Tag Archives: stretchable electronics

Soft things for your brain

A March 5, 2018 news item on Nanowerk describes the latest stretchable electrode (Note: A link has been removed),

Klas Tybrandt, principal investigator at the Laboratory of Organic Electronics at Linköping University [Sweden], has developed new technology for long-term stable neural recording. It is based on a novel elastic material composite, which is biocompatible and retains high electrical conductivity even when stretched to double its original length.

The result has been achieved in collaboration with colleagues in Zürich and New York. The breakthrough, which is crucial for many applications in biomedical engineering, is described in an article published in the prestigious scientific journal Advanced Materials (“High-Density Stretchable Electrode Grids for Chronic Neural Recording”).

A March 5, 2018 Linköping University press release, which originated the news item, gives more detail but does not mention that the nanowires are composed of titanium dioxide (you can find additional details in the abstract for the paper; link and citation will be provided later in this posting)),

The coupling between electronic components and nerve cells is crucial not only to collect information about cell signalling, but also to diagnose and treat neurological disorders and diseases, such as epilepsy.

It is very challenging to achieve long-term stable connections that do not damage neurons or tissue, since the two systems, the soft and elastic tissue of the body and the hard and rigid electronic components, have completely different mechanical properties.

Stretchable soft electrodeThe soft electrode stretched to twice its length Photo credit: Thor Balkhed

“As human tissue is elastic and mobile, damage and inflammation arise at the interface with rigid electronic components. It not only causes damage to tissue; it also attenuates neural signals,” says Klas Tybrandt, leader of the Soft Electronics group at the Laboratory of Organic Electronics, Linköping University, Campus Norrköping.

New conductive material

Klas Tybrandt has developed a new conductive material that is as soft as human tissue and can be stretched to twice its length. The material consists of gold coated titanium dioxide nanowires, embedded into silicone rubber. The material is biocompatible – which means it can be in contact with the body without adverse effects – and its conductivity remains stable over time.

“The microfabrication of soft electrically conductive composites involves several challenges. We have developed a process to manufacture small electrodes that also preserves the biocompatibility of the materials. The process uses very little material, and this means that we can work with a relatively expensive material such as gold, without the cost becoming prohibitive,” says Klas Tybrandt.

The electrodes are 50 µm [microns or micrometres] in size and are located at a distance of 200 µm from each other. The fabrication procedure allows 32 electrodes to be placed onto a very small surface. The final probe, shown in the photograph, has a width of 3.2 mm and a thickness of 80 µm.

The soft microelectrodes have been developed at Linköping University and ETH Zürich, and researchers at New York University and Columbia University have subsequently implanted them in the brain of rats. The researchers were able to collect high-quality neural signals from the freely moving rats for 3 months. The experiments have been subject to ethical review, and have followed the strict regulations that govern animal experiments.

Important future applications

Klas Tybrandt, researcher at Laboratory for Organic ElectronicsKlas Tybrandt, researcher at Laboratory for Organic Electronics Photo credit: Thor Balkhed

“When the neurons in the brain transmit signals, a voltage is formed that the electrodes detect and transmit onwards through a tiny amplifier. We can also see which electrodes the signals came from, which means that we can estimate the location in the brain where the signals originated. This type of spatiotemporal information is important for future applications. We hope to be able to see, for example, where the signal that causes an epileptic seizure starts, a prerequisite for treating it. Another area of application is brain-machine interfaces, by which future technology and prostheses can be controlled with the aid of neural signals. There are also many interesting applications involving the peripheral nervous system in the body and the way it regulates various organs,” says Klas Tybrandt.

The breakthrough is the foundation of the research area Soft Electronics, currently being established at Linköping University, with Klas Tybrandt as principal investigator.

A video has been made available (Note: For those who find any notion of animal testing disturbing; don’t watch the video even though it is an animation and does not feature live animals),

Here’s a link to and a citation for the paper,

High-Density Stretchable Electrode Grids for Chronic Neural Recording by Klas Tybrandt, Dion Khodagholy, Bernd Dielacher, Flurin Stauffer, Aline F. Renz, György Buzsáki, and János Vörös. Advanced Materials 2018. DOI: 10.1002/adma.201706520
 First published 28 February 2018

This paper is open access.

Gamechanging electronics with new ultrafast, flexible, and transparent electronics

There are two news bits about game-changing electronics, one from the UK and the other from the US.

United Kingdom (UK)

An April 3, 2017 news item on Azonano announces the possibility of a future golden age of electronics courtesy of the University of Exeter,

Engineering experts from the University of Exeter have come up with a breakthrough way to create the smallest, quickest, highest-capacity memories for transparent and flexible applications that could lead to a future golden age of electronics.

A March 31, 2017 University of Exeter press release (also on EurekAlert), which originated the news item, expands on the theme (Note: Links have been removed),

Engineering experts from the University of Exeter have developed innovative new memory using a hybrid of graphene oxide and titanium oxide. Their devices are low cost and eco-friendly to produce, are also perfectly suited for use in flexible electronic devices such as ‘bendable’ mobile phone, computer and television screens, and even ‘intelligent’ clothing.

Crucially, these devices may also have the potential to offer a cheaper and more adaptable alternative to ‘flash memory’, which is currently used in many common devices such as memory cards, graphics cards and USB computer drives.

The research team insist that these innovative new devices have the potential to revolutionise not only how data is stored, but also take flexible electronics to a new age in terms of speed, efficiency and power.

Professor David Wright, an Electronic Engineering expert from the University of Exeter and lead author of the paper said: “Using graphene oxide to produce memory devices has been reported before, but they were typically very large, slow, and aimed at the ‘cheap and cheerful’ end of the electronics goods market.

“Our hybrid graphene oxide-titanium oxide memory is, in contrast, just 50 nanometres long and 8 nanometres thick and can be written to and read from in less than five nanoseconds – with one nanometre being one billionth of a metre and one nanosecond a billionth of a second.”

