#Molecular electronics Takes Large Stride Forward Molecular electronics has promised long a day when individual molecules would serve as the basic building blocks for electronics.
That day has moved a bit closer thanks to research out of the Columbia University School of engineering and Applied science.
Researchers there have developed a new technique that makes it possible to produce a diode from a single molecule.
In research published in the journal Nature Nanotechnology, the researchers claim that they have not only produced a single-molecule diode,
but that it greatly outperforms all previous designs. ur new approach created a single-molecule diode that has a high rectification and a high ncurrent,
said Latha Venkataraman, a professor of applied physics at Columbia, in a press release. onstructing a device where the active elements are only a single molecule has long been a tantalizing dream in nanoscience.
This goal, which has been the'holy grail'of molecular electronics ever since its inception with Aviram and Ratner's 1974 seminal paper, represents the ultimate in functional miniaturization that can be achieved for an electronic device."
"Diodes are key elements in integrated circuits. They are two-terminal components with asymmetric conductance, which means that they keep current passing in only one direction.
When negative voltage is applied to them, they shut the current off completely. In doing so, they act as a kind of on-off valve.
Molecule-scale diodesabricated by attaching molecules to metal electrodes to form single-molecule junctions that serve as a host of different circuit elementsave been tried before.
But previous attempts, in which researchers looked to achieve asymmetric conductance by making the diodes asymmetric in design,
have been less than satisfactory. hile such asymmetric molecules do indeed display some diode-like properties, they are explained not effective
Brian Capozzi in the press release. Capozzi, who was the lead author of the paper, is a doctoral candidate in Venkataraman lab. According to Capozzi:
A well-designed diode should only allow current to flow in one directionhe ndirectionnd it should allow a lot of current to flow in that direction.
Asymmetric molecular designs have suffered typically from very low current flow in both nand ffdirections, and the ratio of current flow in the two has typically been low.
Ideally, the ratio of ncurrent to ffcurrent, the rectification ratio, should be very high. To overcome this poor current flow in single-molecule diodes, the Columbia researchers,
in cooperation with colleagues at the University of California Berkeley, looked at putting the asymmetry in the area around the molecular junctionhere the molecule meets the metal electrode.
To do this they simply covered the molecules with an ionic solution and then attached them to gold metal electrodes of differing sizes.
The results were impressive. As Venkataraman pointed out in the press release, the rectification ratios resulting from the new design are as high as 250,
which is 50 times as high as was achieved with previous designs. Further, the ncurrent can be more than 0. 1 microamps,
which is notably high for a single-molecule diode, according to Venkataraman. t amazing to be able to design a molecular circuit,
using concepts from chemistry and physics, and have it do something functional, says Venkataraman, who added that, he length scale is so small that quantum mechanical effects are absolutely a crucial aspect of the device.
So it is truly a triumph to be able to create something that you will never be able to physically see
and that behaves as intended. b
#Damage Recovery Algorithm Could Make All Robots Unstoppable For the last three years, wee been watching as the hexapods created by Antoine Cully
and Jean-Baptiste Mouret have been getting increasingly difficult to put out of action. Using an exceptionally clever algorithm,
the robots have demonstrated that they can shrug off absurd amounts of damage, adapting within minutes to recover their mobility
even if you chop a third of their legs off. Today, this research has made the cover of Nature,
which is a Very Big Deal (at least if youe a scholar), and it brings along with it some updates and even more potential for the future.
Wee covered a lot of the theory and practice behind this research over the last several years Nature being chronically and woefully behind the times relative to IEEE Spectrum.
Now the researchers report that their findings can be applied not only to legged robots but also to a new form factor:
This illustrates how it possible to endow just about any robot with resiliency via this algorithm,
converging on something that works by exploring an enormous pregenerated set of potentially effective motions in about two minutes.
Recovering from damage is just one application for this algorithm: it can also be used to adapt to different terrain,
#Diabetes Has a New Enemy: Robo-Pancreas The first great wonder drug was insulin, the blood-sugar-regulating hormone that was isolated in Canada nearly a century ago.
so those with the disease must work hard to mimic that organ function. If blood sugar goes too low,
and adjust the injection of insulin to account for it All the burden of self management goes on night and day.
