Tag Archives: US Air Force Office of Scientific Research

Yarns that harvest and generate energy

The researchers involved in this work are confident enough about their prospects that they will be  patenting their research into yarns. From an August 25, 2017 news item on Nanowerk,

An international research team led by scientists at The University of Texas at Dallas and Hanyang University in South Korea has developed high-tech yarns that generate electricity when they are stretched or twisted.

In a study published in the Aug. 25 [2017] issue of the journal Science (“Harvesting electrical energy from carbon nanotube yarn twist”), researchers describe “twistron” yarns and their possible applications, such as harvesting energy from the motion of ocean waves or from temperature fluctuations. When sewn into a shirt, these yarns served as a self-powered breathing monitor.

“The easiest way to think of twistron harvesters is, you have a piece of yarn, you stretch it, and out comes electricity,” said Dr. Carter Haines, associate research professor in the Alan G. MacDiarmid NanoTech Institute at UT Dallas and co-lead author of the article. The article also includes researchers from South Korea, Virginia Tech, Wright-Patterson Air Force Base and China.

An August 25, 2017 University of Texas at Dallas news release, which originated the news item, expands on the theme,

Yarns Based on Nanotechnology

The yarns are constructed from carbon nanotubes, which are hollow cylinders of carbon 10,000 times smaller in diameter than a human hair. The researchers first twist-spun the nanotubes into high-strength, lightweight yarns. To make the yarns highly elastic, they introduced so much twist that the yarns coiled like an over-twisted rubber band.

In order to generate electricity, the yarns must be either submerged in or coated with an ionically conducting material, or electrolyte, which can be as simple as a mixture of ordinary table salt and water.

“Fundamentally, these yarns are supercapacitors,” said Dr. Na Li, a research scientist at the NanoTech Institute and co-lead author of the study. “In a normal capacitor, you use energy — like from a battery — to add charges to the capacitor. But in our case, when you insert the carbon nanotube yarn into an electrolyte bath, the yarns are charged by the electrolyte itself. No external battery, or voltage, is needed.”

When a harvester yarn is twisted or stretched, the volume of the carbon nanotube yarn decreases, bringing the electric charges on the yarn closer together and increasing their energy, Haines said. This increases the voltage associated with the charge stored in the yarn, enabling the harvesting of electricity.

Stretching the coiled twistron yarns 30 times a second generated 250 watts per kilogram of peak electrical power when normalized to the harvester’s weight, said Dr. Ray Baughman, director of the NanoTech Institute and a corresponding author of the study.

“Although numerous alternative harvesters have been investigated for many decades, no other reported harvester provides such high electrical power or energy output per cycle as ours for stretching rates between a few cycles per second and 600 cycles per second.”

Lab Tests Show Potential Applications

In the lab, the researchers showed that a twistron yarn weighing less than a housefly could power a small LED, which lit up each time the yarn was stretched.

To show that twistrons can harvest waste thermal energy from the environment, Li connected a twistron yarn to a polymer artificial muscle that contracts and expands when heated and cooled. The twistron harvester converted the mechanical energy generated by the polymer muscle to electrical energy.

“There is a lot of interest in using waste energy to power the Internet of Things, such as arrays of distributed sensors,” Li said. “Twistron technology might be exploited for such applications where changing batteries is impractical.”

The researchers also sewed twistron harvesters into a shirt. Normal breathing stretched the yarn and generated an electrical signal, demonstrating its potential as a self-powered respiration sensor.

“Electronic textiles are of major commercial interest, but how are you going to power them?” Baughman said. “Harvesting electrical energy from human motion is one strategy for eliminating the need for batteries. Our yarns produced over a hundred times higher electrical power per weight when stretched compared to other weavable fibers reported in the literature.”

Electricity from Ocean Waves

“In the lab we showed that our energy harvesters worked using a solution of table salt as the electrolyte,” said Baughman, who holds the Robert A. Welch Distinguished Chair in Chemistry in the School of Natural Sciences and Mathematics. “But we wanted to show that they would also work in ocean water, which is chemically more complex.”

In a proof-of-concept demonstration, co-lead author Dr. Shi Hyeong Kim, a postdoctoral researcher at the NanoTech Institute, waded into the frigid surf off the east coast of South Korea to deploy a coiled twistron in the sea. He attached a 10 centimeter-long yarn, weighing only 1 milligram (about the weight of a mosquito), between a balloon and a sinker that rested on the seabed.

Every time an ocean wave arrived, the balloon would rise, stretching the yarn up to 25 percent, thereby generating measured electricity.

Even though the investigators used very small amounts of twistron yarn in the current study, they have shown that harvester performance is scalable, both by increasing twistron diameter and by operating many yarns in parallel.

“If our twistron harvesters could be made less expensively, they might ultimately be able to harvest the enormous amount of energy available from ocean waves,” Baughman said. “However, at present these harvesters are most suitable for powering sensors and sensor communications. Based on demonstrated average power output, just 31 milligrams of carbon nanotube yarn harvester could provide the electrical energy needed to transmit a 2-kilobyte packet of data over a 100-meter radius every 10 seconds for the Internet of Things.”

Researchers from the UT Dallas Erik Jonsson School of Engineering and Computer Science and Lintec of America’s Nano-Science & Technology Center also participated in the study.

The investigators have filed a patent on the technology.

