Tag Archives: ETH Zurich

Better motor control for prosthetic hands (the illusion of feeling) and a discussion of superprostheses and reality

I have two bits about prosthetics, one which focuses on how most of us think of them and another about science fiction fantasies.

Better motor control

This new technology comes via a collaboration between the University of Alberta, the University of New Brunswick (UNB) and Ohio’s Cleveland Clinic, from a March 18, 2018 article by Nicole Ireland for the Canadian Broadcasting Corporation’s (CBC) news online,

Rob Anderson was fighting wildfires in Alberta when the helicopter he was in crashed into the side of a mountain. He survived, but lost his left arm and left leg.

More than 10 years after that accident, Anderson, now 39, says prosthetic limb technology has come a long way, and he feels fortunate to be using “top of the line stuff” to help him function as normally as possible. In fact, he continues to work for the Alberta government’s wildfire fighting service.

His powered prosthetic hand can do basic functions like opening and closing, but he doesn’t feel connected to it — and has limited ability to perform more intricate movements with it, such as shaking hands or holding a glass.

Anderson, who lives in Grande Prairie, Alta., compares its function to “doing things with a long pair of pliers.”

“There’s a disconnect between what you’re physically touching and what your body is doing,” he told CBC News.

Anderson is one of four Canadian participants in a study that suggests there’s a way to change that. …

Six people, all of whom had arm amputations from below the elbow or higher, took part in the research. It found that strategically placed vibrating “robots” made them “feel” the movements of their prosthetic hands, allowing them to grasp and grip objects with much more control and accuracy.

All of the participants had all previously undergone a specialized surgical procedure called “targeted re-innervation.” The nerves that had connected to their hands before they were amputated were rewired to link instead to muscles (including the biceps and triceps) in their remaining upper arms and in their chests.

For the study, researchers placed the robotic devices on the skin over those re-innervated muscles and vibrated them as the participants opened, closed, grasped or pinched with their prosthetic hands.

While the vibration was turned on, the participants “felt” their artificial hands moving and could adjust their grip based on the sensation. …

I have an April 24, 2017 posting about a tetraplegic patient who had a number of electrodes implanted in his arms and hands linked to a brain-machine interface and which allowed him to move his hands and arms; the implants were later removed. It is a different problem with a correspondingly different technological solution but there does seem to be increased interest in implanting sensors and electrodes into the human body to increase mobility and/or sensation.

Anderson describes how it ‘feels,

“It was kind of surreal,” Anderson said. “I could visually see the hand go out, I would touch something, I would squeeze it and my phantom hand felt like it was being closed and squeezing on something and it was sending the message back to my brain.

“It was a very strange sensation to actually be able to feel that feedback because I hadn’t in 10 years.”

The feeling of movement in the prosthetic hand is an illusion, the researchers say, since the vibration is actually happening to a muscle elsewhere in the body. But the sensation appeared to have a real effect on the participants.

“They were able to control their grasp function and how much they were opening the hand, to the same degree that someone with an intact hand would,” said study co-author Dr. Jacqueline Hebert, an associate professor in the Faculty of Rehabilitation Medicine at the University of Alberta.

Although the researchers are encouraged by the study findings, they acknowledge that there was a small number of participants, who all had access to the specialized re-innervation surgery to redirect the nerves from their amputated hands to other parts of their body.

The next step, they say, is to see if they can also simulate the feeling of movement in a broader range of people who have had other types of amputations, including legs, and have not had the re-innervation surgery.

Here’s a March 15, 2018  CBC New Brunswick radio interview about the work,

This is a bit longer than most of the embedded audio pieces that I have here but it’s worth it. Sadly, I can’t identify the interviewer who did a very good job with Jon Sensinger, associate director of UNB’s Institute of Biomedical Engineering. One more thing, I noticed that the interviewer made no mention of the University of Alberta in her introduction or in the subsequent interview. I gather regionalism reigns supreme everywhere in Canada. Or, maybe she and Sensinger just forgot. It happens when you’re excited. Also, there were US institutions in Ohio and Virginia that participated in this work.

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

Illusory movement perception improves motor control for prosthetic hands by Paul D. Marasco, Jacqueline S. Hebert, Jon W. Sensinger, Courtney E. Shell, Jonathon S. Schofield, Zachary C. Thumser, Raviraj Nataraj, Dylan T. Beckler, Michael R. Dawson, Dan H. Blustein, Satinder Gill, Brett D. Mensh, Rafael Granja-Vazquez, Madeline D. Newcomb, Jason P. Carey, and Beth M. Orzell. Science Translational Medicine 14 Mar 2018: Vol. 10, Issue 432, eaao6990 DOI: 10.1126/scitranslmed.aao6990

This paper is open access.

Superprostheses and our science fiction future

A March 20, 2018 news item on phys.org features an essay on about superprostheses and/or assistive devices,

Assistive devices may soon allow people to perform virtually superhuman feats. According to Robert Riener, however, there are more pressing goals than developing superhumans.

What had until recently been described as a futuristic vision has become a reality: the first self-declared “cyborgs” have had chips implanted in their bodies so that they can open doors and make cashless payments. The latest robotic hand prostheses succeed in performing all kinds of grips and tasks requiring dexterity. Parathletes fitted with running and spring prostheses compete – and win – against the best, non-impaired athletes. Then there are robotic pets and talking humanoid robots adding a bit of excitement to nursing homes.

Some media are even predicting that these high-tech creations will bring about forms of physiological augmentation overshadowing humans’ physical capabilities in ways never seen before. For instance, hearing aids are eventually expected to offer the ultimate in hearing; retinal implants will enable vision with a sharpness rivalling that of any eagle; motorised exoskeletons will transform soldiers into tireless fighting machines.

Visions of the future: the video game Deus Ex: Human Revolution highlights the emergence of physiological augmentation. (Visualisations: Square Enix) Courtesy: ETH Zurich

Professor Robert Riener uses the image above to illustrate the notion of superprosthese in his March 20, 2018 essay on the ETH Zurich website,

All of these prophecies notwithstanding, our robotic transformation into superheroes will not be happening in the immediate future and can still be filed under Hollywood hero myths. Compared to the technology available today, our bodies are a true marvel whose complexity and performance allows us to perform an extremely wide spectrum of tasks. Hundreds of efficient muscles, thousands of independently operating motor units along with millions of sensory receptors and billions of nerve cells allow us to perform delicate and detailed tasks with tweezers or lift heavy loads. Added to this, our musculoskeletal system is highly adaptable, can partly repair itself and requires only minimal amounts of energy in the form of relatively small amounts of food consumed.

Machines will not be able to match this any time soon. Today’s assistive devices are still laboratory experiments or niche products designed for very specific tasks. Markus Rehm, an athlete with a disability, does not use his innovative spring prosthesis to go for walks or drive a car. Nor can today’s conventional arm prostheses help a person tie their shoes or button up their shirt. Lifting devices used for nursing care are not suitable for helping with personal hygiene tasks or in psychotherapy. And robotic pets quickly lose their charm the moment their batteries die.

