MIT: Wearable Electronics ~ From Fitness “Gadgets” to Accurate Medical Devices ~ Are We ‘There’ Yet?



*** From MIT Technology Review

Wearable devices are getting more advanced, but can today’s technology really measure our health?




Until recently, I didn’t know a thing about how my roughly 25-minute bike commute across San Francisco—or any other part of my day, really—affects my body, other than that I inevitably arrive at work sweaty and a bit out of breath when I’m in a big rush. How high is my heart rate? Do my sleep habits affect it? How many calories do I burn?

These questions have been on my mind as a number of activity trackers and smart watches have hit store shelves over the past couple of years, promising to track information like steps, sleep, heart rate, sun exposure, and calories. With one of these sensor-filled gadgets on my wrist, surely I could get accurate information about my body.

That’s the idea, at least. These devices could give you more control over your health by making it easier to collect data previously left unmonitored or, as in the case of heart rate, typically gathered only at a doctor’s office (and even then infrequently). And these devices aren’t just tracking data; companies like Apple, Jawbone, and Microsoft offer advice based on what the sensors in their wrist-worn wearables detect. 

The Microsoft Health app should soon have the ability to compare calendar or contact information with the Microsoft Band’s assessment of, say, your heart rate or skin conductance level—a measure of your skin’s ability to conduct electricity, which tends to climb with stress.

The Apple Watch and Microsoft Band use optical sensors to measure heart rate. The Jawbone Up3, which instead tracks your resting heart rate, uses bioimpedance sensors and several electrodes to measure your skin’s resistance to a small amount of electrical current. These sensors and others in the bands are adequate for measuring routine activity levels, but is the technology really accurate enough to turn wearable devices into digital medical tools?

“We’re at an inflection point, or transition, from lifestyle health stuff to medical metrics,” says cardiologist Eric Topol, a genomics professor at the Scripps Research Institute and a fan of digital health technology. To Topol, the objective is clear: devices that accurately measure vital body signs and even monitor serious health problems like diabetes and heart disease. “It’s the medical metrics where accuracy becomes fundamental,” he says.

The Test

How far away are we from such wearables? I tested the accuracy of a few wrist-measured metrics, including heart rate. For several days, I wore an Apple Watch and a Microsoft Band while biking to and from work. I also wore a Polar H7 Bluetooth chest strap, which is one of the most accurate consumer devices for measuring heart rate. Results varied, and sometimes they varied a lot. 

The Band’s average heart-rate measurements were consistently closer to the results of the Polar chest strap—sometimes within a beat or two per minute, but they could be as many as 13 beats off. The Apple Watch, meanwhile, gave readings as many as 77 beats per minute different from the Polar device.

Measurements of calories burned (something all three bands, including the Up3, track) were also somewhat inconsistent; on one morning commute, for instance, they ranged from 143 to 187. Altogether, the experience was a far cry from the vision of these devices as digital sages drawing deep, accurate insights from the data they collect, helping doctors diagnose ailments, and eventually, perhaps, even predicting health problems or detecting them before they become serious. 

These are hard goals to achieve, for several reasons. While the wrist seems like a great place to start with sensing on the body, and we’re used to adorning it with watches and jewelry, it’s tricky to make a comfortable, good-­looking device that can stand up to all kinds of daily abuse.
And since everyone’s body is different, the wrist is not always a great spot to take accurate measurements. “You can make millions of smart watches that are identical, but you have millions of people who are not identical. It’s really hard to find something that’s robust across all these people,” says Chris Harrison, an assistant professor of human-computer interaction who leads the Future Interfaces Group at Carnegie Mellon University.
Harrison and other experts say arms that are too hairy, sweaty, fat, or thin can make it hard to get a good reading from today’s optical heart-rate sensors, which read blood flow in the wrist. Tattoos can pose a problem, too—as Apple points out on a support page for the Apple Watch, noting that the ink can block light from reaching the sensor. “All of a sudden that translates to thousands of users out there, all of whom are going to be unhappy and say it doesn’t work because it doesn’t work for them,” says Christian Holz, a researcher on human-computer interaction at Yahoo Labs who focuses on the miniaturization of mobile devices.

Beyond workout tracking

There’s hope for wearable devices that actually take the types of measurements that would be helpful for health monitoring. But realizing that hope will probably mean moving on to radically new technologies. And it will certainly mean developing devices that are able to take a wider variety of measurements.

At Quanttus, a startup in Cambridge, Massachusetts, researchers are building a wrist-worn device to track heart rate, respiration, and blood pressure by way of ballistocardiogram, which uses a sensor to measure the itty-bitty movements of your body every time your heart pumps blood. At a conference in late April, cofounder and CEO Shahid Azim said the company is interested in releasing “some number” of wristbands by the end of the year. Cofounder and chief scientific officer David He says it is still “refining the technology.”

Once we can pin down heart-rate and blood-pressure measurements, He believes, we may well be able to monitor most cardiovascular vital signs with wearables. This could be a boon, not just for fitness applications and those wanting to keep an eye on their own health but also for doctors who want noninvasive ways to keep tabs on patients at a level currently possible only in a hospital.

Another Cambridge-based startup, Empatica, is creating a wristband that measures jumps in skin conductance to figure out when the wearer is having a seizure, so it can alert someone to check on the person. Empatica isn’t able to predict seizures yet, however, and it hasn’t released its product either.

