#New way to move atomically thin semiconductors for use in flexible devices Researchers from North carolina State university have developed a new way to transfer thin semiconductor films
which are only one atom thick onto arbitrary substrates paving the way for flexible computing or photonic devices.
The technique is much faster than existing methods and can perfectly transfer the atomic scale thin films from one substrate to others without causing any cracks.
At issue are molybdenum sulfide (Mos2) thin films that are only one atom thick first developed by Dr. Linyou Cao an assistant professor of materials science and engineering at NC State.
Mos2 is an inexpensive semiconductor material with electronic and optical properties similar to materials already used in the semiconductor industry.
The ultimate goal is to use these atomic-layer semiconducting thin films to create devices that are extremely flexible
but to do that we need to transfer the thin films from the substrate we used to make it to a flexible substrate says Cao who is senior author of a paper on the new transfer technique.
You can't make the thin film on a flexible substrate because flexible substrates can't withstand the high temperatures you need to make the thin film.
Cao's team makes Mos2 films that are an atom thick and up to 5 centimeters in diameter.
The researchers needed to find a way to move that thin film without wrinkling or cracking it
Cao's new transfer technique works by applying a drop of water to the thin film
or a scalpel so that the water can begin to penetrate between the Mos2 and the sapphire.
This new transfer technique gets us one step closer to using Mos2 to create flexible computers Cao adds.
#Engineers efficiently'mix'light at the nanoscale The race to make computer components smaller and faster
but the fundamentals of computation, mixing two inputs into a single output, currently require too much space and power when done with light.
Researchers at the University of Pennsylvania have engineered a nanowire system that could pave the way for this ability,
Current computer systems represent bits of informationhe 1's and 0's of binary codeith electricity Circuit elements,
such as transistors, operate on these electric signals, producing outputs that are dependent on their inputs.""Mixing two input signals to get a new output is the basis of computation,
"Agarwal said.""It's easy to do with electric signals, but it's not easy to do with light,
given the gamut of colors on TV or computer screen that are produced solely by combinations of red, green and blue pixels.
The yellows, oranges and purples those displays make, however, are a trick of perception, not of physics.
Red and blue light are experienced simply simultaneously, rather than combined into a single purple wavelength. So-called"nonlinear"materials are capable of this kind of mixing,
"A nonlinear material, such a cadmium sulfide, can change the frequency, and thus the color, of light that passes through it,
That doesn't work for a computer chip.""To reduce the volume of the material and the power of the light needed to do useful signal mixing,
the researchers needed a way to amplify the intensity of a light wave as it passed through a cadmium sulfide nanowire.
partially wrapping the nanowire in a silver shell that acts like an echo chamber. Agarwal's group had employed a similar design before in an effort to create photonic devices that could switch on and off very rapidly.
but, by changing the polarization of the light as it entered the nanowire, the researchers were able to better confine it to the frequency-altering, nonlinear part of the device:
the nanowire core.""By engineering the structure so that light is contained mostly within the cadmium sulfide rather than at the interface between it and the silver shell,
we can maximize the intensity while generating the second harmonic, "Ren said. Like a second harmonic played on a guitar string,
Information in a photonic computer system could be encoded in a wave's frequency, or the number of oscillations it makes in a second.
Being able to manipulate that quality in one wave with another allows for the fundamentals of computer logic."
which can be done by altering the size of the nanowire and the shell.""Most important,
however, was that this frequency mixing was possible on the nanoscale with very high efficiency.
"The frequency-changing efficiency of cadmium sulfide is intrinsic to the material, but it depends on the volume of the material the wave passes through,
and push the device size into the nanoscale. c
#Patent awarded for genetics-based nanotechnology against mosquitoes insect pests Kansas State university researchers have developed a patented method of keeping mosquitoes and other insect pests at bay.
U s. Patent 8841272 Double stranded-rna RNA-Based Nanoparticles for Insect Gene Silencing was awarded recently to the Kansas State university Research Foundation a nonprofit corporation responsible for managing technology transfer activities
at the university. The patent covers microscopic genetics-based technology that can help safely kill mosquitos and other insect pests.
Kun Yan Zhu professor of entomology; Xin Zhang research associate in the Division of Biology;
and Jianzhen Zhang visiting scientist from Shanxi University in China developed the technology: nanoparticles comprised of a nontoxic biodegradable polymer matrix
and insect derived double-stranded ribonucleic acid or dsrna. Double stranded-rna RNA is synthesized a molecule that can trigger a biological process known as RNA interference
or RNAI to destroy the genetic code of an insect in a specific DNA sequence. The technology is expected to have great potential for safe and effective control of insect pests Zhu said.