Solving real problems

There is no denying that advances continue to be made. Since the scientific and industrial revolutions, we have become dependent on relentless progress and growth, and we can no longer separate today’s world from this development. There are, however, more pressing issues to be solved than creating superhumans.

On the one hand, engineers need to dedicate their efforts to solving the real problems of patients, the elderly and people with disabilities. Better technical solutions are needed to help them lead normal lives and assist them in their work. We need motorised prostheses that also work in the rain and wheelchairs that can manoeuvre even with snow on the ground. Talking robotic nurses also need to be understood by hard-of-hearing pensioners as well as offer simple and dependable interactivity. Their batteries need to last at least one full day to be recharged overnight.

In addition, financial resources need to be available so that all people have access to the latest technologies, such as a high-quality household prosthesis for the family man, an extra prosthesis for the avid athlete or a prosthesis for the pensioner. [emphasis mine]

Breaking down barriers

What is just as important as the ongoing development of prostheses and assistive devices is the ability to minimise or eliminate physical barriers. Where there are no stairs, there is no need for elaborate special solutions like stair lifts or stairclimbing wheelchairs – or, presumably, fully motorised exoskeletons.

Efforts also need to be made to transform the way society thinks about people with disabilities. More acknowledgement of the day-to-day challenges facing patients with disabilities is needed, which requires that people be confronted with the topic of disability when they are still children. Such projects must be promoted at home and in schools so that living with impairments can also attain a state of normality and all people can partake in society. It is therefore also necessary to break down mental barriers.

The road to a virtually superhuman existence is still far and long. Anyone reading this text will not live to see it. In the meantime, the task at hand is to tackle the mundane challenges in order to simplify people’s daily lives in ways that do not require technology, that allow people to be active participants and improve their quality of life – instead of wasting our time getting caught up in cyborg euphoria and digital mania.

I’m struck by Riener’s reference to financial resources and access. Sensinger mentions financial resources in his CBC radio interview although his concern is with convincing funders that prostheses that mimic ‘feeling’ are needed.

I’m also struck by Riener’s discussion about nontechnological solutions for including people with all kinds of abilities and disabilities.

There was no grand plan for combining these two news bits; I just thought they were interesting together.

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.

World heritage music stored in DNA

It seems a Swiss team from the École Polytechnique de Lausanne (EPFL) have collaborated with American companies Twist Bioscience and Microsoft, as well as, the University of Washington (state) to preserve two iconic jazz pieces on DNA (deoxyribonucleic acid) according to a Sept. 29, 2017 news item on phys.org,,

Thanks to an innovative technology for encoding data in DNA strands, two items of world heritage – songs recorded at the Montreux Jazz Festival [held in Switzerland] and digitized by EPFL – have been safeguarded for eternity. This marks the first time that cultural artifacts granted UNESCO heritage status have been saved in such a manner, ensuring they are preserved for thousands of years. The method was developed by US company Twist Bioscience and is being unveiled today in a demonstrator created at the EPFL+ECAL Lab.

“Tutu” by Miles Davis and “Smoke on the Water” by Deep Purple have already made their mark on music history. Now they have entered the annals of science, for eternity. Recordings of these two legendary songs were digitized by the Ecole Polytechnique Fédérale de Lausanne (EPFL) as part of the Montreux Jazz Digital Project, and they are the first to be stored in the form of a DNA sequence that can be subsequently decoded and listened to without any reduction in quality.

A Sept. 29, 2017 EPFL press release by Emmanuel Barraud, which originated the news item, provides more details,

This feat was achieved by US company Twist Bioscience working in association with Microsoft Research and the University of Washington. The pioneering technology is actually based on a mechanism that has been at work on Earth for billions of years: storing information in the form of DNA strands. This fundamental process is what has allowed all living species, plants and animals alike, to live on from generation to generation.

The entire world wide web in a shoe box

All electronic data storage involves encoding data in binary format – a series of zeros and ones – and then recording it on a physical medium. DNA works in a similar way, but is composed of long strands of series of four nucleotides (A, T, C and G) that make up a “code.” While the basic principle may be the same, the two methods differ greatly in terms of efficiency: if all the information currently on the internet was stored in the form of DNA, it would fit in a shoe box!

Recent advances in biotechnology now make it possible for humans to do what Mother Nature has always done. Today’s scientists can create artificial DNA strands, “record” any kind of genetic code on them and then analyze them using a sequencer to reconstruct the original data. What’s more, DNA is extraordinarily stable, as evidenced by prehistoric fragments that have been preserved in amber. Artificial strands created by scientists and carefully encapsulated should likewise last for millennia.

To help demonstrate the feasibility of this new method, EPFL’s Metamedia Center provided recordings of two famous songs played at the Montreux Jazz Festival: “Tutu” by Miles Davis, and “Smoke on the Water” by Deep Purple. Twist Bioscience and its research partners encoded the recordings, transformed them into DNA strands and then sequenced and decoded them and played them again – without any reduction in quality.

The amount of artificial DNA strands needed to record the two songs is invisible to the naked eye, and the amount needed to record all 50 years of the Festival’s archives, which have been included in UNESCO’s [United Nations Educational, Scientific and Cultural Organization] Memory of the World Register, would be equal in size to a grain of sand. “Our partnership with EPFL in digitizing our archives aims not only at their positive exploration, but also at their preservation for the next generations,” says Thierry Amsallem, president of the Claude Nobs Foundation. “By taking part in this pioneering experiment which writes the songs into DNA strands, we can be certain that they will be saved on a medium that will never become obsolete!”

A new concept of time

At EPFL’s first-ever ArtTech forum, attendees got to hear the two songs played after being stored in DNA, using a demonstrator developed at the EPFL+ECAL Lab. The system shows that being able to store data for thousands of years is a revolutionary breakthrough that can completely change our relationship with data, memory and time. “For us, it means looking into radically new ways of interacting with cultural heritage that can potentially cut across civilizations,” says Nicolas Henchoz, head of the EPFL+ECAL Lab.

Quincy Jones, a longstanding Festival supporter, is particularly enthusiastic about this technological breakthrough: “With advancements in nanotechnology, I believe we can expect to see people living prolonged lives, and with that, we can also expect to see more developments in the enhancement of how we live. For me, life is all about learning where you came from in order to get where you want to go, but in order to do so, you need access to history! And with the unreliability of how archives are often stored, I sometimes worry that our future generations will be left without such access… So, it absolutely makes my soul smile to know that EPFL, Twist Bioscience and their partners are coming together to preserve the beauty and history of the Montreux Jazz Festival for our future generations, on DNA! I’ve been a part of this festival for decades and it truly is a magnificent representation of what happens when different cultures unite for the sake of music. Absolute magic. And I’m proud to know that the memory of this special place will never be lost.