Building these products takes lots of time. Testing, simulations, modeling, prototyping, and problem-solving are all more extensive when you need to make sure the devices can stand up to the requirements of daily wear, such as frequent exposure to sweat and water. That’s a lot more than you’d normally expect from your electronics. But if companies clear these obstacles, being able to sense things like blood pressure and skin conductivity continuously can also open the door to quantifying stress and mood, since they will make it possible to collect data about your body in all kinds of situations.

And we’re just at the early stages of understanding how much we may be able to do with sensors on the skin. In the next several years, noninvasive sensors may become useful for other biometrics that can currently be tracked only with invasive processes. It might be possible to monitor blood glucose with skin readings rather than a needle prick—something that would be helpful to people with diabetes.

In fact, researchers are working on this particular problem at the University of California, San Diego. They’ve developed a temporary tattoo, printed with electrodes and coated with an enzyme solution, that can measure glucose levels. Joseph Wang, director of UCSD’s Center for Wearable Sensors, has been working on the technology for the past five years. He says it will be at least another two years before it is commercialized—initially, he expects, in the form of a single-use temporary tattoo, and then with tattoos that can measure the wearer’s glucose every 20 or 40 minutes for a day or a week. Topol believes that all kinds of accurate data are coming; it’s just a matter of time. 

“We have a ways to go, but ultimately, that is something machines are really very good for,” he says. “And the algorithms can be developed where for each person it could be a virtual medical assistant.” Given that today’s wristbands still stutter when measuring heart rate during a workout, such applications seem far out of reach. But the research at Quanttus, Empatica, and UCSD suggests that new approaches based on technologies far beyond conventional optical sensors could finally turn wrist-worn devices into tools for monitoring general health.

Nanotechnology to “Super-Size” Green Energy


renewable-energy-wind-and-ocean1

Nanotechnology is a field that’s receiving a lot of attention at the moment as scientists learn more every day about the benefits it can bring to both the environment and our health. There are various ways in which nanotechnology has proved itself useful including in developing enhanced solar cells and more efficient rechargeable batteries, and in saving raw materials and energy.

 

When it comes to nanotechnology, even the smallest achievements make huge differences, and on November 23, 2016, future technologies were presented to the international congress as part of the “Next Generation Solar Energy Meets Nanotechnology.” Out of the ten projects, three of them were located in Wurzburg and are explained in a little more detail below:

  • Eco-friendly inks for organic solar cells: Over at the University of Erlangen-Nuremberg, Professors Vladimir Dyakonov and Christoph Brabec have created eco-friendly photovoltaic inks using nanomaterials and have developed a new simulation process at the same time. Dyakonov explains, “They allow us to predict which combinations of solvents and materials are suitable for the eco-friendly production of organic solar cells.”
  • Nanodiamonds for ultra-fast electrical storage: If we want to have powerful, yet highly efficient electric vehicles then we need some way of storing the energy as a standard battery couldn’t handle it. Supercapacitors are great regarding acting as an efficient energy storage system. But, because their energy density is so low they need to be quite large in order to deliver any reasonable amount of energy. However, further work is being done in this area currently, and progress is promising.  Professor Anke Kruger, head of the project, says “Based on these findings, it is now possible to build application-oriented energy stores and test their applicability.”

 

  • Increased storage capacity of hybrid capacitors: Better energy storage systems were also the focus of Professor Gerhard Sextl and his team’s project. Their hybrid capacitors can store more energy due to the embedded lithium ions and can do it quickly through the use of a supercapacitor. Sextl says, “We have managed to develop a material that combines the advantages of both systems. This has brought us one step closer to implementing a new, fast and reliable storage concept.”

Read More:

Read the rest of the story (click here) NEW SUPER-BATTERIES ARE FINALLY HERE

Czech Battery NanotechnologyCompany HE3DA President Jan Prochazka shows qualities of a new battery during the official start of a battery production line in Prague, on Monday, Dec. 19, 2016. The new battery is based on nanotechnology and is supposed to be be more efficient, long-lasting, cheaper, lighter and above all safer. The battery is designed to store energy from renewable electric sources and cooperate with smart grids. Next planned type will be suitable for electric cars. (Michal Kamaryt /CTK via AP)

It’s been a long time coming, but the wait is now over for a battery that lasts longer than your milk. Having to replace batteries in games, remotes, and other electrical devices are annoying, especially when you seem to be doing it every month. But, that may all be a thing of the past thanks to the Prague-based company, HE3DA. New superbatteries have finally been created that are capable of charging faster and lasting longer than any other technology out there and are being mass produced as you read this.

 

MIT: Researchers design one of the strongest, lightest materials known + Video




Porous, 3-D forms of graphene developed at MIT can be 10 times as strong as steel but much lighter.

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.

The findings are being reported today in the journal Science Advances, in a paper by Markus Buehler, the head of MIT’s Department of Civil and Environmental Engineering (CEE) and the McAfee Professor of Engineering; Zhao Qin, a CEE research scientist; Gang Seob Jung, a graduate student; and Min Jeong Kang MEng ’16, a recent graduate.


Other groups had suggested the possibility of such lightweight structures, but lab experiments so far had failed to match predictions, with some results exhibiting several orders of magnitude less strength than expected. The MIT team decided to solve the mystery by analyzing the material’s behavior down to the level of individual atoms within the structure. They were able to produce a mathematical framework that very closely matches experimental observations.