Professor Craciun, a co-author of the work, added: “Being able to improve data storage is the backbone of tomorrow’s knowledge economy, as well as industry on a global scale. Our work offers the opportunity to completely transform graphene-oxide memory technology, and the potential and possibilities it offers.”

Here’s a link to and a citation for the paper,

Multilevel Ultrafast Flexible Nanoscale Nonvolatile Hybrid Graphene Oxide–Titanium Oxide Memories by V. Karthik Nagareddy, Matthew D. Barnes, Federico Zipoli, Khue T. Lai, Arseny M. Alexeev, Monica Felicia Craciun, and C. David Wright. ACS Nano, 2017, 11 (3), pp 3010–3021 DOI: 10.1021/acsnano.6b08668 Publication Date (Web): February 21, 2017

Copyright © 2017 American Chemical Society

This paper appears to be open access.

United States (US)

Researchers from Stanford University have developed flexible, biodegradable electronics.

A newly developed flexible, biodegradable semiconductor developed by Stanford engineers shown on a human hair. (Image credit: Bao lab)

A human hair? That’s amazing and this May 3, 2017 news item on Nanowerk reveals more,

As electronics become increasingly pervasive in our lives – from smart phones to wearable sensors – so too does the ever rising amount of electronic waste they create. A United Nations Environment Program report found that almost 50 million tons of electronic waste were thrown out in 2017–more than 20 percent higher than waste in 2015.

Troubled by this mounting waste, Stanford engineer Zhenan Bao and her team are rethinking electronics. “In my group, we have been trying to mimic the function of human skin to think about how to develop future electronic devices,” Bao said. She described how skin is stretchable, self-healable and also biodegradable – an attractive list of characteristics for electronics. “We have achieved the first two [flexible and self-healing], so the biodegradability was something we wanted to tackle.”

The team created a flexible electronic device that can easily degrade just by adding a weak acid like vinegar. The results were published in the Proceedings of the National Academy of Sciences (“Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics”).

“This is the first example of a semiconductive polymer that can decompose,” said lead author Ting Lei, a postdoctoral fellow working with Bao.

A May 1, 2017 Stanford University news release by Sarah Derouin, which originated the news item, provides more detail,

In addition to the polymer – essentially a flexible, conductive plastic – the team developed a degradable electronic circuit and a new biodegradable substrate material for mounting the electrical components. This substrate supports the electrical components, flexing and molding to rough and smooth surfaces alike. When the electronic device is no longer needed, the whole thing can biodegrade into nontoxic components.

Biodegradable bits

Bao, a professor of chemical engineering and materials science and engineering, had previously created a stretchable electrode modeled on human skin. That material could bend and twist in a way that could allow it to interface with the skin or brain, but it couldn’t degrade. That limited its application for implantable devices and – important to Bao – contributed to waste.

Flexible, biodegradable semiconductor on an avacado

The flexible semiconductor can adhere to smooth or rough surfaces and biodegrade to nontoxic products. (Image credit: Bao lab)

Bao said that creating a robust material that is both a good electrical conductor and biodegradable was a challenge, considering traditional polymer chemistry. “We have been trying to think how we can achieve both great electronic property but also have the biodegradability,” Bao said.

Eventually, the team found that by tweaking the chemical structure of the flexible material it would break apart under mild stressors. “We came up with an idea of making these molecules using a special type of chemical linkage that can retain the ability for the electron to smoothly transport along the molecule,” Bao said. “But also this chemical bond is sensitive to weak acid – even weaker than pure vinegar.” The result was a material that could carry an electronic signal but break down without requiring extreme measures.

In addition to the biodegradable polymer, the team developed a new type of electrical component and a substrate material that attaches to the entire electronic component. Electronic components are usually made of gold. But for this device, the researchers crafted components from iron. Bao noted that iron is a very environmentally friendly product and is nontoxic to humans.

The researchers created the substrate, which carries the electronic circuit and the polymer, from cellulose. Cellulose is the same substance that makes up paper. But unlike paper, the team altered cellulose fibers so the “paper” is transparent and flexible, while still breaking down easily. The thin film substrate allows the electronics to be worn on the skin or even implanted inside the body.

From implants to plants

The combination of a biodegradable conductive polymer and substrate makes the electronic device useful in a plethora of settings – from wearable electronics to large-scale environmental surveys with sensor dusts.

“We envision these soft patches that are very thin and conformable to the skin that can measure blood pressure, glucose value, sweat content,” Bao said. A person could wear a specifically designed patch for a day or week, then download the data. According to Bao, this short-term use of disposable electronics seems a perfect fit for a degradable, flexible design.

And it’s not just for skin surveys: the biodegradable substrate, polymers and iron electrodes make the entire component compatible with insertion into the human body. The polymer breaks down to product concentrations much lower than the published acceptable levels found in drinking water. Although the polymer was found to be biocompatible, Bao said that more studies would need to be done before implants are a regular occurrence.

Biodegradable electronics have the potential to go far beyond collecting heart disease and glucose data. These components could be used in places where surveys cover large areas in remote locations. Lei described a research scenario where biodegradable electronics are dropped by airplane over a forest to survey the landscape. “It’s a very large area and very hard for people to spread the sensors,” he said. “Also, if you spread the sensors, it’s very hard to gather them back. You don’t want to contaminate the environment so we need something that can be decomposed.” Instead of plastic littering the forest floor, the sensors would biodegrade away.

As the number of electronics increase, biodegradability will become more important. Lei is excited by their advancements and wants to keep improving performance of biodegradable electronics. “We currently have computers and cell phones and we generate millions and billions of cell phones, and it’s hard to decompose,” he said. “We hope we can develop some materials that can be decomposed so there is less waste.”

Other authors on the study include Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister McGuire, and Jeffrey Tok of Stanford University; Tsung-Ching Huang of Hewlett Packard Enterprise; and Lei-Lai Shao and Kwang-Ting Cheng of University of California, Santa Barbara.