A Sept. 29, 2017 Twist Bioscience news release is repetitive in some ways but interesting nonetheless,

Twist Bioscience, a company accelerating science and innovation through rapid, high-quality DNA synthesis, today announced that, working with Microsoft and University of Washington researchers, they have successfully stored archival-quality audio recordings of two important music performances from the archives of the world-renowned Montreux Jazz Festival.
These selections are encoded and stored in nature’s preferred storage medium, DNA, for the first time. These tiny specks of DNA will preserve a part of UNESCO’s Memory of the World Archive, where valuable cultural heritage collections are recorded. This is the first time DNA has been used as a long-term archival-quality storage medium.
Quincy Jones, world-renowned Entertainment Executive, Music Composer and Arranger, Musician and Music Producer said, “With advancements in nanotechnology, I believe we can expect to see people living prolonged lives, and with that, we can also expect to see more developments in the enhancement of how we live. For me, life is all about learning where you came from in order to get where you want to go, but in order to do so, you need access to history! And with the unreliability of how archives are often stored, I sometimes worry that our future generations will be left without such access…So, it absolutely makes my soul smile to know that EPFL, Twist Bioscience and others are coming together to preserve the beauty and history of the Montreux Jazz Festival for our future generations, on DNA!…I’ve been a part of this festival for decades and it truly is a magnificent representation of what happens when different cultures unite for the sake of music. Absolute magic. And I’m proud to know that the memory of this special place will never be lost.”
“Our partnership with EPFL in digitizing our archives aims not only at their positive exploration, but also at their preservation for the next generations,” says Thierry Amsallem, president of the Claude Nobs Foundation. “By taking part in this pioneering experiment which writes the songs into DNA strands, we can be certain that they will be saved on a medium that will never become obsolete!”
The Montreux Jazz Digital Project is a collaboration between the Claude Nobs Foundation, curator of the Montreux Jazz Festival audio-visual collection and the École Polytechnique Fédérale de Lausanne (EPFL) to digitize, enrich, store, show, and preserve this notable legacy created by Claude Nobs, the Festival’s founder.
In this proof-of-principle project, two quintessential music performances from the Montreux Jazz Festival – Smoke on the Water, performed by Deep Purple and Tutu, performed by Miles Davis – have been encoded onto DNA and read back with 100 percent accuracy. After being decoded, the songs were played on September 29th [2017] at the ArtTech Forum (see below) in Lausanne, Switzerland. Smoke on the Water was selected as a tribute to Claude Nobs, the Montreux Jazz Festival’s founder. The song memorializes a fire and Funky Claude’s rescue efforts at the Casino Barrière de Montreux during a Frank Zappa concert promoted by Claude Nobs. Miles Davis’ Tutu was selected for the role he played in music history and the Montreux Jazz Festival’s success. Miles Davis died in 1991.
“We archived two magical musical pieces on DNA of this historic collection, equating to 140MB of stored data in DNA,” said Karin Strauss, Ph.D., a Senior Researcher at Microsoft, and one of the project’s leaders.  “The amount of DNA used to store these songs is much smaller than one grain of sand. Amazingly, storing the entire six petabyte Montreux Jazz Festival’s collection would result in DNA smaller than one grain of rice.”
Luis Ceze, Ph.D., a professor in the Paul G. Allen School of Computer Science & Engineering at the University of Washington, said, “DNA, nature’s preferred information storage medium, is an ideal fit for digital archives because of its durability, density and eternal relevance. Storing items from the Montreux Jazz Festival is a perfect way to show how fast DNA digital data storage is becoming real.”
Nature’s Preferred Storage Medium
Nature selected DNA as its hard drive billions of years ago to encode all the genetic instructions necessary for life. These instructions include all the information necessary for survival. DNA molecules encode information with sequences of discrete units. In computers, these discrete units are the 0s and 1s of “binary code,” whereas in DNA molecules, the units are the four distinct nucleotide bases: adenine (A), cytosine (C), guanine (G) and thymine (T).
“DNA is a remarkably efficient molecule that can remain stable for millennia,” said Bill Peck, Ph.D., chief technology officer of Twist Bioscience.  “This is a very exciting project: we are now in an age where we can use the remarkable efficiencies of nature to archive master copies of our cultural heritage in DNA.   As we develop the economies of this process new performances can be added any time.  Unlike current storage technologies, nature’s media will not change and will remain readable through time. There will be no new technology to replace DNA, nature has already optimized the format.”
DNA: Far More Efficient Than a Computer 
Each cell within the human body contains approximately three billion base pairs of DNA. With 75 trillion cells in the human body, this equates to the storage of 150 zettabytes (1021) of information within each body. By comparison, the largest data centers can be hundreds of thousands to even millions of square feet to hold a comparable amount of stored data.
The Elegance of DNA as a Storage Medium
Like music, which can be widely varied with a finite number of notes, DNA encodes individuality with only four different letters in varied combinations. When using DNA as a storage medium, there are several advantages in addition to the universality of the format and incredible storage density. DNA can be stable for thousands of years when stored in a cool dry place and is easy to copy using polymerase chain reaction to create back-up copies of archived material. In addition, because of PCR, small data sets can be targeted and recovered quickly from a large dataset without needing to read the entire file.
How to Store Digital Data in DNA
To encode the music performances into archival storage copies in DNA, Twist Bioscience worked with Microsoft and University of Washington researchers to complete four steps: Coding, synthesis/storage, retrieval and decoding. First, the digital files were converted from the binary code using 0s and 1s into sequences of A, C, T and G. For purposes of the example, 00 represents A, 10 represents C, 01 represents G and 11 represents T. Twist Bioscience then synthesizes the DNA in short segments in the sequence order provided. The short DNA segments each contain about 12 bytes of data as well as a sequence number to indicate their place within the overall sequence. This is the process of storage. And finally, to ensure that the file is stored accurately, the sequence is read back to ensure 100 percent accuracy, and then decoded from A, C, T or G into a two-digit binary representation.
Importantly, to encapsulate and preserve encoded DNA, the collaborators are working with Professor Dr. Robert Grass of ETH Zurich. Grass has developed an innovative technology inspired by preservation of DNA within prehistoric fossils.  With this technology, digital data encoded in DNA remains preserved for millennia.
About UNESCO’s Memory of the World Register
UNESCO established the Memory of the World Register in 1992 in response to a growing awareness of the perilous state of preservation of, and access to, documentary heritage in various parts of the world.  Through its National Commissions, UNESCO prepared a list of endangered library and archive holdings and a world list of national cinematic heritage.
A range of pilot projects employing contemporary technology to reproduce original documentary heritage on other media began. These included, for example, a CD-ROM of the 13th Century Radzivill Chronicle, tracing the origins of the peoples of Europe, and Memoria de Iberoamerica, a joint newspaper microfilming project involving seven Latin American countries. These projects enhanced access to this documentary heritage and contributed to its preservation.
“We are incredibly proud to be a part of this momentous event, with the first archived songs placed into the UNESCO Memory of the World Register,” said Emily Leproust, Ph.D., CEO of Twist Bioscience.
About ArtTech
The ArtTech Foundation, created by renowned scientists and dignitaries from Crans-Montana, Switzerland, wishes to stimulate reflection and support pioneering and innovative projects beyond the known boundaries of culture and science.
Benefitting from the establishment of a favorable environment for the creation of technology companies, the Foundation aims to position itself as key promoter of ideas and innovative endeavors within a landscape of “Culture and Science” that is still being shaped.
Several initiatives, including our annual global platform launched in the spring of 2017, are helping to create a community that brings together researchers, celebrities in the world of culture and the arts, as well as investors and entrepreneurs from Switzerland and across the globe.
About EPFL
EPFL, one of the two Swiss Federal Institutes of Technology, based in Lausanne, is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.
About Twist Bioscience
At Twist Bioscience, our expertise is accelerating science and innovation by leveraging the power of scale. We have developed a proprietary semiconductor-based synthetic DNA manufacturing process featuring a high throughput silicon platform capable of producing synthetic biology tools, including genes, oligonucleotide pools and variant libraries. By synthesizing DNA on silicon instead of on traditional 96-well plastic plates, our platform overcomes the current inefficiencies of synthetic DNA production, and enables cost-effective, rapid, high-quality and high throughput synthetic gene production, which in turn, expedites the design, build and test cycle to enable personalized medicines, pharmaceuticals, sustainable chemical production, improved agriculture production, diagnostics and biodetection. We are also developing new technologies to address large scale data storage. For more information, please visit www.twistbioscience.com. Twist Bioscience is on Twitter. Sign up to follow our Twitter feed @TwistBioscience at https://twitter.com/TwistBioscience.