For example we can buy cockroach bait that contains a toxic substance to kill cockroaches. However the bait could potentially harm whatever else ingests it Zhu said.
If we can incorporate dsrna specifically targeting a cockroach gene in the bait rather than a toxic substance the bait would not harm other organisms such as pets
because the dsrna is designed to specifically disable the function of the cockroach gene. Researchers developed the technology
while looking at how to disable gene functions in mosquito larvae. After testing a series of unsuccessful genetic techniques the team turned to a nanoparticle-based approach.
Once ingested the nanoparticles act as a Trojan horse releasing the loosely bound dsrna into the insect gut.
The dsrna then triggers a genetic chain reaction that destroys specific MESSENGER RNA or mrna in the developing insects.
MESSENGER RNA carries important genetic information. In the studies on mosquito larvae researchers designed dsrna to target the mrna encoding the enzymes that help mosquitoes produce chitin the main component in the hard exoskeleton of insects crustaceans and arachnids.
Researchers found that the developing mosquitoes produced less chitin. As a result the mosquitoes were more prone to insecticides as they no longer had a sufficient amount of chitin for a normal functioning protective shell.
If the production of chitin can be reduced further the insects can be killed without using any toxic insecticides.
While mosquitos were the primary insect for which the nanoparticle-based method was developed the technology can be applied to other insect pests Zhu said.
Our dsrna molecules were designed based on specific gene sequences of the mosquito Zhu said. You can design species-specific dsrna for the same or different genes for other insect pests.
When you make baits containing gene-specific nanoparticles you may be able to kill the insects through the RNAI pathway.
We see this having really broad applications for insect pest management. Explore further: Protein found in insect blood that helps power pests'immune response e
While STM can provide vast quantities of data about the electronic structural and magnetic properties of materials at atomic resolution its Achilles heel is its inability to characterize elemental species
. But a team from Argonne National Laboratory and Ohio University has found a way around this limitation by combining STM with the spectroscopic versatility of synchrotron x-rays achieving chemical fingerprinting of individual nickel clusters on a copper surface at a resolution
of 2 nm creating a powerful and versatile nanoscale imaging tool with exciting promise and potential for the materials and biological sciences.
Their work was published in Nano Letters. Working at the Center for Nanoscale Materials (CNM)/ X-ray Science Division 26-ID beamline of the U s. Department of energy's Advanced Photon Source the researchers took advantage of some new technological innovations
developed by Argonne researchers. However the team had to overcome some experimental hurdles to combine STM with synchrotron x-rays.
The APS CNM and EMC at Argonne are Office of Science user facilities. The team also developed a filter circuit that separates the chemical and magnetic data from the x-ray-induced currents
and topographical data from conventional tunneling effects into two channels allowing them to be recorded separately without mutual interference.
Using the markedly enhanced resolution and sensitivity made possible with these advances in synchrotron x-ray tunneling microscopy (SX-STM) the Argonne/Ohio University experiment team analyzed nickel clusters deposited on a copper surface.
Usually because chemical fingerprinting using x-rays is based on photoionization cross sections such measurements are averaged over a rather wide surface area and depth.
This has a tremendous impact for many scientific areas including materials science chemistry and energy materials said co-author Volker Rose.
Both that remarkable resolution and the precise chemical fingerprinting of individual nickel nanoclusters were also clearly evident in the topographic images of the sample surface even down to the height of a single atom.
The experimenters note that the thickness of individual clusters appears to have no effect on the contrast intensity of their chemical signature.
because tunneling is a local effect sensitive only to the topmost layer of materials this phenomenon as observed topographically results from the tunneling of x-ray excited photoelectrons from states between the Fermi level and the work function.
Even in its present form the techniques demonstrated here can revolutionize nanoscale imaging in realms far beyond materials science including electronics and biology.
and x-ray microscopy this new work has combined also the strengths of each to create a powerful and versatile imaging tool with an exciting promise and potential l
Today it signals a promising discovery in materials science research that could help next-generation technology-like wearable energy storage devices-get off the ground.
Researchers at Drexel University and Dalian University of Technology in China have engineered chemically a new electrically conductive nanomaterial that is flexible enough to fold
They believe it can be used to improve electrical energy storage water filtration and radiofrequency shielding in technology from portable electronics to coaxial cables.
Finding or making a thin material that is useful for holding and disbursing an electric charge and can be contorted into a variety of shapes is a rarity in the field of materials science.
