Nanorobot for atherosclerosis plaques removing

Atherosclerosis is a major cardiovascular disease involving accumulations of lipids, white blood cells, and other materials on the inside of artery walls. Since the calcification found in the advanced stage of atherosclerosis dramatically enhances the mechanical properties of the plaque, restoring the original lumen of the artery remains a challenge.

Calcification [1] forms among vascular smooth muscle cells of the surrounding muscular layer, specifically in the muscle cells adjacent to atheromas and on the surface of atheroma plaques and tissue. In time, as cells die, this leads to extracellular calcium deposits between the muscular wall and outer portion of the atheromatous plaques.

Complications of advanced atherosclerosis are chronic, slowly progressive and cumulative. Most commonly, soft plaque suddenly ruptures, causing the formation of a thrombus that will rapidly slow or stop blood flow, leading to death of the tissues fed by the artery in approximately 5 minutes. This catastrophic event is called an infarction. One of the most common recognized scenarios is called coronary thrombosis of a coronary artery, causing a heart attack. The same process in an artery to the brain is commonly called stroke. Another common scenario in very advanced disease is claudication from insufficient blood supply to the legs, typically caused by a combination of both stenosis and aneurysmal segments narrowed with clots.

Modern medicine use high-speed rotational atherectomy, when performed with an ablating grinder to remove the plaque, produces much better results in the treatment of calcified plaque compared to other methods [2].

However, the high-speed rotation of the Rotablator commercial rotational atherectomy device produces microcavitation, which should be avoided because of the serious complications it can cause. This research involves the development of a high-speed rotational ablation tool that does not generate microcavitation [2].

Future nanomedical devices can avoid this problem and also they can make atherectomy non-invasive and simply procedure.

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Researchers Optically Levitate a Glowing, Nanoscale Diamond

Researchers at the University of Rochester have measured for the first time light emitted by photoluminescence from a nanodiamond levitating in free space. In a paper published this week in Optics Letters, they describe how they used a laser to trap nanodiamonds in space, and – using another laser – caused the diamonds to emit light at given frequencies.

The experiment, led by Nick Vamivakas, an assistant professor of optics, demonstrates that it is possible to levitate diamonds as small as 100 nanometers (approximately one-thousandth the diameter of a human hair) in free space, by using a technique known as laser trapping.

“Now that we have shown we can levitate nanodiamonds and measure photoluminescence from defects inside the diamonds, we can start considering systems that could have applications in the field of quantum information and computing,” said Vamivakas. He said an example of such a system would be an optomechanical resonator.

Vamivakas explained that optomechanical resonators are structures in which the vibrations of the system, in this case the trapped nanodiamond, can be controlled by light. “We are yet to explore this, but in theory we could encode information in the vibrations of the diamonds and extract it using the light they emit.”

Possible avenues of interest in the long-term with these nano-optomechanical resonators include the creation of what are known as Schrödinger Cat states (macroscopic, or large-scale, systems that are in two quantum states at once). These resonators could also be used as extremely sensitive sensors of forces – for example, to measure tiny displacements in the positions of metal plates or mirrors in configurations used in microchips and understand friction better on the nanoscale.

“Levitating particles such as these could have advantages over other optomechanical oscillators that exist, as they are not attached to any large structures,” Vamivakas explained. “This would mean they are easier to keep cool and it is expected that fragile quantum coherence, essential for these systems to work, will last sufficiently long for experiments to be performed.”

The future experiments that Vamivakas and his team are planning build on previous work by Lukas Novotny, a co-author of the paper formerly at Rochester and now at ETH in Zurich, Switzerland, and Romain Quidant, also a co-author from ICFO, Spain. Novotny, Quidant and their teamsshowed previouslythat by tweaking the trapping laser’s properties, a particle can be pushed towards its quantum ground state. By linking the laser cooling of the crystal resonator with the spin of the internal defect it should be possible to monitor the changes in spin configuration of the internal defect – these changes are called Bohr spin quantum jumps – via the mechanical resonator’s vibrations. Vamivakas explained that experiments like this would expand what we know about the classical-quantum boundary and address fundamental physics questions.

The light emitted by the nanodiamonds is due to photoluminescence. The defects inside the nanodiamonds absorb photons from the second laser – not the one that is trapping the diamonds – which excites the system and changes the spin. The system then relaxes and other photons are emitted. This process is also known as optical pumping.