If you hadn’t read the EPFL press release first, it might have taken a minute to figure out why EPFL is being mentioned in the Twist Bioscience news release. Presumably someone was rushing to make a deadline. Ah well, I’ve seen and written worse.

I haven’t been able to find any video or audio recordings of the DNA-preserved performances but there is an informational video (originally published July 7, 2016) from Microsoft and the University of Washington describing the DNA-based technology,

I also found this description of listening to the DNA-preserved music in an Oct. 6, 2017 blog posting for the Canadian Broadcasting Corporation’s (CBC) Day 6 radio programme,

To listen to them, one must first suspend the DNA holding the songs in a solution. Next, one can use a DNA sequencer to read the letters of the bases forming the molecules. Then, algorithms can determine the digital code those letters form. From that code, comes the music.

It’s complicated but Ceze says his team performed this process without error.

You can find out more about UNESCO’s Memory of the World and its register here , more about the EPFL+ECAL Lab here, and more about Twist Bioscience here.

Bandage with a voice (sort of)

Researchers at Empa (Swiss Federal Laboratories for Materials Testing and Research) have not developed a talking bandage despite the title (Bandage with a Voice) for a July 4, 2017 Empa press release  (also a July 4, 2017 news item on Nanowerk),

A novel bandage alerts the nursing staff as soon as a wound starts healing badly. Sensors incorporated into the base material glow with a different intensity if the wound’s pH level changes. This way even chronic wounds could be monitored at home.


Using a UV lamp, the pH level in the wound can be verified without removing the bandage and the healing process can continue unimpeded. Image: Empa / CSEM

All too often, changing bandages is extremely unpleasant, even for smaller, everyday injuries. It stings and pulls, and sometimes a scab will even start bleeding again. And so we prefer to wait until the bandage drops off by itself.

It’s a different story with chronic wounds, though: normally, the nursing staff has to change the dressing regularly – not just for reasons of hygiene, but also to examine the wound, take swabs and clean it. Not only does this irritate the skin unnecessarily; bacteria can also get in, the risk of infection soars. It would be much better to leave the bandage on for longer and have the nursing staff “read” the condition of the wound from outside.

The idea of being able to see through a wound dressing gave rise to the project Flusitex (Fluorescence sensing integrated into medical textiles), which is being funded by the Swiss initiative Nano-Tera. Researchers from Empa teamed up with ETH Zurich, Centre Suisse d’Electronique et de Microtechnique (CSEM) and University Hospital Zurich to develop a high-tech system that is supposed to supply the nursing staff with relevant data about the condition of a wound. As Luciano Boesel from Empa’s Laboratory for Biomimetic Membranes and Textiles, who is coordinating the project at Empa, explains: “The idea of a smart wound dressing with integrated sensors is to provide continuous information on the state of the healing process without the bandages having to be changed any more frequently than necessary.” This would mean a gentler treatment for patients, less work for the nursing staff and, therefore, lower costs: globally, around 17 billion $ were spent on treating wounds last year.

When wounds heal, the body produces specific substances in a complex sequence of biochemical processes, which leads to a significant variation in a number of metabolic parameters. For instance, the amount of glucose and oxygen rises and falls depending on the phase of the healing process; likewise does the pH level change. All these variations can be detected with specialized sensors. With this in mind, Empa teamed up with project partner CSEM to develop a portable, cheap and easy-to-use device for measuring fluorescence that is capable of monitoring several parameters at once. It should enable nursing staff to keep tabs on the pH as well as on glucose and oxygen levels while the wound heals. If these change, conclusions about other key biochemical processes involved in wound healing can be drawn.

The bandage reveals ist measurings in UV light.
A high pH signals chronic wounds

The pH level is particularly useful for chronic wounds. If the wound heals normally, the pH rises to 8 before falling to 5 or 6. If a wound fails to close and becomes chronic, however, the pH level fluctuates between 7 and 8. Therefore, it would be helpful if a signal on the bandage could inform the nursing staff that the wound pH is permanently high. If the bandage does not need changing for reasons of hygiene and pH levels are low, on the other hand, they could afford to wait.

But how do the sensors work? The idea: if certain substances appear in the wound fluid, “customized” fluorescent sensor molecules respond with a physical signal. They start glowing and some even change color in the visible or ultra-violet (UV) range. Thanks to a color scale, weaker and stronger changes in color can be detected and the quantity of the emitted substance be deduced.

Empa chemist Guido Panzarasa from the Laboratory for Biomimetic Membranes and Textiles vividly demonstrates how a sample containing sensor molecules begins to fluoresce in the lab. He carefully drips a solution with a pH level of 7.5 into a dish. Under a UV light, the change is plain to see. He adds another solution and the luminescence fades. A glance at the little bottle confirms it: the pH level of the second solution is lower.