Tensile strength-the strength of the material when it is stretched -and compressive strength-its ability to support weight-are valuable characteristics for these materials because at just a few atoms thick their utility figures almost entirely on their physical versatility.
Take the electrode of the small lithium-ion battery that powers your watch for example ideally the conductive material in that electrode would be very small
-so you don't have a bulky watch strapped to your wrist -and hold enough energy to run your watch for a long period of time said Michel Barsoum Phd Distinguished Professor in the College of Engineering.
But what if we wanted to make the watch's wristband into the battery? Then we'd still want to use a conductive material that is very thin
and can store energy but it would also need to be flexible enough to bend around your wrist.
As you can see just by changing one physical property of the material-flexibility or tensile strength-we open a new world of possibilities.
This flexible new material which the group has identified as a conductive polymer nanocomposite is the latest expression of the ongoing research in Drexel's Department of Materials science and engineering on a family of composite two-dimensional materials called MXENES.
This development was facilitated by collaboration between research groups of Yury Gogotsi Phd Distinguished University and Trustee Chair professor in the College of Engineering at Drexel and Jieshan Qiu vice dean for research
of the School of Chemical engineering at Dalian University of Technology in China. Zheng Ling a doctoral student from Dalian spent a year at Drexel spearheading the research that led to the first MXENE-polymer composites.
The researchat Drexel was funded by grants from the National Science Foundation and the U s. Department of energy.
The Drexel team has been diligently examining MXENES like a paleontologist carefully brushing away sediment to unearth a scientific treasure.
Since inventing the layered carbide material in 2011 the engineers are finding ways to take advantage of its chemical
and physical makeup to create conductive materials with a variety of other useful properties. One of the most successful ways they've developed to help MXENES express their array of abilities is called a process intercalation
To produce the flexible conductive polymer nanocomposite the researchers intercalated the titanium carbide MXENE with polyvinyl alcohol (PVA)- a polymer widely used as the paper adhesive known as school
They also intercalated with a polymer called PDDA (polydiallyldimethylammonium chloride) commonly used as a coagulant in water purification systems.
The uniqueness of MXENES comes from the fact that their surface is full of functional groups such as hydroxyl leading to a tight bonding between the MXENE flakes and polymer molecules while preserving the metallic conductivity of nanometer-thin
This leads to a nanocomposite with a unique combination of properties said Gogotsi. The results of both sets of MXENE testing were published recently in the Proceedings of the National Academy of Sciences.
We have shown that the volumetric capacitance of an MXENE-polymer nanocomposite can be compared much higher to conventional carbon-based electrodes
or even graphene said Chang Ren Gogotsi's doctoral student at Drexel. When mixing MXENE with PVA containing some electrolyte salt the polymer plays the role of electrolyte
but it also improves the capacitance because it slightly enlarges the interlayer space between MXENE flakes allowing ions to penetrate deep into the electrode;
ions also stay trapped near the MXENE flakes by the polymer. With these conductive electrodes and no liquid electrolyte we can eventually eliminate metal current collectors
and make lighter and thinner supercapacitors. The testing also revealed hydrophilic properties of the nanocomposite
which means that it could have uses in water treatment systems such as membrane for water purification or desalinization because it remains stable in water without breaking up
or dissolving. In addition because the material is extremely flexible it can be rolled into a tube
which early tests have indicated only serves to increase its mechanical strength. These characteristics mark the trail heads of a variety of paths for research on this nanocomposite material for applications from flexible armor to aerospace components.
The next step for the group will be to examine how varying ratios of MXENE and polymer will affect the properties of the resulting nanocomposite
and also exploring other MXENES and stronger and tougher polymers for structural applications. Explore further:
Crumpled graphene could provide an unconventional energy storag g
#Microtubes create cozy space for neurons to grow and grow fast Tiny, thin microtubes could provide a scaffold for neuron cultures to grow
so that researchers can study neural networks, their growth and repair, yielding insights into treatment for degenerative neurological conditions or restoring nerve connections after injury.
Researchers at the University of Illinois at Urbana-Champaign and the University of Wisconsin-Madison created the microtube platform to study neuron growth.
They posit that the microtubes could one day be implanted like stents to promote neuron regrowth at injury sites
or to treat disease.""This is a powerful three-dimensional platform for neuron culture, "said Xiuling Li,
U. of I. professor of electrical and computer engineering who co-led the study along with UW-Madison professor Justin Williams."We can guide,
accelerate and measure the process of neuron growth, all at once.""The team published the results in the journal ACS Nano."
