Posts belonging to Category plasmonics

How To Strengthen 3-D Printed Parts

From aerospace and defense to digital dentistry and medical devices, 3-D printed parts are used in a variety of industries. Currently, 3-D printed parts are very fragile and traditionally used in the prototyping phase of materials or as a toy for display. A doctoral student in the Department of Materials Science and Engineering at Texas A&M University has pioneered a countermeasure to transform the landscape of 3-D printing today.

Brandon Sweeney and his advisor Dr. Micah Green, associate professor in the Department of Chemical Engineering, discovered a way to make 3-D printed parts stronger and immediately useful in real-world applications. Sweeney and Green applied the traditional welding concepts to bond the submillimeter layers in a 3-D printed part together, while in a microwave.

I was able to see the amazing potential of the technology, such as the way it sped up our manufacturing times and enabled our CAD designs to come to life in a matter of hours,” Sweeney said. “Unfortunately, we always knew those parts were not really strong enough to survive in a real-world application.

3-D printed objects are comprised of many thin layers of materials, plastics in this case, deposited on top of each other to form a desired shape. These layers are prone to fracturing, causing issues with the durability and reliability of the part when used in a real-world application, for example a custom printed medical device. “I knew that nearly the entire industry was facing this problem,” Sweeney said. “Currently, prototype parts can be 3-D printed to see if something will fit in a certain design, but they cannot actually be used for a purpose beyond that.”

When Sweeney started his doctorate, he was working with Green in the Department of Chemical Engineering at Texas Tech University. Green had been collaborating with Dr. Mohammad Saed, assistant professor in the electrical and computer engineering department at Texas Tech, on a project to detect carbon nanotubes using microwaves. The trio crafted an idea to use carbon nanotubes in 3-D printed parts, coupled with microwave energy to weld the layers of parts together.

The basic idea is that a 3-D part cannot simply be stuck into an oven to weld it together because it is plastic and will melt,” Sweeney said. “We realized that we needed to borrow from the concepts that are traditionally used for welding parts together where you’d use a point source of heat, like a torch or a TIG welder to join the interface of the parts together. You’re not melting the entire part, just putting the heat where you need it.” The technology is patent-pending and licensed with a local company, Essentium Materials.

The team recently published a paper “Welding of 3-D Printed Carbon Nanotube-Polymer Composites by Locally Induced Microwave Heating,” in Science Advances.


Use The Phone And See 3D Content Without 3D Glasses

RED, the company known for making some truly outstanding high-end cinema cameras, is set to release a smartphone in Q1 of 2018 called the HYDROGEN ONE. RED says that it is a standalone, unlocked and fully-featured smartphone “operating on Android OS that just happens to add a few additional features that shatter the mold of conventional thinking.” Yes, you read that right. This phone will blow your mind, or something – and it will even make phone calls.

In a press release riddled with buzzwords broken up by linking verbs, RED praises their yet-to-be smartphone with some serious adjectives. If we were just shown this press release outside of living on RED‘s actual server, we would swear it was satire. Here are a smattering of phrases found in the release.

Incredible retina-riveting display
Holographic multi-view content
RED Hydrogen 4-View content
Assault your senses
Proprietary H3O algorithm
Multi-dimentional audio

  • There are two models of the phone, which run at different prices. The Aluminum model will cost $1,195, but anyone worth their salt is going to go for the $1,595 Titanium version. Gotta shed that extra weight, you know?

Those are snippets from just the first three sections, of which there are nine. I get hyping a product, but this reads like a catalog seen in the background of a science-fiction comedy, meant to sound ridiculous – especially in the context of a ficticious universe.

Except that this is real life.

After spending a few minutes removing all the glitter words from this release, it looks like it will be a phone using a display similar to what you get with the Nintendo 3DS, or what The Verge points out as perhaps better than the flopped Amazon Fire Phone. Essentially, you should be able to use the phone and see 3D content without 3D glasses. Nintendo has already proven that can work, however it can really tire out your eyes. As an owner of three different Nintendo 3DS consoles, I can say that I rarely use the 3D feature because of how it makes my eyes hurt. It’s an odd sensation. It is probalby why Nintendo has released a new handheld that has the same power as the 3DS, but dropping the 3D feature altogether.