In the U.S., the research was funded by the Air Force, the Air Force Office of Scientific Research, NASA, the Office of Naval Research and the Robert A. Welch Foundation. In Korea, the research was supported by the Korea-U.S. Air Force Cooperation Program and the Creative Research Initiative Center for Self-powered Actuation of the National Research Foundation and the Ministry of Science.

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

Harvesting electrical energy from carbon nanotube yarn twist by Shi Hyeong Kim, Carter S. Haines, Na Li, Keon Jung Kim, Tae Jin Mun, Changsoon Choi, Jiangtao Di, Young Jun Oh, Juan Pablo Oviedo, Julia Bykova, Shaoli Fang, Nan Jiang, Zunfeng Liu, Run Wang, Prashant Kumar, Rui Qiao, Shashank Priya, Kyeongjae Cho, Moon Kim, Matthew Steven Lucas, Lawrence F. Drummy, Benji Maruyama, Dong Youn Lee, Xavier Lepró, Enlai Gao, Dawood Albarq, Raquel Ovalle-Robles, Seon Jeong Kim, Ray H. Baughman. Science 25 Aug 2017: Vol. 357, Issue 6353, pp. 773-778 DOI: 10.1126/science.aam8771

This paper is behind a paywall.

Dexter Johnson in an Aug. 25, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) delves further into the research,

“Basically what’s happening is when we stretch the yarn, we’re getting a change in capacitance of the yarn. It’s that change that allows us to get energy out,” explains Carter Haines, associate research professor at UT Dallas and co-lead author of the paper describing the research, in an interview with IEEE Spectrum.

This makes it similar in many ways to other types of energy harvesters. For instance, in other research, it has been demonstrated—with sheets of rubber with coated electrodes on both sides—that you can increase the capacitance of a material when you stretch it and it becomes thinner. As a result, if you have charge on that capacitor, you can change the voltage associated with that charge.

“We’re more or less exploiting the same effect but what we’re doing differently is we’re using an electric chemical cell to do this,” says Haines. “So we’re not changing double layer capacitance in normal parallel plate capacitors. But we’re actually changing the electric chemical capacitance on the surface of a super capacitor yarn.”

While there are other capacitance-based energy harvesters, those other devices require extremely high voltages to work because they’re using parallel plate capacitors, according to Haines.

Dexter asks good questions and his post is very informative.

Scientists claim off-the-shelf, power-generating clothes almost here

PEDOT-coated yarns act as “normal” wires to transmit electricity from a wall outlet to an incandescent lightbulb. Materials scientist Trisha Andrew at UMass Amherst and colleagues outline in a new paper how they have invented a way to apply breathable, pliable, metal-free electrodes to fabric and off-the-shelf clothing so it feels good to the touch and also transports electricity to power small electronics. Harvesting body motion energy generates the power. Courtesy: UMass Amherst

I’m not quite as optimistic (it’s a long way from the lab to the marketplace) as the scientists do eventually note but this does seem promising (from a May 23, 2017 news item on Nanowerk),

A lightweight, comfortable jacket that can generate the power to light up a jogger at night may sound futuristic, but materials scientist Trisha Andrew at the University of Massachusetts Amherst could make one today.

In a new paper this month, she and colleagues outline how they have invented a way to apply breathable, pliable, metal-free electrodes to fabric and off-the-shelf clothing so it feels good to the touch and also transports enough electricity to power small electronics.

A May 23, 2017 University of Massachusetts Amherst news release (also on EurekAlert), which originated the news item,

She says, “Our lab works on textile electronics. We aim to build up the materials science so you can give us any garment you want, any fabric, any weave type, and turn it into a conductor. Such conducting textiles can then be built up into sophisticated electronics. One such application is to harvest body motion energy and convert it into electricity in such a way that every time you move, it generates power.” Powering advanced fabrics that can monitor health data remotely are important to the military and increasingly valued by the health care industry, she notes.

Generating small electric currents through relative movement of layers is called triboelectric charging, explains Andrew, who trained as a polymer chemist and electrical engineer. Materials can become electrically charged as they create friction by moving against a different material, like rubbing a comb on a sweater. “By sandwiching layers of differently materials between two conducting electrodes, a few microwatts of power can be generated when we move,” she adds.

In the current early online edition of Advanced Functional Materials, she and postdoctoral researcher Lu Shuai Zhang in her lab describe the vapor deposition method they use to coat fabrics with a conducting polymer, poly(3,4-ethylenedioxytiophene) also known as PEDOT, to make plain-woven, conducting fabrics that are resistant to stretching and wear and remain stable after washing and ironing. The thickest coating they put down is about 500 nanometers, or about 1/10 the diameter of a human hair, which retains a fabric’s hand feel.

The authors report results of testing electrical conductivity, fabric stability, chemical and mechanical stability of PEDOT films and textile parameter effects on conductivity for 14 fabrics, including five cottons with different weaves, linen and silk from a craft store.

“Our article describes the materials science needed to make these robust conductors,” Andrew says. “We show them to be stable to washing, rubbing, human sweat and a lot of wear and tear.” PEDOT coating did not change the feel of any fabric as determined by touch with bare hands before and after coating. Coating did not increase fabric weight by more than 2 percent. The work was supported by the Air Force Office of Scientific Research.

