Israel sets up $27 million fund to boost quantum research


 

Israel hopes the funding of researchers in the field will boost the nation’s standing, even as other countries pour billions of dollars into the emerging field

 

The Defense Ministry and the Israel Science Foundation have set up a new NIS 100 million ($27 million) fund over five years to boost the study of quantum technologies and develop the research infrastructure necessary to boost Israel’s global position in the growing field.

The fund “will continue to place Israel at the top of global technology and research,” said Prime Minister Benjamin Netanyahu, who is also the defense minister, in a statement. “From the cyber power to the quantum superpower, we will continue to lead significant breakthroughs for the State of Israel.”

Quantum physics, discovered at the beginning of the 20th century,describes the properties of microscopic particles. Within the scientific community, the study of quantum physics is considered as revolutionary as the study of nanotechnology. The US, China and European countries are rushing to develop technologies based on quantum principles, pouring billions of dollars into research efforts and vying for a leading spot in the emerging field.

Israel’s ministries of defense, science, and finance and the Israel Innovation Authority, which is in charge of setting out the nation’s policies for its tech sector, are currently formulating a national plan for the quantum field. The setting up of the fund is a first step in the bid to create an ecosystem in the field, the Defense Ministry said in a statement.

Some NIS 75 million of the money will be aimed at supporting “outstanding research groups” at Israeli universities that will undertake research and development in the sector. The money will be used to finance both the research expenses and to purchase or upgrade the equipment required for the research, the statement said.

The fund will invest in a variety of fields, including quantum communications, quantum simulation, quantum sensors such as atomic clocks, magnetic field meters and quantum materials.

The remaining funds will be earmarked for other purposes, according to need, the statement said.

“Quantum has been growing globally in recent years, and is expected to change the way we examine reality both in routine situations as well as in emergency situations, in a variety of aspects such as navigation, safe communications, calculations,” said Brig. Gen Daniel Gold of the Defense Ministry.

“The global race is already underway,” said Prof. Yaffa Zilbershats, the chairwoman of the Planning and Budgeting Committee of the Israel Council for Higher Education. “Various countries are investing huge sums in developing the field, and if we do not run forward, the State of Israel will be left behind. ”

The Defense Ministry has been active in the field of quantum technologies for many years, and is working to exploit the unique advantages of these technologies as in its operational needs, the statement said.

The program will help “leapfrog” Israel’s capabilities, the ministry said, leading it to applications that that were until now considered imaginary.

Quantum theory has already succeeded in explaining the structure of matter — the atom, the molecule, the chemical bonds between particles, solid matter and crystals. It has also provided the basis for developments such as transistor, laser, light waves, fast communication and atomic clocks that are the basis for satellite navigation systems and medical imaging methods such as MRI, among others.

Prof. Uri Sivan of the Faculty of Physics at the Technion — Israel Institute of Technology will head the steering committee for the fund along with academic experts in the field, the statement said.

In Israel, the Planning and Budgeting Committee of the Council for Higher Education said last year that it would invest tens of millions of dollars in quantum technology research in its five-year plan.

In May, Prime Minister Benjamin Netanyahu announced a projectthat would enhance Israel’s intelligence gathering capacities through the use of quantum technology.

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New Hybrid solar cells harness energy from … raindrops?


Renewable energy is the cleanest and inexhaustible source of energy. They are a great alternative to fossil fuels.

Renewable energy doesn’t emit any greenhouse gases in the environment. They are environment-friendly and help us tackle the most important concern of the 21st Century – Climate Change.

Solar is one of the most important forms of renewable energy. Sun is an inexhaustible source of energy and solar cells help capture that clean energy for both commercial and domestic purposes. Despite all these advantages, Solar cells are not efficient when it comes to producing energy during rainy seasons. Since the input energy gets reduced, solar cells become practically useless when rain clouds are overhead.

But what if we could overcome this problem?  What if we could actually generate energy from raindrops?

Scientists from the University of Soochow, China have overcome the design flaw of solar cells by allowing them to generate energy both in the sunny and rainy season.

This technology holds the potential of revolutionizing renewable energy completely.

The key part of this new Hybrid solar technology is the triboelectric nanogenerator or TENG. A device capable of producing an electric charge from the friction of two materials rubbing together.

How Hybrid solar cells work?

These new hybrid solar cells works using a material called Graphene. It has the ability to produce energy from raindrops.

Like any other solar panel, these hybrid solar cells also generate electricity during a normal sunny day using the current technology, but when cloud gathers and raindrop falls, this solar panels system switch to its graphene system.

Graphene, in its liquid form, can produce electricity due to the presence of delocalized electrons that help us create a pseudocapacitor framework. This pseudo framework helps us generate electricity.

When raindrops fall on hybrid solar panels, they get separated as positive ions and negative ions.

These positive ions are mainly salt-related ions, like sodium and calcium which accumulates on the surface of graphene. These positive ions interact with the loosely associated negative ions in graphene and create a system that acts like a pseudocapacitor.