"There are a lot of diseases that are very difficult to figure out the mechanisms of in the body,
so people grow cultures on platforms so we can see the dynamics under a microscope,
"said U. of I. graduate student Paul Froeter, the first author of the study.""If we can see what's happening,
hopefully we can figure out the cause of the deficiency and remedy it, and later integrate that into the body."
"The biggest challenge facing researchers trying to culture neurons for study is that it's very difficult to recreate the cozy, soft, three-dimensional environment of the brain.
made with a technique pioneered in Li's lab for electronics applications such as 3-D inductors.
Very thin membranes of silicon nitride roll themselves up into tubes of precise dimensions. The tubes are about as wide as the cells
Froeter devised a way to mount the microtubes on glass slides, the standard for biological cultures.
The thin silicon nitride tubes are transparent, so researchers can watch the live neuron cells as they grow using a conventional microscope."
Williams, a professor of biomedical engineering at UW-Madison.""Without this we may have noticed an overall increase in growth rates,
"The microtubes not only provide structure for the neural network, guiding connections, but also accelerate the nerve cells'growth
-and time is crucial for restoring severed connections in the case of spinal cord injury or limb reattachment.
Li and Froeter have sent already microtube arrays of various dimensions to other research groups studying neural networks for diverse applications.
For Li's group, the next step is to put electrodes in the microtubes so researchers can measure the electrical signals that the nerves conduct."
"If we place electrodes inside the tube, since they are directly in contact with the axon,
""Getting to the clinic will take a long time, but that is what keeps us motivated, "Li said d
#What exactly is Google's'cancer nanodetector'?'Last week US tech giants Google made a splash in the media announcing plans to develop new'disease-detecting magnetic nanoparticles'.
'This was welcomed almost universally after all trying to detect diseases earlier is something that's a focus of many research organisations including ours.
But when we tried to dig deeper into the detail behind the story things remained pretty light on actual context and detail.
So we spoke to Professor Duncan Graham a UK-based nanoscientist from University of Strathclyde
and expert advisor to Cancer Research UK to get his take on the announcement. The technical definition is that a nanoparticle is an object that is less than 100 nanometres wide along one of its edges Professor Graham told us.
A nanometre is a thousandth of a thousandth of a millimetre. In other words it's tiny.
At that scale things behave differently. You get a different biology chemistry and physics than you do with bigger things.
And that's really attractive to scientists. Nanoparticles can be made of anything they can be metallic organic
or inorganic and they come in all manner of different shapes and sizes he said. As a result they have a variety of origins.
whereas others can be made in the lab sometimes from complex biological molecules. No says Graham.
Nanoparticles have been around for centuries. Ancient art has used nanoparticles. They're in stained glass windows. The Lycurgus Cup in The british Museum looks so magical
because it's made of glass containing gold nanoparticles. And more immediately they're already used in medical detectors for example the pregnancy tests you buy over-the-counter work use gold nanoparticles attached to antibodies.
They're really nothing new although they're incredibly interesting to researchers. Another ubiquitous use is in antimicrobial products
which can contain suspensions of silver nanoparticles (but don't drink them you'll go blue). Why are they good for medical detection?
Nanoparticles have an extremely high surface area in relation to their volume. This means they can carry a lot of'stuff'on their surface proteins from blood for example.
And this means they're good for detecting things because they can really boost a signalfor example a protein that's relatively scarce in the blood
and therefore difficult to measure can collect on some nanoparticles in amounts large enough to detect.
But how does this work in practice? That's difficult to give a single answer to says Graham.
There's a bewildering amount of modification that researchers around the world are adding to the surface of nanoparticles.
You can attach biomolecules like proteins or DNA to them and make them change properties
so they produce optical magnetic or electrochemical signals. There are a lot of applications because there's so much chemistry you can do on their surface.
Professor Graham is perplexed somewhat by the recent media hubub. It's been quite challenging to work out
what Google are actually planning apart from getting a lot of coverage in the media he says.
There are no concrete proposals no peer-reviewed references no research strategy all the things that we in the science community normally take as given.
But then they're Google he says. They do things differently. The way traditional science works is to map out all the possible risks demonstrate you've accounted for them
and then ask for funding based on your robust well-discussed ideas. Google are doing the opposite they're saying'we want to get to here we'll worry about the details later'.
'One thing my colleagues and I who are also relatively sceptical about this did note was the fact that they've pulled together a pretty high-powered team who all have excellent track records.
Google have been similarly vague about the precise form of nanotechnology they aim to use Graham points out:
How does all this fit into the wider field of nanotechnology and diagnostics? This isn't all about Google says Graham.
It's worth pointing out that Google are far from being the only show in town.