Now, after half a century of work, a solution at last is in the offing: the artificial pancreas.
It links data from an implanted blood-sugar sensor to a computer, which then controls how a pump worn on the hip dribbles insulin under the skin through a pipette.
an electrical engineer working on the problem at the Institut de Recherches Cliniques de Montréal (IRCM). Such technology is used, for instance,
or to govern the processing of crude oil in a refinery. Haidar group is one of a number of academic and corporate teams vying to create a closed-loop system for an artificial pancreas. ach patient is represented by a set of differential equations,
Then the algorithm figures out how to administer that dose from one minute to the next to keep the glucose levels within safe bounds.
The work of Haidar group and others is finally promising to complete a vision that began more than a half-century ago
and closed-loop systems that take over more of the diabetes management are in trials. Finally, everybody in the field agrees that a solution is nigh.
A slew of improvements in sensors, actuators, algorithms, and insulin are coming together to create the artificial pancreas.
during a trial in New york city of a system devised at the University of Virginia. he thing that was cool about it was that it works,
and nights in a controlled setting, surrounded by doctors and engineers. e used a Dexcom continuous glucose sensor,
hooked through a cellphone with an algorithm and to a Roche pump, linked to it by a Bluetooth signal,
says Herrick, recalling each detail as if the trial had happened just. ne night my blood sugar was 80 milligrams of glucose per deciliter of blood,
but with some help from a Dexcom glucose sensor that he applies to his upper arm,
it beams data to the screen of a pager-size reader. He uses the information to help decide what to eat
(although technically he is supposed to recheck the numbers with a finger stick before an injection).
Once the data is in the servers, there a lot we can do to affect disease management.
For instance, doctors could mine the data for patterns in which patients suffer from low blood sugar,
then adjust diet or insulin dosage accordingly. The information can also be used to prove to insurers that the money they spend on health care is producing results. ealth care providers are more and more being paid for outcomes,
Valdes says. ayers want patients to stay on the system; now they can make sure that patients do.
The development of the technology has proceeded by measured steps, much like the progress toward the driverless carirst antilock brakes, next GPS navigation, then adaptive cruise control and self-parking.
Finally, at the end of the rainbow, the Google self-driving car. The first step toward a robotic pancreas came in 1964,
when a hospital-based experiment proved, in principle, that it was possible to achieve near-normal blood-sugar control.
In the 1970s, Dean Kamen invented the insulin pump, making it possible for patients to administer insulin to themselves in a continuous fashion,
rather than through frequent injections. Soon after, a hospital system called Biostator GCIIS was released in Germany;
it combined a pump with a large, complex continuous glucose monitor. In recent years, pumps have become smaller, more reliable, more programmable,
Continuous glucose monitors were approved first a decade ago, and they are beginning to replace the finger-prick method,
now that improved coatings and other engineering details have allowed patients to keep their superthin electrochemical sensors under the skin for seven days. e had this one in for eight,
when its algorithm merely predicts that the patient blood sugar will drop. It on the market in Australia and is set to sell in Europe later this year.
says Francine R. Kaufmann, the company chief medical officer and a practicing endocrinologist. Why the long delay between the proof of concept and routine use?
Pumps clog, algorithms misfire, sensors get walled off by scar tissue. Some of the recent technical advances are proprietary and still under wraps,
and Dexcom have developed biocompatible coatings as well as sensors with multiple electrochemical sites that can be polled to see which ones no longer work properly.
Glucose sensors typically show you where your blood sugar was 10 minutes ago, but because they also track changes over time,
says Roman Hovorka, a specialist in mathematical informatics at the University of Cambridge, in England. wo analogues in development are about 15 minutes faster than todaynd that nowhere close enough.
the closed-loop robo-pancreas is ahead of such biological approaches, says IRCM Haidar, even though it will never duplicate the human body. e know an airplane isn better than a bird,
he says. ee not replicating a pancrease can never beat how the body works. One way to speed the insulin effects is to implant a pump right inside the abdominal cavity,
so the insulin can get to the liver more quickly. ut youe talking about surgery, Haidar says. f you have a 2-year-old daughter,
Besides the sensor and the pump are the algorithms, the secret sauce that allows the artificial pancreas to analyze,
Another one, sometimes called an expert system, sets up a table that pairs problems with responses in the form f this happens,
a medical geneticist who heads artificial pancreas research for the JDRF. A third kind of algorithm tries to model human physiology, for instance by considering how quickly food passes through your system
and how long the insulin takes to work. he beauty of this approach is that it like chess programming:
You reset the variable when your opponent makes his movehat is, when new data arrive,
says Kowalski. Tuning these algorithms requires big data, gathered from both the individual patient and the larger community of patients.