The research was funded by the Air Force Office for Scientific Research; BASF; Marie Curie Cofund; Beatriu de Pinós fellowship; and the Kodak Graduate Fellowship.

Here’s a link to and a citation for the team’s latest paper,

Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics by Ting Lei, Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister F. McGuire, Tsung-Ching Huang, Leilai Shao, Kwang-Ting Cheng, Jeffrey B.-H. Tok, and Zhenan Bao. PNAS 2017 doi: 10.1073/pnas.1701478114 published ahead of print May 1, 2017

This paper is behind a paywall.

The mention of cellulose in the second item piqued my interest so I checked to see if they’d used nanocellulose. No, they did not. Microcrystalline cellulose powder was used to constitute a cellulose film but they found a way to render this film at the nanoscale. From the Stanford paper (Note: Links have been removed),

… Moreover, cellulose films have been previously used as biodegradable substrates in electronics (28⇓–30). However, these cellulose films are typically made with thicknesses well over 10 μm and thus cannot be used to fabricate ultrathin electronics with substrate thicknesses below 1–2 μm (7, 18, 19). To the best of our knowledge, there have been no reports on ultrathin (1–2 μm) biodegradable substrates for electronics. Thus, to realize them, we subsequently developed a method described herein to obtain ultrathin (800 nm) cellulose films (Fig. 1B and SI Appendix, Fig. S8). First, microcrystalline cellulose powders were dissolved in LiCl/N,N-dimethylacetamide (DMAc) and reacted with hexamethyldisilazane (HMDS) (31, 32), providing trimethylsilyl-functionalized cellulose (TMSC) (Fig. 1B). To fabricate films or devices, TMSC in chlorobenzene (CB) (70 mg/mL) was spin-coated on a thin dextran sacrificial layer. The TMSC film was measured to be 1.2 μm. After hydrolyzing the film in 95% acetic acid vapor for 2 h, the trimethylsilyl groups were removed, giving a 400-nm-thick cellulose film. The film thickness significantly decreased to one-third of the original film thickness, largely due to the removal of the bulky trimethylsilyl groups. The hydrolyzed cellulose film is insoluble in most organic solvents, for example, toluene, THF, chloroform, CB, and water. Thus, we can sequentially repeat the above steps to obtain an 800-nm-thick film, which is robust enough for further device fabrication and peel-off. By soaking the device in water, the dextran layer is dissolved, starting from the edges of the device to the center. This process ultimately releases the ultrathin substrate and leaves it floating on water surface (Fig. 3A, Inset).

Finally, I don’t have any grand thoughts; it’s just interesting to see different approaches to flexible electronics.

Turning gold into see-through rubber for an updated Rumpelstiltskin story

Rumpelstiltskin is a fairy tale whereby a young girl is trapped by her father’s lie that she can spin straw into gold. She is forced to spin gold by the King under pain of execution when an imp offers to help in exchange for various goods. As she succeeds each time, the King demands more until finally she has nothing left to trade for the imp’s help. Well, there is one last thing: her first-born child. She agrees to the bargain and she marries the King. On the birth of their first child, the imp reappears and under pressure of her pleas makes one last bargain. She must guess his name which she does, Rumplestiltskin. (The full story along with variants is here in this Wikipedia entry.)

With this latest research, we have a reverse Rumpelstiltskin story where gold is turned into something else according to a June 13, 2016 news item on Nanowerk (Note: A link has been removed),

Flexible solar panels that could be rolled up for easy transport and other devices would benefit from transparent metal electrodes that can conduct electricity, are stretchable, and resist damage following repeated stretching. Researchers found that topology and the adhesion between a metal nanomesh and the underlying substrate played key roles in creating such materials. The metal nanomesh can be stretched to three times its length while maintaining a transparency comparable to similar commercial materials used in solar cells and flat panel displays. Also, nanomeshes on pre-stretched slippery substrates led to electrodes that didn’t wear out, even after being stretched 50,000 times (Proceedings of the National Academy of Sciences, “Fatigue-free, superstretchable, transparent, and biocompatible metal electrodes”).

Tuning topology and adhesion of metal nanomeshes has led to super stretchable, transparent electrodes that don’t wear out. The scanning electron microscopy image shows the structure of a gold mesh created with a special lithographic technique that controlled the dimensions of the mesh structure. Optimizing this structure and its adhesion to the substrate was key to achieving super stretchability and long lifetimes in use—nanomeshes on pre-stretched slippery substrates did not show signs of wear even after repeated stretching, up to 50,000 cycles.

Tuning topology and adhesion of metal nanomeshes has led to super stretchable, transparent electrodes that don’t wear out. The scanning electron microscopy image shows the structure of a gold mesh created with a special lithographic technique that controlled the dimensions of the mesh structure. Optimizing this structure and its adhesion to the substrate was key to achieving super stretchability and long lifetimes in use—nanomeshes on pre-stretched slippery substrates did not show signs of wear even after repeated stretching, up to 50,000 cycles.

A June 9, 2016 US Dept. of Energy news release,which originated the news item, provides more detail,

Next-generation flexible electronics require highly stretchable and transparent electrodes. Fatigue, structural damage due to repeated use, is deadly in metals as it leads to poor conductivity and it commonly occurs in metals with repeated stretching—even with short elongations. However, few electronic conductors are transparent and stretchable, even fewer can be cyclically stretched to a large strain without causing fatigue. Now researchers led by the University of Houston found that optimizing topology of a metal nanomesh and its adhesion to an underlying substrate improved stretchability and eliminated fatigue, while maintaining transparency. A special lithographic technique called “grain boundary lithography” controlled the dimensions of the mesh structure. The metal nanomesh remained transparent after being stretched to three times its length. Gold nanomeshes on prestretched slippery substrates impressively showed no wear when stretched 50,000 times. The slippery surface advantageously allowed the structure of the nanomesh to reorient to relax the stress. Such electrically conductive, flexible, and transparent electrodes could lead to next-generation flexible electronics such as advanced solar cells.  The nanomesh electrodes are also promising for implantable electronics because the nanomeshes are biocompatible.

