Category Archives: electronics

Making nanoscale transistor chips out of thin air—sort of

Caption: The nano-gap transistors operating in air. As gaps become smaller than the mean-free path of electrons in air, there is ballistic electron transport. Credit: RMIT University

A November 19, 2018 news item on Nanowerk describes the ‘airy’ work ( Note: A link has been removed),

Researchers at RMIT University [Ausralia] have engineered a new type of transistor, the building block for all electronics. Instead of sending electrical currents through silicon, these transistors send electrons through narrow air gaps, where they can travel unimpeded as if in space.

The device unveiled in material sciences journal Nano Letters (“Metal–Air Transistors: Semiconductor-free field-emission air-channel nanoelectronics”), eliminates the use of any semiconductor at all, making it faster and less prone to heating up.

A November 19, 2018 RMIT University news release on EurkeAlert, which originated the news item, describes the work and possibilities in more detail,

Lead author and PhD candidate in RMIT’s Functional Materials and Microsystems Research Group, Ms Shruti Nirantar, said this promising proof-of-concept design for nanochips as a combination of metal and air gaps could revolutionise electronics.

“Every computer and phone has millions to billions of electronic transistors made from silicon, but this technology is reaching its physical limits where the silicon atoms get in the way of the current flow, limiting speed and causing heat,” Nirantar said.

“Our air channel transistor technology has the current flowing through air, so there are no collisions to slow it down and no resistance in the material to produce heat.”

The power of computer chips – or number of transistors squeezed onto a silicon chip – has increased on a predictable path for decades, roughly doubling every two years. But this rate of progress, known as Moore’s Law, has slowed in recent years as engineers struggle to make transistor parts, which are already smaller than the tiniest viruses, smaller still.

Nirantar says their research is a promising way forward for nano electronics in response to the limitation of silicon-based electronics.

“This technology simply takes a different pathway to the miniaturisation of a transistor in an effort to uphold Moore’s Law for several more decades,” Shruti said.

Research team leader Associate Professor Sharath Sriram said the design solved a major flaw in traditional solid channel transistors – they are packed with atoms – which meant electrons passing through them collided, slowed down and wasted energy as heat.

“Imagine walking on a densely crowded street in an effort to get from point A to B. The crowd slows your progress and drains your energy,” Sriram said.

“Travelling in a vacuum on the other hand is like an empty highway where you can drive faster with higher energy efficiency.”

But while this concept is obvious, vacuum packaging solutions around transistors to make them faster would also make them much bigger, so are not viable.

“We address this by creating a nanoscale gap between two metal points. The gap is only a few tens of nanometers, or 50,000 times smaller than the width of a human hair, but it’s enough to fool electrons into thinking that they are travelling through a vacuum and re-create a virtual outer-space for electrons within the nanoscale air gap,” he said.

The nanoscale device is designed to be compatible with modern industry fabrication and development processes. It also has applications in space – both as electronics resistant to radiation and to use electron emission for steering and positioning ‘nano-satellites’.

“This is a step towards an exciting technology which aims to create something out of nothing to significantly increase speed of electronics and maintain pace of rapid technological progress,” Sriram said.

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

Metal–Air Transistors: Semiconductor-free field-emission air-channel nanoelectronics by
Shruti Nirantar, Taimur Ahmed, Guanghui Ren, Philipp Gutruf, Chenglong Xu, Madhu Bhaskaran, Sumeet Walia, and Sharath Sriram. Nano Lett., DOI: 10.1021/acs.nanolett.8b02849 Publication Date (Web): November 16, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Defending nanoelectronics from cyber attacks

There’s a new program at the University of Stuttgart (Germany) and their call for projects was recently announced. First, here’s a description of the program in a May 30, 2019 news item on Nanowerk,

Today’s societies critically depend on electronic systems. Past spectacular cyber-attacks have clearly demonstrated the vulnerability of existing systems and the need to prevent such attacks in the future. The majority of available cyber-defenses concentrate on protecting the software part of electronic systems or their communication interfaces.

However, manufacturing technology advancements and the increasing hardware complexity provide a large number of challenges so that the focus of attackers has shifted towards the hardware level. We saw already evidence for powerful and successful hardware-level attacks, including Rowhammer, Meltdown and Spectre.

These attacks happened on products built using state-of-the-art microelectronic technology, however, we are facing completely new security challenges due to the ongoing transition to radically new types of nanoelectronic devices, such as memristors, spintronics, or carbon nanotubes and graphene based transistors.

The use of such emerging nanotechnologies is inevitable to address the key challenges related to energy efficiency, computing power and performance. Therefore, the entire industry, are switching to emerging nano-electronics alongside scaled CMOS technologies in heterogeneous integrated systems.

These technologies come with new properties and also facilitate the development of radically different computer architectures. The new technologies and architectures provide new opportunities for achieving security targets, but also raise questions about their vulnerabilities to new types of hardware attacks.

A May 28, 2019 University of Stuttgart press release provides more information about the program and the call for projects,

Whether it’s cars, industrial plants or the government network, spectacular cyber attacks over the past few months have shown how vulnerable modern electronic systems are. The aim of the new Priority Program “Nano Security”, which is coordinated by the University of Stuttgart, is protecting you and preventing the cyber attacks of the future. The program, which is funded by the German Research Foundation (DFG), emphasizes making the hardware into a reliable foundation of a system or a layer of security.

The challenges of nanoelectronics

Completely new challenges also emerge as a result of the switch to radically new nanoelectronic components, which for example are used to master the challenges of the future in terms of energy efficiency, computing power and secure data transmission. For example, memristors (components which are not just used to store information but also function as logic modules), the spintronics, which exploit quantum-mechanical effects, or carbon nanotubes.

The new technologies, as well as the fundamentally different computer architecture associated with them, offer new opportunities for cryptographic primitives in order to achieve an even more secure data transmission. However, they also raise questions about their vulnerability to new types of hardware attacks.

The problem is part of the solution

In this context, a better understanding should be developed of what consequences the new nanoelectronic technologies have for the security of circuits and systems as part of the new Priority Program. Here, the hardware is not just thought of as part of the problem but also as an important and necessary part of the solution to security problems. The starting points here for example are the hardware-based generation of cryptographic keys, the secure storage and processing of sensitive data, and the isolation of system components which is guaranteed by the hardware. Lastly, it should be ensured that an attack cannot be spread further by the system.

In this process, the scientists want to assess the possible security risks and weaknesses which stem from the new type of nanoelectronics. Furthermore, they want to develop innovative approaches for system security which are based on nanoelectronics as a security anchor.

The Priority Program promotes cooperation between scientists, who develop innovative security solutions for the computer systems of the future on different levels of abstraction. Likewise, it makes methods available to system designers to keep ahead in the race between attackers and security measures over the next few decades.

The call has started

The DFG Priority Program “Nano Security. From Nano-Electronics to Secure Systems“ (SPP 2253) is scheduled to last for a period of six years. The call for projects for the first three-year funding period was advertised a few days ago, and the first projects are set to start at the beginning of 2020.

For more information go to the Nano Security: From Nano-Electronics to Secure Systems webpage on the University of Stuttgart website.

Chen Qiufan, garbage, and Chinese science fiction stories

Garbage has been dominating Canadian news headlines for a few weeks now. First, it was Canadian garbage in the Philippines and now it’s Canadian garbage in Malaysia. Interestingly, we’re also having problems with China, since December 2018, when we detained a top executive from Huawe, a China-based international telecommunicatons company, in accordance with an official request from the US government and, in accordance, with what Prime Minister Justin Trudeau calls the ‘rule of law’. All of this provides an interesting backdrop (for Canadians anyway) on the topic of China, garbage, and science fiction.