Hovorka group at the University of Cambridge is conducting trials of advanced systems in the home, not just in controlled settings.
Hovorka is also working with a corporate partner, but he won say which one. He notes,
He says his algorithms learn by doing and so adapt to the patient. he algorithm analyzes during the day
and between days for short-term learning and also longer term, Hovorka says. f somebody goes skiing,
Every 10 to 12 minutes we run the algorithm for predictive control. We have a number of models running in parallel,
with each given a probabilistic value based on how well it fitted the data in the past. e can achieve
Glucagon works in the opposite direction by stimulating the liver to turn that starch back into sugar
People with diabetes often carry a special pen charged with glucagon for others to use on them
But at a diabetes technology conference held in Paris this past February, funding organizations appeared to have doubled down on the simpler one-hormone system in the hope that it will get approved more easily.
One cause of the change was a recent report by researchers from IRCM. They compared the one-and two-hormone systems and found no significant advantage for the dual-hormone method.
and we want to put all our money on bringing the closed loop to market. What next?
As the millions of people with type 1 diabetes work out the kinks in the new technology,
it will spread to the hundreds of millions with type 2 diabetes, many of whom would also benefit from insulin
The payload of a human works in a similar way, except that sometimes we can cheat, by offloading the mass of an object to the ground,
At ICRA 2015 last week, researchers from University of Tokyo JSK Laboratory led by Professors Masayuki Inaba
and Masayuki Inaba from the University of Tokyo, was presented at ICRA 2015 in Seattle, Wash A
#Green Microchips Created on Cellulose Nanofibril Paper In September 2007, while leafing through his copy of IEEE Spectrum, Zhenqiang"Jack"Ma, an engineer at the University of Wisconsin-Madison whose research focus is microwave electronics,
came across a news item that left him baffled: was shocked by the number of cell phones that are discarded daily in the U s
each cell phone contains chips made of poisonous gallium arsenide (Gaas. In the 26 may issue of Nature Communications, Ma and his colleague, materials scientist Shaoqin arahgong, plus collaborators at UW-Madison and the Madison-based U s. Dept of agriculture Forest Products
Laboratory (FPL) published research describing a technique for making biodegradable semiconductor chips out of wood.
What more, they demonstrated that microwave transmitter and receiver chips made this way perform as well as their silicon or Gaas counterparts. ctually,
our work was inspired by the IEEE Spectrum article, says Ma. Unlike the silicon, Gaas, and petroleum-based plastic substrates that are used in electronicsnd are not biodgradablehe substrate for Ma
and company"green"chips is made of a type of paper. But unlike paper which typically consists of wood fibers 10 micrometers thick
and biggeraking it rough and fairly easy to tear, they used much smaller fibers. f you chop down the wood into nanosize fibers,
you find that the fibers are single crystals. If you put this material together to make a substrate,
it becomes very strongtronger than the paper we use, says Ma. t also becomes transparent
and has low RF energy loss, "he adds. The cellulose nanofibril (CNF) aperhey used is about 200 micrometers thick.
Although the researchers coated it with a thin epoxy layer to protect it from moisture
this does not affect its biodegradability.""If we put it in a fungus environment, the fungus can still eat it,
"says the Wisconsin researcher. To create the green chips, the researchers started out with silicon
or Gaas devices sitting atop substrates made of the same material. Then they released the circuits from their original substrates
and transfer-printed them onto the nanofibril substrates. Using this technique, the researchers created several microwave Gaas devices, such as arrays of Gainp/Gaas heterojunction bipolar transistors,
as well as circuits containing capacitors, RF inductors and Schottky diodes. The performance of these flexible devices is exactly the same as that of rigid circuits
reports Ma. The group also demonstrated several silicon-based digital logic circuits on paper substrates.