The difference in potential between these ions produces current and voltage.

Although, it is important to mention that this is not a first attempt to invent all-weathered Solar panels. Earlier, researchers created a solar panel with triboelectric nanogenerator on top, an insulating layer in the middle and solar panel at the bottom. But this system possessed too much electrical resistance and sunlight was not able to reach the solar cells due to the opaque nature of insulators.

The newly designed hybrid solar panel is an efficient device, where the triboelectric nanogenerator and the solar panel share a common and transparent electrode. There are special grooves incorporated in the material which increases the efficiency of both raindrops and sunlight captured.

According to the researchers, the idea of special grooves was derived from commercial DVD’s. DVD’s come pre-etched with parallel grooves just hundreds of nanometer across. Designing the device with this grooves helps to boost the surface interaction of raindrops and sunlight that would be otherwise lost to reflection.

Benefits of Solar Hybrid Panels  

Until now solar cells have this drawback of producing energy only in the presence of sunlight, making it impossible to harness energy during the rainy season. Countries in the northern hemisphere were not able to switch to solar energy due to the presence of low-intensity sunlight.

With hybrid solar panels, anyone in the world could harness solar power. Researchers expect that in a few years, these panels will be efficient enough to provide electricity for homes and businesses and thus ending our dependency on fossil fuels.

They will also save a lot of money on daily electricity bills. Even though the initial setup costs are higher, countries with good exposure to both sunlight and rain can expect a good ROI.

Hurdles in Solar hybrid panels    

The current designs are not efficient enough to be used commercially. The device was tested in various simulated weather conditions, in sunlight, the device was able to produce around 13% efficiency and simulated raindrops had an efficiency of around 6%.

Currently used commercial solar cells gives an efficiency of around 15%, thus the new design is a viable option for presently used solar panels. However, the efficiency of triboelectric nanogenerators was not reported.

Conclusion

With continuous depletion of non-renewable sources and the disastrous climate change occurring due to fossil fuels, many countries are moving towards eco-friendly alternatives. Solar energy is one of the cleanest energy available. With the advent of new technology like the hybrid solar panels, we can hope to achieve a viable method of electricity generation.

Researchers are continuously trying to improve the efficiency of hybrid solar cells in order to make it commercially available. This will boost our efforts of producing energy in all-weather condition, which is not possible with the currently available technology. With the expansion of solar energy projects worldwide, researchers of hybrid solar cells are expecting to roll out commercial designs in next five years.

Researchers at china are even trying to integrate this new technology into mobile and electronic device such as electronic clothing.     

Update Rice University – Researchers develop a method to make atom-flat sensors that seamlessly integrate with devices – technique will make active sensors or devices possible for telecommunication and bio-sensing, plasmonics


Rice U Flat Atom structure DuEfkhxWwAAfEGTRice University engineers have developed a method to transfer complete, flexible, two-dimensional circuits from their fabrication platforms to curved and other smooth surfaces. Such circuits are able to couple with near-field …more

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by  scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices to report on what they perceive.

Electronically active 2-D materials have been the subject of much research since the introduction of graphene in 2004. Even though they are often touted for their strength, they’re difficult to move to where they’re needed without destroying them.Nano Sensor 1 FANG

The Ajayan and Lou groups, along with the lab of Rice engineer Jacob Robinson, have a new way to keep the materials and their associated circuitry, including electrodes, intact as they’re moved to curved or other smooth surfaces.

The results of their work appear in the American Chemical Society journal ACS Nano.

Rice logo_rice3The Rice team tested the concept by making a 10-nanometer-thick indium selenide photodetector with gold electrodes and placing it onto an . Because it was so close, the near-field sensor effectively coupled with an evanescent field—the oscillating electromagnetic wave that rides the surface of the fiber—and accurately detected the flow of information inside.

The benefit is that these sensors can now be imbedded into such fibers where they can monitor performance without adding weight or hindering the signal flow.

“This paper proposes several interesting possibilities for applying 2-D devices in real applications,” Lou said. “For example, optical fibers at the bottom of the ocean are thousands of miles long, and if there’s a problem, it’s hard to know where it occurred. If you have these sensors at different locations, you can sense the damage to the fiber.”

Lou said labs have gotten good at transferring the growing roster of 2-D materials from one surface to another, but the addition of electrodes and other components complicates the process. “Think about a transistor,” he said. “It has source, drain and gate electrodes and a dielectric (insulator) on top, and all of these have to be transferred intact. That’s a very big challenge, because all of those materials are different.”

Raw 2-D materials are often moved with a layer of polymethyl methacrylate (PMMA), more commonly known as Plexiglas, on top, and the Rice researchers make use of that technique. But they needed a robust bottom layer that would not only keep the circuit intact during the move but could also be removed before attaching the device to its target. (The PMMA is also removed when the circuit reaches its destination.)

The ideal solution was poly-dimethyl-glutarimide (PMGI), which can be used as a device fabrication platform and easily etched away before transfer to the target. “We’ve spent quite some time to develop this sacrificial layer,” Lou said. PMGI appears to work for any 2-D material, as the researchers experimented successfully with molybdenum diselenide and other materials as well.