Two-dimensional materials — basically flat sheets that are just one atom in thickness but can be indefinitely large in the other dimensions — have exceptional strength as well as unique electrical properties. But because of their extraordinary thinness, “they are not very useful for making 3-D materials that could be used in vehicles, buildings, or devices,” Buehler says. “What we’ve done is to realize the wish of translating these 2-D materials into three-dimensional structures.”

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 Qin. 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.

Buehler says that what happens to their 3-D graphene material, which is composed of curved surfaces under deformation, resembles what would happen with sheets of paper. Paper has little strength along its length and width, and can be easily crumpled up. But when made into certain shapes, for example rolled into a tube, suddenly the strength along the length of the tube is much greater and can support substantial weight. Similarly, the geometric arrangement of the graphene flakes after treatment naturally forms a very strong configuration.

The new configurations have been made in the lab using a high-resolution, multimaterial 3-D printer. They were mechanically tested for their tensile and compressive properties, and their mechanical response under loading was simulated using the team’s theoretical models. The results from the experiments and simulations matched accurately.

The new, more accurate results, based on atomistic computational modeling by the MIT team, ruled out a possibility proposed previously by other teams: that it might be possible to make 3-D graphene structures so lightweight that they would actually be lighter than air, and could be used as a durable replacement for helium in balloons. The current work shows, however, that at such low densities, the material would not have sufficient strength and would collapse from the surrounding air pressure.

But many other possible applications of the material could eventually be feasible, the researchers say, for uses that require a combination of extreme strength and light weight. “You could either use the real graphene material or use the geometry we discovered with other materials, like polymers or metals,” Buehler says, to gain similar advantages of strength combined with advantages in cost, processing methods, or other material properties (such as transparency or electrical conductivity).

“You can replace the material itself with anything,” Buehler says. “The geometry is the dominant factor. It’s something that has the potential to transfer to many things.”

The unusual geometric shapes that graphene naturally forms under heat and pressure look something like a Nerf ball — round, but full of holes. These shapes, known as gyroids, are so complex that “actually making them using conventional manufacturing methods is probably impossible,” Buehler says. The team used 3-D-printed models of the structure, enlarged to thousands of times their natural size, for testing purposes.

For actual synthesis, the researchers say, one possibility is to use the polymer or metal particles as templates, coat them with graphene by chemical vapor deposit before heat and pressure treatments, and then chemically or physically remove the polymer or metal phases to leave 3-D graphene in the gyroid form. For this, the computational model given in the current study provides a guideline to evaluate the mechanical quality of the synthesis output.

The same geometry could even be applied to large-scale structural materials, they suggest. For example, concrete for a structure such a bridge might be made with this porous geometry, providing comparable strength with a fraction of the weight. This approach would have the additional benefit of providing good insulation because of the large amount of enclosed airspace within it.

Because the shape is riddled with very tiny pore spaces, the material might also find application in some filtration systems, for either water or chemical processing. The mathematical descriptions derived by this group could facilitate the development of a variety of applications, the researchers say.

“This is an inspiring study on the mechanics of 3-D graphene assembly,” says Huajian Gao, a professor of engineering at Brown University, who was not involved in this work. “The combination of computational modeling with 3-D-printing-based experiments used in this paper is a powerful new approach in engineering research. It is impressive to see the scaling laws initially derived from nanoscale simulations resurface in macroscale experiments under the help of 3-D printing,” he says.

This work, Gao says, “shows a promising direction of bringing the strength of 2-D materials and the power of material architecture design together.”

The research was supported by the Office of Naval Research, the Department of Defense Multidisciplinary University Research Initiative, and BASF-North American Center for Research on Advanced Materials.

Duke University: Silver nanowire inks enable paper-based printable electronics



By suspending tiny metal nanoparticles in liquids, Duke University scientists are brewing up conductive ink-jet printer “inks” to print inexpensive, customizable circuit patterns on just about any surface.

Printed electronics, which are already being used on a wide scale in devices such as the anti-theft radio frequency identification (RFID) tags you might find on the back of new DVDs, currently have one major drawback: for the circuits to work, they first have to be heated to melt all the nanoparticles together into a single conductive wire, making it impossible to print circuits on inexpensive plastics or paper.

A new study by Duke researchers shows that tweaking the shape of the nanoparticles in the ink might just eliminate the need for heat.

Silver Nanostructures

Duke University chemists have found that silver nanowire films like these conduct electricity well enough to form functioning circuits without applying high temperatures, enabling printable electronics on heat-sensitive materials like paper or plastic. (Image: Ian Stewart and Benjamin Wiley)

By comparing the conductivity of films made from different shapes of silver nanostructures, the researchers found that electrons zip through films made of silver nanowires much easier than films made from other shapes, like nanospheres or microflakes. In fact, electrons flowed so easily through the nanowire films that they could function in printed circuits without the need to melt them all together.

“The nanowires had a 4,000 times higher conductivity than the more commonly used silver nanoparticles that you would find in printed antennas for RFID tags,” said Benjamin Wiley, assistant professor of chemistry at Duke. “So if you use nanowires, then you don’t have to heat the printed circuits up to such high temperature and you can use cheaper plastics or paper.”

