No spoilers!” say many directors. Their concern is that if publications or moviegoers reveal plotlines and surprises, the public won’t want to pay for the movie. But is that concern well-founded?
To examine this question, the research team examined daily box office revenues for movies released between January 2013 and December 2017 in the United States. These movies were then matched with their respective reviews collected from Internet Movie Database (IMDb), the most popular movie review platform in the United States. The researchers also developed a measurement of spoiler intensity, or the degree of plot uncertainty resolved by reading spoilers in movie reviews. The study results indicate that spoiler intensity has a positive and significant relationship with box office revenue.
Ryoo explains that “We postulate that uncertainty reduction is the driving mechanism behind this positive spoiling effect. If potential moviegoers are unsure about the quality of a movie, they are likely to benefit from the plot-related content of spoiler reviews when making their purchase decisions.” Consistent with this, the research reveals an inverted-U relationship between average ratings and spoiler intensity, which suggests that the positive spoiling effect is stronger for movies that receive moderate or mixed ratings compared to movies that receive either very high or very low ratings. The positive spoiling effect is also stronger for movies that receive less advertising. Advertising can serve an informative function for consumers and is seen as a credible signal of quality in the movie industry. Less advertising should therefore lead to greater uncertainty about movie quality for potential moviegoers. Wang adds “The positive spoiling effect is also stronger for movies with limited release, which is a strategy often employed by independent and arthouse studios associated with greater uncertainty in terms of artistic quality. And the positive spoiling effect declines over time, likely because consumers have greater uncertainty in the earlier periods of a movie’s life cycle.”
This leads to several implications for stakeholders in the movie industry. Foremost among these is that online review platforms can potentially increase consumer welfare by using spoiler reviews. “The uncertainty-reduction mechanism suggests a spoiler-friendly review platform can help consumers make appropriate purchase decisions. We recommend that review platforms keep the warning labels on spoiler reviews because of the benefit of allowing consumers to self-select into the exposure to spoilers,” says Lu.

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Materials provided by American Marketing Association. Original written by Matt Weingarden. Note: Content may be edited for style and length. More

Solving the equations of general relativity for colliding black holes is no simple matter.
Physicists began using supercomputers to obtain solutions to this famously hard problem back in the 1960s. In 2000, with no solutions in sight, Kip Thorne, 2018 Nobel Laureate and one of the designers of LIGO, famously bet that there would be an observation of gravitational waves before a numerical solution was reached.
He lost that bet when, in 2005, Carlos Lousto, then at The University of Texas at Brownsville, and his team generated a solution using the Lonestar supercomputer at the Texas Advanced Computing Center. (Concurrently, groups at NASA and Caltech derived independent solutions.)
In 2015, when the Laser Interferometer Gravitational-Wave Observatory (LIGO) first observed such waves, Lousto was in shock.
“It took us two weeks to realize this was really from nature and not from inputting our simulation as a test,” said Lousto, now a professor of mathematics at Rochester Institute of Technology (RIT). “The comparison with our simulations was so obvious. You could see with your bare eyes that it was the merger of two black holes.”
Lousto is back again with a new numerical relativity milestone, this time simulating merging black holes where the ratio of the mass of the larger black hole to the smaller one is 128 to 1 — a scientific problem at the very limit of what is computational possible. His secret weapon: the Frontera supercomputer at TACC, the eighth most powerful supercomputer in the world and the fastest at any university.

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His research with collaborator James Healy, supported by the National Science Foundation (NSF), was published in Physical Review Letters this week. It may require decades to confirm the results experimentally, but nonetheless it serves as a computational achievement that will help drive the field of astrophysics forward.
“Modeling pairs of black holes with very different masses is very computational demanding because of the need to maintain accuracy in a wide range of grid resolutions,” said Pedro Marronetti, program director for gravitational physics at NSF. “The RIT group has performed the world’s most advanced simulations in this area, and each of them takes us closer to understanding observations that gravitational-wave detectors will provide in the near future.”
LIGO is only able to detect gravitational waves caused by small and intermediate mass black holes of roughly equal size. It will take observatories 100 times more sensitive to detect the type of mergers Lousto and Healy have modeled. Their findings show not only what the gravitational waves caused by a 128:1 merger would look like to an observer on Earth, but also characteristics of the ultimate merged black hole including its final mass, spin, and recoil velocity. These led to some surprises.
“These merged black holes can have speeds much larger than previously known,” Lousto said. “They can travel at 5,000 kilometers per second. They kick out from a galaxy and wander around the universe. That’s another interesting prediction.”
The researchers also computed the gravitational waveforms — the signal that would be perceived near Earth — for such mergers, including their peak frequency, amplitude, and luminosity. Comparing those values with predictions from existing scientific models, their simulations were within 2 percent of the expected results.