Nano sensors 2 electronics_vision_10-11-17

The Rice labs have only developed passive sensors so far, but the researchers believe their technique will make active  or devices possible for telecommunication, biosensing, plasmonics and other applications.

 Explore further: Fluorine flows in, makes material metal

More information: Zehua Jin et al, Near-Field Coupled Integrable Two-Dimensional InSe Photosensor on Optical Fiber, ACS Nano (2018). DOI: 10.1021/acsnano.8b07159

 

Sprayable gel could help the body fight off cancer … after surgery


sprayablegelA scanning electron microscope image of a gel developed by UCLA researchers that could help prevent cancer from recurring after surgery. Credit: University of California, Los Angeles

Many people who are diagnosed with cancer will undergo some type of surgery to treat their disease—almost 95 percent of people with early-diagnosed breast cancer will require surgery and it’s often the first line of treatment for people with brain tumors, for example. But despite improvements in surgical techniques over the past decade, the cancer often comes back after the procedure.

AAfter surgery sprayable gel kp69pm-800x533

Now, a UCLA-led  has developed a spray gel embedded with immune-boosting drugs that could help. In a peer-reviewed study, the substance was successful half of the time in awakening lab animals’ immune systems to stop the cancer from recurring and inhibit it from spreading to other parts of the body.

A paper describing the work is published online in the journal Nature Nanotechnology.

The researchers, led by Zhen Gu, a professor of bioengineering at the UCLA Samueli School of Engineering and member of the UCLA Jonsson Comprehensive Cancer Center, tested the biodegradable spray gel in mice that had advanced melanoma tumors surgically removed. They found that the gel reduced the growth of the tumor cells that remained after surgery, which helped prevent recurrences of the cancer: After receiving the treatment, 50 percent of the mice survived for at least 60 days without their tumors regrowing.

The spray not only inhibited the recurrence of tumors from the area on the body where it was removed, but it also controlled the development of tumors in other parts of the body, said Gu, who is also a member of the California NanoSystems Institute at UCLA.

Cancer-treatment-655x353The substance will have to go through further testing and approvals before it could be used in humans. But Gu said that the scientists envision the gel being applied to the tumor resection site by surgeons immediately after the tumor is removed during surgery.

“This sprayable gel shows promise against one of the greatest obstacles in curing cancer,” Gu said. “One of the trademarks of cancers is that it spreads. In fact, around 90 percent of people with cancerous tumors end up dying because of  recurrence or metastasis. Being able to develop something that helps lower this risk for this to occur and has low toxicity is especially gratifying.”

The researchers loaded nanoparticles with an antibody specifically targeted to block CD47, a protein that cancer cells release as a “don’t-eat-me” signal. By blocking CD47, the antibody enables the immune system to find and ultimately destroy the cancer cells.

The nanoparticles are made of calcium carbonate, a substance that is the main component of egg shells and is often found in rocks. Researchers chose  because it can be gradually dissolved in surgical wound sites, which are slightly acidic, and because it boosts the activity of a type of macrophage that helps rid the body of foreign objects, said Qian Chen, the study’s lead author and a  in Gu’s lab.

“We also learned that the gel could activate T cells in the immune system to get them to work together as another line of attack against lingering  cells,” Chen said.

Once the solution is sprayed on the surgical site, it quickly forms a gel embedded with the nanoparticles. The gel helps stop at the surgical site and promotes would healing; the nanoparticles gradually dissolve and release the anti-CD47 antibodies into the body.

The  will continue testing the approach in animals to learn the optimal dose, best mix of nanoparticles and ideal treatment frequency, before testing the gel on human patients.

 Explore further: Gradual release of immunotherapy at site of tumor surgery prevents tumors from returning

More information: Qian Chen et al. In situ sprayed bioresponsive immunotherapeutic gel for post-surgical cancer treatment, Nature Nanotechnology (2018). DOI: 10.1038/s41565-018-0319-4

 

MIT Team invents method to shrink objects to the nanoscale – “Implosion Manufacturing” – Applications from Optics to Medicine to Robotics – Materials from Quantum Dots, Metals and DNA


MIT Implosion mfg mitteaminvenAccording to professor Ed Boyden, many research labs are already stocked with the equipment required for this kind of fabrication. Credit: The researchers

” … These tiny structures could have applications in many fields, from optics to medicine to robotics, the researchers say.”

MIT researchers have invented a way to fabricate nanoscale 3-D objects of nearly any shape. They can also pattern the objects with a variety of useful materials, including metals, quantum dots, and DNA.

“It’s a way of putting nearly any kind of material into a 3-D pattern with nanoscale precision,” says Edward Boyden, an associate professor of biological engineering and of brain and cognitive sciences at MIT.

Using the , the researchers can create any shape and structure they want by patterning a  with a laser. After attaching other useful materials to the scaffold, they shrink it, generating structures one thousandth the volume of the original.