“There is really nothing else I can think of besides these silver nanowires that you can just print and it’s simply conductive, without any post-processing,” Wiley added.

These types of printed electronics could have applications far beyond smart packaging; researchers envision using the technology to make solar cells, printed displays, LEDS, touchscreens, amplifiers, batteries and even some implantable bio-electronic devices. The results appeared online in ACS Applied Materials and Interfaces (“Effect of Morphology on the Electrical Resistivity of Silver Nanostructure Films”).

Silver has become a go-to material for making printed electronics, Wiley said, and a number of studies have recently appeared measuring the conductivity of films with different shapes of silver nanostructures. However, experimental variations make direct comparisons between the shapes difficult, and few reports have linked the conductivity of the films to the total mass of silver used, an important factor when working with a costly material.

“We wanted to eliminate any extra materials from the inks and simply hone in on the amount of silver in the films and the contacts between the nanostructures as the only source of variability,” said Ian Stewart, a recent graduate student in Wiley’s lab and first author on the ACS paper.

Stewart used known recipes to cook up silver nanostructures with different shapes, including nanoparticles, microflakes, and short and long nanowires, and mixed these nanostructures with distilled water to make simple “inks.” He then invented a quick and easy way to make thin films using equipment available in just about any lab — glass slides and double-sided tape.

“We used a hole punch to cut out wells from double-sided tape and stuck these to glass slides,” Stewart said. By adding a precise volume of ink into each tape “well” and then heating the wells — either to relatively low temperature to simply evaporate the water or to higher temperatures to begin melting the structures together — he created a variety of films to test.

The team say they weren’t surprised that the long nanowire films had the highest conductivity. Electrons usually flow easily through individual nanostructures but get stuck when they have to jump from one structure to the next, Wiley explained, and long nanowires greatly reduce the number of times the electrons have to make this “jump”.

But they were surprised at just how drastic the change was. “The resistivity of the long silver nanowire films is several orders of magnitude lower than silver nanoparticles and only 10 times greater than pure silver,” Stewart said.

The team is now experimenting with using aerosol jets to print silver nanowire inks in usable circuits. Wiley says they also want to explore whether silver-coated copper nanowires, which are significantly cheaper to produce than pure silver nanowires, will give the same effect.

Source: Duke University

Researchers succeed in producing OLED electrodes from graphene


Orange luminous OLED on a graphene electrode. The two-euro coin serves as a comparison of sizes. (Image: Fraunhofer FEP)

Researchers succeed in producing OLED electrodes from graphene

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP from Dresden, together with partners, has succeeded for the first time in producing OLED electrodes from graphene. The electrodes have an area of 2 × 1 square centimeters.

“This was a real breakthrough in research and integration of extremely demanding materials,” says FEP’s project leader Dr. Beatrice Beyer. The process was developed and optimized in the EU-funded project “Gladiator” (Graphene Layers: Production, Characterization and Integration) together with partners from industry and research.


Orange luminous OLED on a graphene electrode. The two-euro coin serves as a comparison of sizes. (Image: Fraunhofer FEP)

Graphene is considered a new miracle material. The advantages of the carbon compound are impressive: graphene is light, transparent and extremely hard and has more tensile strength than steel.

Moreover, it is flexible and extremely conductive for heat or electricity. Graphene consists of a single layer of carbon atoms which are assembled in a kind of honeycomb pattern. It is only 0.3 nanometers thick, which is about one hundred thousandth of a human hair. Graphene has a variety of applications – for example, as a touchscreen in smartphones.

Chemical reaction of copper, methane and hydrogen

The production of the OLED electrodes takes place in a vacuum. In a steel chamber, a wafer plate of high-purity copper is heated to about 800 degrees. The research team then supplies a mixture of methane and hydrogen and initiates a chemical reaction. The methane dissolves in the copper and forms carbon atoms, which spread on the surface. This process only takes a few minutes. After a cooling phase, a carrier polymer is placed on the graphene and the copper plate is etched away.

Gladiator project was launched in November 2013. The Fraunhofer team is working on the next steps until the conclusion in April 2017. During the remainder of the project, impurities and defects which occur during the transfer of the wafer-thin graphene to another carrier material are to be minimized.

The project is supported by the EU Commission with a total of 12.4 million euros. The Fraunhofer Institute’s important industrial partners are the Spanish company Graphenea S.A., which is responsible for the production of the graphene electrodes, as well as the British Aixtron Ltd., which is responsible for the construction of the production CVD reactors.

Applications from photovoltaics to medicine

“The first products could already be launched in two to three years”, says Beyer with confidence.

Due to their flexibility, the graphene electrodes are ideal for touch screens. They do not break when the device drops to the ground. Instead of glass, one would use a transparent polymer film. 
Many other applications are also conceivable: in windows, the transparent graphene could regulate the light transmission or serve as an electrode in polarization filters.

Graphene can also be used in photovoltaics, high-tech textiles and even in medicine.

Source: Fraunhofer Institute for Electron Beam and Plasma Technology FEP

MIT: Printable electronics: New stamping technique creates functional features at nanoscale dimensions.