A May 16, 2019 article by Anjie Zheng for Fast Company explores some of the latest and greatest from China’s science fiction writing community,

Like any good millennial, I think about my smartphone, to the extent that I do at all, in terms of what it does for me. It lets me message friends, buy stuff quickly, and amass likes. I hardly ever think about what it actually is—a mass of copper wires, aluminum alloys, and lithium battery encased in glass—or where it goes when I upgrade.

Chen Qiufan wants us to think about that. His debut novel, Waste Tide, is set in a lightly fictionalized version of Guiyu, the world’s largest electronic waste disposal. First published in Chinese in 2013, the book was recently released in the U.S. with a very readable translation into English by Ken Liu.

Chen, who has been called “China’s William Gibson,” is part of a younger generation of sci-fi writers who have achieved international acclaim in recent years. Liu Cixin became the first Chinese to win the prestigious Hugo Award for his Three Body Problem in 2015. The Wandering Earth, based on a short story by Liu, became China’s first science-fiction blockbuster when it was released in 2018. It was the highest-grossing film in the fastest-growing film market in the world last year and was recently scooped up by Netflix.

Aynne Kokas in a March 13, 2019 article for the Washington Post describes how the hit film, The Wandering Earth, fits into an overall Chinese-led movie industry focused on the future and Hollywood-like, i. e. like US movie industry, domination,

“The Wandering Earth,” directed by Frant Gwo, takes place in a future where the people of Earth must flee their sun as it swells into a red giant. Thousands of engines — the first of them constructed in Hangzhou, one of China’s tech hubs — propel the entire planet toward a new solar system, while everyone takes refuge from the cold in massive underground cities. On the surface, the only visible reminders of the past are markers of China’s might. The Shanghai Tower, the Oriental Pearl Tower and a stadium for the Shanghai 2044 Olympics all thrust out of the ice, having apparently survived the journey’s tsunamis, deep freeze and cliff-collapsing earthquakes.

The movie is China’s first big-budget sci-fi epic, and its production was ambitious, involving some 7,000 workers and 10,000 specially-built props. Audience excitement was correspondingly huge: Nearly half a million people wrote reviews of the film on Chinese social network site Douban. Having earned over $600 million in domestic sales, “The Wandering Earth” marks a major achievement for the country’s film industry.

It is also a major achievement for the Chinese government.

Since opening up the country’s film market in 2001, the Chinese government has aspired to learn from Hollywood how to make commercially appealing films, as I detail in my book “Hollywood Made in China.” From initial private offerings for state media companies, to foreign investment in films, studios and theme parks, the government allowed outside capital and expertise to grow the domestic commercial film industry — but not at the expense of government oversight. This policy’s underlying aim was to expand China’s cultural clout and political influence.

Until recently, Hollywood films dominated the country’s growing box office. That finally changed in 2015, with the release of major local blockbusters “Monster Hunt” and “Lost in Hong Kong.” The proliferation of homegrown hits signaled that the Chinese box office profits no longer depend on Hollywood studio films — sending an important message to foreign trade negotiators and studios.

Kokas provides some insight into how the Chinese movie industry is designed to further the Chinese government’s vision of the future. As a Canadian, I don’t see that much difference between the US and China industry’s vision. Both tout themselves as the answer to everything, both target various geographic regions for the ‘bad guys’, and both tout their national moral superiority in their films. I suppose the same can be said for most countries’ film industries but both China and the US can back themselves with economic might.

Zheng’s article delves deeper into garbage, and Chen Qiufan’s science fiction while illuminating the process of changing a ‘good guy’ into a ‘bad guy’,

Chen, 37, grew up a few miles from the real Guiyu. Mountains of scrap electronics are shipped there every year from around the world. Thousands of human workers sort through the junk for whatever can be reduced to reusable precious metals. They strip wires and disassemble circuit boards, soaking them in acid baths for bits of copper, tin, platinum, and gold. Whatever can’t be processed is burned. The water in Guiyu has been so contaminated it is undrinkable; the air is toxic. The workers, migrants from poor rural areas in China, have an abnormally high rate of respiratory diseases and cancer.

For the decades China was revving its economic engine, authorities were content to turn a blind eye to the human costs of the recycling business. It was an economic win-win. For developed countries like the U.S., it’s cheaper to ship waste to places like China than trying to recycle it themselves. And these shipments create jobs and profits for the Chinese.

In recent years, however, steps have been taken to protect workers and the environment in China. …

Waste Tide highlights the danger of “throw-away culture,” says Chen, also known in English as Stanley Chan. When our personal electronics stop serving us, whether because they break or our lust for the newest specs get the better of us, we toss them. Hopefully we’re conscientious enough to bring them to local recyclers that claim they’ll dispose of them properly. But that’s likely the end of our engagement with the trash. Out of sight, out of mind.

Fiction, and science fiction in particular, is an apt medium for Chen to probe the consequences of this arrangement. “It’s not journalism,” he says. Instead, the story is an imaginative, action-packed tale of power imbalances, and the individual characters that think they’re doing good. Waste Tide culminates, expectedly, in an insurgency of the workers against their exploitative overlords.

Guiyu has been fictionalized in Waste Tide as “Silicon Isle.” (A homophone of the Chinese character “gui” translates to “Silicon,” and “yu” is an island). The waste hell is ruled by three ruthless family clans, dominated by the Luo clan. They treat workers as slaves and derisively call them “waste people.”

Technology in the near-future has literally become extensions of selves and only exacerbates class inequality. Prosthetic inner ears improve balance; prosthetic limbs respond to mental directives; helmets heighten natural senses. The rich “switch body parts as easily as people used to switch phones.” Those with fewer means hack discarded prosthetics to get the same kick. When they’re no longer needed, synthetic body parts contaminated with blood and bodily fluids are added to the detritus.

At the center of the story is Mimi, a migrant worker who dreams of earning enough money to return home and live a quiet life. She strikes up a relationship with Kaizong, a Chinese-American college graduate trying to rediscover his roots. But the good times are short-lived. The boss of the Luo clan becomes convinced that Mimi holds the key to rousing his son from his coma and soon kidnaps the hapless girl.

For all the advanced science, there is a backwards superstition that animates Silicon Isle. [emphasis mine] The clan bosses subscribe to “a simple form of animism.” They pray to the wind and sea for ample supplies of waste. They sacrifice animals (and some humans) to bring them luck, and use local witches to exorcise evil spirits. Boss Luo has Mimi kidnapped and tortured in an effort to appease the gods in the hopes of waking up his comatose son. The torture of Mimi infects her with a mysterious disease that splits her consciousness. The waste people are enraged by her violation, which eventually sparks a war against the ruling clans. [emphasis mine]

A parallel narrative involves an American, Scott Brandle, who works for an environmental company. While in town trying to set up a recycling facility, he stumbles onto the truth about the virus that may have infected Mimi: a chemical weapon developed and used by the U.S. [emphasis mine] years earlier. Invented by a Japanese researcher [emphasis mine] working in the U.S., the drug is capable of causing mass hallucinations and terror. When Brandle learns that Mimi may have been infected with this virus, he wants a piece of her [emphasis mine] too, so that scientists back home can study its effects.

Despite portraying the future of China in a less-than-positive light, [emphasis mine] Waste Tide has not been banned–a common result for works that displease Beijing; instead, the book won China’s prestigious Nebula award for science fiction, and is about to be reprinted on the mainland. …

An interview with Chen (it’s worthwhile to read his take on what he’s doing) follows the plot description in this intriguing and what seems to be a sometimes disingenuous article.