The defects come about because of nitrogen vacancies, which occur when one or more of the carbon atoms in diamond is replaced by a nitrogen atom. The chemical structure is such that at the nitrogen site it is possible to excite electrons, using a laser, between different available energy levels. Previous experiments have shown that these nitrogen vacancy centers in diamonds are good, stable sources of single photons, which is why the researchers were keen to levitate these particles.

Using lasers to trap ions, atoms and more recently larger particles is a well-established field of physics. Nanodiamonds, however, had never been levitated. To position these 100 nanometers diamonds in the correct spot an aerosol containing dissolved nanodiamonds sprays into a chamber about 10 inches in diameter, where the laser’s focus point is located. The diamonds are attracted to this focus point and when they drift into this spot they are trapped by the laser. Graduate student Levi Neukirch explains that sometimes “it takes a couple of squirts and in a few minutes we have a trapped nanodiamond; other times I can be here for half an hour before any diamond gets caught. Once a diamond wanders into the trap we can hold it for hours.”

The Rochester researchers collaborated on this paper with Lukas Novotny, formerly at the University of Rochester and now at ETH Zurich, Switzerland, and with Jan Gieseler and Romain Quidant, at ICFO in Barcelona, Spain.

The researchers acknowledge the support from the University of Rochester, the European Community’s Seventh Framework Program, Fundació privada CELLEX and from the U.S. Department of Energy.

http://www.rochester.edu/news/show.php?id=6902

 

Diamond encrusted nano-saw to slash silicon waste

Over half the cost of today’s solar cells is the silicon wafer, so reducing wafer thickness is a way to save money. Scientists at Fraunhofer in Germany and CSIRO in Australia have teamed up to make an ultra-thin saw made of carbon nanotubes (CNT) sprinkled with diamonds. Their new nano-saw promises to slice thinner silicon wafers and cut down on the ‘dust’ – or kerf – generated from wafer manufacturing in the photovoltaic and semiconductor industries.
Today, steel wires with a diameter of 140µm slice up silicon ingots, but subsurface damage and variations in the thickness of 180µm wafers results in the loss of almost half of the material, according to Manuel Mee, project scientist at the Fraunhofer Institute for Mechanics of Materials in Freiburg, Germany. His solution is a CNT yarn encrusted with diamonds.

Growing diamonds on nanotubes is tricky, however, as they need to be deposited from a hydrocarbon gas onto a hot surface and the material ends up being a mixture of diamond and other carbon allotropes, such as graphite. The trick to get only diamond is to have a reactive gas atmosphere that selectively removes the non-diamond allotropes, but leaves any carbon with diamond bonding. ‘This is typically accomplished by having copious amounts of atomic hydrogen present. If you try to deposit diamond onto a non-diamond carbon surface [such as carbon nanotubes], you end up etching away the non-diamond carbon as you deposit the diamond,’ explains material scientist Nick Glumac at the University of Illinois, Urbana-Champaign, US. ‘You need a buffer layer to protect the non-diamond substrates.’ This is the secret of the new method, which was discovered serendipitously.

During early experiments, fused silica from the reaction chamber accidentally came into contact with the coating plasma. It settled on the substrate and protected it from the hydrogen. To the team’s surprise, diamonds grew on this layer. They then studied the silicon oxide layer in order to find a way of controlling the deposition and optimising the process.

Glumac describes the buffer layer solution as clever. ‘In terms of required developments,’ he adds, ‘I think you need to show the diamond has good adhesion and doesn’t degrade the mechanical properties of the underlying CNT wire.’ He adds that the proposed technique could probably be incorporated into existing wire-based cutting machines, though making continuous wires from nanotubes isn’t easy.

‘At present, sawing silicon is a very well established and major industry where efficiency and reliability are critical to profitability,’ says CSIRO’s Stephen Hawkins. ‘Replacing a significant part of this activity with CNT diamond saw wire will necessitate demonstration of substantially improved performance in these areas. Scaling and simplifying the production of CNT yarn and the diamond coating process are significant technical challenges before this demonstration can happen.’