Here’s a link to and a citation for the paper,

Fatigue-free, superstretchable, transparent, and biocompatible metal electrodes by Chuan Fei Guo, Qihan Liu, Guohui Wang, Yecheng Wang, Zhengzheng Shi, Zhigang Suo, Ching-Wu Chu, and Zhifeng Ren. Proceedings of the National Academy of Sciences, vol. 112 no. 40,  12332–12337, doi: 10.1073/pnas.1516873112

This paper appears to be open access.

A new Shrinky Dinks story: super-wrinkled and super-crumpled graphene for self-cleaning surfaces and other applications

Caption: Wrinkles and crumples, introduced by placing graphene on shrinky polymers, can enhance graphene's properties. Credit: Hurt and Wong Labs / Brown University

Caption: Wrinkles and crumples, introduced by placing graphene on shrinky polymers, can enhance graphene’s properties. Credit: Hurt and Wong Labs / Brown University

A March 21, 2016 news item on ScienceDaily describes how Brown University (US) researchers developed super-wrinkled and super-crumpled graphene,

Crumple a piece of paper and it’s probably destined for the trash can, but new research shows that repeatedly crumpling sheets of the nanomaterial graphene can actually enhance some of its properties. In some cases, the more crumpled the better.

The research by engineers from Brown University shows that graphene, wrinkled and crumpled in a multi-step process, becomes significantly better at repelling water–a property that could be useful in making self-cleaning surfaces. Crumpled graphene also has enhanced electrochemical properties, which could make it more useful as electrodes in batteries and fuel cells.

A March 21, 2016 Brown University news release (also on EurekAlert), which originated the news item, provides more detail about the current and previous research,

This new research builds on previous work done by Robert Hurt and Ian Wong, from Brown’s School of Engineering. The team had previously showed that by introducing wrinkles into graphene, they could make substrates for culturing cells that were more similar to the complex environments in which cells grow in the body. For this latest work, the researchers led by Po-Yen Chen, a Hibbit postdoctoral fellow, wanted to build more complex architectures incorporating both wrinkles and crumples. “I wanted to see if there was a way to create higher-generational structures,” Chen said.

To do that, the researchers deposited layers of graphene oxide onto shrink films–polymer membranes that shrink when heated (kids may know these as Shrinky Dinks [emphasis mine]). As the films shrink, the graphene on top is compressed, causing it to wrinkle and crumple. To see what kind of structures they could create, the researchers compressed same graphene sheets multiple times. After the first shrink, the film was dissolved away, and the graphene was placed in a new film to be shrunk again.

The researchers experimented with different configurations in the successive generations of shrinking. For example, sometimes they clamped opposite ends of the films, which caused them to shrink only along one axis. Clamped films yielded graphene sheets with periodic, basically parallel wrinkles across its surface. Unclamped films shrank in two dimensions, both length- and width-wise, creating a graphene surface that was crumpled in random shapes.

The team experimented with those different modes of shrinking over three successive generations. For example, they might shrink the same graphene sheet on a clamped film, then an unclamped film, then clamped again; or unclamped, clamped, unclamped. They also rotated the graphene in different configurations between shrinkings, sometimes placing the sheet perpendicular to its original orientation.

The team found that the multi-generational approach could substantially compress the graphene sheets, making them as small as one-fortieth their original size. They also showed that successive generations could create interesting patterns along the surface–wrinkles and crumples that were superimposed onto each other, for example.

“As you go deeper into the generations you tend to get larger wavelength structures with the original, smaller wavelength structure from earlier generations built into them,” said Robert Hurt, a professor of engineering at Brown and one of the paper’s corresponding authors.

A sheet that was shrunk clamped, unclamped, and then clamped looked different from ones that were unclamped, clamped, unclamped, for example.

“The sequence matters,” said Wong, also a corresponding author on the paper. “It’s not like multiplication where 2 times 3 is the same as 3 times 2. The material has a ‘memory’ and we get different results when we wrinkle or crumple in a different order.”

The researchers generated a kind of taxonomy of structures born from different shrinking configurations. They then tested several of those structures to see how they altered the properties of the graphene sheets.

Enhanced properties

They showed that a highly crumpled graphene surface becomes superhydrophobic–able to resist wetting by water. When water touches a hydrophobic surface, it beads up and rolls off. When the contact angle of those water beads with an underlying surface exceeds 160 degrees–meaning very little of the water bead’s surface touches the material–the material is said to be superhydrophobic. The researchers showed that they could make superhydrophobic graphene with three unclamped shrinks.

The team also showed that crumpling could enhance the electrochemical behaviors of graphene, which could be useful in next-generation energy storage and generation. The research showed that crumpled graphene used as a battery electrode had as much as a 400 percent increase in electrochemical current density over flat graphene sheets. That increase in current density could make for vastly more efficient batteries.

“You don’t need a new material to do it,” Chen said. “You just need to crumple the graphene.”

In additional to batteries and water resistant coatings, graphene compressed in this manner might also be useful in stretchable electronics–a wearable sensor, for example.

The group plans to continue experimenting with different ways of generating structures on graphene and other nanomaterials.

“There are many new two-dimensional nanomaterials that have interesting properties, not just graphene,” Wong said. “So other materials or combinations of materials may also organize into interesting structures with unexpected functionalities.”