The animism and the war against the ruling class? It reminds me a little of the tales told about old Chine and Mao’s campaign to overthrow the ruling classes who had kept control of the proletariat, in part, by encouraging ‘superstitious religious belief’.

As far as I’m concerned the interpretation can go either or both ways: a critique of the current government’s policies and where they might lead in the future and/or a reference back to the glorious rising of China’s communist government. Good fiction always contains ambiguity; it’s what fuels courses in literature.

Also, the bad guys are from the US and Japan, countries which have long been allied with each other and with which China has some serious conflicts.

Interesting, non? And, it’s not that different from what you’ll see in US (or any other country’s for that matter) science fiction wiring and movies, except that the heroes are Chinese.

Getting back to the garbage in the Philippines, there are 69 containers on their way back to Canada as of May 30, 2019. As for why all this furor about Canadian garbage in the Philippines and Malaysia, it’s hard to believe that Canada is the only sinner. Of course, we are in China’s bad books due to the Huawei executive’s detention here (she is living in her home in Vancouver and goes out and about as she wishes, albeit under surveillance).

Anyway, I can’t help but wonder if indirect pressure is being exerted by China or if the Philippines and Malaysia have been incentivized in some way by China. The timing has certainly been interesting.

Political speculation aside, it’s probably a good thing that countries are refusing to take our garbage. As I’m sure more than one environmentalist would be happy to point out, it’s about time we took care of our own mess.

Two approaches to memristors

Within one day of each other in October 2018, two different teams working on memristors with applications to neuroprosthetics and neuromorphic computing (brainlike computing) announced their results.

Russian team

An October 15, 2018 (?) Lobachevsky University press release (also published on October 15, 2018 on EurekAlert) describes a new approach to memristors,

Biological neurons are coupled unidirectionally through a special junction called a synapse. An electrical signal is transmitted along a neuron after some biochemical reactions initiate a chemical release to activate an adjacent neuron. These junctions are crucial for cognitive functions, such as perception, learning and memory.

A group of researchers from Lobachevsky University in Nizhny Novgorod investigates the dynamics of an individual memristive device when it receives a neuron-like signal as well as the dynamics of a network of analog electronic neurons connected by means of a memristive device. According to Svetlana Gerasimova, junior researcher at the Physics and Technology Research Institute and at the Neurotechnology Department of Lobachevsky University, this system simulates the interaction between synaptically coupled brain neurons while the memristive device imitates a neuron axon.

A memristive device is a physical model of Chua’s [Dr. Leon Chua, University of California at Berkeley; see my May 9, 2008 posting for a brief description Dr. Chua’s theory] memristor, which is an electric circuit element capable of changing its resistance depending on the electric signal received at the input. The device based on a Au/ZrO2(Y)/TiN/Ti structure demonstrates reproducible bipolar switching between the low and high resistance states. Resistive switching is determined by the oxidation and reduction of segments of conducting channels (filaments) in the oxide film when voltage with different polarity is applied to it. In the context of the present work, the ability of a memristive device to change conductivity under the action of pulsed signals makes it an almost ideal electronic analog of a synapse.

Lobachevsky University scientists and engineers supported by the Russian Science Foundation (project No.16-19-00144) have experimentally implemented and theoretically described the synaptic connection of neuron-like generators using the memristive interface and investigated the characteristics of this connection.

“Each neuron is implemented in the form of a pulse signal generator based on the FitzHugh-Nagumo model. This model provides a qualitative description of the main neurons’ characteristics: the presence of the excitation threshold, the presence of excitable and self-oscillatory regimes with the possibility of a changeover. At the initial time moment, the master generator is in the self-oscillatory mode, the slave generator is in the excitable mode, and the memristive device is used as a synapse. The signal from the master generator is conveyed to the input of the memristive device, the signal from the output of the memristive device is transmitted to the input of the slave generator via the loading resistance. When the memristive device switches from a high resistance to a low resistance state, the connection between the two neuron-like generators is established. The master generator goes into the oscillatory mode and the signals of the generators are synchronized. Different signal modulation mode synchronizations were demonstrated for the Au/ZrO2(Y)/TiN/Ti memristive device,” – says Svetlana Gerasimova.

UNN researchers believe that the next important stage in the development of neuromorphic systems based on memristive devices is to apply such systems in neuroprosthetics. Memristive systems will provide a highly efficient imitation of synaptic connection due to the stochastic nature of the memristive phenomenon and can be used to increase the flexibility of the connections for neuroprosthetic purposes. Lobachevsky University scientists have vast experience in the development of neurohybrid systems. In particular, a series of experiments was performed with the aim of connecting the FitzHugh-Nagumo oscillator with a biological object, a rat brain hippocampal slice. The signal from the electronic neuron generator was transmitted through the optic fiber communication channel to the bipolar electrode which stimulated Schaffer collaterals (axons of pyramidal neurons in the CA3 field) in the hippocampal slices. “We are going to combine our efforts in the design of artificial neuromorphic systems and our experience of working with living cells to improve flexibility of prosthetics,” concludes S. Gerasimova.

The results of this research were presented at the 38th International Conference on Nonlinear Dynamics (Dynamics Days Europe) at Loughborough University (Great Britain).

This diagram illustrates an aspect of the work,

Caption: Schematic of electronic neurons coupling via a memristive device. Credit: Lobachevsky University

US team

The American Institute of Physics (AIP) announced the publication of a ‘memristor paper’ by a team from the University of Southern California (USC) in an October 16, 2018 news item on phys.org,

Just like their biological counterparts, hardware that mimics the neural circuitry of the brain requires building blocks that can adjust how they synapse, with some connections strengthening at the expense of others. One such approach, called memristors, uses current resistance to store this information. New work looks to overcome reliability issues in these devices by scaling memristors to the atomic level.

An October 16, 2018 AIP news release (also on EurekAlert), which originated the news item, delves further into the particulars of this particular piece of memristor research,

A group of researchers demonstrated a new type of compound synapse that can achieve synaptic weight programming and conduct vector-matrix multiplication with significant advances over the current state of the art. Publishing its work in the Journal of Applied Physics, from AIP Publishing, the group’s compound synapse is constructed with atomically thin boron nitride memristors running in parallel to ensure efficiency and accuracy.

The article appears in a special topic section of the journal devoted to “New Physics and Materials for Neuromorphic Computation,” which highlights new developments in physical and materials science research that hold promise for developing the very large-scale, integrated “neuromorphic” systems of tomorrow that will carry computation beyond the limitations of current semiconductors today.

“There’s a lot of interest in using new types of materials for memristors,” said Ivan Sanchez Esqueda, an author on the paper. “What we’re showing is that filamentary devices can work well for neuromorphic computing applications, when constructed in new clever ways.”

Current memristor technology suffers from a wide variation in how signals are stored and read across devices, both for different types of memristors as well as different runs of the same memristor. To overcome this, the researchers ran several memristors in parallel. The combined output can achieve accuracies up to five times those of conventional devices, an advantage that compounds as devices become more complex.

The choice to go to the subnanometer level, Sanchez said, was born out of an interest to keep all of these parallel memristors energy-efficient. An array of the group’s memristors were found to be 10,000 times more energy-efficient than memristors currently available.

“It turns out if you start to increase the number of devices in parallel, you can see large benefits in accuracy while still conserving power,” Sanchez said. Sanchez said the team next looks to further showcase the potential of the compound synapses by demonstrating their use completing increasingly complex tasks, such as image and pattern recognition.