Until recently, she and Zhang point out, textile scientists have tended not to use vapor deposition because of technical difficulties and high cost of scaling up from the laboratory. But over the last 10 years, industries such as carpet manufacturers and mechanical component makers have shown that the technology can be scaled up and remain cost-effective. The researchers say their invention also overcomes the obstacle of power-generating electronics mounted on plastic or cladded, veneer-like fibers that make garments heavier and/or less flexible than off-the-shelf clothing “no matter how thin or flexible these device arrays are.”

“There is strong motivation to use something that is already familiar, such as cotton/silk thread, fabrics and clothes, and imperceptibly adapting it to a new technological application.” Andrew adds, “This is a huge leap for consumer products, if you don’t have to convince people to wear something different than what they are already wearing.”

Test results were sometimes a surprise, Andrew notes. “You’d be amazed how much stress your clothes go through until you try to make a coating that will survive a shirt being pulled over the head. The stress can be huge, up to a thousand newtons of force. For comparison, one footstep is equal to about 10 newtons, so it’s yanking hard. If your coating is not stable, a single pull like that will flake it all off. That’s why we had to show that we could bend it, rub it and torture it. That is a very powerful requirement to move forward.”

Andrew is director of wearable electronics at the Center for Personalized Health Monitoring in UMass Amherst’s Institute of Applied Life Sciences (IALS). Since the basic work reported this month was completed, her lab has also made a wearable heart rate monitor with an off-the-shelf fitness bra to which they added eight monitoring electrodes. They will soon test it with volunteers on a treadmill at the IALS human movement facility.

She explains that a hospital heart rate monitor has 12 electrodes, while the wrist-worn fitness devices popular today have one, which makes them prone to false positives. They will be testing a bra with eight electrodes, alone and worn with leggings that add four more, against a control to see if sensors can match the accuracy and sensitivity of what a hospital can do. As the authors note in their paper, flexible, body-worn electronics represent a frontier of human interface devices that make advanced physiological and performance monitoring possible.

For the future, Andrew says, “We’re working on taking any garment you give us and turning it into a solar cell so that as you are walking around the sunlight that hits your clothes can be stored in a battery or be plugged in to power a small electronic device.”

Zhang and Andrew believe their vapor coating is able to stick to fabrics by a process called surface grafting, which takes advantage of free bonds dangling on the surface chemically bonding to one end of the polymer coating, but they have yet to investigate this fully.

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

Rugged Textile Electrodes for Wearable Devices Obtained by Vapor Coating Off-the-Shelf, Plain-Woven Fabrics by Lushuai Zhang, Marianne Fairbanks, and Trisha L. Andrew. Advanced Functional Materials DOI: 10.1002/adfm.201700415 Version of Record online: 2 MAY 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

When an atom more or less makes a big difference

As scientists continue exploring the nanoscale, it seems that finding the number of atoms in your particle makes a difference is no longer so surprising. From a Jan. 28, 2016 news item on ScienceDaily,

Combining experimental investigations and theoretical simulations, researchers have explained why platinum nanoclusters of a specific size range facilitate the hydrogenation reaction used to produce ethane from ethylene. The research offers new insights into the role of cluster shapes in catalyzing reactions at the nanoscale, and could help materials scientists optimize nanocatalysts for a broad class of other reactions.

A Jan. 28, 2016 Georgia Institute of Technology (Georgia Tech) news release (*also on EurekAlert*), which originated the news item, expands on the theme,

At the macro-scale, the conversion of ethylene has long been considered among the reactions insensitive to the structure of the catalyst used. However, by examining reactions catalyzed by platinum clusters containing between 9 and 15 atoms, researchers in Germany and the United States found that at the nanoscale, that’s no longer true. The shape of nanoscale clusters, they found, can dramatically affect reaction efficiency.

While the study investigated only platinum nanoclusters and the ethylene reaction, the fundamental principles may apply to other catalysts and reactions, demonstrating how materials at the very smallest size scales can provide different properties than the same material in bulk quantities. …

“We have re-examined the validity of a very fundamental concept on a very fundamental reaction,” said Uzi Landman, a Regents’ Professor and F.E. Callaway Chair in the School of Physics at the Georgia Institute of Technology. “We found that in the ultra-small catalyst range, on the order of a nanometer in size, old concepts don’t hold. New types of reactivity can occur because of changes in one or two atoms of a cluster at the nanoscale.”

The widely-used conversion process actually involves two separate reactions: (1) dissociation of H2 molecules into single hydrogen atoms, and (2) their addition to the ethylene, which involves conversion of a double bond into a single bond. In addition to producing ethane, the reaction can also take an alternative route that leads to the production of ethylidyne, which poisons the catalyst and prevents further reaction.

The project began with Professor Ueli Heiz and researchers in his group at the Technical University of Munich experimentally examining reaction rates for clusters containing 9, 10, 11, 12 or 13 platinum atoms that had been placed atop a magnesium oxide substrate. The 9-atom nanoclusters failed to produce a significant reaction, while larger clusters catalyzed the ethylene hydrogenation reaction with increasingly better efficiency. The best reaction occurred with 13-atom clusters.

Bokwon Yoon, a research scientist in Georgia Tech’s Center for Computational Materials Science, and Landman, the center’s director, then used large-scale first-principles quantum mechanical simulations to understand how the size of the clusters – and their shape – affected the reactivity. Using their simulations, they discovered that the 9-atom cluster resembled a symmetrical “hut,” while the larger clusters had bulges that served to concentrate electrical charges from the substrate.