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Previously, the largest mass ratio that had ever been solved with high-precision was 16 to 1 — eight times less extreme than Lousto’s simulation. The challenge of simulating larger mass ratios is that it requires resolving the dynamics of the interacting systems at additional scales.
Like computer models in many fields, Lousto uses a method called adaptive mesh refinement to get precise models of the dynamics of the interacting black holes. It involves putting the black holes, the space between them, and the distant observer (us) on a grid or mesh, and refining the areas of the mesh with greater detail where it is needed.
Lousto’s team approached the problem with a methodology that he compares to Zeno’s first paradox. By halving and halving the mass ratio while adding internal grid refinement levels, they were able to go from 32:1 black hole mass ratios to 128:1 binary systems that undergo 13 orbits before merger. On Frontera, it required seven months of constant computation.
“Frontera was the perfect tool for the job,” Lousto said. “Our problem requires high performance processors, communication, and memory, and Frontera has all three.”
The simulation isn’t the end of the road. Black holes can have a variety of spins and configurations, which impact the amplitude and frequency of the gravitational waves their merger produces. Lousto would like to solve the equations 11 more times to get a good first range of possible “templates” to compare with future detections.
The results will help the designers of future Earth- and space-based gravitational wave detectors plan their instruments. These include advanced, third generation ground based gravitational wave detectors and the Laser Interferometer Space Antenna (LISA), which is targeted for launch in the mid-2030s.
The research may also help answer fundamental mysteries about black holes, such as how some can grow so big — millions of times the mass of the Sun.
“Supercomputers help us answer these questions,” Lousto said. “And the problems inspire new research and pass the torch to the next generation of students.” More

Researchers have found a way to produce nylon fibres that are smart enough to produce electricity from simple body movement, paving the way for smart clothes that will monitor our health through miniaturised sensors and charge our devices without any external power source.
This discovery — a collaboration between the University of Bath, the Max Planck Institute for Polymer Research in Germany and the University of Coimbra in Portugal — is based on breakthrough work on solution-processed piezoelectric nylons led by Professor Kamal Asadi from the Department of Physics at Bath and his former PhD student Saleem Anwar.
Piezoelectricity describes the phenomenon where mechanical energy is transformed into electric energy. To put it simply, when you tap on or distort a piezoelectric material, it generates a charge. Add a circuit and the charge can be taken away, stored in a capacitor for instance and then put to use — for example, to power your mobile phone.
While wearing piezoelectric clothing, such as a shirt, even a simple movement like swinging your arms would cause sufficient distortions in the shirt’s fibres to generate electricity.
Professor Asadi said: “There’s growing demand for smart, electronic textiles, but finding cheap and readily available fibres of electronic materials that are suitable for modern-day garments is a challenge for the textile industry.
“Piezoelectric materials make good candidates for energy harvesting from mechanical vibrations, such as body motion, but most of these materials are ceramic and contain lead, which is toxic and makes their integration in wearable electronics or clothes challenging.”
Scientists have been aware of the piezoelectric properties of nylon since the 1980s, and the fact that this material is lead-free and non-toxic has made it particularly appealing. However, the silky, human-made fabric often associated with cheap T-shirts and women’s stockings is “a very difficult material to handle,” according to Professor Asadi.

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“The challenge is to prepare nylon fibres that retain their piezoelectric properties,” he said.
In its raw polymer form, nylon is a white powder that can be blended with other materials (natural or human-made) and then moulded into myriad products, from clothes and toothbrush bristles to food packaging and car parts. It’s when nylon is reduced to a particular crystal form that it becomes piezoelectric. The established method for creating these nylon crystals is to melt, rapidly cool and then stretch the nylon. However this process results in thick slabs (known as ‘films’) that are piezoelectric but not suited to clothing. The nylon would need to be stretched to a thread to be of woven into garments, or to a thin film to be used in wearable electronics.
The challenge of producing thin piezoelectric nylon films was thought to be insurmountable, and initial enthusiasm for creating piezoelectric nylon garments turned to apathy, resulting in research in this area virtually grinding to a halt in the 1990s.
On a whim, Professor Asadi and Mr Anwar — a textile engineering- took a completely new approach to producing piezoelectric nylon thin films. They dissolved the nylon powder in an acid solvent rather than by melting it. However, they found that the finished film contained solvent molecules that were locked inside the materials, thereby preventing formation of the piezoelectric phase.
“We needed to find a way to remove the acid to make the nylon useable,” said Professor Asadi, who started this research at the Max Planck Institute for Polymer Research in Germany before moving to Bath in September.

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By chance, the pair discovered that by mixing the acid solution with the acetone (a chemical best known as a paint thinner or nail varnish remover), they were able to dissolve the nylon and then extract the acid efficiently, leaving the nylon film in a piezoelectric phase.
“The acetone bonds very strongly to the acid molecules, so when the acetone is evaporated from nylon solution, it takes the acid with it. What you’re left with is nylon in its piezoelectric crystalline phase. The next step is to turn nylon into yarns and then integrate it into fabrics.”
Developing piezoelectric fibres is a major step towards being able to produce electronic textiles with clear applications in the field of wearable electronics. The goal is to integrate electronic elements, such as sensors, in a fabric, and to generate power while we’re on the move. Most likely, the electricity harvested from the fibres of piezoelectric clothing would be stored in a battery nestled in a pocket. This battery would then connect to a device either via a cable or wirelessly.
“In years to come, we could be using our T-shirts to power a device such as our mobile phone as we walk in the woods, or for monitoring our health,” said Professor Asadi. More