Designing and building nanocomponents to spec

Hybrid, multifunctional nanostructures with diverse 3D shapes and complex material composition can now be manufactured with a precise and efficient fabrication technique

August 13, 2013

The realisation of nanomachines is inching ever closer to reality. Researchers at the Max Planck Institute for Intelligent Systems in Stuttgart are helping make one of the grand challenges of nanoscience become reality. They have developed a method that makes it possible to manufacture an assortment of unusually shaped and functionalisable nanostructures. It lets them combine materials with widely varying chemical and physical properties at the smallest of scales. The team of scientists headed by Peer Fischer have even grown helical light antennas that are less than 100nm in length from materials which can typically not be shaped at the nanoscale. This is achieved by vapour depositing the material onto a super-cooled rotating disk. Not only does the process allow for the fabrication of nanostructures more exactly than previous methods, several billion of such nanoparticles can be produced in parallel in a rapid manner.

Several of the proposed ideas about what nanotechnology might achieve are rather daring: miniscule robots could transport medications in the human body to foci of diseases or be small enough to operate within a human cell. It could be possible for nanomotors to act as light or toxin sensors at length scales 2.000 times smaller than the thickness of a human hair. Information could be packed into storage devices at densities many times higher than what is achievable with today’s technology. Research into realising some of these goals is already quite close. Now, a team headed by Peer Fischer, Leader of a Research Group at the Max Planck Institute for Intelligent Systems, has come even closer. “We’ve developed a versatile, precise, and efficient process with which three-dimensional nanostructures can be custom fabricated from various materials”, says Peer Fischer. “Up to now, structures less than 100 nanometres could only be created in very symmetrical, primarily spherical or cylindrical shapes.”

With their new method, the researchers are now able to produce hybrid nanoscopic hooks, screws, and zigzag structures by processing materials with very diverse physical properties – metals, semiconductors, magnetic materials, and insulators. As an example of the possible applications, the researchers produced helices of gold that are suitable as nanoantennas for light. The colour of light that the antennas absorb can be controlled by their shape and material composition. With them, circularly polarised light can for instance be filtered, a process used in projectors for 3D movies. Also, the plane of oscillation of an electromagnetic wave – which is what polarized light is – is rotated either clockwise or anticlockwise depending upon the rotational sense of the metal nanohelix. The effect is orders of magnitude larger per helix than what is seen with naturally occurring materials.

Nanostructures from a stream of vapour onto gold nanodot islands

Exact control over the shape and structure of the nanocomponents was achieved by the researchers in Stuttgart by means of their elegant method, which can produce several hundred billion copies of a complex structure in about an hour. With the help of micellar nanolithography, which has been available for several years, they first place billions of regularly arranged nanoparticles of gold onto the surface of a silicon or glass wafer. They deposit gold particles covered in a polymeric shell onto the substrate, which then arrange themselves into a tightly packed, regular pattern. After removing the polymer shell with a plasma, the gold dots remain behind bound to the substrate. The scientists then place the pre-patterned wafer into what is essentially a stream of metallic vapour at an angle oblique enough that the metallic atoms can only see the tiny gold islands and deposit themselves only at those points. Thus, they quickly grow into nanostructures which can have feature sizes as small as 20 nm.

If the researchers slowly rotate the substrate during the during the vapour deposition, the rods wind into a helix. If they rotate the substrate abruptly, a zigzag shape forms. If the material that is being vaporised in the chamber during the process is changed, a composite material, such as a metal alloy, is formed. And of course, all of these neat tricks can be combined. For example, they attached copper hooks to aluminium oxide rods using a thin layer of titanium to adhere the two materials together.

The crucial idea: liquid nitrogen cooling
“Larger structures have been produced for a while already in a similar fashion”, explains Andrew G. Mark, a Max Planck researcher who played an important role in developing the method. “Up to now, this method could not be transferred to nanostructures, however.” This is because the hot, mobile atoms deposited from the vapour rapidly arrange themselves on the surface into a sphere due to energy considerations. “We therefore came up with the idea of cooling the substrate using liquid nitrogen at about minus 200 degrees Celsius, which flows through the substrate holder, so that an atom is quickly frozen and fixed into position as soon as it lands on the apex of the growing nanobody”, says John G. Gibbs, who likewise contributed significantly to the work at the Max Planck Institute for Intelligent Systems.