“That one atom changes the whole activity of the catalyst,” Landman said. “We found that the extra atom operates like a lightning rod. The distribution of the excess charge from the substrate helps facilitate the reaction. Platinum 9 has a compact shape that doesn’t facilitate the reaction, but adding just one atom changes everything.”

Here’s an illustration featuring the difference between a 9 atom cluster and a 10 atom cluster,

A single atom makes a difference in the catalytic properties of platinum nanoclusters. Shown are platinum 9 (top) and platinum 10 (bottom). (Credit: Uzi Landman, Georgia Tech)

A single atom makes a difference in the catalytic properties of platinum nanoclusters. Shown are platinum 9 (top) and platinum 10 (bottom). (Credit: Uzi Landman, Georgia Tech)

The news release explains why the larger clusters function as catalysts,

Nanoclusters with 13 atoms provided the maximum reactivity because the additional atoms shift the structure in a phenomena Landman calls “fluxionality.” This structural adjustment has also been noted in earlier work of these two research groups, in studies of clusters of gold [emphasis mine] which are used in other catalytic reactions.

“Dynamic fluxionality is the ability of the cluster to distort its structure to accommodate the reactants to actually enhance reactivity,” he explained. “Only very small aggregates of metal can show such behavior, which mimics a biochemical enzyme.”

The simulations showed that catalyst poisoning also varies with cluster size – and temperature. The 10-atom clusters can be poisoned at room temperature, while the 13-atom clusters are poisoned only at higher temperatures, helping to account for their improved reactivity.

“Small really is different,” said Landman. “Once you get into this size regime, the old rules of structure sensitivity and structure insensitivity must be assessed for their continued validity. It’s not a question anymore of surface-to-volume ratio because everything is on the surface in these very small clusters.”

While the project examined only one reaction and one type of catalyst, the principles governing nanoscale catalysis – and the importance of re-examining traditional expectations – likely apply to a broad range of reactions catalyzed by nanoclusters at the smallest size scale. Such nanocatalysts are becoming more attractive as a means of conserving supplies of costly platinum.

“It’s a much richer world at the nanoscale than at the macroscopic scale,” added Landman. “These are very important messages for materials scientists and chemists who wish to design catalysts for new purposes, because the capabilities can be very different.”

Along with the experimental surface characterization and reactivity measurements, the first-principles theoretical simulations provide a unique practical means for examining these structural and electronic issues because the clusters are too small to be seen with sufficient resolution using most electron microscopy techniques or traditional crystallography.

“We have looked at how the number of atoms dictates the geometrical structure of the cluster catalysts on the surface and how this geometrical structure is associated with electronic properties that bring about chemical bonding characteristics that enhance the reactions,” Landman added.

I highlighted the news release’s reference to gold nanoclusters as I have noted the number issue in two April 14, 2015 postings, neither of which featured Georgia Tech, Gold atoms: sometimes they’re a metal and sometimes they’re a molecule and Nature’s patterns reflected in gold nanoparticles.

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

Structure sensitivity in the nonscalable regime explored via catalysed ethylene hydrogenation on supported platinum nanoclusters by Andrew S. Crampton, Marian D. Rötzer, Claron J. Ridge, Florian F. Schweinberger, Ueli Heiz, Bokwon Yoon, & Uzi Landman.  Nature Communications 7, Article number: 10389  doi:10.1038/ncomms10389 Published 28 January 2016

This paper is open access.

*’also on EurekAlert’ added Jan. 29, 2016.

Northwestern University’s (US) International Institute for Nanotechnology (IIN) rakes in some cash

Within less than a month Northwestern University’s International Institute for Nanotechnology (IIN) has been granted awarded two grants by the US Department of Defense.

4D printing

The first grant, for 4D printing, was announced in a June 11, 2015 Northwestern news release by Megan Fellman (Note: A link has been removed),

Northwestern University’s International Institute for Nanotechnology (IIN) has received a five-year, $8.5 million grant from the U.S. Department of Defense’s competitive Multidisciplinary University Research Initiative (MURI) program to develop a “4-dimensional printer” — the next generation of printing technology for the scientific world.

Once developed, the 4-D printer, operating on the nanoscale, will be used to construct new devices for research in chemistry, materials sciences and U.S. defense-related areas that could lead to new chemical and biological sensors, catalysts, microchip designs and materials designed to respond to specific materials or signals.

“This research promises to bring transformative advancement to the development of biosensors, adaptive optics, artificially engineered tissues and more by utilizing nanotechnology,” said IIN director and chemist Chad A. Mirkin, who is leading the multi-institution project. Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences.

The award, issued by the Air Force Office of Scientific Research, supports a team of experts from Northwestern, the University of Miami, the University of California, San Diego, and the University of Maryland.

In science, “printing” encodes information at specific locations on a material’s surface, similar to how we print words on paper with ink. The 4-dimensional printer will consist of millions of tiny elastomeric “pens” that can be used individually and independently to create nanometer-size features composed of hard or soft materials.

The information encoded can be in the form of materials with a defined set of chemical and physical properties. The printing speed and resolution determine the amount and complexity of the information that can be encoded.

Progress in fields ranging from biology to chemical sensing to computing currently are limited by the lack of low-cost equipment that can perform high-resolution printing and 3-dimensional patterning on hard materials (e.g., metals and semiconductors) and soft materials (e.g., organic and biological materials) at nanometer resolution (approximately 1,000 times smaller than the width of a human hair).