Anyway, back to the HYDROGEN ONE, RED says that it will work in tandem with their cameras as a user interface and monitor. It will also display what RED is calling “holographic content,” which isn’t well-described by RED in this release. We can assume it is some sort of mixed-dimensional view that makes certain parts of a video or image stand out over the others.


3-D Printed Graphene Foam

Nanotechnologists from Rice University and China’s Tianjin University have used 3-D laser printing to fabricate centimeter-sized objects of atomically thin graphene. The research could yield industrially useful quantities of bulk graphene and is described online in a new study in the American Chemical Society journal ACS Nano.

Laser sintering was used to 3-D print objects made of graphene foam, a 3-D version of atomically thin graphene. At left is a photo of a fingertip-sized cube of graphene foam; at right is a close-up of the material as seen with a scanning electron microscope

This study is a first of its kind,” said Rice chemist James Tour, co-corresponding author of the paper. “We have shown how to make 3-D graphene foams from nongraphene starting materials, and the method lends itself to being scaled to graphene foams for additive manufacturing applications with pore-size control.”

Graphene, one of the most intensely studied nanomaterials of the decade, is a two-dimensional sheet of pure carbon that is both ultrastrong and conductive. Scientists hope to use graphene for everything from nanoelectronics and aircraft de-icers to batteries and bone implants. But most industrial applications would require bulk quantities of graphene in a three-dimensional form, and scientists have struggled to find simple ways of creating bulk 3-D graphene.

For example, researchers in Tour’s lab began using lasers, powdered sugar and nickel to make 3-D graphene foam in late 2016. Earlier this year they showed that they could reinforce the foam with carbon nanotubes, which produced a material they dubbed “rebar graphene” that could retain its shape while supporting 3,000 times its own weight. But making rebar graphene was no simple task. It required a pre-fabricated 3-D mold, a 1,000-degree Celsius chemical vapor deposition (CVD) process and nearly three hours of heating and cooling.  “This simple and efficient method does away with the need for both cold-press molds and high-temperature CVD treatment,” said co-lead author Junwei Sha, a former student in Tour’s lab who is now a postdoctoral researcher at Tianjin. “We should also be able to use this process to produce specific types of graphene foam like 3-D printed rebar graphene as well as both nitrogen- and sulfur-doped graphene foam by changing the precursor powders.” Sha and colleagues conducted an exhaustive study to find the optimal amount of time and laser power to maximize graphene production. The foam created by the process is a low-density, 3-D form of graphene with large pores that account for more than 99 percent of its volume.

The 3-D graphene foams prepared by our method show promise for applications that require rapid prototyping and manufacturing of 3-D carbon materials, including energy storage, damping and sound absorption,” said co-lead author Yilun Li, a graduate student at Rice.


Semiconductors As Thin As An Atom

A two-dimensional material developed by physicist Prof. Dr. Axel Enders (Bayreuth University  in Germany) together with international partners could revolutionize electronicsSemiconductors that are as thin as an atom are no longer the stuff of .  Thanks to its semiconductor properties, this material could be much better suited for high tech applications than graphene, the discovery of which in 2004 was celebrated worldwide as a . This new material contains carbon, boron, and nitrogen, and its chemical name is “Hexagonal Boron-Carbon-Nitrogen (h-BCN)”. The new development was published in the journal ACS Nano.

2D material Bayreuth University

Our findings could be the starting point for a new generation of electronic transistors, circuits, and sensors that are much smaller and more bendable than the electronic elements used to date. They are likely to enable a considerable decrease in power consumption,” Prof. Enders predicts, citing the CMOS technology that currently dominates the electronics industry. This technology has clear limits with regard to further miniaturization. “h-BCN is much better suited than graphene when it comes to pushing these limits,” according to Enders.

Graphene is a two-dimensional lattice made up entirely of carbon atoms. It is thus just as thin as a single atom. Once scientists began investigating these structures more closely, their remarkable properties were greeted with enthusiasm across the world. Graphene is 100 to 300 times stronger than steel and is, at the same time, an excellent conductor of heat and electricity.