Here’s a link to and a citation for the paper,

Multiscale Graphene Topographies Programmed by Sequential Mechanical Deformation by Po-Yen Chen, Jaskiranjeet Sodhi, Yang Qiu, Thomas M. Valentin, Ruben Spitz Steinberg, Zhongying Wang, Robert H. Hurt, and Ian Y. Wong. Advanced Materials DOI: 10.1002/adma.201506194 Article first published online: 21 MAR 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

As for Shrinky Dinks, I first featured this material and its use in science research in an Aug. 16, 2010 posting about Shrinky Dinks and nanopatterning. It was originally developed by Betty J. Morris as craft material for children. Both she and the scientist kindly answered some followup questions inspired by the original news release and published in the 2010 post.

L’Oréal introduces wearable cosmetic electronic patch (my UV patch)

You don’t (well, I don’t) expect a cosmetics company such as L’Oréal to introduce products at the Consumer Electronics Show (CES) held in Las Vegas (Nevada, US) annually (Jan. 6 – 9, 2016).

A Jan. 6, 2016 article by Zoe Kleinman for BBC (British Broadcasting Corporation) news online explains,

Beauty giant L’Oreal has unveiled a smart skin patch that can track the skin’s exposure to harmful UV rays at the technology show CES in Las Vegas.

The product will be launched in 16 countries including the UK this summer, and will be available for free [emphasis mine].

It contains a photosensitive blue dye, which changes colour when exposed to ultraviolet light.

But the wearer must take a photo of it and then upload it to an app to see the results.

It’s a free app, eh? A cynic might suggest that the company will be getting free data in return.

A Jan. 6, 2016 L’Oréal press release, also on PR Newswire, provides more details (Note: Links have been removed),

Today [Jan. 6, 2016] at the Consumer Electronics Show, L’Oréal unveiled My UV Patch, the first-ever stretchable skin sensor designed to monitor UV exposure and help consumers educate themselves about sun protection. The new technology arrives at a time when sun exposure has become a major health issue, with 90% of nonmelanoma skin cancers being associated with exposure to ultraviolet (UV) radiation from sun* in addition to attributing to skin pigmentation and photoaging.

To address these growing concerns, L’Oréal Group’s leading dermatological skincare brand, La Roche-Posay, is introducing a first-of-its kind stretchable electronic, My UV Patch. The patch is a transparent adhesive that, unlike the rigid wearables currently on the market, stretches and adheres directly to any area of skin that consumers want to monitor. Measuring approximately one square inch in area and 50 micrometers thick – half the thickness of an average strand of hair – the patch contains photosensitive dyes that factor in the baseline skin tone and change colors when exposed to UV rays to indicate varying levels of sun exposure.

Consumers will be able to take a photo of the patch and upload it to the La Roche-Posay My UV Patch mobile app, which analyzes the varying photosensitive dye squares to determine the amount of UV exposure the wearer has received. The My UV Patch mobile app will be available on both iOS and Android, incorporating Near Field Communications (NFC)-enabled technology into the patch-scanning process for Android. My UV Patch is expected to be made available to consumers later this year.

“Connected technologies have the potential to completely disrupt how we monitor the skin’s exposure to various external factors, including UV,” says Guive Balooch, Global Vice President of L’Oréal’s Technology Incubator. “Previous technologies could only tell users the amount of potential sun exposure they were receiving per hour while wearing a rigid, non-stretchable device. The key was to design a sensor that was thin, comfortable and virtually weightless so people would actually want to wear it. We’re excited to be the first beauty company entering the stretchable electronics field and to explore the many potential applications for this technology within our industry and beyond.”

My UV Patch was developed by L’Oréal’s U.S.-based Technology Incubator, a business division dedicated entirely to technological innovation, alongside MC10, Inc., a leading stretchable electronics company using cutting-edge innovation to create the most intelligent, stretchable systems for biometric healthcare analytics. L’Oréal also worked with PCH who design engineered the sensor. The stretchable, peel-and-stick wearable unites L’Oréal Group’s extensive scientific research on the skin and expertise with UV protection with MC10’s strong technological capabilities in physiological sensing and pattern recognition algorithms to measure skin changes over time, and PCH’s 20-year experience in product development, manufacturing and supply chain.

“With My UV Patch, L’Oréal is taking the lead in developing the next generation of smart skincare technology powered by MC10’s unique, stretchable electronics platform, that truly addresses a consumer need,” said Scott Pomerantz, CEO of MC10. “This partnership with L’Oréal marks an exciting new milestone for MC10 and underscores the intersection of tech and beauty and the boundless potential of connected devices within the beauty market.”

*Source: Skin Cancer Foundation 2015

“Together with La Roche-Posay dermatologists like myself, we share a mission to help increase sun safe behavior,” added Alysa Herman, MD.  “La Roche-Posay recently commissioned a global study in 23 countries, which surveyed 19,000 women and men and found a huge gap in consumer behavior: even though 92% were aware that unprotected sun exposure can cause health problems, only 26% of Americans protect themselves all year round, whatever the season. With the new My UV Patch, for the first time, we are leveraging technology to help incite a true behavioral change through real-time knowledge. ”

About L’Oréal

L’Oréal has devoted itself to beauty for over 105 years. With its unique international portfolio of 32 diverse and complementary brands, the Group generated sales amounting to 22.5 billion euros in 2014 and employs 78,600 people worldwide. As the world’s leading beauty company, L’Oréal is present across all distribution networks: mass market, department stores, pharmacies and drugstores, hair salons, travel retail and branded retail.

Research and innovation, and a dedicated research team of 3,700 people, are at the core of L’Oréal’s strategy, working to meet beauty aspirations all over the world and attract one billion new consumers in the years to come. L’Oréal’s new sustainability commitment for 2020 “Sharing Beauty With All” sets out ambitious sustainable development objectives across the Group’s value chain. www.loreal.com


Recommended by more than 25,000 dermatologists worldwide, La Roche-Posay offers a unique range of daily skincare developed with dermatologists to meet their standards in efficacy, tolerance and elegant textures for increased compliance. The products, which are developed using a strict formulation charter, include a minimal number of ingredients to reduce side effects and reactivity and are formulated with effective ingredients at optimal concentrations for increased efficacy. Additionally, La Roche-Posay products undergo stringent clinical testing to guarantee efficacy and safety, even on sensitive skin.