Despite the versatility of the method, not all shapes can be created with it. “Because the structure always grows away from the wafer, no rings, closed triangles or squares can form”, says Fischer. “We are not able to build a nanoscale Eifel Tower.” Nevertheless, wide-ranging opportunities are open to him and his team. “Our long-term goal is to construct nanomachinery”, says Peer Fischer. “Nature builds motors on the scale of about 20 nanometres. We would like to couple our components to these motors.” Then it may be possible for many of the nanoreseachers’ dreams to become a reality.

How cancer chromosome abnormalities form in living cells

For the first time, scientists have directly observed events that lead to the formation of a chromosome abnormality that is often found in cancer cells. The abnormality, called a translocation, occurs when part of a chromosome breaks off and becomes attached to another chromosome. The results of this study, conducted by scientists at the National Cancer Institute (NCI), part of the National Institutes of Health, appeared Aug. 9, 2013, in the journal Science.

Chromosomes are thread-like structures inside cells that carry genes and function in heredity. Human chromosomes each contain a single piece of DNA, with the genes arranged in a linear fashion along its length.

Chromosome translocations have been found in almost all cancer cells, and it has long been known that translocations can play a role in cancer development. However, despite many years of research, just exactly how translocations form in a cell has remained a mystery. To better understand this process, the researchers created an experimental system in which they induced, in a controlled fashion, breaks in the DNA of different chromosomes in living cells. Using sophisticated imaging technology, they were then able to watch as the broken ends of the chromosomes were reattached correctly or incorrectly inside the cells.

Translocations are very rare events, and the scientists’ ability to visualize their occurrence in real time was made possible by recently available technology at NCI that enables investigators to observe changes in thousands of cells over long time periods. “Our ability to see this fundamental process in cancer formation was possible only because of access to revolutionary imaging technology,” said the study’s senior author, Tom Misteli, Ph.D., Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, NCI.

The scientists involved with this study were able to demonstrate that translocations can occur within hours of DNA breaks and that their formation is independent of when the breaks happen during the cell division cycle. Cells have built-in repair mechanisms that can fix most DNA breaks, but translocations occasionally occur.

To explore the role of DNA repair in translocation formation, the researchers inhibited key components of the DNA damage response machinery within cells and monitored the effects on the repair of DNA breaks and translocation formation. They found that inhibition of one component of DNA damage response machinery, a protein called DNAPK-kinase, increased the occurrence of translocations almost 10-fold. The scientists also determined that translocations formed preferentially between pre-positioned genes.

“These observations have allowed us to formulate a time and space framework for elucidating the mechanisms involved in the formation of chromosome translocations,” said Vassilis Roukos, Ph.D., NCI, and lead scientist of the study.

“We can now finally begin to really probe how these fundamental features of cancer cells form,” Misteli added.

This research was supported by the Intramural Research Program of the NCI’s Center for Cancer Research.

Berkeley Lab Researchers Discover a Tiny Twist in Bilayer Graphene That May Solve a Mystery

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a unique new twist to the story of graphene, sheets of pure carbon just one atom thick, and in the process appear to have solved a mystery that has held back device development.

Electrons can race through graphene at nearly the speed of light – 100 times faster than they move through silicon. In addition to being superthin and superfast when it comes to conducting electrons, graphene is also superstrong and superflexible, making it a potential superstar material in the electronics and photonics fields, the basis for a host of devices, starting with ultrafast transistors. One big problem, however, has been that graphene’s electron conduction can’t be completely stopped, an essential requirement for on/off devices.

The on/off problem stems from monolayers of graphene having no bandgaps – ranges of energy in which no electron states can exist. Without a bandgap, there is no way to control or modulate electron current and therefore no way to fully realize the enormous promise of graphene in electronic and photonic devices. Berkeley Lab researchers have been able to engineer precisely controlled bandgaps in bilayer graphene through the application of an external electric field. However, when devices were made with these engineered bandgaps, the devices behaved strangely, as if conduction in those bandgaps had not been stopped. Why such devices did not pan out has been a scientific mystery until now.

Working at Berkeley Lab’s Advanced Light Source (ALS), a DOE national user facility, a research team led by ALS scientist Aaron Bostwick has discovered that in the stacking of graphene monolayers subtle misalignments arise, creating an almost imperceptible twist in the final bilayer graphene. Tiny as it is – as small as 0.1 degree – this twist can lead to surprisingly strong changes in the bilayer graphene’s electronic properties.