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MIT researchers have fabricated a stamp made from forests of carbon nanotubes that is able to print electronic inks onto rigid and flexible surfaces. Photo: Sanha Kim and Dhanushkodi Mariappan

The next time you place your coffee order, imagine slapping onto your to-go cup a sticker that acts as an electronic decal, letting you know the precise temperature of your triple-venti no-foam latte. Someday, the high-tech stamping that produces such a sticker might also bring us food packaging that displays a digital countdown to warn of spoiling produce, or even a window pane that shows the day’s forecast, based on measurements of the weather conditions outside.

Engineers at MIT have invented a fast, precise printing process that may make such electronic surfaces an inexpensive reality. In a paper published today in Science Advances, the researchers report that they have fabricated a stamp made from forests of carbon nanotubes that is able to print electronic inks onto rigid and flexible surfaces.

A. John Hart, the Mitsui Career Development Associate Professor in Contemporary Technology and Mechanical Engineering at MIT, says the team’s stamping process should be able to print transistors small enough to control individual pixels in high-resolution displays and touchscreens. The new printing technique may also offer a relatively cheap, fast way to manufacture electronic surfaces for as-yet-unknown applications.

“There is a huge need for printing of electronic devices that are extremely inexpensive but provide simple computations and interactive functions,” Hart says. “Our new printing process is an enabling technology for high-performance, fully printed electronics, including transistors, optically functional surfaces, and ubiquitous sensors.”

Sanha Kim, a postdoc in MIT’s department of Mechanical Engineering, is the lead author, and Hart is the senior author. Their co-authors are Hossein Sojoudi, a postdoc in mechanical engineering and chemical engineering; Hangbo Zhao and Dhanushkodi Mariappan, graduate students in mechanical engineering; Gareth McKinley, the School of Engineering Professor of Teaching Innovation; and Karen Gleason, professor of chemical engineering and MIT’s associate provost.

A stamp from tiny pen quills

There have been other attempts in recent years to print electronic surfaces using inkjet printing and rubber stamping techniques, but with fuzzy results. Because such techniques are difficult to control at very small scales, they tend to produce “coffee ring” patterns where ink spills over the borders, or uneven prints that can lead to incomplete circuits.

“There are critical limitations to existing printing processes in the control they have over the feature size and thickness of the layer that’s printed,” Hart says. “For something like a transistor or thin film with particular electrical or optical properties, those characteristics are very important.”

Hart and his team sought to print electronics much more precisely, by designing “nanoporous” stamps. (Imagine a stamp that’s more spongy than rubber and shrunk to the size of a pinky fingernail, with patterned features that are much smaller than the width of a human hair.) They reasoned that the stamp should be porous, to allow a solution of nanoparticles, or “ink,” to flow uniformly through the stamp and onto whatever surface is to be printed. Designed in this way, the stamp should achieve much higher resolution than conventional rubber stamp printing, referred to as flexography.

Kim and Hart hit upon the perfect material to create their highly detailed stamp: carbon nanotubes — strong, microscopic sheets of carbon atoms, arranged in cylinders. Hart’s group has specialized in growing forests of vertically aligned nanotubes in carefully controlled patterns that can be engineered into highly detailed stamps.

“It’s somewhat serendipitous that the solution to high-resolution printing of electronics leverages our background in making carbon nanotubes for many years,” Hart says. “The forests of carbon nanotubes can transfer ink onto a surface like massive numbers of tiny pen quills.”

Printing circuits, roll by roll

To make their stamps, the researchers used the group’s previously developed techniques to grow the carbon nanotubes on a surface of silicon in various patterns, including honeycomb-like hexagons and flower-shaped designs. They coated the nanotubes with a thin polymer layer (developed by Gleason’s group) to ensure the ink would penetrate throughout the nanotube forest and the nanotubes would not shrink after the ink was stamped. Then they infused the stamp with a small volume of electronic ink containing nanoparticles such as silver, zinc oxide, or semiconductor quantum dots.

The key to printing tiny, precise, high-resolution patterns is in the amount of pressure applied to stamp the ink. The team developed a model to predict the amount of force necessary to stamp an even layer of ink onto a substrate, given the roughness of both the stamp and the substrate, and the concentration of nanoparticles in the ink.

To scale up the process, Mariappan built a printing machine, including a motorized roller, and attached to it various flexible substrates. The researchers fixed each stamp onto a platform attached to a spring, which they used to control the force used to press the stamp against the substrate.

“This would be a continuous industrial process, where you would have a stamp, and a roller on which you’d have a substrate you want to print on, like a spool of plastic film or specialized paper for electronics,” Hart says. “We found, limited by the motor we used in the printing system, we could print at 200 millimeters per second, continuously, which is already competitive with the rates of industrial printing technologies. This, combined with a tenfold improvement in the printing resolution that we demonstrated, is encouraging.”

After stamping ink patterns of various designs, the team tested the printed patterns’ electrical conductivity. After annealing, or heating, the designs after stamping — a common step in activating electronic features — the printed patterns were indeed highly conductive, and could serve, for example, as high-performance transparent electrodes.

Going forward, Hart and his team plan to pursue the possibility of fully printed electronics.

“Another exciting next step is the integration of our printing technologies with 2-D materials, such as graphene, which together could enable new, ultrathin electronic and energy conversion devices,” Hart says.

This research was supported, in part, by the National Science Foundation and the MIT Energy Initiative.