“Ultimately, the 4-D printer will provide a foundation for a new generation of tools to develop novel architectures, wherein the hard materials that form the functional components of electronics can be merged with biological or soft materials,” said Milan Mrksich, a co-principal investigator on the grant.

Mrksich is the Henry Wade Rogers Professor of Biomedical Engineering, Chemistry and Cell and Molecular Biology, with appointments in the McCormick School of Engineering and Applied Science, Weinberg and Northwestern University Feinberg School of Medicine.

A July 10, 2015 article about the ‘4D printer’ grant  by Madeline Fox for the Daily Northwestern features a description of 4D printing from Milan Mrksich, a co-principal investigator on the grant,

Milan Mrksich, one of the project’s five senior participants, said that while most people are familiar with the three dimensions of length, width and depth, there are often misconceptions about the fourth property of a four-dimensional object. Mrksich used Legos as an analogy to describe 4D printing technology.

“If you take Lego blocks, you can basically build any structure you want by controlling which Lego is connected to which Lego and controlling all their dimensions in space,” Mrksich said. “Within an object made up of nanoparticles, we’re controlling the placement — as we use a printer to control the placement of every particle, our fourth dimension lets us choose which nanoparticle with which property would be at each position.”

Thank you Dr. Mrksich and Ms. Fox for that helpful analogy.

Designing advanced bioprogrammable nanomaterials

The second grant, announced in a July 6, 2015 Northwestern news release by Megan Fellman, is apparently the only one of its kind in the US (Note: A link has been removed),

Northwestern University’s International Institute for Nanotechnology (IIN) has been awarded a U.S. Air Force Center of Excellence grant to design advanced bioprogrammable nanomaterials for solutions to challenging problems in the areas of energy, the environment, security and defense, as well as for developing ways to monitor and mitigate human stress.

The five-year, $9.8 million grant establishes the Center of Excellence for Advanced Bioprogrammable Nanomaterials (C-ABN), the only one of its kind in the country. After the initial five years, the grant potentially could be renewed for an additional five years.

“Northwestern University was chosen to lead this Center of Excellence because of its investment in infrastructure development, including new facilities and instrumentation; its recruitment of high-caliber faculty members and students; and its track record in bio-nanotechnology and cognitive sciences,” said Timothy Bunning, chief scientist at the U.S. Air Force Research Laboratory (AFRL) Materials and Manufacturing Directorate.

Led by IIN director Chad A. Mirkin, C-ABN will support collaborative, discovery-based research projects aimed at developing bioprogrammable nanomaterials that will meet both military and civilian needs and facilitate the efficient transition of these new technologies from the laboratory to marketplace.

Bioprogrammable nanomaterials are structures that typically contain a biomolecular component, such as nucleic acids or proteins, which give the materials a variety of novel capabilities. [emphasis mine] Nanomaterials can be designed to assemble into large 3-D structures, to interface with biological structures inside cells or tissues, or to interface with existing macroscale devices, for example. These new bioprogrammable nanomaterials and the fundamental knowledge gained through their development will ultimately lead to the creation of wearable, portable and/or human-interactive devices with extraordinary capabilities that will significantly impact both civilian and Air Force needs.

In one research area, scientists will work to understand the molecular underpinnings of vulnerability and resilience to stress. They will use bioprogrammable nanomaterials to develop ultrasensitive sensors capable of detecting and quantifying biomarkers for human stress in biological fluids (e.g., saliva, perspiration or blood), providing means to easily monitor the soldier during times of extreme stress. Ultimately, these bioprogrammable materials may lead to methods to increase human cellular resilience to the effects of stress and/or to correct genetic mutations that decrease cellular resilience of susceptible individuals.

Other research projects, encompassing a wide variety of nanotechnology-enabled goals, include:

Developing hybrid wearable energy-storage devices;
Developing devices to identify chemical and biological targets in a field environment;
Developing flexible bio-electronic circuits;
Designing a new class of flat optics; and
Advancing understanding of design rules between 2-D and 3-D architectures.

The analysis of these nanostructures also will extend fundamental knowledge in the fields of materials science and engineering, human performance, chemistry, biology and physics.

The center will be housed under the IIN, providing researchers with access to IIN’s strong entrepreneurial community and its close ties with Northwestern’s renowned Kellogg School of Management.

This second news release provides an interesting contrast to a recent news release from Sweden’s Karolinska Intitute where the writer was careful to note that the enzymes and organic electronic ion pumps were not living as noted in my June 26, 2015 posting. It seems nucleic acids (as in RNA and DNA) can be mentioned without a proviso in the US. as there seems to be little worry about anti-GMO (genetically modified organisms) and similar backlashes affecting biotechnology research.

Entangling thousands of atoms

Quantum entanglement as an idea seems extraordinary to me like something from of the fevered imagination made possible only with certain kinds of hallucinogens. I suppose you could call theoretical physicists who’ve conceptualized entanglement a different breed as they don’t seem to need chemical assistance for their flights of fancy, which turn out to be reality. Researchers at MIT (Massachusetts Institute of Technology) and the University of Belgrade (Serbia) have entangled thousands of atoms with a single photon according to a March 26, 2015 news item on Nanotechnology Now,

Physicists from MIT and the University of Belgrade have developed a new technique that can successfully entangle 3,000 atoms using only a single photon. The results, published today in the journal Nature, represent the largest number of particles that have ever been mutually entangled experimentally.

The researchers say the technique provides a realistic method to generate large ensembles of entangled atoms, which are key components for realizing more-precise atomic clocks.