About MC10

MC10’s mission is to improve human health through digital healthcare solutions. The company combines its proprietary ultra-thin, stretchable body-worn sensors with advanced analytics to unlock health insights from physiological data. MC10 partners with healthcare organizations and researchers to advance medical knowledge and create monitoring and diagnostic solutions for patients and physicians. Backed by a strong syndicate of financial and strategic investors, MC10 has received widespread recognition for its innovative technology, including being named a 2014 CES Innovation in Design Honoree. MC10 is headquartered in Lexington, MA.  Visit MC10 online at www.mc10inc.com.

About PCH

PCH designs custom product solutions for startups and Fortune 500 companies. Whether design engineering and development, manufacturing and fulfilment, distribution or retail, PCH takes on the toughest challenges. If it can be imagined, it can be made. At PCH, we make. www.pchintl.com. Twitter: @PCH_Intl

Ryan O’Hare’s Jan. 6, 2016 article for the UK’s DailyMailOnline provides some additional technology details and offers images of the proposed patch, not reproduced here, (Note: A link has been removed),

The patch and free app, which will be launched in the summer, have been welcomed by experts.

Dr Christopher Rowland Payne, consultant dermatologist to The London Clinic, said: ‘This is an exciting device that will motivate people in a positive way to take control of their sun exposure and will encourage them to know when it is time to leave the sun or to reapply their sunscreen.

‘It is an ingenious way of giving people the information they need. I hope it will also get people talking to each other about safe sun exposure.’

The technology used in the UV patches is based on ‘biostamps’ designed by tech firm MC10.

They were originally designed to help medical teams measure the health of their patients either remotely, or without the need for large expensive machinery.

Motorola were exploring the patches as an alternative to using traditional passwords for security and access to devices.

Getting back to this ‘free app’ business, the data gathered could be used to help the company create future skincare products. If they are planning to harvest your data, there’s nothing inherently wrong with the practice but the company isn’t being as straightforward as it could be. In any event, you may want to take a good at the user agreement and decide for yourself.

Finally, I think it’s time to acknowledge medical writer, Dr. Susan Baxter, (not for the first time and not the last either) as I likely wouldn’t have thought past my general cynicism about data harvesting for a reason, additional to any humanitarian motivations L’Oréal might have, for offering a free mobile app. She doesn’t post on her blog that frequently but it’s always worth taking a look (http://www.susanbaxter.ca/blog-page/) and I recommend this July 30, 2014 post titled, ‘Civil Scientific Discourse RIP’ which focuses on vaccination and anti-vaccination positions. Do not expect a comfortable read.

A wearable, stretchable body sensor based on chewing gum and carbon nanotubes

Any work which features a scientist chewing gum preparatory to using it for research purposes should be widely disseminated. In all the talk about science and equipment, it’s easy to forget that scientists are capable of great ingenuity with simple, every day materials. Also, the researchers are Canadian and based at the University of Manitoba. From a Dec. 2, 2015 American Chemical Society (ACS) news release (also on EurekAlert),

Body sensors, which were once restricted to doctors’ offices, have come a long way. They now allow any wearer to easily track heart rate, steps and sleep cycles around the clock. Soon, they could become even more versatile — with the help of chewing gum. Scientists report in the journal ACS Applied Materials & Interfaces a unique sensing device made of gum and carbon nanotubes that can move with your most bendable parts and track your breathing.

Most conventional sensors today are very sensitive and detect the slightest movement, but many are made out of metal. That means when they’re twisted or pulled too much, they stop working. But for sensors to monitor the full range of a body’s bending and stretching, they need a lot more give. To meet that need, some researchers have tried developing sensors using stretchy plastics and silicones. But what they gained in flexibility, they lost in sensitivity. Malcolm Xing and colleagues found a better solution right under their noses — and in their mouths.

To make their supple sensor, a team member chewed a typical piece of gum for 30 minutes, washed it with ethanol and let it sit overnight. The researchers then added a solution of carbon nanotubes, the sensing material. Simple pulling and folding coaxed the tubes to align properly. Human finger-bending and head-turning tests showed the material could keep working with high sensitivity even when strained 530 percent. The sensor also could detect humidity changes, a feature that could be used to track breathing, which releases water vapor with every exhale.

Here’s a link to and a citation for the paper,

Gum Sensor: A Stretchable, Wearable, and Foldable Sensor Based on Carbon Nanotube/Chewing Gum Membrane by Mohammad Ali Darabi, Ali Khosrozadeh, Quan Wang, and Malcolm Xing. ACS Appl. Mater. Interfaces, 2015, 7 (47), pp 26195–26205 DOI: 10.1021/acsami.5b08276 Publication Date (Web): November 2, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

This video lets you see the gum/CNT material at work,


Clothing which turns you into a billboard

This work from a Belgian-Dutch initiative has the potential to turn us into billboards. From a Sept. 2, 2015 news item on Nanowerk,

Researchers from Holst Centre (set up by TNO and imec), imec and CMST, imec’s associated lab at Ghent University [Belgium], have demonstrated the world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles. This paves the way to wearable displays in clothing providing users with feedback.

Here’s what it looks like,

A Sept. 2, 2015 Holst Centre press release, which originated the news item, provides more details,

“Wearable devices allow people to monitor their fitness and health so they can live full and active lives for longer. But to maximize the benefits wearables can offer, they need to be able to provide feedback on what users are doing as well as measuring it. By combining imec’s patented stretch technology with our expertise in active-matrix backplanes and integrating electronics into fabrics, we’ve taken a giant step towards that possibility,” says Edsger Smits, Senior research scientist at Holst Centre.