“The introduction of the twist generates a completely new electronic structure in the bilayer graphene that produces massive and massless Dirac fermions,” says Bostwick. “The massless Dirac fermion branch produced by this new structure prevents bilayer graphene from becoming fully insulating even under a very strong electric field. This explains why bilayer graphene has not lived up to theoretical predictions in actual devices that were based on perfect or untwisted bilayer graphene.”

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a unique new twist to the story of graphene, sheets of pure carbon just one atom thick, and in the process appear to have solved a mystery that has held back device development.

Electrons can race through graphene at nearly the speed of light – 100 times faster than they move through silicon. In addition to being superthin and superfast when it comes to conducting electrons, graphene is also superstrong and superflexible, making it a potential superstar material in the electronics and photonics fields, the basis for a host of devices, starting with ultrafast transistors. One big problem, however, has been that graphene’s electron conduction can’t be completely stopped, an essential requirement for on/off devices.

The on/off problem stems from monolayers of graphene having no bandgaps – ranges of energy in which no electron states can exist. Without a bandgap, there is no way to control or modulate electron current and therefore no way to fully realize the enormous promise of graphene in electronic and photonic devices. Berkeley Lab researchers have been able to engineer precisely controlled bandgaps in bilayer graphene through the application of an external electric field. However, when devices were made with these engineered bandgaps, the devices behaved strangely, as if conduction in those bandgaps had not been stopped. Why such devices did not pan out has been a scientific mystery until now.

Working at Berkeley Lab’s Advanced Light Source (ALS), a DOE national user facility, a research team led by ALS scientist Aaron Bostwick has discovered that in the stacking of graphene monolayers subtle misalignments arise, creating an almost imperceptible twist in the final bilayer graphene. Tiny as it is – as small as 0.1 degree – this twist can lead to surprisingly strong changes in the bilayer graphene’s electronic properties.

“The introduction of the twist generates a completely new electronic structure in the bilayer graphene that produces massive and massless Dirac fermions,” says Bostwick. “The massless Dirac fermion branch produced by this new structure prevents bilayer graphene from becoming fully insulating even under a very strong electric field. This explains why bilayer graphene has not lived up to theoretical predictions in actual devices that were based on perfect or untwisted bilayer graphene.”

“The combination of ARPES and Beamline 7.0.1 enabled us to easily identify the electronic spectrum from the twist in the bilayer graphene,” says Rotenberg. “The spectrum we observed was very different from what has been assumed and contains extra branches consisting of massless Dirac fermions. These new massless Dirac fermions move in a completely unexpected way governed by the symmetry twisted layers.”

Massless Dirac fermions, electrons that essentially behave as if they were photons, are not subject to the same bandgap constraints as conventional electrons. In their Nature Materials paper, the authors state that the twists that generate this massless Dirac fermion spectrum may be nearly inevitable in the making of bilayer graphene and can be introduced as a result of only ten atomic misfits in a square micron of bilayer graphene.

“Now that we understand the problem, we can search for solutions,” says lead author Kim. “For example, we can try to develop fabrication techniques that minimize the twist effects, or reduce the size of the bilayer graphene we make so that we have a better chance of producing locally pure material.”

Beyond solving a bilayer graphene mystery, Kim and his colleagues say the discovery of the twist establishes a new framework on which various fundamental properties of bilayer graphene can be more accurately predicted.

“A lesson learned here is that even such a tiny structural distortion of atomic-scale materials should not be dismissed in describing the electronic properties of these materials fully and accurately,” Kim says.

This research was supported by the DOE Office of Science.

DEVICE CAPTURES SIGNATURES WITH TINY PIEZO-PHOTOTRONIC LEDS

Researchers at the Georgia Institute of Technology want to put your signature up in lights – tiny lights, that is. Using thousands of nanometer-scale wires, the researchers have developed a sensor device that converts mechanical pressure – from a signature or a fingerprint – directly into light signals that can be captured and processed optically.

The sensor device could provide an artificial sense of touch, offering sensitivity comparable to that of the human skin. Beyond collecting signatures and fingerprints, the technique could also be used in biological imaging and micro-electromechanical (MEMS) systems. Ultimately, it could provide a new approach for human-machine interfaces.