Michigan Tech: A Bright future for energy devices


sodium-161220175546_1_540x360A scanning electron microscope image of sodium-embedded carbon reveals the nanowall structure and pores of the material. Credit: Yun Hang Hu, Michigan Tech

A little sodium goes a long way. At least that’s the case in carbon-based energy technology. Specifically, embedding sodium in carbon materials can tremendously improve electrodes.

A research team led by Yun Hang Hu, the Charles and Carroll McArthur Professor of materials science and engineering at Michigan Tech, created a brand-new way to synthesize sodium-embedded carbon nanowalls. Previously, the material was only theoretical and the journal Nano Letters recently published this invention.

High electrical conductivity and large accessible surface area, which are required for ideal electrode materials in energy devices, are opposed to each other in current materials. Amorphous carbon has low conductivity but large surface area. Graphite, on the other hand, has high conductivity but low surface area. Three-dimensional graphene has the best of both properties — and the sodium-embedded carbon invented by Hu at Michigan Tech is even better.

“Sodium-embedded carbon’s conductivity is two orders of magnitude larger than three-dimensional graphene,” Hu says. “The nanowall structure, with all its channels and pores, also has a large accessible surface area comparable to graphene.”

This is different from metal-doped carbon where metals are simply on the surface of carbon and are easily oxidized; embedding a metal in the actual carbon structure helps protect it. To make such a dream material, Hu and his team had to create a new process. They used a temperature-controlled reaction between sodium metal and carbon monoxide to create a black carbon powder that trapped sodium atoms. Furthermore, in collaboration with researchers at University of Michigan and University of Texas at Austin, they demonstrated that the sodium was embedded inside the carbon instead of adhered on the surface of the carbon. The team then tested the material in several energy devices.

In the dye-sensitized solar cell world, every tenth of a percent counts in making devices more efficient and commercially viable. In the study, the platinum-based solar cell reached a power conversion efficiency of 7.89 percent, which is considered standard. In comparison, the solar cell using Hu’s sodium-embedded carbon reached efficiencies of 11.03 percent.

Super-Capacitors can accept and deliver charges much faster than rechargeable batteries and are ideal for cars, trains, elevators and other heavy-duty equipment. The power of their electrical punch is measured in farads (F); the material’s density, in grams (g), also matters.

Activated carbon is commonly used for supercapacitors; it packs a 71 F g-1 punch. Three-dimensional graphene has more power with a 112 F g-1 measurement. Sodium-embedded carbon knocks them both out of the ring with a 145 F g-1 measurement. Plus, after 5,000 charge/discharge cycles, the material retains a 96.4 percent capacity, which indicates electrode stability.

Hu says innovation in energy devices is in great demand. He sees a bright future for sodium-embedded carbon and the improvements it offers in solar tech, batteries, fuel cells, and supercapacitors.


Story Source:

Materials provided by Michigan Technological University. Note: Content may be edited for style and length.


Journal Reference:

  1. Wei Wei, Liang Chang, Kai Sun, Alexander J. Pak, Eunsu Paek, Gyeong S. Hwang, Yun Hang Hu. The Bright Future for Electrode Materials of Energy Devices: Highly Conductive Porous Na-Embedded Carbon. Nano Letters, 2016; 16 (12): 8029 DOI: 10.1021/acs.nanolett.6b04742

University of Michigan: Nanodiscs deliver personalized cancer therapy to immune system


FDA-Has-Approved-Device-to-Combat-Drug-OverdoseResearchers at the University of Michigan have had initial success in mice using nanodiscs to deliver a customized therapeutic vaccine for the treatment of colon and melanoma cancer tumors.

“We are basically educating the immune system with these nanodiscs so that can attack cancer cells in a personalized manner,” said James Moon, the John Gideon Searle assistant professor of and biomedical engineering.

Personalized immunotherapy is a fast-growing field of research in the fight against cancer.

The therapeutic cancer vaccine employs nanodiscs loaded with tumor neoantigens, which are unique mutations found in tumor cells. By generating T-cells that recognize these specific neoantigens, the targets cancer mutations and fights to eliminate cancer cells and prevent tumor growth.

Unlike preventive vaccinations, therapeutic cancer vaccines of this type are meant to kill established cancer cells.

“The idea is that these vaccine nanodiscs will trigger the immune system to fight the existing cancer cells in a personalized manner,” Moon said.

The nanodisc technology was tested in mice with established melanoma and colon cancer tumors. After the vaccination, twenty-seven percent of T-cells in the blood of the mice in the study targeted the tumors.

When combined with immune checkpoint inhibitors, an existing technology that amplifies T-cell tumor-fighting responses, the nanodisc technology killed tumors within 10 days of treatment in the majority of the mice. After waiting 70 days, researchers then injected the same mice with the same , and the tumors were rejected by the immune system and did not grow.

“This suggests the ‘remembered’ the for long-term immunity,” said Rui Kuai, U-M doctoral student in pharmaceutical sciences and lead author of the study.

“The holy grail in is to eradicate tumors and prevent future recurrence without systemic toxicity, and our studies have produced very promising results in mice,” Moon said.

The technology is made of extremely small, synthetic high density lipoproteins measuring roughly 10 nanometers. By comparison, a human hair is 80,000 to 100,000 nanometers wide.

Drug Delivery 050815 onereallytin

“It’s a powerful vaccine technology that efficiently delivers vaccine components to the right cells in the right tissues. Better delivery translates to better T-cell responses and better efficacy,” said study co-senior author Anna Schwendeman, U-M assistant professor of pharmacy.