New Material Ten Times Stronger Than Steel, Designed From Graphene

A team of researchers at MIT has designed one of the strongest lightweight materials known, by compressing and fusing flakes of graphene, a two-dimensional form of carbon. The new material, a sponge-like configuration with a density of just 5 percent, can have a strength 10 times that of steel. In its two-dimensional form, graphene is thought to be the strongest of all known materials. But researchers until now have had a hard time translating that two-dimensional strength into useful three-dimensional materials.

The new findings show that the crucial aspect of the new 3-D forms has more to do with their unusual geometrical configuration than with the material itself, which suggests that similar strong, lightweight materials could be made from a variety of materials by creating similar geometric features.

graphene material

The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure whose form resembles that of some corals and microscopic creatures called diatoms. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong. “Once we created these 3-D structures, we wanted to see what’s the limit — what’s the strongest possible material we can produce,” says Zhao Qin, research scientist at MIT. To do that, they created a variety of 3-D models and then subjected them to various tests. In computational simulations, which mimic the loading conditions in the tensile and compression tests performed in a tensile loading machine, “one of our samples has 5 percent the density of steel, but 10 times the strength,” Qin says.
The findings have been reported in the journal Science Advances.


How To Erase Chips Remotely

A military drone flying on a reconnaissance mission is captured behind enemy lines, setting into motion a team of engineers who need to remotely delete sensitive information carried on the drone’s chips. Because the chips are optical and not electronic, the engineers can now simply flash a beam of UV light onto the chip to instantly erase all content. Disaster averted.

This James Bond-esque chip is closer to reality because of a new development in a nanomaterial developed by Yuebing Zheng, a professor of mechanical engineering and materials science and engineering in the Cockrell School of Engineering. His team described its findings in the journal Nano Letters.


The molecules in this material are very sensitive to light, so we can use a UV light or specific light wavelengths to erase or create optical components,” Zheng said. “Potentially, we could incorporate this LED into the chip and erase its contents wirelessly. We could even time it to disappear after a certain period of time.”

To test their innovation, the researchers used a green laser to develop a waveguide — a structure or tunnel that guides light waves from one point to another — on their nanomaterial. They then erased the waveguide with a UV light, and re-wrote it on the same material using the green laser. The researchers believe they are the first to rewrite a waveguide, which is a crucial photonic component and a building block for integrated circuits, using an all-optical technique.


Swiches For Electricity: Atomic-Scale Manufacturing

Robert Wolkow is no stranger to mastering the ultra-small and the ultra-fast. A pioneer in atomic-scale science with a Guinness World Record to boot (for a needle with a single atom at the point), Wolkow’s team, together with collaborators at the Max Planck Institute in Hamburg, have just released findings that detail how to create atomic switches for electricity, many times smaller than what is currently used. With applications for practical systems like silicon semi-conductor electronics, it means smaller, more efficient, more energy-conserving nanocomputers, as just one example of the technology revolution that is unfolding right before our very eyes (if you can squint that hard).


It’s something you don’t even hear about yet, but atom-scale manufacturing is going to be world-changing. This is just the beginning of what will be at least a century of developments in atom-scale manufacturing, and it will be transformational“.  “This is the first time anyone’s seen a switching of a single-atom channel,” explains Wolkow, a physics professor at the University of Alberta and the Principal Research Officer at Canada’s National Institute for Nanotechnology. “You’ve heard of a transistor—a switch for electricity—well, our switches are almost a hundred times smaller than the smallest on the market today.

Today’s tiniest transistors operate at the 14 nanometer level, which still represents thousands of atoms. Wolkow’s and his team at the University of Alberta, NINT, and his spinoff QSi, have worked the technology down to just a few atoms. Since computers are simply a composition of many on/off switches, the findings point the way not only to ultra-efficient general purpose computing but also to a new path to quantum computing.


Light Makes OscillatorTo Oscillate Indefinitely

Researchers have designed a device that uses light to manipulate its mechanical properties. The device, which was fabricated using a plasmomechanical metamaterial, operates through a unique mechanism that couples its optical and mechanical resonances, enabling it to oscillate indefinitely using energy absorbed from light.

metamaterialThis work demonstrates a metamaterial-based approach to develop an optically-driven mechanical oscillator. The device can potentially be used as a new frequency reference to accurately keep time in GPS, computers, wristwatches and other devices, researchers said. Other potential applications that could be derived from this metamaterial-based platform include high precision sensors and quantum transducers..