“You can make the argument that a single photon cannot possibly change the state of 3,000 atoms, but this one photon does — it builds up correlations that you didn’t have before,” says Vladan Vuletic, the Lester Wolfe Professor in MIT’s Department of Physics, and the paper’s senior author. “We have basically opened up a new class of entangled states we can make, but there are many more new classes to be explored.”

A March 26, 2015 MIT news release by Jennifer Chu (also on EurekAlert but dated March 25, 2015), which originated the news item, describes entanglement with particular attention to how it relates to atomic timekeeping,

Entanglement is a curious phenomenon: As the theory goes, two or more particles may be correlated in such a way that any change to one will simultaneously change the other, no matter how far apart they may be. For instance, if one atom in an entangled pair were somehow made to spin clockwise, the other atom would instantly be known to spin counterclockwise, even though the two may be physically separated by thousands of miles.

The phenomenon of entanglement, which physicist Albert Einstein once famously dismissed as “spooky action at a distance,” is described not by the laws of classical physics, but by quantum mechanics, which explains the interactions of particles at the nanoscale. At such minuscule scales, particles such as atoms are known to behave differently from matter at the macroscale.

Scientists have been searching for ways to entangle not just pairs, but large numbers of atoms; such ensembles could be the basis for powerful quantum computers and more-precise atomic clocks. The latter is a motivation for Vuletic’s group.

Today’s best atomic clocks are based on the natural oscillations within a cloud of trapped atoms. As the atoms oscillate, they act as a pendulum, keeping steady time. A laser beam within the clock, directed through the cloud of atoms, can detect the atoms’ vibrations, which ultimately determine the length of a single second.

“Today’s clocks are really amazing,” Vuletic says. “They would be less than a minute off if they ran since the Big Bang — that’s the stability of the best clocks that exist today. We’re hoping to get even further.”

The accuracy of atomic clocks improves as more and more atoms oscillate in a cloud. Conventional atomic clocks’ precision is proportional to the square root of the number of atoms: For example, a clock with nine times more atoms would only be three times as accurate. If these same atoms were entangled, a clock’s precision could be directly proportional to the number of atoms — in this case, nine times as accurate. The larger the number of entangled particles, then, the better an atomic clock’s timekeeping.

It seems weak lasers make big entanglements possible (from the news release),

Scientists have so far been able to entangle large groups of atoms, although most attempts have only generated entanglement between pairs in a group. Only one team has successfully entangled 100 atoms — the largest mutual entanglement to date, and only a small fraction of the whole atomic ensemble.

Now Vuletic and his colleagues have successfully created a mutual entanglement among 3,000 atoms, virtually all the atoms in the ensemble, using very weak laser light — down to pulses containing a single photon. The weaker the light, the better, Vuletic says, as it is less likely to disrupt the cloud. “The system remains in a relatively clean quantum state,” he says.

The researchers first cooled a cloud of atoms, then trapped them in a laser trap, and sent a weak laser pulse through the cloud. They then set up a detector to look for a particular photon within the beam. Vuletic reasoned that if a photon has passed through the atom cloud without event, its polarization, or direction of oscillation, would remain the same. If, however, a photon has interacted with the atoms, its polarization rotates just slightly — a sign that it was affected by quantum “noise” in the ensemble of spinning atoms, with the noise being the difference in the number of atoms spinning clockwise and counterclockwise.

“Every now and then, we observe an outgoing photon whose electric field oscillates in a direction perpendicular to that of the incoming photons,” Vuletic says. “When we detect such a photon, we know that must have been caused by the atomic ensemble, and surprisingly enough, that detection generates a very strongly entangled state of the atoms.”

Vuletic and his colleagues are currently using the single-photon detection technique to build a state-of-the-art atomic clock that they hope will overcome what’s known as the “standard quantum limit” — a limit to how accurate measurements can be in quantum systems. Vuletic says the group’s current setup may be a step toward developing even more complex entangled states.

“This particular state can improve atomic clocks by a factor of two,” Vuletic says. “We’re striving toward making even more complicated states that can go further.”

This research was supported in part by the National Science Foundation, the Defense Advanced Research Projects Agency, and the Air Force Office of Scientific Research.

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

Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon by Robert McConnell, Hao Zhang, Jiazhong Hu, Senka Ćuk & Vladan Vuletić. Nature 519 439–442 (26 March 2015) doi:10.1038/nature14293 Published online 25 March 2015

This article is behind a paywall but there is a free preview via ReadCube Access.

This image illustrates the entanglement of a large number of atoms. The atoms, shown in purple, are shown mutually entangled with one another. Image: Christine Daniloff/MIT and Jose-Luis Olivares/MIT

This image illustrates the entanglement of a large number of atoms. The atoms, shown in purple, are shown mutually entangled with one another.
Image: Christine Daniloff/MIT and Jose-Luis Olivares/MIT

US Air Force wants to merge classical and quantum physics

The US Air Force wants to merge classical and quantum physics for practical purposes according to a May 5, 2014 news item on Azonano,

The Air Force Office of Scientific Research has selected the Harvard School of Engineering and Applied Sciences (SEAS) to lead a multidisciplinary effort that will merge research in classical and quantum physics and accelerate the development of advanced optical technologies.

Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, will lead this Multidisciplinary University Research Initiative [MURI] with a world-class team of collaborators from Harvard, Columbia University, Purdue University, Stanford University, the University of Pennsylvania, Lund University, and the University of Southampton.