The next step is to test the nanodisc technology in a larger group of larger animals, Moon said.

EVOQ Therapeutics, a new U-M spinoff biotech company, has been founded to translate these results to the clinic. Lukasz Ochyl, a doctoral student in pharmaceutical sciences, is also a co-author.

The study, “Designer vaccine nanodiscs for personalized immunotherapy,” is scheduled for advance online publication Dec. 26 on the Nature Materials website.

Explore further: Fighting cancer with the power of immunity

More information: Designer vaccine nanodiscs for personalized cancer immunotherapy, Nature Materials, nature.com/articles/doi:10.1038/nmat4822

 

Rice University: Graphene Quantum Dots take on a NEW ‘green’ recycling role


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Graphene quantum dots may offer a simple way to recycle waste carbon dioxide into valuable fuel rather than release it into the atmosphere or bury it underground, according to Rice University scientists.

Nitrogen-doped (NGQDs) are an efficient electrocatalyst to make complex hydrocarbons from carbon dioxide, according to the research team led by Rice materials scientist Pulickel Ajayan. Using electrocatalysis, his lab has demonstrated the conversion of the greenhouse gas into small batches of ethylene and ethanol.

The research is detailed this week in Nature Communications.

Though they don’t entirely understand the mechanism, the researchers found NGQDs worked nearly as efficiently as copper, which is also being tested as a catalyst to reduce carbon dioxide into liquid fuels and chemicals. And NGQDs keep their catalytic activity for a long time, they reported.

“It is surprising because people have tried all different kinds of catalysts. And there are only a few real choices such as copper,” Ajayan said. “I think what we found is fundamentally interesting, because it provides an efficient pathway to screen new types of catalysts to convert carbon dioxide to higher-value products.”

Those problems are hardly a secret. Atmospheric carbon dioxide rose above 400 parts per million earlier this year, the highest it’s been in at least 800,000 years, as measured through ice-core analysis.

Carbon dots dash toward 'green' recycling role
Nitrogen-doped graphene quantum dots stand out from a substrate in a transmission electron microscope image. The dots are effective electrocatalysts that can reduce carbon dioxide, a greenhouse gas, to valuable hydrocarbons like ethylene …more

 

“If we can convert a sizable fraction of the carbon dioxide that is emitted, we could curb the rising levels of levels, which have been linked to climate change,” said co-author Paul Kenis of the University of Illinois.

In lab tests, NGQDs proved able to reduce carbon dioxide by up to 90 percent and convert 45 percent into either ethylene or alcohol, comparable to copper electrocatalysts.

Graphene quantum dots are atom-thick sheets of carbon atoms that have been split into particles about a nanometer thick and just a few nanometers wide. The addition of nitrogen atoms to the dots enables varying chemical reactions when an electric current is applied and a feedstock like carbon dioxide is introduced.

“Carbon is typically not a catalyst,” Ajayan said. “One of our questions is why this doping is so effective. When nitrogen is inserted into the hexagonal graphitic lattice, there are multiple positions it can take. Each of these positions, depending on where nitrogen sits, should have different . So it’s been a puzzle, and though people have written a lot of papers in the last five to 10 years on doped and defective carbon being catalytic, the puzzle is not really solved.”

Carbon dots dash toward 'green' recycling role
An illustration of a nitrogen-doped graphene quantum dot like those being tested at Rice University for use as catalysts to reduce carbon dioxide, a greenhouse gas, into valuable hydrocarbons. Credit: Ajayan Group/Rice University

 

“Our findings suggest that the pyridinic nitrogen (a basic organic compound) sitting at the edge of graphene leads the catalytic conversion of to hydrocarbons,” said Rice postdoctoral researcher Jingjie Wu, co-lead author of the paper. “The next task is further increasing nitrogen concentration to help increase the yield of hydrocarbons.” (Article continued below)

rice QD finetuneWhat is … A Quantum Dot

A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions. As a result, they have properties that are between those of bulk semiconductors and those of discrete molecules. They were discovered by Louis E. Brus, who was then at Bell Labs. The term “Quantum Dot” was coined by Mark Reed.

Researchers have studied quantum dots in transistors, solar cells, LEDs, and diode lasers. They have also investigated quantum dots as agents for medical imaging and hope to use them as qubits.

 

(Article Continued) Ajayan noted that while electrocatalysis is effective at lab scales for now, industry relies on scalable thermal catalysis to produce fuels and chemicals. “For that reason, companies probably won’t use it any time soon for large-scale production. But electrocatalysis can be easily done in the lab, and we showed it will be useful in the development of new catalysts.”

Explore further: Catalyst could make production of key chemical more eco-friendly

More information: Jingjie Wu et al, A metal-free electrocatalyst for carbon dioxide reduction to multi-carbon hydrocarbons and oxygenates, Nature Communications (2016). DOI: 10.1038/ncomms13869

 

Researchers build liquid biopsy chip that detects metastatic cancer cells in blood: One blood sample can be tested for a comprehensive array of cancer cell markers.


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A chip developed by mechanical engineers at Worcester Polytechnic Institute (WPI) can trap and identify metastatic cancer cells in a small amount of blood drawn from a cancer patient. The breakthrough technology uses a simple mechanical method that has been shown to be more effective in trapping cancer cells than the microfluidic approach employed in many existing devices.