These tiny structures could have applications in many fields, from optics to medicine to robotics, the researchers say. The technique uses equipment that many biology and materials science labs already have, making it widely accessible for researchers who want to try it.

Boyden, who is also a member of MIT’s Media Lab, McGovern Institute for Brain Research, and Koch Institute for Integrative Cancer Research, is one of the senior authors of the paper, which appears in the Dec. 13 issue of Science. The other senior author is Adam Marblestone, a Media Lab research affiliate, and the paper’s lead authors are graduate students Daniel Oran and Samuel Rodriques.

MIT-Implosion-Fabrication-01Implosion fabrication

Existing techniques for creating nanostructures are limited in what they can accomplish. Etching patterns onto a surface with light can produce 2-D nanostructures but doesn’t work for 3-D structures. It is possible to make 3-D nanostructures by gradually adding layers on top of each other, but this process is slow and challenging. And, while methods exist that can directly 3-D print nanoscale objects, they are restricted to specialized materials like polymers and plastics, which lack the functional properties necessary for many applications. Furthermore, they can only generate self-supporting structures. (The technique can yield a solid pyramid, for example, but not a linked chain or a hollow sphere.)

To overcome these limitations, Boyden and his students decided to adapt a technique that his lab developed a few years ago for high-resolution imaging of brain tissue. This technique, known as expansion microscopy, involves embedding tissue into a hydrogel and then expanding it, allowing for high resolution imaging with a regular microscope. Hundreds of research groups in biology and medicine are now using expansion microscopy, since it enables 3-D visualization of cells and tissues with ordinary hardware.

By reversing this process, the researchers found that they could create large-scale objects embedded in expanded hydrogels and then shrink them to the nanoscale, an approach that they call “implosion fabrication.”

As they did for , the researchers used a very absorbent material made of polyacrylate, commonly found in diapers, as the scaffold for their nanofabrication process. The scaffold is bathed in a solution that contains molecules of fluorescein, which attach to the scaffold when they are activated by laser light.

Using two-photon microscopy, which allows for precise targeting of points deep within a structure, the researchers attach fluorescein molecules to specific locations within the gel. The fluorescein molecules act as anchors that can bind to other types of molecules that the researchers add.

“You attach the anchors where you want with light, and later you can attach whatever you want to the anchors,” Boyden says. “It could be a quantum dot, it could be a piece of DNA, it could be a gold nanoparticle.”

“It’s a bit like film photography—a latent image is formed by exposing a sensitive material in a gel to light. Then, you can develop that latent image into a real image by attaching another material, silver, afterwards. In this way implosion fabrication can create all sorts of structures, including gradients, unconnected structures, and multi-material patterns,” Oran says.

Once the desired molecules are attached in the right locations, the researchers shrink the entire structure by adding an acid. The acid blocks the negative charges in the polyacrylate gel so that they no longer repel each other, causing the gel to contract. Using this technique, the researchers can shrink the objects 10-fold in each dimension (for an overall 1,000-fold reduction in volume). This ability to shrink not only allows for increased resolution, but also makes it possible to assemble materials in a low-density scaffold. This enables easy access for modification, and later the material becomes a dense solid when it is shrunk.

“People have been trying to invent better equipment to make smaller nanomaterials for years, but we realized that if you just use existing systems and embed your  in this gel, you can shrink them down to the nanoscale, without distorting the patterns,” Rodriques says.

Currently, the researchers can create objects that are around 1 cubic millimeter, patterned with a resolution of 50 nanometers. There is a tradeoff between size and resolution: If the researchers want to make larger objects, about 1 cubic centimeter, they can achieve a resolution of about 500 nanometers. However, that resolution could be improved with further refinement of the process, the researchers say.

Better optics

The MIT team is now exploring potential applications for this technology, and they anticipate that some of the earliest applications might be in optics—for example, making specialized lenses that could be used to study the fundamental properties of light. This technique might also allow for the fabrication of smaller, better lenses for applications such as cell phone cameras, microscopes, or endoscopes, the researchers say. Farther in the future, the researchers say that this approach could be used to build nanoscale electronics or robots.

“There are all kinds of things you can do with this,” Boyden says. “Democratizing nanofabrication could open up frontiers we can’t yet imagine.”

Many research labs are already stocked with the equipment required for this kind of fabrication. “With a laser you can already find in many biology labs, you can scan a pattern, then deposit metals, semiconductors, or DNA, and then shrink it down,” Boyden says.

 Explore further: High-resolution imaging with conventional microscopes

More information: D. Oran el al., “3D nanofabrication by volumetric deposition and controlled shrinkage of patterned scaffolds,” Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aau5119

T.E. Long el al., “Printing nanomaterials in shrinking gels,” Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aav5712

 

LLNL Researchers Develop New Class of 3D PRINTED METAMATERIALS that Strengthen “On Demand” – Applications for armor that responds on impact; car seats that reduce whiplash and NextGen Neck braces


Combining 3D printing with a magnetic ink injection, researchers at Lawrence Livermore National Laboratory (LLNL) have created a new class of metamaterial – engineered with behaviors outside their nature.