Here’s an image illustrating the parallel artificial synapses,

Caption: Hardware that mimics the neural circuitry of the brain requires building blocks that can adjust how they synapse. One such approach, called memristors, uses current resistance to store this information. New work looks to overcome reliability issues in these devices by scaling memristors to the atomic level. Researchers demonstrated a new type of compound synapse that can achieve synaptic weight programming and conduct vector-matrix multiplication with significant advances over the current state of the art. They discuss their work in this week’s Journal of Applied Physics. This image shows a conceptual schematic of the 3D implementation of compound synapses constructed with boron nitride oxide (BNOx) binary memristors, and the crossbar array with compound BNOx synapses for neuromorphic computing applications. Credit: Ivan Sanchez Esqueda

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

Efficient learning and crossbar operations with atomically-thin 2-D material compound synapses by Ivan Sanchez Esqueda, Huan Zhao and Han Wang. The article will appear in the Journal of Applied Physics Oct. 16, 2018 (DOI: 10.1063/1.5042468).

This paper is behind a paywall.

*Title corrected from ‘Two approaches to memristors featuring’ to ‘Two approaches to memristors’ on May 31, 2019 at 1455 hours PDT.

Electron quantum materials, a new field in nanotechnology?

Physicists name and codify new field in nanotechnology: ‘electron quantum metamaterials’

UC Riverside’s Nathaniel Gabor and colleague formulate a vision for the field in a perspective article

Courtesy: University of California at Riverside

Bravo to whomever put the image of a field together together with a subhead that includes the phrases ‘vision for a field’ and ‘perspective article’. It’s even better if you go to the November 5, 2018 University of California at Riverside (UCR) news release (also on EurekAlert) by Iqbal Pittalwala to see the original format,

When two atomically thin two-dimensional layers are stacked on top of each other and one layer is made to rotate against the second layer, they begin to produce patterns — the familiar moiré patterns — that neither layer can generate on its own and that facilitate the passage of light and electrons, allowing for materials that exhibit unusual phenomena. For example, when two graphene layers are overlaid and the angle between them is 1.1 degrees, the material becomes a superconductor.

“It’s a bit like driving past a vineyard and looking out the window at the vineyard rows. Every now and then, you see no rows because you’re looking directly along a row,” said Nathaniel Gabor, an associate professor in the Department of Physics and Astronomy at the University of California, Riverside. “This is akin to what happens when two atomic layers are stacked on top of each other. At certain angles of twist, everything is energetically allowed. It adds up just right to allow for interesting possibilities of energy transfer.”

This is the future of new materials being synthesized by twisting and stacking atomically thin layers, and is still in the “alchemy” stage, Gabor added. To bring it all under one roof, he and physicist Justin C. W. Song of Nanyang Technological University, Singapore, have proposed this field of research be called “electron quantum metamaterials” and have just published a perspective article in Nature Nanotechnology.

“We highlight the potential of engineering synthetic periodic arrays with feature sizes below the wavelength of an electron. Such engineering allows the electrons to be manipulated in unusual ways, resulting in a new range of synthetic quantum metamaterials with unconventional responses,” Gabor said.

Metamaterials are a class of material engineered to produce properties that do not occur naturally. Examples include optical cloaking devices and super-lenses akin to the Fresnel lens that lighthouses use. Nature, too, has adopted such techniques – for example, in the unique coloring of butterfly wings – to manipulate photons as they move through nanoscale structures.

“Unlike photons that scarcely interact with each other, however, electrons in subwavelength structured metamaterials are charged, and they strongly interact,” Gabor said. “The result is an enormous variety of emergent phenomena and radically new classes of interacting quantum metamaterials.”

Gabor and Song were invited by Nature Nanotechnology to write a review paper. But the pair chose to delve deeper and lay out the fundamental physics that may explain much of the research in electron quantum metamaterials. They wrote a perspective paper instead that envisions the current status of the field and discusses its future.

“Researchers, including in our own labs, were exploring a variety of metamaterials but no one had given the field even a name,” said Gabor, who directs the Quantum Materials Optoelectronics lab at UCR. “That was our intent in writing the perspective. We are the first to codify the underlying physics. In a way, we are expressing the periodic table of this new and exciting field. It has been a herculean task to codify all the work that has been done so far and to present a unifying picture. The ideas and experiments have matured, and the literature shows there has been rapid progress in creating quantum materials for electrons. It was time to rein it all in under one umbrella and offer a road map to researchers for categorizing future work.”

In the perspective, Gabor and Song collect early examples in electron metamaterials and distil emerging design strategies for electronic control from them. They write that one of the most promising aspects of the new field occurs when electrons in subwavelength-structure samples interact to exhibit unexpected emergent behavior.

“The behavior of superconductivity in twisted bilayer graphene that emerged was a surprise,” Gabor said. “It shows, remarkably, how electron interactions and subwavelength features could be made to work together in quantum metamaterials to produce radically new phenomena. It is examples like this that paint an exciting future for electronic metamaterials. Thus far, we have only set the stage for a lot of new work to come.”

Gabor, a recipient of a Cottrell Scholar Award and a Canadian Institute for Advanced Research Azrieli Global Scholar Award, was supported by the Air Force Office of Scientific Research Young Investigator Program and a National Science Foundation Division of Materials Research CAREER award.

There is a video illustrating the ideas which is embedded in a November 5, 2018 news item on phys.oirg,


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

Electron quantum metamaterials in van der Waals heterostructures by Justin C. W. Song & Nathaniel M. Gabor. Nature Nanotechnology, volume 13, pages986–993 (2018) DOI: https://doi.org/10.1038/s41565-018-0294-9 Published: 05 November 2018

This paper is behind a paywall.

Bendable phones that are partially organic

It’s been about nine  or 10 years since I first heard about bendable phones (my September 29, 2010 posting). The concept keeps popping up from time to time (my April 25, 2017 posting) and this time, we have Australian scientists to thank for this latest work described in an October 5, 2018 news item on Nanowerk (Note: A link has been removed),

Engineers at ANU [Australian National University] have invented a semiconductor with organic and inorganic materials that can convert electricity into light very efficiently, and it is thin and flexible enough to help make devices such as mobile phones bendable (Advanced Materials, “Efficient and Layer-Dependent Exciton Pumping across Atomically Thin Organic–Inorganic Type-I Heterostructures”).

The invention also opens the door to a new generation of high-performance electronic devices made with organic materials that will be biodegradable or that can be easily recycled, promising to help substantially reduce e-waste.

An October 5, 2018 ANU press release (also on EurekAlert but published October 4, 2018) expands on the theme,

The huge volumes of e-waste generated by discarded electronic devices around the world is causing irreversible damage to the environment. Australia produces 200,000 tonnes of e-waste every year – only four per cent of this waste is recycled.

The organic component has the thickness of just one atom – made from just carbon and hydrogen – and forms part of the semiconductor that the ANU team developed. The inorganic component has the thickness of around two atoms. The hybrid structure can convert electricity into light efficiently for displays on mobile phones, televisions and other electronic devices.

Lead senior researcher Associate Professor Larry Lu said the invention was a major breakthrough in the field.

“For the first time, we have developed an ultra-thin electronics component with excellent semiconducting properties that is an organic-inorganic hybrid structure and thin and flexible enough for future technologies, such as bendable mobile phones and display screens,” said Associate Professor Lu from the ANU Research School of Engineering.

PhD researcher Ankur Sharma, who recently won the ANU 3-Minute Thesis competition, said experiments demonstrated the performance of their semiconductor would be much more efficient than conventional semiconductors made with inorganic materials such as silicon.

“We have the potential with this semiconductor to make mobile phones as powerful as today’s supercomputers,” said Mr Sharma from the ANU Research School of Engineering.

“The light emission from our semiconducting structure is very sharp, so it can be used for high-resolution displays and, since the materials are ultra-thin, they have the flexibility to be made into bendable screens and mobile phones in the near future.”