Researchers engineered the metamaterial-based device by integrating tiny light absorbing nanoantennas onto nanomechanical oscillators. The study was led by Ertugrul Cubukcu, a professor of nanoengineering and electrical engineering at the University of California San Diego. The work, which Cubukcu started as a faculty member at the University of Pennsylvania and is continuing at the Jacobs School of Engineering at UC San Diego, demonstrates how efficient light-matter interactions can be utilized for applications in novel nanoscale devices.

Metamaterials are artificial materials that are engineered to exhibit exotic properties not found in nature. For example, metamaterials can be designed to manipulate light, sound and heat waves in ways that can’t typically be done with conventional materials.

Metamaterials are generally considered “lossy” because their metal components absorb light very efficiently. “The lossy trait of metamaterials is considered a nuisance in photonics applications and telecommunications systems, where you have to transmit a lot of power. We’re presenting a unique metamaterials approach by taking advantage of this lossy feature,” Cubukcu said. The researchers also point out that because the plasmomechanical metamaterial can efficiently absorb light, it can function under a broad optical resonance. That means this metamaterial can potentially respond to a light source like an LED and won’t need a strong laser to provide the energy.

Using plasmonic metamaterials, we were able to design and fabricate a device that can utilize light to amplify or dampen microscopic mechanical motion more powerfully than other devices that demonstrate these effects. Even a non-laser light source could still work on this device,” said Hai Zhu, a former graduate student in Cubukcu’s lab and first author of the study.

Optical metamaterials enable the chip-level integration of functionalities such as light-focusing, spectral selectivity and polarization control that are usually performed by conventional optical components such as lenses, optical filters and polarizers. Our particular metamaterial-based approach can extend these effects across the electromagnetic spectrum,” adds Fei Yi, a postdoctoral researcher who worked in Cubukcu’s lab.

The research was published in the journal Nature Photonics.


Solar Cells: How To Transform More Solar Energy Into Electricity

Sagrario Domínguez-Fernández, a Spanish telecommunications engineer at CEMITEC, has managed to increase light absorption in silicon by means of nanostructures etched onto photovoltaic cells. This increases the efficiency obtained in these electronic devices which are made of this element and which transform solar energy into electricity.
solar cells

Over 30 percent of the sunlight that strikes a silicon is reflected, which means it cannot be used in the photoelectric conversion,” explained Sagrario Domínguez. “Because the nanostructures on the surface of a material have dimensions in the light wavelength range, they interfere with the surface in a particular way and allow the amount of reflected light to be modified.”

Sagrario Domínguez designed and optimised structures on a nanometric scaleto try and find one that would minimise the reflectance [ability of a surface to reflect light] of the silicon in the wavelength range in which solar cells function.” In their manufacturing process, she resorted to what is known as laser interference lithography which consists of applying laser radiation to a photo-sensitive material to create structures on a nanometric scale. Specifically, she used polished silicon wafers to which she gave the shape of cylindrical pillar and obtained a 77 percent reduction in the reflectance of this element.

Sagrario Domínguez then went on to modify the manufacturing processes to produce the nanostructures on the silicon substrates used in commercial solar cells. “These substrates have dimensions and a surface roughness that makes them, ‘a priori’, unsuitable for processes,” pointed out the researcher. Having overcome the difficulties, she incorporated nanostructures onto following the standard processes of the photovoltaics industry. “According to the literature, this is the first time that it has been possible to manufacture periodic nanostructures; they are the ones that on the surface of a material are continuously repeated on substrates of this type, and therefore, the first standard solar cell with periodic nanostructures,” pointed out the new MIT PhD holder. The efficiency obtained is 15.56 percent, which is a very promising value when compared with others included in the literature.