The WPI device uses antibodies attached to an array of carbon nanotubes at the bottom of a tiny well. Cancer cells settle to the bottom of the well, where they selectively bind to the antibodies based on their surface markers (unlike other devices, the chip can also trap tiny structures called exosomes produced by cancers cells). This “liquid biopsy,” described in a recent issue of the journal Nanotechnology, could become the basis of a simple lab test that could quickly detect early signs of metastasis and help physicians select treatments targeted at the specific cancer cells identified.

Metastasis is the process by which a cancer can spread from one organ to other parts of the body, typically by entering the bloodstream. Different types of tumors show a preference for specific organs and tissues; circulating , for example, are likely to take root in bones, lungs, and the brain. The prognosis for metastatic cancer (also called stage IV cancer) is generally poor, so a technique that could detect these circulating tumor cells before they have a chance to form new colonies of tumors at distant sites could greatly increase a patient’s survival odds.

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A cross section of one of the wells in the WPI device, showing how cancer cells sink to the bottom of a blood sample, where they are captured by antibodies bound to carbon nanotubes. The bound cells trigger an electrical response, which is …more

“The focus on capturing circulating tumor cells is quite new,” said Balaji Panchapakesan, associate professor of mechanical engineering at WPI and director of the Small Systems Laboratory. “It is a very difficult challenge, not unlike looking for a needle in a haystack. There are billions of , tens of thousands of , and, perhaps, only a small number of tumor cells floating among them. We’ve shown how those cells can be captured with high precision.”

The device developed by Panchapakesan’s team includes an array of tiny elements, each about a tenth of an inch (3 millimeters) across. Each element has a well, at the bottom of which are antibodies attached to carbon nanotubes. Each well holds a specific antibody that will bind selectively to one type of cancer cell type, based on genetic markers on its surface. By seeding elements with an assortment of antibodies, the device could be set up to capture several different cancer cells types using a single blood sample. In the lab, the researchers were able to fill a total of 170 wells using just under 0.3 fluid ounces (0.85 milliliter) of blood. Even with that small sample, they captured between one and a thousand cells per device, with a capture efficiency of between 62 and 100 percent.

The carbon nanotubes used in the device act as semiconductors. When a cancer cell binds to one of the attached antibodies, it creates an electrical signature that can be detected. These signals can be used to identify which of the elements in the array have captured cancer cells. Those individual arrays can then be removed and taken to a lab, where the captured cells can be stained and identified under a microscope. In the lab, the binding and electrical signature generation process took just a few minutes, suggesting the possibility of getting same-day results from a blood test using the chip, Panchapakesan says.

In a paper published in the journal Nanotechnology, Panchapakesan’s team, which includes graduate students Farhad Khosravi, the paper’s lead author, and researchers at the University of Louisville and Thomas Jefferson University, describe a study in which antibodies specific for two markers of metastatic breast cancer, EpCam and Her2, were attached to the carbon nanotubes in the chip. When a blood sample that had been “spiked” with cells expressing those markers was placed on the chip, the device was shown to reliably capture only the marked cells.

In addition to capturing tumor cells, Panchapakesan says the chip will also latch on to tiny structures called exosomes, which are produced by cancers cells and carry the same markers. “These highly elusive 3-nanometer structures are too small to be captured with other types of liquid biopsy devices, such as microfluidics, due to shear forces that can potentially destroy them,” he noted. “Our chip is currently the only device that can potentially capture circulating tumor cells and exosomes directly on the chip, which should increase its ability to detect metastasis. This can be important because emerging evidence suggests that tiny proteins excreted with exosomes can drive reactions that may become major barriers to effective cancer drug delivery and treatment.”

Panchapakesan said the chip developed by his team has additional advantages over other liquid biopsy devices, most of which use microfluidics to capture cancer cells. In addition to being able to capture circulating far more efficiently than microfluidic chips (in which cells must latch onto anchored antibodies as they pass by in a stream of moving liquid), the WPI device is also highly effective in separating cancer cells from the other cells and material in the blood through differential settling.

“White blood cells, in particular, are a problem, because they are quite numerous in blood and they can be mistaken for cancer cells,” he said. “Our device uses what is called a passive leukocyte depletion strategy. Because of density differences, the tend to settle to the bottom of the wells (and this only happens in a narrow window), where they encounter the antibodies. The remainder of the blood contents stays at the top of the wells and can simply be washed away.”

While the initial tests with the chip have focused on breast cancer, Panchapakesan says the device could be set up to detect a wide range of tumor types, and plans are already in the works for development of an advanced device as well as testing for other cancer types, including lung and pancreas cancer. He says he envisions a day when a device like his could be employed not only for regular follow ups for patients who have had cancer, but in routine cancer screening.

“Imagine going to the doctor for your yearly physical,” he said. “You have blood drawn and that one can be tested for a comprehensive array of cancer cell markers. Cancers would be caught at their earliest stage and other stages of development, and doctors would have the necessary protein or genetic information from these captured to customize your treatment based on the specific markers for your cancer. This would really be a way to put your health in your own hands.”

Explore further: New device could improve cancer detection

More information: Farhad Khosravi et al. Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip, Nanotechnology (2016). DOI: 10.1088/0957-4484/27/44/44LT03