The grant is expected to advance physics and materials science in directions that could lead to very sophisticated lenses, communication technologies, quantum information devices, and imaging technologies.

“This is one of the world’s strongest possible teams,” said Capasso. “I am proud to lead this group of people, who are internationally renowned experts in their fields, and I believe we can really break new ground.”

A May 1, 2014 Harvard University School of Engineering and Applied Sciences news release, which originated the news item, provides a description of project focus: nanophotonics and metamaterials along with some details of Capasso’s work in these areas (Note: Links have been removed),

The premise of nanophotonics is that light can interact with matter in unusual ways when the material incorporates tiny metallic or dielectric features that are separated by a distance shorter than the wavelength of the light. Metamaterials are engineered materials that exploit these phenomena, producing strange effects, enabling light to bend unnaturally, twist into a vortex, or disappear entirely. Yet the fabrication of thick, or bulk, metamaterials—that manipulate light as it passes through the material—has proven very challenging.

Recent research by Capasso and others in the field has demonstrated that with the right device structure, the critical manipulations can actually be confined to the very surface of the material—what they have dubbed a “metasurface.” These metasurfaces can impart an instantaneous shift in the phase, amplitude, and polarization of light, effectively controlling optical properties on demand. Importantly, they can be created in the lab using fairly common fabrication techniques.

At Harvard, the research has produced devices like an extremely thin, flat lens, and a material that absorbs 99.75% of infrared light. But, so far, such devices have been built to order—brilliantly suited to a single task, but not tunable.

This project, however,is focused on the future (Note: Links have been removed),

“Can we make a rapidly configurable metasurface so that we can change it in real time and quickly? That’s really a visionary frontier,” said Capasso. “We want to go all the way from the fundamental physics to the material building blocks and then the actual devices, to arrive at some sort of system demonstration.”

The proposed research also goes further. A key thrust of the project involves combining nanophotonics with research in quantum photonics. By exploiting the quantum effects of luminescent atomic impurities in diamond, for example, physicists and engineers have shown that light can be captured, stored, manipulated, and emitted as a controlled stream of single photons. These types of devices are essential building blocks for the realization of secure quantum communication systems and quantum computers. By coupling these quantum systems with metasurfaces—creating so-called quantum metasurfaces—the team believes it is possible to achieve an unprecedented level of control over the emission of photons.

“Just 20 years ago, the notion that photons could be manipulated at the subwavelength scale was thought to be some exotic thing, far fetched and of very limited use,” said Capasso. “But basic research opens up new avenues. In hindsight we know that new discoveries tend to lead to other technology developments in unexpected ways.”

The research team includes experts in theoretical physics, metamaterials, nanophotonic circuitry, quantum devices, plasmonics, nanofabrication, and computational modeling. Co-principal investigator Marko Lončar is the Tiantsai Lin Professor of Electrical Engineering at Harvard SEAS. Co-PI Nanfang Yu, Ph.D. ’09, developed expertise in metasurfaces as a student in Capasso’s Harvard laboratory; he is now an assistant professor of applied physics at Columbia. Additional co-PIs include Alexandra Boltasseva and Vladimir Shalaev at Purdue, Mark Brongersma at Stanford, and Nader Engheta at the University of Pennsylvania. Lars Samuelson (Lund University) and Nikolay Zheludev (University of Southampton) will also participate.

The bulk of the funding will support talented graduate students at the lead institutions.

The project, titled “Active Metasurfaces for Advanced Wavefront Engineering and Waveguiding,” is among 24 planned MURI awards selected from 361 white papers and 88 detailed proposals evaluated by a panel of experts; each award is subject to successful negotiation. The anticipated amount of the Harvard-led grant is up to $6.5 million for three to five years.

For anyone who’s not familiar (that includes me, anyway) with MURI awards, there’s this from Wikipedia (Note: links have been removed),

Multidisciplinary University Research Initiative (MURI) is a basic research program sponsored by the US Department of Defense (DoD). Currently each MURI award is about $1.5 million a year for five years.

I gather that in addition to the Air Force, the Army and the Navy also award MURI funds.

Desktop nanofabrication is in the laboratory but not in the marketplace yet

Another Chad Mirkin, Northwestern University (Chicago, Illinois, US), research breakthrough has been announced (this man, with regard to research,  is as prolific as a bunny) in a July 19, 2013 news item on ScienceDaily,

A new low-cost, high-resolution tool is primed to revolutionize how nanotechnology is produced from the desktop, according to a new study by Northwestern University researchers.

Currently, most nanofabrication is done in multibillion-dollar centralized facilities called foundries. This is similar to printing documents in centralized printing shops. Consider, however, how the desktop printer revolutionized the transfer of information by allowing individuals to inexpensively print documents as needed. This paradigm shift is why there has been community-wide ambition in the field of nanoscience to create a desktop nanofabrication tool.

“With this breakthrough, we can construct very high-quality materials and devices, such as processing semiconductors over large areas, and we can do it with an instrument slightly larger than a printer,” said Chad A. Mirkin, senior author of the study.

The July 19, 2013 Northwestern University news release (on EurekAlert), which originated the news item, provides details,

The tool Mirkin’s team has created produces working devices and structures at the nanoscale level in a matter of hours, right at the point of use. It is the nanofabrication equivalent of a desktop printer.