“You can write with your pen and the sensor will optically detect what you write at high resolution and with a very fast response rate,” said Zhong Lin Wang, Regents’ professor and Hightower Chair in the School of Materials Science and Engineering at Georgia Tech. “This is a new principle for imaging force that uses parallel detection and avoids many of the complications of existing pressure sensors.”

Individual zinc oxide (ZnO) nanowires that are part of the device operate as tiny light emitting diodes (LEDs) when placed under strain from the mechanical pressure, allowing the device to provide detailed information about the amount of pressure being applied. Known as piezo-phototronics, the technology – first described by Wang in 2009 – provides a new way to capture information about pressure applied at very high resolution: up to 6,300 dots per inch.

The research was reported August 11, 2013, in the journal Nature Photonics. It was sponsored by the U.S. Department of Energy’s Office of Basic Energy Sciences, the National Science Foundation, and the Knowledge Innovation Program of the Chinese Academy of Sciences.

Piezoelectric materials generate a charge polarization when they are placed under strain. The piezo-phototronic devices rely on that physical principle to tune and control the charge transport and recombination by the polarization charges present at the ends of individual nanowires. Grown atop a gallium nitride (GaN) film, the nanowires create pixeled light emitters whose output varies with the pressure, creating an electroluminescent signal that can be integrated with on-chip photonics for data transmission, processing and recording.

“When you have a zinc oxide nanowire under strain, you create a piezoelectric charge at both ends which forms a piezoelectric potential,” Wang explained. “The presence of the potential distorts the band structure in the wire, causing electrons to remain in the p-n junction longer and enhancing the efficiency of the LED.”

The efficiency increase in the LED is proportional to the strain created. Differences in the amount of strain applied translate to differences in light emitted from the root where the nanowires contact the gallium nitride film.

To fabricate the devices, a low-temperature chemical growth technique is used to create a patterned array of zinc oxide nanowires on a gallium nitride thin film substrate with the c-axis pointing upward. The interfaces between the nanowires and the gallium nitride film form the bottom surfaces of the nanowires. After infiltrating the space between nanowires with a PMMA thermoplastic, oxygen plasma is used to etch away the PMMA enough to expose the tops of the zinc oxide nanowires.

A nickel-gold electrode is then used to form ohmic contact with the bottom gallium-nitride film, and a transparent indium-tin oxide (ITO) film is deposited on the top of the array to serve as a common electrode.

When pressure is applied to the device through handwriting or other source of pressure, nanowires are compressed along their axial directions, creating a negative piezo-potential, while uncompressed nanowires have no potential.

The researchers have pressed letters into the top of the device, which produces a corresponding light output from the bottom of the device. This output – which can all be read at the same time – can be processed and transmitted.

The ability to see all of the emitters simultaneously allows the device to provide a quick response. “The response time is fast, and you can read a million pixels in a microsecond,” said Wang. “When the light emission is created, it can be detected immediately with the optical fiber.”

The nanowires stop emitting light when the pressure is relieved. Switching from one mode to the other takes 90 milliseconds or less, Wang said.

The researchers studied the stability and reproducibility of the sensor array by examining the light emitting intensity of the individual pixels under strain for 25 repetitive on-off cycles. They found that the output fluctuation was approximately five percent, much smaller than the overall level of the signal. The robustness of more than 20,000 pixels was studied.

A spatial resolution of 2.7 microns was recorded from the device samples tested so far. Wang believes the resolution could be improved by reducing the diameter of the nanowires – allowing more nanowires to be grown in a given space – and by using a high-temperature fabrication process.

In addition to Wang, the research team also included Caofeng Pan, Lin Dong, Guang Zhu, Simiao Niu, Ruomeng Yo, Qing Yang and Ying Liu, all associated with Georgia Tech. In addition, Pan is associated with the Beijing Institute of Nanoenergy and Nanosystems in the Chinese Academy of Sciences.

This research was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-07ER46394; the National Science Foundation (NSF) under award CMMI-040367; and by the Knowledge Innovation program of the Chinese Academy of Sciences under KJCX2-YW-M13. The opinions and conclusions expressed are those of the authors and do not necessarily represent the official views of the DOE or NSF.

CITATION: Caofeng Pan, et al., “High resolution electroluminescent imaging of pressure distribution using a piezoelectric nanowire-LED array,” (Nature Photonics 2013). http://dx.doi.org/10.1038/nphoton.2013.191