Luminous molecules under UV

The Empa team designed a molecule composed of benzalkonium chloride and pyranine. While benzalkonium chloride is a substance also used for conventional medical soap to combat bacteria, fungi and other microorganisms, pyranine is a dye found in highlighters that glows under UV light. “This biomarker works really well,” says Panzarasa; “especially at pH levels between 5.5 and 7.5. The colors can be visualized with simple UV lamps available in electronics stores.” The Empa team recently published their results in the journal “Sensors and Actuators”.

The designer molecule has another advantage: thanks to the benzalkonium chloride, it has an antimicrobial effect, as researchers from Empa’s Laboratory for Biointerfaces confirmed for the bacteria strain Staphylococcus aureus. Unwelcome bacteria might potentially also be combatted by selecting the right bandage material in future. As further investigations, such as on the chemical’s compatibility with cells and tissues, are currently lacking, however, the researchers do not yet know how their sensor works in a complex wound.

Keen interest from industry

In order to illustrate what a smart wound dressing might actually look like in future, Boesel places a prototype on the lab bench. “You don’t have to cover the entire surface of wound dressings with sensors,” he explains. “It’s enough for a few small areas to be impregnated with the pyranine benzalkonium molecules and integrated into the base material. This means the industrial wound dressings won’t be much pricier than they are now – only up to 20% more expensive.” Empa scientists are currently working on this in the follow-up project FlusiTex-Gateway in cooperation with industrial partners Flawa, Schöller, Kenzen and Theranoptics.
Panzarasa now drips various liquids with different pH levels onto all the little cylinders on the wound pad prototype. Sure enough, the lighter and darker dots are also clearly discernible as soon as the UV lamp is switched on. They are even visible to the naked eye and glow in bright yellow if liquids with a high pH come into contact with the sensor. The scientists are convinced: since the pH level is so easy to read and provides precise information about the acidic or alkaline state of the sample, this kind of wound dressing is just the ticket as a diagnostic tool. Using the fluorescence meter developed by CSEM, more accurate, quantitative measure-ments of the pH level can be accomplished for medical purposes.

According to Boesel, it might one day even be possible to read the signals with the aid of a smartphone camera. Combined with a simple app, nursing staff and doctors would have a tool that enables them to easily and conveniently read the wound status “from outside”, even without a UV lamp. And patients would then also have the possibility of detecting the early onset of a chronic wound at home.

I wonder how long or even if this innovation will ever make its way into medical practice. I’m guessing this stage would be described as ‘proof of concept’ and that clinical testing is still many years away.

The metaphor in the press release’s title helped to wake me up. Thank you to whoever wrote it.

Nanoparticle behaviour in the environment unpredictable

These Swiss researchers took on a fairly massive project according to an April 19, 2017 news item on ScienceDaily,

The nanotech industry is booming. Every year, several thousands of tonnes of man-made nanoparticles are produced worldwide; sooner or later, a certain part of them will end up in bodies of water or soil. But even experts find it difficult to say exactly what happens to them there. It is a complex question, not only because there are many different types of man-made (engineered) nanoparticles, but also because the particles behave differently in the environment depending on the prevailing conditions.

Researchers led by Martin Scheringer, Senior Scientist at the Department of Chemistry and Applied Biosciences, wanted to bring some clarity to this issue. They reviewed 270 scientific studies, and the nearly 1,000 laboratory experiments described in them, looking for patterns in the behaviour of engineered nanoparticles. The goal was to make universal predictions about the behaviour of the particles.

An April 19, 2017ETH Zurich press release by Fabio Bergamin (also on EurekAlert), which originated the news item, elaborates,

Particles attach themselves to everything

However, the researchers found a very mixed picture when they looked at the data. “The situation is more complex than many scientists would previously have predicted,” says Scheringer. “We need to recognise that we can’t draw a uniform picture with the data available to us today.”

Nicole Sani-Kast, a doctoral student in Scheringer’s group and first author of the analysis published in the journal PNAS [Proceedings of the National Academy of Sciences], adds: “Engineered nanoparticles behave very dynamically and are highly reactive. They attach themselves to everything they find: to other nanoparticles in order to form agglomerates, or to other molecules present in the environment.”

Network analysis

To what exactly the particles react, and how quickly, depends on various factors such as the acidity of the water or soil, the concentration of the existing minerals and salts, and above all, the composition of the organic substances dissolved in the water or present in the soil. The fact that the engineered nanoparticles often have a surface coating makes things even more complicated. Depending on the environmental conditions, the particles retain or lose their coating, which in turn influences their reaction behaviour.

To evaluate the results available in the literature, Sani-Kast used a network analysis for the first time in this research field. It is a technique familiar in social research for measuring networks of social relations, and allowed her to show that the data available on engineered nanoparticles is inconsistent, insufficiently diverse and poorly structured.

More method for machine learning

“If more structured, consistent and sufficiently diverse data were available, it may be possible to discover universal patterns using machine learning methods,” says Scheringer, “but we’re not there yet.” Enough structured experimental data must first be available.

“In order for the scientific community to carry out such experiments in a systematic and standardised manner, some kind of coordination is necessary,” adds Sani-Kast, but she is aware that such work is difficult to coordinate. Scientists are generally well known for preferring to explore new methods and conditions rather than routinely performing standardized experiments.

[additional material]

Distinguishing man-made and natural nanoparticles

In addition to the lack of systematic research, there is also a second tangible problem in researching the behaviour of engineered nanoparticles: many engineered nanoparticles consist of chemical compounds that occur naturally in the soil. So far it has been difficult to measure the engineered particles in the environment since it is hard to distinguish them from naturally occurring particles with the same chemical composition.

However, researchers at ETH Zurich’s Department of Chemistry and Applied Biosciences, under the direction of ETH Professor Detlef Günther, have recently established an effective method that makes such a distinction possible in routine investigations. They used a state-of-the-art and highly sensitive mass spectrometry technique (called spICP-TOF mass spectrometry) to determine which chemical elements make up individual nanoparticles in a sample.

In collaboration with scientists from the University of Vienna, the ETH researchers applied the method to soil samples with natural cerium-containing particles, into which they mixed engineered cerium dioxide nanoparticles. Using machine learning methods, which were ideally suited to this particular issue, the researchers were able to identify differences in the chemical fingerprints of the two particle classes. “While artificially produced nanoparticles often consist of a single compound, natural nanoparticles usually still contain a number of additional chemical elements,” explains Alexander Gundlach-Graham, a postdoc in Günther’s group.

The new measuring method is very sensitive: the scientists were able to measure engineered particles in samples with up to one hundred times more natural particles.