Like 4D printed objects, LLNL’s 3D printed lattices rely on the fourth element of time to become something “other” than their natural resting state. However, in contrast to its relatives, that often transform in response to temperatures or water, the change in LLNL’s new structures is almost instantaneous – they stiffen when a magnetic field is applied.

This unique class is the next step forward in metamaterials that can be tuned “on-the-fly” to achieve desired properties, and applied to make intuitive objects: e.g. armor that responds on impact; car seats that reduce whiplash; and next generation neck braces.

A 3D printed lattice injected with magnetic fluid. Image via Science Advances, supplementary materials/LLNL

A 3D printed lattice injected with magnetic fluid. Image via Science Advances, supplementary materials/LLNL

Harnessing the power of lattices

In the first stage of this development, the LLNL team performed a digital simulation of their metamaterial lattices. By doing so, the team could determine how the shape would respond to a magnetic field, and therefore optimize its structure for desired mechanical properties.

Mark Messner, former LLNL researcher and co-author of a study presenting the new metamaterial, explains, “The design space of possible lattice structures is huge, so the model and the optimization process helped us choose likely structures with favorable properties before [it was] printed, filled and tested the actual specimens, which is a lengthy process.”

After optimization, experimental lattices were 3D printed using a method of Large Area Projection Microstereolithography (LAPµSL). With microscale precision, LAPµSL enabled the team to create thin walls that could support injected fluid.

Lead author Julie Jackson Mancini explains, “In this paper we really wanted to focus on the new concept of metamaterials with tunable properties, and even though it’s a little more of a manual fabrication process,” i.e. with the injection of material, “it still highlights what can be done, and that’s what I think is really exciting.”

Materials with “on-the-fly” tunability 

The ink inside the LLNL lattice is a magnetorheological fluid, containing minute magnetic particles.

Like a “dancing” iron filing experiment, when a magnetic field is applied to this lattice, the particles realign, making the structure stiff and supportive of added weight.

This newfound strength is demonstrated through a test in which a 10g weight is added to the top of the lattice. As the magnet beneath the lattice is moved away, the structure gradually gives way, and eventually drops the weight.

Demonstration showing a 3D printing magnetic metamaterial lattice, and its response to the removal of a magnetic field. Image via Science Advance, supplementary materials/LLNL

Demonstration showing a 3D printing magnetic metamaterial lattice, and its response to the removal of a magnetic field. Image via Science Advance, supplementary materials/LLNL

“What’s really important,” explains Mancini, “is it’s not just an on and off response, by adjusting the magnetic field strength applied we can get a wide range of mechanical properties,”

“THE IDEA OF ON-THE-FLY, REMOTE TUNABILITY OPENS THE DOOR TO A LOT OF APPLICATIONS.”

Future development

The next steps for the LLNL metamaterial team is to develop a means of integrating the ink-injection stage of lattice fabrication, and to increase the size of objects that can be 3D printed.

Results of the lab’s most recent study, “Field responsive mechanical metamaterials” are published online in Science Advances journal. It’s co-authors are listed as Julie A. JacksonMark C. MessnerNikola A. Dudukovic, William L. SmithLogan BekkerBryan MoranAlexandra M. GolobicAndrew J. PascallEric B. DuossKenneth J. Loh, and Christopher M. Spadaccini.

Nominate 3D Printing Research Team of the Year and more now for the 2019 3D Printing Industry Awards.

Artificial synapses made from Zinc-Oxide nanowires – ideal candidate for use in building bioinspired “neuromorphic” processors


Image captured by an electron microscope of a single nanowire memristor (highlighted in colour to distinguish it from other nanowires in the background image). Blue: silver electrode, orange: nanowire, yellow: platinum electrode. Blue bubbles are dispersed over the nanowire. They are made up of silver ions and form a bridge between the electrodes which increases the resistance. Credit: Forschungszentrum Jülich

Scientists from Jülich together with colleagues from Aachen and Turin have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell.

The component is able to save and process information, as well as receive numerous signals in parallel. The resistive switching cell made from oxide crystal nanowires is thus an ideal candidate for use in building bioinspired “neuromorphic” processors, able to take over the diverse functions of biological synapses and neurons.

Computers have learned a lot in recent years. Thanks to rapid progress in artificial intelligence they are now able to drive cars, translate texts, defeat world champions at chess, and much more besides.
In doing so, one of the greatest challenges lies in the attempt to artificially reproduce the signal processing in the human brain.
In , data are stored and processed to a high degree in parallel. Traditional computers, on the other hand, rapidly work through tasks in succession and clearly distinguish between the storing and processing of information.
As a rule, neural networks can only be simulated in a very cumbersome and inefficient way using conventional hardware.

Systems with neuromorphic chips that imitate the way the  works offer significant advantages. These types of computers work in a decentralised way, having at their disposal a multitude of processors, which, like neurons in the brain, are connected to each other by networks. If a processor breaks down, another can take over its function.