The team grew the organic semiconductor component molecule by molecule, in a similar way to 3D printing. The process is called chemical vapour deposition.

“We characterised the opto-electronic and electrical properties of our invention to confirm the tremendous potential of it to be used as a future semiconductor component,” Associate Professor Lu said.

“We are working on growing our semiconductor component on a large scale, so it can be commercialised in collaboration with prospective industry partners.”

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

Efficient and Layer‐Dependent Exciton Pumping across Atomically Thin Organic–Inorganic Type‐I Heterostructures by Linglong Zhang, Ankur Sharma, Yi Zhu, Yuhan Zhang, Bowen Wang, Miheng Dong, Hieu T. Nguyen, Zhu Wang, Bo Wen, Yujie Cao, Boqing Liu, Xueqian Sun, Jiong Yang, Ziyuan Li. Advanced Materials Volume30, Issue 40 1803986 (October 4, 2018) DOI:https://doi.org/10.1002/adma.201803986 First published [onliine]: 30 August 2018

This paper is behind a paywall.

Wearable electronic textiles from the UK, India, and Canada: two different carbon materials

It seems wearable electronic textiles may be getting nearer to the marketplace. I have three research items (two teams working with graphene and one working with carbon nanotubes) that appeared on my various feeds within two days of each other.

UK/China

This research study is the result of a collaboration between UK and Chinese scientists. From a May 15, 2019 news item on phys.org (Note: Links have been removed),


Wearable electronic components incorporated directly into fabrics have been developed by researchers at the University of Cambridge. The devices could be used for flexible circuits, healthcare monitoring, energy conversion, and other applications.

The Cambridge researchers, working in collaboration with colleagues at Jiangnan University in China, have shown how graphene – a two-dimensional form of carbon – and other related materials can be directly incorporated into fabrics to produce charge storage elements such as capacitors, paving the way to textile-based power supplies which are washable, flexible and comfortable to wear.

The research, published in the journal Nanoscale, demonstrates that graphene inks can be used in textiles able to store electrical charge and release it when required. The new textile electronic devices are based on low-cost, sustainable and scalable dyeing of polyester fabric. The inks are produced by standard solution processing techniques.

Building on previous work by the same team, the researchers designed inks which can be directly coated onto a polyester fabric in a simple dyeing process. The versatility of the process allows various types of electronic components to be incorporated into the fabric.

Schematic of the textile-based capacitor integrating GNP/polyesters as electrodes and h-BN/polyesters as dielectrics. Credit: Felice Torrisi

A May 16, 2019 University of Cambridge press release, which originated the news item, probes further,

Most other wearable electronics rely on rigid electronic components mounted on plastic or textiles. These offer limited compatibility with the skin in many circumstances, are damaged when washed and are uncomfortable to wear because they are not breathable.

“Other techniques to incorporate electronic components directly into textiles are expensive to produce and usually require toxic solvents, which makes them unsuitable to be worn,” said Dr Felice Torrisi from the Cambridge Graphene Centre, and the paper’s corresponding author. “Our inks are cheap, safe and environmentally-friendly, and can be combined to create electronic circuits by simply overlaying different fabrics made of two-dimensional materials on the fabric.”

The researchers suspended individual graphene sheets in a low boiling point solvent, which is easily removed after deposition on the fabric, resulting in a thin and uniform conducting network made up of multiple graphene sheets. The subsequent overlay of several graphene and hexagonal boron nitride (h-BN) fabrics creates an active region, which enables charge storage. This sort of ‘battery’ on fabric is bendable and can withstand washing cycles in a normal washing machine.

“Textile dyeing has been around for centuries using simple pigments, but our result demonstrates for the first time that inks based on graphene and related materials can be used to produce textiles that could store and release energy,” said co-author Professor Chaoxia Wang from Jiangnan University in China. “Our process is scalable and there are no fundamental obstacles to the technological development of wearable electronic devices both in terms of their complexity and performance.”

The work done by the Cambridge researchers opens a number of commercial opportunities for ink based on two-dimensional materials, ranging from personal health and well-being technology, to wearable energy and data storage, military garments, wearable computing and fashion.

“Turning textiles into functional energy storage elements can open up an entirely new set of applications, from body-energy harvesting and storage to the Internet of Things,” said Torrisi “In the future our clothes could incorporate these textile-based charge storage elements and power wearable textile devices.”

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

Wearable solid-state capacitors based on two-dimensional material all-textile heterostructures by Siyu Qiang, Tian Carey, Adrees Arbab, Weihua Song, Chaoxia Wang and Felice Torris. Nanoscale, 2019, Advance Article DOI: 10.1039/C9NR00463G First published on 18 Apr 2019

This paper is behind a paywall.

India

Prior to graphene’s reign as the ‘it’ carbon material, carbon nanotubes (CNTs) ruled. It’s been quieter on the CNT front since graphene took over but a May 15, 2019 Nanowerk Spotlight article by Michael Berger highlights some of the latest CNT research coming out of India,


The most important technical challenge is to blend the chemical nature of raw materials with fabrication techniques and processability, all of which are diametrically conflicting for textiles and conventional energy storage devices. A team from Indian Institute of Technology Bombay has come out with a comprehensive approach involving simple and facile steps to fabricate a wearable energy storage device. Several scientific and technological challenges were overcome during this process.

First, to achieve user-comfort and computability with clothing, the scaffold employed was the the same as what a regular fabric is made up of – cellulose fibers. However, cotton yarns are electrical insulators and therefore practically useless for any electronics. Therefore, the yarns are coated with single-wall carbon nanotubes (SWNTs).

SWNTs are hollow, cylindrical allotropes of carbon and combine excellent mechanical strength with electrical conductivity and surface area. Such a coating converts the electrical insulating cotton yarn to a metallic conductor with high specific surface area. At the same time, using carbon-based materials ensures that the final material remains light-weight and does not cause user discomfort that can arise from metallic wires such as copper and gold. This CNT-coated cotton yarn (CNT-wires) forms the electrode for the energy storage device.

Next, the electrolyte is composed of solid-state electrolyte sheets since no liquid-state electrolytes can be used for this purpose. However, solid state electrolytes suffer from poor ionic conductivity – a major disadvantage for energy storage applications. Therefore, a steam-based infiltration approach that enhances the ionic conductivity of the electrolyte is adopted. Such enhancement of humidity significantly increases the energy storage capacity of the device.


The integration of the CNT-wire electrode with the electrolyte sheet was carried out by a simple and elegant approach of interweaving the CNT-wire through the electrolyte (see Figure 1). This resulted in cross-intersections which are actually junctions where the electrical energy can be stored. Each such junction is now an energy storage unit, referred to as sewcap.

The advantage of this process is that several 100s and 1000s of sewcaps can be made in a small area and integrated to increase the total amount of energy stored in the system. This scalability is unique and critical aspect of this work and stems from the approach of interweaving.

Further, this process is completely adaptable with current processes used in textile industries. Hence, a proportionately large energy-storage is achieved by creating sewcap-junctions in various combinations.

All components of the final sewcap device are flexible. However, they need to be protected from environmental effects such as temperature, humidity and sweat while retaining the mechanical flexibility. This is achieved by laminating the entire device between polymer sheets. The process is exactly similar to the one used for protecting documents and ID cards.

The laminated sewcap can be integrated easily on clothing and fabrics while retaining the flexibility and sturdiness. This is demonstrated by the unchanged performance of the device during extreme and harsh mechanical testing such as striking repeatedly with a hammer, complete flexing, bending and rolling and washing in a laundry machine.

In fact, this is the first device that has been proven to be stable under rigorous washing conditions in the presence of hot water, detergents and high torque (spinning action of washing machine). This provides the device with comprehensive mechanical stability.