The conformable display is very thin and mechanically stretchable. A fine-grain version of the proven meander interconnect technology was developed by the CMST lab at Ghent University and Holst Centre to link standard (rigid) LEDs into a flexible and stretchable display. The LED displays are fabricated on a polyimide substrate and encapsulated in rubber, allowing the displays to be laminated in to textiles that can be washed. Importantly, the technology uses fabrication steps that are known to the manufacturing industry, enabling rapid industrialization.

Following an initial demonstration at the Society for Information Display’s Display Week in San Jose, USA earlier this year, Holst Centre has presented the next generation of the display at the International Meeting on Information Display (IMID) in Daegu, Korea, 18-21 August 2015. Smaller LEDs are now mounted on an amorphous indium-gallium-zinc oxide (a-IGZO) TFT backplane that employs a two-transistor and one capacitor (2T-1C) pixel engine to drive the LEDs. These second-generation displays offer higher pitch and increased, average brightness. The presentation will feature a 32×32 pixel demonstrator with a resolution of 13 pixels per inch (ppi) and average brightness above 200 candelas per square meter (cd/m2). Work is ongoing to further industrialize this technology.

There are some references for the work offered at the end of the press release but I believe they are citing their conference presentations,

9.4: Stretchable 45 × 80 RGB LED Display Using Meander Wiring Technology, Ohmae et al. SID 2015, June 2015

1.2: Rollable, Foldable and Stretchable Displays, Gelinck et al. IMID, Aug. 2015.

13.4 A conformable Active Matrix LED Display, Tripathi et al. IMID, Aug. 2015

For anyone interested in imec formerly the Interuniversity Microelectronics Centre, there’s this Wikipedia entry, and in TNO (Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek in Dutch), there’s this Wikipedia entry.

Hyper stretchable nanogenerator

There’s a lot of talk about flexibility, stretchability and bendability in electronics and the latest is coming from Korea. An April 13, 2015 Korea Advanced Institute for Science and Technology (KAIST) news release on EurekAlert describes the situation and the Korean scientists’ most recent research into stretchable electronics,

A research team led by Professor Keon Jae Lee of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed a hyper-stretchable elastic-composite energy harvesting device called a nanogenerator.

Flexible electronics have come into the market and are enabling new technologies like flexible displays in mobile phone, wearable electronics, and the Internet of Things (IoTs). However, is the degree of flexibility enough for most applications? For many flexible devices, elasticity is a very important issue. For example, wearable/biomedical devices and electronic skins (e-skins) should stretch to conform to arbitrarily curved surfaces and moving body parts such as joints, diaphragms, and tendons. They must be able to withstand the repeated and prolonged mechanical stresses of stretching. In particular, the development of elastic energy devices is regarded as critical to establish power supplies in stretchable applications. Although several researchers have explored diverse stretchable electronics, due to the absence of the appropriate device structures and correspondingly electrodes, researchers have not developed ultra-stretchable and fully-reversible energy conversion devices properly.

Recently, researchers from KAIST and Seoul National University (SNU) have collaborated and demonstrated a facile methodology to obtain a high-performance and hyper-stretchable elastic-composite generator (SEG) using very long silver nanowire-based stretchable electrodes. Their stretchable piezoelectric generator can harvest mechanical energy to produce high power output (~4 V) with large elasticity (~250%) and excellent durability (over 104 cycles). These noteworthy results were achieved by the non-destructive stress- relaxation ability of the unique electrodes as well as the good piezoelectricity of the device components. The new SEG can be applied to a wide-variety of wearable energy-harvesters to transduce biomechanical-stretching energy from the body (or machines) to electrical energy.

Professor Lee said, “This exciting approach introduces an ultra-stretchable piezoelectric generator. It can open avenues for power supplies in universal wearable and biomedical applications as well as self-powered ultra-stretchable electronics.”

Here’s a link to and a citation for the paper,

A Hyper-Stretchable Elastic-Composite Energy Harvester by Chang Kyu Jeong, Jinhwan Lee, Seungyong Han, Jungho Ryu, Geon-Tae Hwang, Dae Yong Park, Jung Hwan Park, Seung Seob Lee, Mynghwan Byun, Seung Hwan Ko, and Keon Jae Lee. Advanced Materials DOI: 10.1002/adma.201500367 30 March 2015Full

This paper is behind a paywall.

The researchers have prepared a short video (22 secs. and silent),

3D printing soft robots and flexible electronics with metal alloys

This research comes from Purdue University (Indiana, US) which seems to be on a publishing binge these days. From an April 7, 2015 news item on Nanowerk,

New research shows how inkjet-printing technology can be used to mass-produce electronic circuits made of liquid-metal alloys for “soft robots” and flexible electronics.

Elastic technologies could make possible a new class of pliable robots and stretchable garments that people might wear to interact with computers or for therapeutic purposes. However, new manufacturing techniques must be developed before soft machines become commercially feasible, said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University.

“We want to create stretchable electronics that might be compatible with soft machines, such as robots that need to squeeze through small spaces, or wearable technologies that aren’t restrictive of motion,” she said. “Conductors made from liquid metal can stretch and deform without breaking.”

A new potential manufacturing approach focuses on harnessing inkjet printing to create devices made of liquid alloys.

“This process now allows us to print flexible and stretchable conductors onto anything, including elastic materials and fabrics,” Kramer said.

An April 7, 2015 Purdue University news release (also on EurekAlert) by Emil Venere, which originated the news item, expands on the theme,

A research paper about the method will appear on April 18 [2015] in the journal Advanced Materials. The paper generally introduces the method, called mechanically sintered gallium-indium nanoparticles, and describes research leading up to the project. It was authored by postdoctoral researcher John William Boley, graduate student Edward L. White and Kramer.

A printable ink is made by dispersing the liquid metal in a non-metallic solvent using ultrasound, which breaks up the bulk liquid metal into nanoparticles. This nanoparticle-filled ink is compatible with inkjet printing.