There are loads of different research groups looking into what is called collectively'biosensing'continuous monitoring of
either using optical (light-based) detection where nanoparticles are used to either emit light directly or change the optical properties of their surroundings or magnetic systems.
One of the top people in this field as far as cancer goes is called a guy Sanjiv Gambhir at Stanford university in the US.
His team are doing some really interesting stuff with regards imaging using nanoparticles says Graham.
it seems according to this article in Wired that Gambhir originally advised Google about nanotechnology. What are the current challenges facing nanodetectors?
In Professor Graham's view there are two serious hurdles for nanotechnologists to overcome before particle-based biosensing becomes a reality:
when you put nanoparticles into the body they tend to get removed from the body in the urine via the kidneys.
So for Google's biomonitor they need to work out how to keep the particles in the body
But then you run into problem number two known as'biofouling'.'This is where random nonspecific molecules stick to the nanoparticles
and clog them up or deactivate them. The key thing to emphasise is that there's so much research that needs to be done before we can say'this is a disease-specific diagnostic'says Graham.
And of course any biosensor needs to be accurate. You need to know the numbers. Is it 100%accurate?
when we use the word'diagnose'its doctors not instruments that actually diagnose patients. An instrument can only ever highlight a set of conditions to a clinician it's always going to be the doctor who makes a call as to
whether someone has a disease. There is of course a wider issue here. What utility does the information you're producing actually have?
If I'm wearing a gadget that suddenly tells me I have a form of brain cancer that's incurable
what practical use is that to me? How has helped that my life? This is something Google really seem to have ducked in their announcement.
We don't need to dwell on it too much but there's been a lot in the press in the last year about who has access to Google's data and under
what circumstances says Graham referring to reports of Government agencies accessing user data from tech companies like Google and Facebook.
Are there any other applications of nanotechnology in the field of cancer? Of course it's not all about diagnostics.
There are other ways nanotechnology is being explored by cancer researchers. The other big focus of nanotech in cancer is to deliver treatments says Graham.
This is a field that's in its infancy lots of basic research in animals some of it promising
but much of it plagued with small numbers and less than-robust statistical analyses. One group who have caught my eye is a US company called Nanospectra.
and neck cancers and lung cancer it will be incredibly exciting to see what this approach yields.
Professor Graham's'take-home'message is that it's a mistake to see Google as the only organisation focusing on nanotechnology to detect disease it's a vibrant active field with incredible potential but still in its early days.
Google seeks way to search bodies for diseas s
#Cancer-killing nanodaisies NC State researchers have developed a potential new weapon in the fight against cancer:
a daisy-shaped drug carrier that's many thousands of times smaller than the period at the end of this sentence.
By using one nanocarrier to contain two different drugs we can potentially reduce their dose
and toxicity said Dr. Zhen Gu assistant professor in the Joint Department of Biomedical engineering at NC State and UNC-Chapel hill.
The nanocarriers are made from a polymer called polyethylene glycol (PEG) to which researchers attach the cancer-killing drug camptothecin (CPT) like bunches of grapes on a vine.
A second drug doxorubicin also floats in solution around the PEG. Both drugs are hydrophobic meaning they dislike water
The resulting nanocarrier is shaped like a flower#hence the term nanodaisy. The idea came from thinking actively about folding proteins in nature noted Gu referring to the way amino acids can assemble themselves into thousands of different shapes.
The result is that the drugs launch an attack on cancer that's more closely#coordinated
So far in vivo testing in mice has shown that this approach produces significant accumulation of drugs in tumor sites instead of healthy organs.
Gu noted that in vitro testing had demonstrated also the potential of nanodaisies to effectively target different kinds of cancer.
It's shown a broad killing effect for a variety of cancer cell lines including leukemia breast
Gu has led other research that#has yielded a bio-inspired cocoon that tricks cells into consuming anticancer drugs and an injectable nanonetwork that controls blood sugar levels in diabetics.
He is supported by faculty staff and Ph d. students in the Joint Department of Biomedical engineering a partnership between NC State and UNC-Chapel hill that tackles urgent biomedical problems.
The next step for nanodaisies is preclinical testing to determine whether they might be ready to fight cancer in humans.
For Gu that prospect has personal significance: His father was diagnosed with cancer when Gu was still in the womb.
When friends and family came to console Gu's mother she told#them that the baby she was carrying might#one day help to treat cancer.
I don't want to say it's a mission but it is a passion that drives
. I did research on conducting plastics for electronic devices. When I moved into the cancer treatments with nanotechnology that's when my mum became really excited about my work.
Explore further:''Nanodaisies'deliver drug cocktail to cancer cell o
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