CNTs have high surface area and electrical conductivity. The CNT-wire combines these properties of CNTs with stability and porosity of cellulose yarns. The junction created by interweaving is essentially comprised of two such CNT-wires that are sandwiching an electrolyte. Application of potential difference leads to polarization of the electrolyte thus enabling energy storage similar to the way in which a conventional capacitor acts.

“We use the advantage of the interweaving process and create several such junctions. So, with each junction being able to store a certain amount of electrical energy, all the junctions synchronized are able to store a large amount of energy. This provides high energy density to the device,” Prof. C. Subramaniam, Department of Chemistry, IIT Bombay and corresponding author of the paper points out.

The device has also been employed for lighting up an LED [light-emitting diode]. This can be potentially scaled to provide electrical energy demanded by the application.

This image accompanies the paper written by Prof. C. Subramaniam and his team,

Courtesy: IACS Applied Materials Interfaces

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

Interwoven Carbon Nanotube Wires for High-Performing, Mechanically Robust, Washable, and Wearable Supercapacitors by Mihir Kumar Jha, Kenji Hata, and Chandramouli Subramaniam. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.8b22233 Publication Date (Web): April 29, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Canada

A research team from the University of British Columbia (UBC at the Okanagan Campus) joined the pack with a May 16, 2019 news item on ScienceDaily,

Forget the smart watch. Bring on the smart shirt.

Researchers at UBC Okanagan’s School of Engineering have developed a low-cost sensor that can be interlaced into textiles and composite materials. While the research is still new, the sensor may pave the way for smart clothing that can monitor human movement.

A May 16, 2019 UBC news release (also on EurekAlert), which originated the news item, describes the work in more detail,


“Microscopic sensors are changing the way we monitor machines and humans,” says Hoorfar, lead researcher at the Advanced Thermo-Fluidic Lab at UBC’s Okanagan campus. “Combining the shrinking of technology along with improved accuracy, the future is very bright in this area.”

This ‘shrinking technology’ uses a phenomenon called piezo-resistivity—an electromechanical response of a material when it is under strain. These tiny sensors have shown a great promise in detecting human movements and can be used for heart rate monitoring or temperature control, explains Hoorfar.

Her research, conducted in partnership with UBC Okanagan’s Materials and Manufacturing Research Institute, shows the potential of a low-cost, sensitive and stretchable yarn sensor. The sensor can be woven into spandex material and then wrapped into a stretchable silicone sheath. This sheath protects the conductive layer against harsh conditions and allows for the creation of washable wearable sensors.

While the idea of smart clothing—fabrics that can tell the user when to hydrate, or when to rest—may change the athletics industry, UBC Professor Abbas Milani says the sensor has other uses. It can monitor deformations in fibre-reinforced composite fabrics currently used in advanced industries such as automotive, aerospace and marine manufacturing.

The low-cost stretchable composite sensor has also shown a high sensitivity and can detect small deformations such as yarn stretching as well as out-of-plane deformations at inaccessible places within composite laminates, says Milani, director of the UBC Materials and Manufacturing Research Institute.

The testing indicates that further improvements in its accuracy could be achieved by fine-tuning the sensor’s material blend and improving its electrical conductivity and sensitivity This can eventually make it able to capture major flaws like “fibre wrinkling” during the manufacturing of advanced composite structures such as those currently used in airplanes or car bodies.

“Advanced textile composite materials make the most of combining the strengths of different reinforcement materials and patterns with different resin options,” he says. “Integrating sensor technologies like piezo-resistive sensors made of flexible materials compatible with the host textile reinforcement is becoming a real game-changer in the emerging era of smart manufacturing and current automated industry trends.”

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

Graphene‐Coated Spandex Sensors Embedded into Silicone Sheath for Composites Health Monitoring and Wearable Applications by Hossein Montazerian, Armin Rashidi, Arash Dalili, Homayoun Najjaran, Abbas S. Milani, Mina Hoorfar. Small Volume15, Issue17 April 26, 2019 1804991 DOI: https://doi.org/10.1002/smll.201804991 First published: 28 March 2019

This paper is behind a paywall.

Will there be one winner or will they find CNTs better for one type of wearable tech textile while graphene excels for another type of wearable tech textile?

The van Gogh-Roosegaarde path, a solar powered bike path

From YouTube, Heijmans NV Published on Nov 12, 2014 Inspired by Vincent van Gogh’s work, the cycle path combines innovation and design with cultural heritage and tourism. The Van Gogh-Roosegaarde cycle path is being constructed by Heijmans from a design by Daan Roosegaarde and forms part of the Van Gogh cycle route in Brabant.

According to other sources, the path was inspired by van Gogh’s ‘Starry Night’. From a November 21, 2014 article by Elizabeth Montalbano for Design News (Note: A link has been removed),

The Dutch are known for their love of bicycling, and they’ve also long been early adopters of green-energy and smart-city technologies. So it seems fitting that a town in which painter Vincent van Gogh once lived has given him a very Dutch-like tribute — a bike path lit by a special smart paint in the style of the artist’s “Starry Night” painting.

Designed by artist Daan Roosegaarde of Studio Roosegaarde, the van Gogh-Roosegaarde bike path — in the Dutch town of Nuenen en Eindhoven, where van Gogh lived from 1883-1885 — is a kilometer long and features technologies developed as part of the Smart Highway project, a joint venture of the studio and Dutch infrastructure company Heijmans.

A team of 12 designers and engineers worked on the project for eight months, while site production took 10 days. The opening of the path marked the official launch of the international van Gogh 2015 year.

The path uses stones painted with a smart coating that charges by the heat of the sun during the day and then glow at night for up to eight hours. When there is not enough sunlight during the day to charge the stones, the path can draw electricity from a solar panel installed nearby. There are also LEDs in the path that provides lighting.

How does the technology work?

Despite my best efforts, I never did unearth a good technical explanation. There is some sort of photoluminescent powder or paint. I vote for a powder that’s been emulsified in a paint/coating. material. Somehow, this material is charged by sunlight and then at night glows with the help of a solar panel and light-emitting diodes (LEDs).

Here’s the clearest explanation I found; it’s from Dan Howarth’s November 12, 2014 article for dezeen.com (Note: A link has been removed), ,

The surface of the Van Gogh-Roosegaarde Bicycle Path is coated with a special paint that uses energy gathered during the day to glow after dark.


[Daan] Roosegaarde told Dezeen that this method of illumination is “more gentle to the eye and surrounding nature” that other lighting infrastructure, and creates a “connection with cultural history”.

A nearby solar panel is used to generate power to illuminate the coated surface, which was developed with infrastructure firm Heijmans. LEDs along the side of certain curves in the path cast extra light, meaning the path will still be partially lit if the weather has been too cloudy for the panel to charge the surface to its full brightness.

“It’s a new total system that is self-sufficient and practical, and just incredibly poetic,” said Roosegaarde.

Lily Hay Newman’s November 14, 2014 article for Slate.com succinctly sums up the technical aspects,

The path is coated in photoluminescent paint that’s also embedded with small LEDs powered by nearby solar panels. The path essentially charges all day so that it can glow during the night, and it also has backup power in case it’s overcast.

This October 30, 2012 article by Liat Clark for Wired.com provides a bit more detail about the powder/paint as Clark delves into the Roosegaarde Studo’s Smart Highway project (the cycle path made use of the same technology) ,

The studio has developed a photo-luminising powder that will replace road markings – it charges up in sunlight, giving it up to 10 hours of glow-in-the-dark time come nightfall. “It’s like the glow in the dark paint you and I had when we were children,” designer Roosegaarde explained, “but we teamed up with a paint manufacturer and pushed the development. Now, it’s almost radioactive“. [perhaps not the wisest choice of hyperbole]

Special paint will also be used to paint markers like snowflakes across the road’s surface – when temperatures fall to a certain point, these images will become visible, indicating that the surface will likely be slippery. Roosegaarde says this technology has been around for years, on things like baby food – the studio has just upscaled it.