“Liquid metal in its native form is not inkjet-able,” Kramer said. “So what we do is create liquid metal nanoparticles that are small enough to pass through an inkjet nozzle. Sonicating liquid metal in a carrier solvent, such as ethanol, both creates the nanoparticles and disperses them in the solvent. Then we can print the ink onto any substrate. The ethanol evaporates away so we are just left with liquid metal nanoparticles on a surface.”

After printing, the nanoparticles must be rejoined by applying light pressure, which renders the material conductive. This step is necessary because the liquid-metal nanoparticles are initially coated with oxidized gallium, which acts as a skin that prevents electrical conductivity.

“But it’s a fragile skin, so when you apply pressure it breaks the skin and everything coalesces into one uniform film,” Kramer said. “We can do this either by stamping or by dragging something across the surface, such as the sharp edge of a silicon tip.”

The approach makes it possible to select which portions to activate depending on particular designs, suggesting that a blank film might be manufactured for a multitude of potential applications.

“We selectively activate what electronics we want to turn on by applying pressure to just those areas,” said Kramer, who this year was awarded an Early Career Development award from the National Science Foundation, which supports research to determine how to best develop the liquid-metal ink.

The process could make it possible to rapidly mass-produce large quantities of the film.

Future research will explore how the interaction between the ink and the surface being printed on might be conducive to the production of specific types of devices.

“For example, how do the nanoparticles orient themselves on hydrophobic versus hydrophilic surfaces? How can we formulate the ink and exploit its interaction with a surface to enable self-assembly of the particles?” she said.

The researchers also will study and model how individual particles rupture when pressure is applied, providing information that could allow the manufacture of ultrathin traces and new types of sensors.

Here’s a link to and a citation for the paper,

Nanoparticles: Mechanically Sintered Gallium–Indium Nanoparticles by John William Boley, Edward L. White and Rebecca K. Kramer. Advanced Materials Volume 27, Issue 14, page 2270, April 8, 2015 DOI: 10.1002/adma.201570094 Article first published online: 7 APR 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

Bend it, twist it, any way you want to—a foldable lithium-ion battery

Feb. 26, 2013 news item on ScienceDaily features an extraordinary lithium-ion battery,

Northwestern University’s Yonggang Huang and the University of Illinois’ John A. Rogers are the first to demonstrate a stretchable lithium-ion battery — a flexible device capable of powering their innovative stretchable electronics.

No longer needing to be connected by a cord to an electrical outlet, the stretchable electronic devices now could be used anywhere, including inside the human body. The implantable electronics could monitor anything from brain waves to heart activity, succeeding where flat, rigid batteries would fail.

Huang and Rogers have demonstrated a battery that continues to work — powering a commercial light-emitting diode (LED) — even when stretched, folded, twisted and mounted on a human elbow. The battery can work for eight to nine hours before it needs recharging, which can be done wirelessly.

The researchers at Northwestern have produced a video where they demonstrate the battery’s ‘stretchability’,

The Northwestern University Feb. 26, 2013 news release by Megan Fellman, which originated the news item, offers this detail,

“We start with a lot of battery components side by side in a very small space, and we connect them with tightly packed, long wavy lines,” said Huang, a corresponding author of the paper. “These wires provide the flexibility. When we stretch the battery, the wavy interconnecting lines unfurl, much like yarn unspooling. And we can stretch the device a great deal and still have a working battery.”

The power and voltage of the stretchable battery are similar to a conventional lithium-ion battery of the same size, but the flexible battery can stretch up to 300 percent of its original size and still function.

Huang and Rogers have been working together for the last six years on stretchable electronics, and designing a cordless power supply has been a major challenge. Now they have solved the problem with their clever “space filling technique,” which delivers a small, high-powered battery.

For their stretchable electronic circuits, the two developed “pop-up” technology that allows circuits to bend, stretch and twist. They created an array of tiny circuit elements connected by metal wire “pop-up bridges.” When the array is stretched, the wires — not the rigid circuits — pop up.

This approach works for circuits but not for a stretchable battery. A lot of space is needed in between components for the “pop-up” interconnect to work. Circuits can be spaced out enough in an array, but battery components must be packed tightly to produce a powerful but small battery. There is not enough space between battery components for the “pop-up” technology to work.

Huang’s design solution is to use metal wire interconnects that are long, wavy lines, filling the small space between battery components. (The power travels through the interconnects.)

The unique mechanism is a “spring within a spring”: The line connecting the components is a large “S” shape and within that “S” are many smaller “S’s.” When the battery is stretched, the large “S” first stretches out and disappears, leaving a line of small squiggles. The stretching continues, with the small squiggles disappearing as the interconnect between electrodes becomes taut.

“We call this ordered unraveling,” Huang said. “And this is how we can produce a battery that stretches up to 300 percent of its original size.”

The stretching process is reversible, and the battery can be recharged wirelessly. The battery’s design allows for the integration of stretchable, inductive coils to enable charging through an external source but without the need for a physical connection.

Huang, Rogers and their teams found the battery capable of 20 cycles of recharging with little loss in capacity. The system they report in the paper consists of a square array of 100 electrode disks, electrically connected in parallel.

I’d like to see this battery actually powering a device even though the stretching is quite alluring in its way. For those who are interested here’s a citation and a link to the research paper,

Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems by Sheng Xu, Yihui Zhang, Jiung Cho, Juhwan Lee, Xian Huang, Lin Jia, Jonathan A. Fan, Yewang Su, Jessica Su, Huigang Zhang, Huanyu Cheng, Bingwei Lu,           Cunjiang Yu, Chi Chuang, Tae-il Kim, Taeseup Song, Kazuyo Shigeta, Sen Kang, Canan Dagdeviren, Ivan Petrov  et al.   Nature Communications 4, Article number: 1543 doi: 10.1038/ncomms2553  Published 26 February 2013

The article is behind a paywall.