The researchers have produced a visualization of their network analysis,

The researchers evaluated the experimental data published in the scientific literature using a network analysis. This analysis reveals which types of nanoparticles (blue) have been studied under which environmental conditions (red). (Visualisations: Thomas Kast)

Here are links and citation for two papers associated with this research,

A network perspective reveals decreasing material diversity in studies on nanoparticle interactions with dissolved organic matter by Nicole Sani-Kast, Jérôme Labille, Patrick Ollivier, Danielle Slomberg, Konrad Hungerbühler, and Martin Scheringer. PNAS 2017, 114: E1756-E1765, DOI: 10.1073/pnas.1608106114

Single-particle multi-element fingerprinting (spMEF) using inductively-coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) to identify engineered nanoparticles against the elevated natural background in soils by Antonia Praetorius, Alexander Gundlach-Graham, Eli Goldberg, Willi Fabienke, Jana Navratilova, Andreas Gondikas, Ralf Kaegi, Detlef Günther, Thilo Hofmann, and Frank von der Kammer. Environonmental Science: Nano 2017, 4: 307-314, DOI: 10.1039/c6en00455e

Both papers are behind a paywall.

‘No kiln’ ceramics

Sometimes it’s hard to believe what one reads and this piece about ceramics made without kilns  (for me) fits into that category (from a Feb. 28, 2017 ETH Zurich [English: Swiss Federal Institute of Technology in Zurich] [German: Eidgenössische Technische Hochschule Zürich]) press release (also on EurekAlert) by Fabio Bergamin),

The manufacture of cement, bricks, bathroom tiles and porcelain crockery normally requires a great deal of heat: a kiln is used to fire the ceramic materials at temperatures well in excess of 1,000°C. Now, material scientists from ETH Zurich have developed what seems at first glance to be an astonishingly simple method of manufacture that works at room temperature. The scientists used a calcium carbonate nanopowder as the starting material and instead of firing it, they added a small amount of water and then compacted it.

“The manufacturing process is based on the geological process of rock formation,” explains Florian Bouville, a postdoc in the group of André Studart, Professor of Complex Materials. Sedimentary rock is formed from sediment that is compressed over millions of years through the pressure exerted by overlying deposits. This process turns calcium carbonate sediment into limestone with the help of the surrounding water. As the ETH researchers used calcium carbonate with an extremely fine particle size (nanoparticles) as the starting material, their compacting process took only an hour. “Our work is the first evidence that a piece of ceramic material can be manufactured at room temperature in such a short amount of time and with relatively low pressures,” says ETH professor Studart.

Stronger than concrete

As tests have shown, the new material can withstand about ten times as much force as concrete before it breaks, and is as stiff as stone or concrete. In other words, it is just as hard to deform.

So far, the scientists have produced material samples of about the size of a one-franc piece using a conventional hydraulic press such as those normally used in industry. “The challenge is to generate a sufficiently high pressure for the compacting process. Larger workpieces require a correspondingly greater force,” says Bouville. According to the scientists, ceramic pieces the size of small bathroom tiles should theoretically be feasible.

Energy-efficient and environmentally benign

“For a long time, material scientists have been searching for a way to produce ceramic materials under mild conditions, as the firing process requires a large amount of energy,” says Studart. The new room-temperature method – which experts refer to as cold sintering — is much more energy-efficient and also enables the production of composite materials containing, for example, plastic.

The technique is also of interest with a view to a future CO2-neutral society. Specifically, the carbonate nanoparticles could conceivably be produced using CO2 captured from the atmosphere or from waste gases from thermal power stations. In this scenario, the captured CO2 is allowed to react with a suitable rock in powder form to produce carbonate, which could then be used to manufacture ceramics at room temperature. The climate-damaging CO2 would thus be stored in ceramic products in the long term. These would constitute a CO2 sink and could help thermal power stations to operate on a carbon-neutral basis.

According to the scientists, in the long term, the new approach of cold sintering even has the potential to lead to more environmentally friendly substitutes for cement-based materials. However, great research efforts are needed to reach this goal. Cement production is not only energy-intensive, but it also generates large amounts of CO2 – unlike potential cold-sintered replacement materials.

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

Geologically-inspired strong bulk ceramics made with water at room temperature by Florian Bouville & André R. Studart. Nature Communications 8, Article number: 14655 (2017) doi:10.1038/ncomms14655 Published online: 06 March 2017

This paper is open access.

Florian Bouville’s work in ceramics was last mentioned here in a March 25, 2014 posting.

New model to track flow of nanomaterials through our air, earth, and water

Just how many tons of nanoparticles are making their way through the environment? Scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa) have devised a new model which could help answer that question. From a May 12, 2016 news item on phys.org,

Carbon nanotubes remain attached to materials for years while titanium dioxide and nanozinc are rapidly washed out of cosmetics and accumulate in the ground. Within the National Research Program “Opportunities and Risks of Nanomaterials” (NRP 64) a team led by Empa scientist Bernd Nowack has developed a new model to track the flow of the most important nanomaterials in the environment.

A May 12, 2016 Empa press release by Michael Hagmann, which also originated the news item, provides more detail such as an estimated tonnage for titanium dioxide nanoparticles produced annually in Europe,

How many man-made nanoparticles make their way into the air, earth or water? In order to assess these amounts, a group of researchers led by Bernd Nowack from Empa, the Swiss Federal Laboratories for Materials Science and Technology, has developed a computer model as part of the National Research Program “Opportunities and Risks of Nanomaterials” (NRP 64). “Our estimates offer the best available data at present about the environmental accumulation of nanosilver, nanozinc, nano-tinanium dioxide and carbon nanotubes”, says Nowack.

In contrast to the static calculations hitherto in use, their new, dynamic model does not just take into account the significant growth in the production and use of nanomaterials, but also makes provision for the fact that different nanomaterials are used in different applications. For example, nanozinc and nano-titanium dioxide are found primarily in cosmetics. Roughly half of these nanoparticles find their way into our waste water within the space of a year, and from there they enter into sewage sludge. Carbon nanotubes, however, are integrated into composite materials and are bound in products such as which are immobilized and are thus found for example in tennis racquets and bicycle frames. It can take over ten years before they are released, when these products end up in waste incineration or are recycled.

39,000 metric tons of nanoparticles

The researchers involved in this study come from Empa, ETH Zurich and the University of Zurich. They use an estimated annual production of nano-titanium dioxide across Europe of 39,000 metric tons – considerably more than the total for all other nanomaterials. Their model calculates how much of this enters the atmosphere, surface waters, sediments and the earth, and accumulates there. In the EU, the use of sewage sludge as fertilizer (a practice forbidden in Switzerland) means that nano-titanium dioxide today reaches an average concentration of 61 micrograms per kilo in affected soils.

Knowing the degree of accumulation in the environment is only the first step in the risk assessment of nanomaterials, however. Now this data has to be compared with results of eco-toxicological tests and the statutory thresholds, says Nowack. A risk assessment has not been carried out with his new model so far. Earlier work with data from a static model showed, however, that the concentrations determined for all four nanomaterials investigated are not expected to have any impact on the environment.