Not everyone is in love

Shaunacy Ferro’s July 26, 2017 article for dentalfloss.com highlights a glow-in-the-dark path project for Singapore and a little criticism (Note: Links have been removed),

Glow-in-the-dark materials are no longer for toys. Photoluminescence can help cities feel safer at night, whether it’s part of a mural, a bike lane, or a highway. Glow-in-the-dark paths have been tested in several European cities (the above is a Van Gogh-inspired bike path by the Dutch artist Daan Roosegaarde) and in Texas, but now, the technology may be coming to Singapore. The city-state is currently developing a 15-mile greenway called the Rail Corridor, and it now has a glow-in-the-dark path, as Mashable reports.

The 328-foot stretch of glowing path is part of a test of multiple surface materials that might eventually be used throughout the park, depending on public opinion. In addition to the strontium aluminate-beaded [emphasis mine] path that glows at night, there are also three other 328-foot stretches of the path that are paved with fine gravel, cement aggregate, and part-grass/part-gravel. The glow-in-the-dark material embedded in the walkway absorbs UV light from the sun during the day and can emit light for up to eight hours once the sun goes down.

However, in practice, glow-in-the-dark paths can be less dazzling than they seem. [emphasis mine] Mashable’s reporter called the glowing effect on Singapore’s path “disappointingly feeble.” [emphasis mine] In 2014, a glowing highway-markings pilot by Studio Roosegaarde in the Netherlands revealed that the first road markings faded after exposure to heavy rains. [emphases mine] When it comes to glowing roads, the renderings tend to look better than the actual result, [emphasis mine] and there are still kinks to work out. (The studio worked the issue out eventually.) While a person walking or biking down Singapore’s glowing path might be able to tell that they were staying on the path better than if they were fumbling along dark pavement, it’s not the equivalent of a streetlight, for sure.

Ferro had reported earlier on Studio Roosegaarde’s Smart Highway project in an October 23, 2014 article for Fast Company where Ferro first mentioned the rain problem (Note: Links have been removed),

Glowing Lanes is a collaboration between Dutch engineering company Heijmans and Daan Roosegaarde, a tech-loving artist and designer whose previous work includes Intimacy 2.0, a dress that becomes transparent when the wearer gets aroused. The glow-in-the-dark lane markers are intended to increase road visibility in a more energy-efficient way than traditional street lighting. Photoluminescent paint charges during the day and slowly emits light over the course of eight hours during the evening.

After a few technical challenges (an early version of the markers didn’t fare so well in the rain), the final system has been installed, and according to Studio Roosegaarde, the kinks have been worked out, and initial reports of the paint fading were “overstated.” [emphases mine]

“This was part of any normal learning process,” according to an email from the studio’s PR, and “now the project is ‘matured.’”

But not to the point where it’s no longer a novelty. According to the email from Studio Roosegaarde, the glowing highway caused a minor traffic jam last night as people rushed to look at it.

… Roosegaarde has also been asked to create a smart highway design for Afsluitdijk–an almost 20-mile-long dike that connects North Holland to the province of Friesland across the water–and according to his studio, there are plans in the works to launch the glowing lanes in China and Japan as well.

Comments

In the following excerpt, there’s a reference to strontium aluminate-coated materials, given the interview which follows this section, the project in Singapore did not use the photoluminescent paint developed by Roosegaarde Studio. I found this paint reference in a July 26, 2017 article by Yi Shu Ng for Mashable (h/t Ferro’s July 26, 2017 article) which notes the product’s ubiquity,

The track glows because it’s got strontium aluminate compounds embedded in it — the chemical is commonly found in glow-in-the-dark products, which absorb ultraviolet light in the day, to emit luminescence at night.

There are some inconsistencies in the reporting about the number of hours, eight hours or 10 hours, the bicycle path or smart highway remains lit after being charged. Given that this was a newish technology being used in a new application, the rain problem and other technical glitches were to be expected. I wish the writer had been a little less dismissive and that the studio had been a little more forthcoming about how they solved the problems. In any case, I dug further and this is what I got.

Interview

I’m not sure who answered the questions but this comes direct from Studio Roosegaarde,

  • Could you give me a capsule description of what’s happened since the path was opened in 2014/15? For example, How does the bike path look these days? Does it still glow? Don’t the bicycles on the path destroy the ‘Starry Night’ pattern over time? Do the stones have to be coated over and over again to maintain their solar charging capacities? 

    The Van Gogh Path is still working perfectly and is visited every night by couples, tourists and local people. The stones are inside the concrete so are still in place and will work for a minimum of 10 years. It is great to see we have created a place of wonder. It is the most published bicycle path in the world. We have even had children books published about it.
  • Are there more bike paths like the Van Gogh Path in other parts of Holland and/or elsewhere?

    No, this is the only one. There have been some copycats in other countries.The Smart Highway project is still growing, and our recent Gates of Light is the next step of poetic and energy-neutral landscapes like the Van Gogh Path:  https://www.studioroosegaarde.net/project/gates-of-light
  • How has your project evolved? And, have there been any unanticipated benefits and/or setbacks? Is there a change in the technology, I noticed you were investigating bioluminscence.

    Yes, we are still developing new landscapes of the future. What we have learned from Van Gogh Path we have applied in new projects such as Glowing Nature: https://www.studioroosegaarde.net/project/glowing-nature We also do something new.
  • I was struck by how gentle the lighting is. I understand there has been some criticism about how much light the path radiates and I’m wondering about your thoughts on that.

    Yes, since the path is a nature protected environment, normal LED lighting was not allowed. So the light is gentle but still visible, and sustainable.There are some bad copy-cats using cheap materials which don’t work well, like the one in Singapore. But we are happy that our path is still working.

Thank you to the folks at Studio Roosegaarde for taking the time to provide this interview. Here are links to Studio Roosegaarde and their industrial partner, Heijmans.

How do nanoparticles interact with the environment and with humans over time?

I meant to get this piece published sooner but good intentions don’t get you far.

At Northwestern University, scientists have researched the impact engineered nanoparticles (ENPs) might have as they enter the food chain. An October 18, 2019 Northwestern University news release (also on EurekAlert) by Megan Fellman describes research on an investigation of ENPs and their interaction with living organisms,

Personal electronic devices — smartphones, computers, TVs, tablets, screens of all kinds — are a significant and growing source of the world’s electronic waste. Many of these products use nanomaterials, but little is known about how these modern materials and their tiny particles interact with the environment and living things.

Now a research team of Northwestern University chemists and colleagues from the national Center for Sustainable Nanotechnology has discovered that when certain coated nanoparticles interact with living organisms it results in new properties that cause the nanoparticles to become sticky. Fragmented lipid coronas form on the particles, causing them to stick together and grow into long kelp-like strands. Nanoparticles with 5-nanometer diameters form long structures that are microns in size in solution. The impact on cells is not known.

“Why not make a particle that is benign from the beginning?” said Franz M. Geiger, professor of chemistry in Northwestern’s Weinberg College of Arts and Sciences. He led the Northwestern portion of the research.

“This study provides insight into the molecular mechanisms by which nanoparticles interact with biological systems,” Geiger said. “This may help us understand and predict why some nanomaterial/ligand coating combinations are detrimental to cellular organisms while others are not. We can use this to engineer nanoparticles that are benign by design.”