Without requiring millions of dollars in instrumentation costs, the tool is poised to prototype a diverse range of functional structures, from gene chips to protein arrays to building patterns that control how stem cells differentiate to making electronic circuits.

“Instead of needing to have access to millions of dollars, in some cases billions of dollars of instrumentation, you can begin to build devices that normally require that type of instrumentation right at the point of use,” Mirkin said.

The paper details the advances Mirkin’s team has made in desktop nanofabrication based upon easily fabricated beam-pen lithography (BPL) pen arrays, structures that consist of an array of polymeric pyramids, each coated with an opaque layer with a 100 nanometer aperture at the tip. Using a digital micromirror device, the functional component of a projector, a single beam of light is broken up into thousands of individual beams, each channeled down the back of different pyramidal pens within the array and through the apertures at the tip of each pen.

The nanofabrication tool allows one to rapidly process substrates coated with photosensitive materials called resists and generate structures that span the macro-, micro- and nanoscales, all in one experiment.

Key advances made by Mirkin’s team include developing the hardware, writing the software to coordinate the direction of light onto the pen array and constructing a system to make all of the pieces of this instrument work together in synchrony. This approach allows each pen to write a unique pattern and for these patterns to be stitched together into functional devices.

“There is no need to create a mask or master plate every time you want to create a new structure,” Mirkin said. “You just assign the beams of light to go in different places and tell the pens what pattern you want generated.”

Because the materials used to make the desktop nanofabrication tool are easily accessible, commercialization may be as little as two years away, Mirkin said. In the meantime, his team is working on building more devices and prototypes.

In the paper, Mirkin explains how his lab produced a map of the world, with nanoscale resolution that is large enough to see with the naked eye, a feat never before achieved with a scanning probe instrument. Not only that, but closer inspection with a microscope reveals that this image is actually a mosaic of individual chemical formulae made up of nanoscale points. Making this pattern showcases the instrument’s capability of simultaneously writing centimeter-scale patterns with nanoscale resolution.

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

Desktop nanofabrication with massively multiplexed beam pen lithography by Xing Liao, Keith A. Brown, Abrin L. Schmucker, Guoliang Liu, Shu He, Wooyoung Shim, & Chad A. Mirkin. Nature Communications 4, Article number: 2103 doi:10.1038/ncomms3103 Published 19 July 2013

This paper is behind a paywall. As an alternative of sorts, you might like to check out this March 22, 2012 video of Mirkin’s presentation entitled, A Chemist’s Approach to Nanofabrication: Towards a “Desktop Fab” for the US Air Force Office of Scientific Research.

US Air Force takes baby steps toward shapeshifting materials

When I see information about US military futuristic projects it’s usually from the US Army’s DARPA (Defense Advanced Research Projects Agency).  Consequently, I was surprised to notice that this shapeshifting project is being funded by the US Air Force Office of Scientific Research according to the July 11, 2012 news item on phys.org,

An international research team has received a $2.9 million grant from the Air Force Office of Scientific Research to design nanomaterials whose internal structure changes shape in response to stimuli such as heat or light.

Each of these novel materials will be constructed from three types of components: inorganic nanoparticles with desired optical or electrical properties; peptides that bond to these nanoparticles; and special molecules called spacers, which sit between the peptides and bend in the presence of heat, light or other triggers.

When stimulated, the spacers will cause the arrangement of nanoparticles within the material to morph — a process that can lead to interesting and useful effects.

Shape-shifting materials of the kind the researchers are planning to create could have use in applications including color-changing sensors and plasmonic circuits that divert light in two directions.

The news item originated from a July 11, 2012 news release from the State University of New York (SUNY) at Buffalo,

The project is being led by Paras Prasad, SUNY Distinguished Professor in the University at Buffalo’s departments of chemistry, physics, electrical engineering and medicine, and executive director of UB’s Institute for Lasers, Photonics and Biophotonics (ILPB). …

Prasad’s fellow investigators include Aidong Zhang, professor and chair of the Department of Computer Science and Engineering at UB; Mark T. Swihart, professor of chemical and biological engineering at UB and director of the UB 2020 Integrated Nanostructured Systems Strategic Strength; Tiffany R. Walsh, associate professor at the Institute for Frontier Materials at Deakin University in Australia; and Marc R. Knecht, associate professor of chemistry at the University of Miami.

The palette of parts the team will use to build the nanomaterials includes spacers of different sizes, along with seven types of nanoparticles — gold, silver, silica, iron-oxide, iron-platinum, cadmium-sulfide and zinc-sulfide.

To identify the combinations of components that will produce the most interesting materials, the scientists will use high-throughput experiments and data-mining techniques to screen and analyze the vast number of possible combinations of nanostructures, biomolecular linking elements (the peptides) and assembly conditions.

“One of our goals is to contribute to the fundamental understanding of how the spatial arrangement of nanoscale components in materials affects their optical, magnetic and plasmonic properties,” Prasad said. “The high-throughput techniques we are using were pioneered in the field of bioinformatics, but also have extraordinary promise in the exploration of advanced materials.”

Zhang said, “The computational capabilities offered by informatics and data mining will enable us to maximize the value of our data regarding the nanoassemblies, to generate and to construct new assemblies that span a wide range of inorganic and bimolecular components so as to achieve desired combinatorics-based properties.”

It’s not exactly the shapeshifting one sees in science fiction but this will be the real stuff (not to be confused with The Right Stuff, a 1983 movie about the US space travel programme of the late 1950s to 1960s).