But in the case of nanozinc at least, its concentration in the environment is approaching the critical level. This is why this particular nanomaterial has to be given priority in future eco-toxicological studies – even though nanozinc is produced in smaller quantities than nano-titanium dioxide. Furthermore, eco-toxicological tests have until now been carried out primarily with freshwater organisms. The researchers conclude that additional investigations using soil-dwelling organisms are a priority.

Here are links to and citations for papers featuring the work,

Dynamic Probabilistic Modeling of Environmental Emissions of Engineered Nanomaterials by Tian Yin Sun†, Nikolaus A. Bornhöft, Konrad Hungerbühler, and Bernd Nowack. Environ. Sci. Technol., 2016, 50 (9), pp 4701–4711 DOI: 10.1021/acs.est.5b05828 Publication Date (Web): April 04, 2016

Copyright © 2016 American Chemical Society

Probabilistic environmental risk assessment of five nanomaterials (nano-TiO2, nano-Ag, nano-ZnO, CNT, and fullerenes) by Claudia Coll, Dominic Notter, Fadri Gottschalk, Tianyin Sun, Claudia Som, & Bernd Nowack. Nanotoxicology Volume 10, Issue 4, 2016 pages 436-444 DOI: 10.3109/17435390.2015.1073812 Published online: 10 Nov 2015

The first paper, which is listed in Environmental Science & Technology, appears to be open access while the second paper is behind a paywall.

The Weyl fermion and new electronics

This story concerns a quasiparticle (Weyl fermion) which is a different kind of particle than the nanoparticles usually mentioned here. A March 17, 2016 news item on Nanowerk profiles research that suggests the Weyl fermion may find applications in the field of electronics,

The Weyl fermion, just discovered in the past year, moves through materials practically without resistance. Now researchers are showing how it could be put to use in electronic components.

Today electronic devices consume a lot of energy and require elaborate cooling mechanisms. One approach for the development of future energy-saving electronics is to use special particles that exist only in the interior of materials but can move there practically undisturbed. Electronic components based on these so-called Weyl fermions would consume considerably less energy than present-day chips. That’s because up to now devices have relied on the movement of electrons, which is inhibited by resistance and thus wastes energy.

Evidence for Weyl fermions was discovered only in the past year, by several research teams including scientists from the Paul Scherrer Institute (PSI). Now PSI researchers have shown — within the framework of an international collaboration with two research institutions in China and the two Swiss technical universities, ETH Zurich and EPF Lausanne — that there are materials in which only one kind of Weyl fermion exists. That could prove decisive for applications in electronic components, because it makes it possible to guide the particles’ flow in the material.

A March 17, 2016 Paul Scherrer Institute (PSI) press release by Paul Piwnicki, which originated the news item, describes the work in more detail (Note: There is some redundancy),

In the past year, researchers of the Paul Scherrer Institute PSI were among those who found experimental evidence for a particle whose existence had been predicted in the 1920s — the Weyl fermion. One of the particle’s peculiarities is that it can only exist in the interior of materials. Now the PSI researchers, together with colleagues at two Chinese research institutions as well as at ETH Zurich and EPF Lausanne, have made a subsequent discovery that opens the possibility of using the movement of Weyl fermions in future electronic devices. …

Today’s computer chips use the flow of electrons that move through the device’s conductive channels. Because, along the way, electrons are always colliding with each other or with other particles in the material, a relatively high amount of energy is needed to maintain the flow. That means not only that the device wastes a lot of energy, but also that it heats itself up enough to necessitate an elaborate cooling mechanism, which in turn requires additional space and energy.

In contrast, Weyl fermions move virtually undisturbed through the material and thus encounter practically no resistance. “You can compare it to driving on a highway where all of the cars are moving freely in the same direction,” explains Ming Shi, a senior scientist at the PSI. “The electron flow in present-day chips is more comparable to driving in congested city traffic, with cars coming from all directions and getting in each other’s way.”

Important for electronics: only one kind of particle

While in the materials examined last year there were always several kinds of Weyl fermions, all moving in different ways, the PSI researchers and their colleagues have now produced a material in which only one kind of Weyl fermion occurs. “This is important for applications in electronics, because here you must be able to precisely steer the particle flow,” explains Nan Xu, a postdoctoral researcher at the PSI.

Weyl fermions are named for the German mathematician Hermann Weyl, who predicted their existence in 1929. These particles have some striking characteristics, such as having no mass and moving at the speed of light. Weyl fermions were observed as quasiparticles in so-called Weyl semimetals. In contrast to “real” particles, quasiparticles can only exist inside materials. Weyl fermions are generated through the collective motion of electrons in suitable materials. In general, quasiparticles can be compared to waves on the surface of a body of water — without the water, the waves would not exist. At the same time, their movement is independent of the water’s motion.

The material that the researchers have now investigated is a compound of the chemical elements tantalum and phosphorus, with the chemical formula TaP. The crucial experiments were carried out with X-rays at the Swiss Light Source (SLS) of the Paul Scherrer Institute.

Studying novel materials with properties that could make them useful in future electronic devices is a central research area of the Paul Scherrer Institute. In the process, the researchers pursue a variety of approaches and use many different experimental methods.

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

Observation of Weyl nodes and Fermi arcs in tantalum phosphide by N. Xu, H. M. Weng, B. Q. Lv, C. E. Matt, J. Park, F. Bisti, V. N. Strocov, D. Gawryluk, E. Pomjakushina, K. Conder, N. C. Plumb, M. Radovic, G. Autès, O. V. Yazyev, Z. Fang, X. Dai, T. Qian, J. Mesot, H. Ding & M. Shi. Nature Communications 7, Article number: 11006  doi:10.1038/ncomms11006 Published 17 March 2016

This paper is open access.

How vibrations affect nanoscale materials

A March 9, 2016 news item on ScienceDaily announces work concerning atomic vibrations,

All materials are made up of atoms, which vibrate. These vibrations, or ‘phonons’, are responsible, for example, for how electric charge and heat is transported in materials. Vibrations of metals, semiconductors, and insulators in are well studied; however, now materials are being nanosized to bring better performance to applications such as displays, sensors, batteries, and catalytic membranes. What happens to vibrations when a material is nanosized has until now not been understood.

A March 9, 2016 ETH Zurich press release (also on EurekAlert), which originated the news item, describes the world of vibration at the nanoscale and the potential impact this new information could have,

Soft Surfaces Vibrate Strongly

In a recent publication in Nature, ETH Professor Vanessa Wood and her colleagues explain what happens to atomic vibrations when materials are nanosized and how this knowledge can be used to systematically engineer nanomaterials for different applications.

The paper shows that when materials are made smaller than about 10 to 20 nanometers – that is, 5,000 times thinner than a human air – the vibrations of the outermost atomic layers on surface of the nanoparticle are large and play an important role in how this material behaves.