Using experiments and computer simulations, the research team studied how gold nanoparticles wrapped in strings having positively charged beads interact with a variety of bilayer membrane models. The researchers found that a nearly circular layer of lipids forms spontaneously around the particles. Formation of these “fragmented lipid coronas” have never been seen before to form from membranes.

The study points to solving problems with chemistry. Scientists can use the findings to design a better ligand coating for nanoparticles that avoids the ammonium-phosphate interaction, which causes the aggregation. (Ligands are used in nanomaterials for layering.)

The results will be published Oct. 18 [2018] in the journal Chem.

Geiger is the study’s corresponding author. Other authors include scientists from the Center for Sustainable Nanotechnology’s other institutional partners. Based at the University of Wisconsin-Madison, the center studies engineered nanomaterials and their interaction with the environment, including biological systems — both the negative and positive aspects.

“The nanoparticles pick up parts of the lipid cellular membrane like a snowball rolling in a snowfield, and they become sticky,” Geiger said. “This unintended effect happens because of the presence of the nanoparticle. It can bring lipids to places in cells where lipids are not meant to be.”

The experiments were conducted in idealized laboratory settings that nevertheless are relevant to environments found during the late summer in a landfill — at 21-22 degrees Celsius and a couple feet below ground, where soil and groundwater mix and the food chain begins.

By pairing spectroscopic and imaging experiments with atomistic and coarse-grain simulations, the researchers identified that ion pairing between the lipid head groups of biological membranes and the polycations’ ammonium groups in the nanoparticle wrapping leads to the formation of fragmented lipid coronas. These coronas engender new properties, including composition and stickiness, to the particles with diameters below 10 nanometers.

The study’s insights help predict the impact that the increasingly widespread use of engineered nanomaterials has on the nanoparticles’ fate once they enter the food chain, which many of them may eventually do.

“New technologies and mass consumer products are emerging that feature nanomaterials as critical operational components,” Geiger said. “We can upend the existing paradigm in nanomaterial production towards one in which companies design nanomaterials to be sustainable from the beginning, as opposed to risking expensive product recalls — or worse — down the road.” [emphases mine]

Here’s an image illustrating the work,

Caption: This is a computer simulation of a lipid corona around a 5-nanometer nanoparticle showing ammonium-phosphate ion pairing. Credit: Northwestern University

The curious can find the paper here,

Lipid Corona Formation from Nanoparticle Interactions with Bilayers by Laura L. Olenick, Julianne M. Troiano, Ariane Vartanian, Eric S. Melby, Arielle C. Mensch, Leili Zhang, Jiewei Hong, Oluwaseun Mesele, Tian Qiu, Jared Bozich, Samuel Lohse, Xi Zhang, Thomas R. Kuech, Augusto Millevolte, Ian Gunsolus, Alicia C. McGeachy, Merve Doğangün, Tianzhe Li, Dehong Hu, Stephanie R. Walter, Aurash Mohaimani, Angela Schmoldt, Marco D. Torelli, Katherine R. Hurley, Joe Dalluge, Gene Chong, Z. Vivian Feng, Christy L. Haynes, Robert J. Hamers, Joel A. Pedersen, Qiang Cui, Rigoberto Hernandez, Rebecca Klaper, Galya Orr, Catherine J. Murphy, Franz M. Geiger. Chem Volume 4, ISSUE 11, P2709-2723, November 08, 2018 DOI:https://doi.org/10.1016/j.chempr.2018.09.018 Published:October 18, 2018

This paper is behind a paywall.

I am a sound speaker/loudspeaker (well, maybe one day)

Caption: From left are Saewon Kang, Professor Hyunhyub Ko, and Seungse Cho in the School of Energy and Chemical Engineering at UNIST. Credit: UNIST

What are these scientists so happy about? A September 18, 2018 news item on ScienceDaily reveals all,

An international team of researchers, affiliated with UNIST [Ulsan National Institute of Science and Technology] has presented an innovative wearable technology that will turn your skin into a loudspeaker.

An August 6, 2018 UNIST press release (also on EurekAlert but published September 17,2018), which originated the news item, delves further into the research,

This breakthrough has been led by Professor Hyunhyub Ko in the School of Energy and Chemical Engineering at UNIST. Created in part to help the hearing and speech impaired, the new technology can be further explored for various potential applications, such as wearable IoT sensors and conformal health care devices.

In the study, the research team has developed ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, consisting of an orthogonal silver nanowire array embedded in a polymer matrix. They, then, demonstrated their nanomembrane by making it into a loudspeaker that can be attached to almost anything to produce sounds. The researchers also introduced a similar device, acting as a microphone, which can be connected to smartphones and computers to unlock voice-activated security systems.

Nanomembranes (NMs) are molcularly thin seperation layers with nanoscale thickness. Polymer NMs have attracted considerable attention owing to their outstanding advantages, such as extreme flexibility, ultralight weight, and excellent adhesibility in that they can be attached directly to almost any surface. However, they tear easily and exhibit no electrical conductivity.

The research team has solved such issues by embedding a silver nanowire network within a polymer-based nanomembrane. This has enabled the demonstration of skin-attachable and imperceptible loudspeaker and microphone.

“Our ultrathin, transparent, and conductive hybrid NMs facilitate conformal contact with curvilinear and dynamic surfaces without any cracking or rupture,” says  Saewon Kang in the doctroral program of Energy and Chemical Engineering at UNIST, the first author of the study.

He adds, “These layers are capable of detecting sounds and vocal vibrations produced by the triboelectric voltage signals corresponding to sounds, which could be further explored for various potential applications, such as sound input/output devices.”

Using the hybrid NMs, the research team fabricated skin-attachable NM loudspeakers and microphones, which would be unobtrusive in appearance because of their excellent transparency and conformal contact capability. These wearable speakers and microphones are paper-thin, yet still capable of conducting sound signals.

“The biggest breakthrough of our research is the development of ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, less than 100 nanometers,” says Professor Ko. “These outstanding optical, electrical, and mechanical properties of nanomembranes enable the demonstration of skin-attachable and imperceptible loudspeaker and microphone.”The skin-attachable NM loudspeakers work by emitting thermoacoustic sound by the temperature-induced oscillation of the surrounding air. The periodic Joule heating that occurs when an electric current passes through a conductor and produces heat leads to these temperature oscillations. It has attracted considerable attention for being a stretchable, transparent, and skin-attachable loudspeaker.

Wearable microphones are sensors, attached to a speaker’s neck to even sense the vibration of the vocal folds. This sensor operates by converting the frictional force generated by the oscillation of the transparent conductive nanofiber into electric energy. For the operation of the microphone, the hybrid nanomembrane is inserted between elastic films with tiny patterns to precisely detect the sound and the vibration of the vocal cords based on a triboelectric voltage that results from the contact with the elastic films.

“For the commercial applications, the mechanical durability of nanomebranes and the performance of loudspeaker and microphone should be improved further,” says Professor Ko.

Thankfully, the researchers have made video that lets us hear this sound speaker,


Paper-thin stick-on speakers, developed by Professor Hyunhyub Ko and his research team at UNIST.

Thank you to the folks at UNIST for including something with the sound. Strangely, it’s not common practice to include audio when publishing research on sound, not in my experience anyway..

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

Transparent and conductive nanomembranes with orthogonal silver nanowire arrays for skin-attachable loudspeakers and microphones by Saewon Kang, Seungse Cho, Ravi Shanker, Hochan Lee, Jonghwa Park, Doo-Seung Um, Youngoh Lee, and Hyunhyub Ko. Science Advances 03 Aug 2018: Vol. 4, no. 8, eaas8772 DOI: 10.1126/sciadv.aas8772

This paper appears to be open access.