Smart Glass

Most smartphones have a slick, sizable piece of glass on their face. But the glass itself is notsmart” — the intelligent components lie beneath. That could soon change, thanks to researchers at the University of Adelaide in Australia who have lent “smart potential” to glass. They’ve done so by embedding light-emitting nanoparticles within the glass without affecting the glass’s physical properties — its transparency and malleability, for example.

This method for embedding light-emitting nanoparticles into glass without losing any of their unique properties – a major step towards ‘smart glass’ applications such as 3D display screens or remote radiation sensors.

The new “hybrid glass” successfully combines the properties of these special luminescent (or light-emitting) nanoparticles with the well-known aspects of glass, such as transparency and the ability to be processed into various shapes including very fine optical fibres.

smart glass2An illustration shows light-emitting nanoparticles embedded in glass

These novel luminescent nanoparticles, called upconversion nanoparticles, have become promising candidates for a whole variety of ultra-high tech applications such as biological sensing, biomedical imaging and 3D volumetric displays,” says lead author Dr Tim Zhao, from the University of Adelaide’s School of Physical Sciences and Institute for Photonics and Advanced Sensing (IPAS).

Integrating these nanoparticles into glass, which is usually inert, opens up exciting possibilities for new hybrid materials and devices that can take advantage of the properties of nanoparticles in ways we haven’t been able to do before. For example, neuroscientists currently use dye injected into the brain and lasers to be able to guide a glass pipette to the site they are interested in. If fluorescent nanoparticles were embedded in the glass pipettes, the unique luminescence of the hybrid glass could act like a torch to guide the pipette directly to the individual neurons of interest”, adds Dr Zhao.

The research, in collaboration with Macquarie University and University of Melbourne, has been published online in the journal Advanced Optical Materials.


Solar Cell Converts 34,5% Of The Sunlight To Electricity

A new solar cell configuration developed by engineers at the University of New South Wales (UNSW) in Australia, has pushed sunlight-to-electricity conversion efficiency to 34.5% – establishing a new world record for unfocused sunlight and nudging closer to the theoretical limits for such a device. The record was set by Dr Mark Keevers and Professor Martin Green, Senior Research Fellow and Director, respectively, of UNSW’s Australian Centre for Advanced Photovoltaics, using a 28-cm2 four-junction mini-module – embedded in a prism – that extracts the maximum energy from sunlight. It does this by splitting the incoming rays into four bands, using a hybrid four-junction receiver to squeeze even more electricity from each beam of sunlight. The new UNSW result, confirmed by the US National Renewable Energy Laboratory, is almost 44% better than the previous record – made by Alta Devices of the USA, which reached 24% efficiency, but over a larger surface area of 800-cm2.


This encouraging result shows that there are still advances to come in photovoltaics research to make solar cells even more efficient,” said Keevers. “Extracting more energy from every beam of sunlight is critical to reducing the cost of electricity generated by solar cells as it lowers the investment needed, and delivering payback faster.”

The result was obtained by the same UNSW team that set a world record in 2014, achieving an electricity conversion rate of over 40% by using mirrors to concentrate the light – a technique known as CPV (concentrator photovoltaics) – and then similarly splitting out various wavelengths. The new result, however, was achieved using normal sunlight with no concentrators.


Nano-Robots Enter Living Cells

Researchers have developed the world’s tiniest engine – just a few billionths of a metre in size – which uses light to power itself. The nanoscale engine, developed by researchers at the University of Cambridge, could form the basis of future nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease. The prototype device is made of tiny charged particles of gold, bound together with temperature-responsive polymers in the form of a gel. When the ‘nano-engine’ is heated to a certain temperature with a laser, it stores large amounts of elastic energy in a fraction of a second, as the polymer coatings expel all the water from the gel and collapse. This has the effect of forcing the gold nanoparticles to bind together into tight clusters. But when the device is cooled, the polymers take on water and expand, and the gold nanoparticles are strongly and quickly pushed apart, like a spring.


It’s like an explosion,” said Dr Tao Ding from Cambridge’s Cavendish Laboratory, and the paper’s first author. “We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them.
We know that light can heat up water to power steam engines,” said study co-author Dr Ventsislav Valev, now based at the University of Bath. “But now we can use light to power a piston engine at the nanoscale.”

The results are reported in the journal PNAS.