“For some applications, like catalysis, thermoelectrics, or superconductivity, these large vibrations may be good, but for other applications like LEDs or solar cells, these vibrations are undesirable,” explains Wood.

Indeed, the paper explains why nanoparticle-based solar cells have until now not met their full promise.  The researchers showed using both experiment and theory that surface vibrations interact with electrons to reduce the photocurrent in solar cells.

“Now that we have proven that surface vibrations are important, we can systematically design materials to suppress or enhance these vibrations,” say Wood.

Improving Solar Cells

Wood’s research group has worked for a long time on a particular type of nanomaterial – colloidal nanocrystals – semiconductors with a diameter of 2 to 10 nanometers.  These materials are interesting because their optical and electrical properties are dependent on their size, which can be easily changed during their synthesis.

These materials are now used commercially as red- and green-light emitters in LED-based TVs and are being explored as possible materials for low cost, solution-processed solar cells.  Researchers have noticed that placing certain atoms around the surface of the nanocrystal can improve the performance of solar cells. The reason why this worked had not been understood.  The work published in the Nature paper now gives the answer:  a hard shell of atoms can suppress the vibrations and their interaction with electrons.  This means a higher photocurrent and a higher efficiency solar cell.

Big Science to Study the Nanoscale

Experiments were conducted in Professor Wood’s labs at ETH Zurich and at the Swiss Spallation Neutron Source at the Paul Scherrer Institute. By observing how neutrons scatter off atoms in a material, it is possible to quantify how atoms in a material vibrate. To understand the neutron measurements, simulations of the atomic vibrations were run at the Swiss National Supercomputing Center (CSCS) in Lugano. Wood says, “without access to these large facilities, this work would not have been possible. We are incredibly fortunate here in Switzerland to have these world class facilities.”

The researchers have made available an image illustrating their work,

Vibrations of atoms in materials, the "phonons", are responsible for how electric charge and heat is transported in materials (Graphics: Deniz Bozyigit / ETH Zurich)

Vibrations of atoms in materials, the “phonons”, are responsible for how electric charge and heat is transported in materials (Graphics: Deniz Bozyigit / ETH Zurich)

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

Soft surfaces of nanomaterials enable strong phonon interactions by Deniz Bozyigit, Nuri Yazdani, Maksym Yarema, Olesya Yarema, Weyde Matteo Mario Lin, Sebastian Volk, Kantawong Vuttivorakulchai, Mathieu Luisier, Fanni Juranyi, & Vanessa Wood. Nature (2016)  doi:10.1038/nature16977 Published online 09 March 2016

This paper is behind a paywall.

Nanowalls (like waffles) for touchscreens

ETH Zurich has announced a new technique for creating transparent electrodes in a Jan. 6, 2016 news item on ScienceDaily,

Transparent electrodes have been manufactured for use in touchscreens using a novel nanoprinting process. The new electrodes are some of the most transparent and conductive that have ever been developed.

From smartphones to the operating interfaces of ticket machines and cash dispensers, every touchscreen we use requires transparent electrodes: The devices’ glass surface is coated with a barely visible pattern made of conductive material. It is because of this that the devices recognise whether and where exactly a finger is touching the surface.

Here’s an image illustrating the new electrodes,

With a special mode of electrohydrodynamic ink-jet printing scientists can create a grid of ultra fine gold walls. (Visualisations: Ben Newton / Digit Works)

With a special mode of electrohydrodynamic ink-jet printing scientists can create a grid of ultra fine gold walls. (Visualisations: Ben Newton / Digit Works)

I think these electrodes resemble waffles,

[downloaded from https://github.com/jhermann/Stack-O-Waffles] Credit: jherman

[downloaded from https://github.com/jhermann/Stack-O-Waffles] Credit: jherman

Getting back to the electrodes themselves, a Jan. 6, 2016 ETH Zurich press release (also on EurekAlert*)by Fabio Bergamin, which originated the news item, provides more details,

Researchers under the direction of Dimos Poulikakos, Professor of Thermodynamics, have now used 3D print technology to create a new type of transparent electrode, which takes the form of a grid made of gold or silver “nanowalls” on a glass surface. The walls are so thin that they can hardly be seen with the naked eye. It is the first time that scientists have created nanowalls like these using 3D printing. The new electrodes have a higher conductivity and are more transparent than those made of indium tin oxide, the standard material used in smartphones and tablets today. This is a clear advantage: The more transparent the electrodes, the better the screen quality. And the more conductive they are, the more quickly and precisely the touchscreen will work.

Third dimension

“Indium tin oxide is used because the material has a relatively high degree of transparency and the production of thin layers has been well researched, but it is only moderately conductive,” says Patrik Rohner, a PhD student in Poulikakos’ team. In order to produce more conductive electrodes, the ETH researchers opted for gold and silver, which conduct electricity much better. But because these metals are not transparent, the scientists had to make use of the third dimension. ETH professor Poulikakos explains: “If you want to achieve both high conductivity and transparency in wires made from these metals, you have a conflict of objectives. As the cross-sectional area of gold and silver wires grows, the conductivity increases, but the grid’s transparency decreases.”

The solution was to use metal walls only 80 to 500 nanometres thick, which are almost invisible when viewed from above. Because they are two to four times taller than they are wide, the cross-sectional area, and thus the conductivity, is sufficiently high.

Ink-jet printer with tiny print head

The researchers produced these tiny metal walls using a printing process known as Nanodrip, which Poulikakos and his colleagues developed three years ago. Its basic principle is a process called electrohydrodynamic ink-jet printing. In this process scientists use inks made from metal nanoparticles in a solvent; an electrical field draws ultra-small droplets of the metallic ink out of a glass capillary. The solvent evaporates quickly, allowing a three-dimensional structure to be built up drop by drop.

What is special about the Nanodrip process is that the droplets that come out of the glass capillary are about ten times smaller than the aperture itself. This allows for much smaller structures to be printed. “Imagine a water drop hanging from a tap that is turned off. And now imagine that another tiny droplet is hanging from this drop – we are only printing the tiny droplet,” Poulikakos explains. The researchers managed to create this special form of droplet by perfectly balancing the composition of metallic ink and the electromagnetic field used.

Cost-efficient production

The next big challenge will now be to upscale the method and develop the print process further so that it can be implemented on an industrial scale. To achieve this, the scientists are working with colleagues from ETH spin-off company Scrona.

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

Electrohydrodynamic NanoDrip Printing of High Aspect Ratio Metal Grid Transparent Electrodes by Julian Schneider, Patrick Rohner, Deepankur Thureja, Martin Schmid, Patrick Galliker, Dimos Poulikalos. Advanced Functional Materials DOI: 10.1002/adfm.201503705 First published: 15 December 2015

This paper is behind a paywall.

*'(also on EurekAlert)’ added on Jan. 7, 2016.