What is more, just like in the brain, where practice leads to improved signal transfer, a bioinspired processor should have the capacity to learn.

“With today’s semiconductor technology, these functions are to some extent already achievable. These systems are, however, suitable for particular applications and require a lot of space and energy,” says Dr. Ilia Valov from Forschungszentrum Jülich. “Our nanowire devices made from zinc oxide crystals can inherently process and even store information, and are extremely small and energy efficient.”

For years, memristive cells have been ascribed the best chances of taking over the function of neurons and synapses in bioinspired computers. They alter their electrical resistance depending on the intensity and direction of the electric current flowing through them.

In contrast to conventional transistors, their last resistance value remains intact even when the electric current is switched off. Memristors are thus fundamentally capable of learning.

In order to create these properties, scientists at Forschungszentrum Jülich and RWTH Aachen University used a single zinc oxide nanowire, produced by their colleagues from the polytechnic university in Turin. Measuring approximately one 10,000th of a millimeter in size, this type of nanowire is over 1,000 times thinner than a human hair. The resulting memristive component not only takes up a tiny amount of space, but is also able to switch much faster than flash memory.

Nanowires offer promising novel physical properties compared to other solids and are used among other things in the development of new types of solar cells, sensors, batteries and computer chips. Their manufacture is comparatively simple. Nanowires result from the evaporation deposition of specified materials onto a suitable substrate, where they practically grow of their own accord.

In order to create a functioning cell, both ends of the nanowire must be attached to suitable metals, in this case platinum and silver. The metals function as electrodes, and in addition, release ions triggered by an appropriate electric current. The metal ions are able to spread over the surface of the wire and build a bridge to alter its conductivity.

Components made from single are, however, still too isolated to be of practical use in chips. Consequently, the next step being planned by the Jülich and Turin researchers is to produce and study a memristive element, composed of a larger, relatively easy to generate group of several hundred nanowires offering more exciting functionalities.

More information: Gianluca Milano et al, Self-limited single nanowire systems combining all-in-one memristive and neuromorphic functionalities, Nature Communications (2018).  DOI: 10.1038/s41467-018-07330-7

Provided by Forschungszentrum Juelich

Explore further: Scientists create a prototype neural network based on memristors

Nano-textiles: The Fabric of the Future


nanopattern

 

When you think of futuristic clothing, you probably imagine lots of metallics, holographic accents, and textures. In fact, the sci-fi imagery that springs to mind is coming back into fashion, as evidenced by some recent runway trends (Below: Figure 1).

futuristic fashion.png
Figure 1. An amalgam of different futuristic looks that graced the runway in early 2017 (image by Cristina Cifuentes)

While we can’t say for certain what the fashion of the future will look like, many of us hope that clothing a few years from now will have some greatly enhanced function, making use of science to create cleaner, safer textiles. One way to achieve these goals is to use nanotechnology to do things like kill bacteria or remove dirt.

Nanotechnology in the clothing industry is not a new phenomenon. Beginning in the mid-2000s, many clothing companies started incorporating silver nanoparticles into their products. Silver nanoparticles are antimicrobial, which means they kill the bacteria that cause bad odors. By including these nanoparticles in fabric to prevent odor, the resulting clothes need to be washed less frequently. These nano-infused items range from socks to t-shirts and are still popular today.1 To learn more about the environmental implications of silver-nanoparticle impregnated fabric, visit our previous blog post here.

nanosilver.png
Figure 2. Nanosilver is being incorporated into clothing items like socks to prevent odor by killing odor-causing bacteria (adapted from images by Theivasanthi and Scott Bauer)

There is a lot more new technology beyond antimicrobial nanoparticles coming from the field of nano-fabrics. Other desirable clothing characteristics that could be achieved with nanotechnology include self-cleaning fabrics, water-repelling textiles, and clothing that can reduce odors by chemically changing the compounds that cause bad odor.2 These innovations would take advantage of nano- specific properties, particularly the high surface area per volume ratio of nano-sized materials that increase the exposure of active surfaces to the surrounding environment.

Some of these more futuristic-sounding features are already in development. Recently, fabrics coated with silver and copper nanomaterials were produced that can degrade organic matter, such as food and dirt, upon exposure to the sun. These nanomaterials absorb visible light, producing high energy “hot” electrons that can break down surrounding organic matter. The nano features are helpful because the increased surface area of silver or copper metal drastically increases surface-exposed sites that can form the “hot” electrons to help break down food and dirt.2,3 Incorporating these nanomaterials could thus help create clothes that clean themselves!

Nanotechnology can also be harnessed to produce water-repelling, or hydrophobic, materials. This application draws its inspiration from nature: many plants have foliage that is hydrophobic because of nano-scale structures on the leaves. You can observe water-repelling plant leaves on a dewy summer morning. Water droplets on a leaf tend to ball up into spheres instead of being absorbed into the surface (Figure 3). This phenomenon is called the “lotus effect” because it is especially potent for the leaves of the lotus plant.

lotus effect.png
Figure 3.The Lotus Effect in action (image by Sweetaholic)

The hydrophobicity of the lotus leaf also makes it self-cleaning; dirt that initially sticks to the leaf surface is often washed away by beads of water that roll off the plant due to its hydrophobicity (Figure 4).4 After studying the physical structure of lotus leaves, researchers understand that their superhydrophobic nature is partially due to the presence of nanostructures, which create a rough surface that repels water.4

nanopattern.png
Figure 4. Nanopatterned surfaces can exploit the Lotus effect, causing them to be hydrophobic enough for water droplets to ball up and roll off the fabric surface, removing dirt particles in their path (image by William Thielicke)

Researchers are working to exploit the lotus effect to create artificial superhydrophobic fabrics. Imagine how convenient it would be if rain was completely repelled by your umbrella, to the point that you could wrap it up when you get inside- no having to shake it off or leave it open to dry! New nanofabrics can do just this because they contain patterned nano-silicone spikes. Silicone is naturally water resistant, and the use of nano-sized patterns makes the material even more hydrophobic. When a water droplet comes into contact with the surface of these materials, it balls up and slides off instead of being absorbed.5

Nanotechnology can also be used to chemically target and eliminate odor-causing molecules. Whereas the silver nanoparticles mentioned earlier prevent odor formation by killing bacteria, a second generation of odor-busting nanoparticles work by chemically targeting and modifying stinky compounds. Whereas things like fabric or room sprays merely mask odor, fabrics modified with these new nanomaterials could break down the source of the odor, making them better and more efficient at deodorizing. One group of researchers found that copper coated silica nanoparticles were effective at eliminating odor arising from ethyl mercaptan, which is a stinky chemical typically added to petroleum gas (which is odorless) to enable us to smell gas leaks. Interacting with the copper-silica nanoparticles modifies the ethyl mercaptan molecules and binds them to the surface of the particles, so there is less ethyl mercaptan left to smell bad.6 This second generation of odor-reducing nanoparticles may be more environmentally sound than antimicrobial silver, because the mechanism of odor elimination is targeted towards specific compounds as opposed to general bacterial toxicity.

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Figure 5. Microscopy image showing copper clusters (arrow) on the surface of a silica nanoparticle. These nanoparticles were used to modify and bind to stinky ethyl mercaptan, greatly reducing odor. (image adapted from Singh et al. 2010,6 with permission from the American Chemical Society)

So, will nano-fabrics be the future of clothing, enabling us to all have self-cleaning, water-resistant clothes that we only have to wash a few times a year? Only time will tell. The field of nano-fabrics is still very much in its infancy and it still faces some challenges. For example, washing clothes that contain antimicrobial silver releases nanoparticles into the waste water, giving them a limited effective lifetime as the nanomaterial washes out. Perhaps more important is the potential environmental risk of this nanoparticle release into the environment, which has incited continued debate and controversy, as metal nanoparticles can dissolve into toxic ions when exposed to environmental conditions.7,8 Newer nanofabric technologies may carry their own concerns, which have not yet been thoroughly studied. However, the potential benefits of nano-enhanced fabrics makes their use worth exploration. And with continued scientific advancement that will allow us to address environmental concerns, this sector of nanotechnology can only continue to grow.


EDUCATIONAL RESOURCES


REFERENCES

  1. Soutter, W. Nanotechnology in Clothing. AZO Nano, 2012.   https://www.azonano.com/article.aspx?ArticleID=3129.
  2. Osborne, H. Self-cleaning clothes edge closer as scientists create textile cleansed of dirt by sunlight. International Business Times, 2016.    https://www.ibtimes.co.uk/self-cleaning-clothes-edge-closer-scientists-create-textile-cleansed-dirt-by-sunlight-1551240.
  3. Anderson, S. R.; Mohammadtaheri, M.; Kumar, D.; O’Mullane, A. P.; Field, M. R.; Ramanathan, R.; Bansal, V. Adv. Mater. Interfaces 20163(6), 1–8. DOI: 10.1002/admi.201500632.
  4. Nanowerk. Nanotechnology solutions for self-cleaning, dirt and water-repellent coatings. 2011.   https://www.nanowerk.com/spotlight/spotid=19644.php.
  5. Evans, J. Nanotech clothing fabric ‘never gets wet.’ New Scientist, 2008 https://www.newscientist.com/article/dn16126-nanotech-clothing-fabric-never-gets-wet/.
  6. Singh, A.; Krishna, V.; Angerhofer, A.; Do, B.; MacDonald, G.; Moudgil, B. Langmuir 201026(20), 15837–15844. doi: 10.1021/la100793u
  7. Mole, B. News Brief: Wash removes nano germ-killers https://www.sciencenewsforstudents.org/article/news-brief-wash-removes-nano-germ-killers.
  8. American Chemical Society. The impact of anti-odor clothing on the environment (press release) 2016.   https://www.acs.org/content/acs/en/pressroom/presspacs/2016/acs-presspac-april-13-2016/the-impact-of-anti-odor-clothing-on-the-environment.html.

Penn State – 3D Imaging Technique Unlocks Properties of Perovskite Crystals – Applications for Perovskite Solar Cells


A reconstruction of a perovskite crystal (CaTiO3) grown on a similar perovskite substrate (NdGaO3) showing electron density and oxygen octahedral tilt. (insert) Artist’s conception of the interface between substrate and film. Credit: Yakun Yuan/Penn State

A team of materials scientists from Penn State, Cornell and Argonne National Laboratory have, for the first time, visualized the 3D atomic and electron density structure of the most complex perovskite crystal structure system decoded to date.

Perovskites are minerals that are of interest as electrical insulators, semiconductors, metals or superconductors, depending on the arrangement of their atoms and electrons.

Perovskite crystals have an unusual grouping of oxygen atoms that form an octahedron, an eight-sided polygon. This arrangement of oxygen atoms acts like a cage that can hold a large number of the elemental atoms in the periodic table. Additionally, other atoms can be fixed to the corners of a cube outside of the cage at precise locations to alter the material’s properties, for instance in changing a metal into an insulator, or a non-magnet into a ferromagnet.

In their current work, the team grew the very first discovered perovskite crystal, called calcium titanate, on top of a series of other perovskite crystal substrates with similar but slightly different oxygen cages at their surfaces. Because the thin film perovskite on top wants to conform to the structure of the thicker substrate, it contorts its cages in a process known as tilt epitaxy.

The researchers found this tilt epitaxy of calcium titanate caused a very ordinary material to take on the property of ferroelectricity, a spontaneous polarization, and to remain ferroelectric up to 900 Kelvin, around three times hotter than room temperature. They were also able to visualize the three-dimensional electron density distribution in calcium titanate thin film for the first time.

“We have been able to see atoms for quite some time, but not map them and their electron distribution in space in a crystal in three dimensions,” said Venkat Gopalan, professor of materials science and physics, Penn State. “If we can see not just where atomic nuclei are located in space, but also how their electron clouds are shared, that will tell us basically everything we need to know about the material in order to infer its properties.”

That was the challenge the team set for itself over five years ago when Gopalan gave his student and lead author of a new report in Nature Communications, Yakun Yuan, the project.

Based on a rarely used x-ray visualization technique called COBRA, for coherent Bragg rod analysis, originally developed by a group in Israel, Yuan figured out how to expand and modify the technique to analyze one of the most complicated, least symmetrical material systems studied to date: the strained three-dimensional perovskite crystal with octahedral tilts in all directions, grown on another equally complex crystal structure.

“To reveal 3D structural details at the atomic level, we had to collect extensive datasets using the most brilliant synchrotron X-ray source available at Argonne National Labs and carefully analyze them with the COBRA analysis code modified for accommodating the complexity of such low symmetry,” said Yakun Yuan.

Gopalan went on to explain that very few perovskite oxygen cages are perfectly aligned throughout the material. Some rotate counterclockwise in one layer of atoms and clockwise in the next. Some cages are squeezed out of shape or tilt in directions that are in or out of plane to the substrate surface.

From the interface of a film with the substrate it is grown on, all the way to its surface, each atomic layer may have unique changes in their structure and pattern.  All of these distortions make a difference in the material properties, which they can predict using a computational technique called density functional theory (DFT).

“The predictions from the DFT calculations provide insights that complement the experimental data and help explain the way that material properties change with the alignment or tilting of the perovskite oxygen cages,” said Prof. Susan Sinnott, whose group performed the theoretical calculations.

The team also validated their advanced COBRA technique against multiple images of their material using the powerful Titan transmission electron microscope in the Materials Research Institute at Penn State.  Since the electron microscopes image extremely thin electron transparent samples in a 2-dimensional projection, not all of the 3-dimensional image could be captured even with the best microscope available today and with multiple sample orientations.

Why Perovskite Solar Cells Are So Efficient

This is an area where 3-dimensional imaging by the COBRA technique outperformed the electron microscopy in such complex structures.

The researchers believe their COBRA technique is applicable to the study of many other three-dimensional low-symmetry atomic crystals.

Additional authors on “Three-dimensional atomic scale electron density reconstruction of octahedral tilt epitaxy in functionals perovskites” are Yanfu Lu, a Ph.D. student in Sinnott’s group, Greg Stone, Gopalan’s former postdoctoral scholar, Ke Wang, a staff scientist in Penn State’s Materials Research Institute, Darrell Schlom and his Ph.D. student Charles Brooks, Cornell University, and Hua Zhou, staff scientist, Argonne National Laboratory.

img_0885-1Penn State University

Funding was provided by the National Science Foundation with additional support provided through the Department of Energy and the Penn State 2D Crystal Consortium, a NSF Materials Innovation Platform, and the Penn State institute for CyberScience.

Contact Venkat Gopalan at vxg8@psu.edu or Hua Zhou at hzhou@aps.anl.gov.