Nanofibril films may be used in photovoltaic cells and also in displays because they have better light-transmission properties than glass,
says Ma. Using paper substrates would allow a reduction in the amount of Gaas used in chips by a factor of 3000,
which would make chips conform to the pollution standards for arsenic set by the U s. Environmental protection agency.
Additionally, this technique would help cut costs, reducing the amount of expensive materials, such as gallium arsenide and highly purified silicon, that are packed into electronic gadgets."
"What we are looking at are future applications, says Ma. The paper includes a market survey comparing today's production of rigid electronics with the projected flexible electronics production.
The volume of flexible electronics is expected to largely exceed rigid electronics. e
#Graphene Heating system Dramatically Reduces Home energy Costs Breakthroughs in energy generation using nanomaterialsike their enabling of better supercapacitors
or photovoltaicsften grab the headlines. But it is unheralded in the area of energy savings that nanomaterials are perhaps making the biggest inroads.
A startup in the UK called Xefro is bridging this divide between energy generation and energy savings through its development of a heating system that the company claims marks the first time that the onder materialgraphene has been used as a heating element.
Depending on the kind of heating system currently used in a home the company estimates that this graphene-based heating system can reduce energy costs by anywhere from 25 to 70 percent.
Xefro uses graphene-based ink that can be printed on a variety of materials and into just about any configuration.
The system takes advantage of graphene's minimal thermal mass so the heat can be turned on and off quickly,
and leverages graphene large surface area so that energy isn wasted in heating up the heater itself. he innovation is all about getting useable heat where it is needed,
explained Tim Harper, a founder of Xefro and co-inventor of the graphene heating element,
in an e-mail interview with IEEE Spectrum. hile it is true that electrical resistive heating is almost 100-percent efficient in converting electricity into heat,
and that led us to evaluate a wide range of heating materials and systems before we finally arrived at graphene. o meet the company third criteria,
placing the heating element inside a metal box that reflects back most of the infrared energy,
and ensure that most of the heat is emitted out into the room rather than simply heating up the wall behind the heater. hile graphene does offer some attractive properties for reducing wasted energy,
this allows a number of smart switching algorithms to be used, says Harper. he energy savings come
when the heaters are deployed as a system throughout a building. The heaters are linked with the control system via Wi-fi,
allowing the system to learn your behavior as well as the optimum heating required to maintain a comfortable temperature. arper says the systems will be available in July 2015 through Xefro distributors in the UK.
#Graphene coating Could Save Millions in Power plant Energy costs Earlier this week, we covered a company, Xefro,
producing energy savings over traditional systems. Now research out of MIT is showing that coating power plant condensers with graphene could make them more energy efficient.
In research published in the journal Nano Letters, the MIT team addressed one of the basic elements of steam-generated electricity:
heat transfer in water condensation. In a steam-powered power plant, water is heated up to create steam that turns a turbine.
The turning of the turbine produces electricity. In this process, the steam is condensed back into water
and the whole process begins again. The MIT team looked at these condensers and found that by layering their surfaces with graphene they can improve the rate of heat transfer by a factor of four.
so that an overall power plant efficiency could be improved by as much as 2 to 3 percent based on figures from the Electric power Research Institute."
"That translates into millions of dollars per power plant per year, "said Daniel Preston, one of the MIT authors of the paper, in a press release.
While polymer coatings have been used to achieve more or less this same effect, the polymers degrade rapidly. Even worse, the polymer coatings are sometimes so thick that they actually pose a bigger problem to the heat transfer than the films they are supposed to be combating.
After testing the material in an environment of pure water vapor at 100 degrees Celsius the researcher found that the graphene coating offered a fourfold improvement in heat transfer compared to bare metal.
The MIT researchers have calculated also that these numbers could be improved to a five to seven times improvement by optimizing temperature differences in the system.
Most importantly, the graphene coating showed no sign of measurable degradation over the two-week period of the test.
a polymer coating solution started to degrade in the environment within three hours and completely failed within 12.
#Graphene Shines in World's Thinnest Light bulb Back in April, we covered news that graphene was going to make a commercial breakout of sorts as a coating in an LED light bulb to reduce its energy consumption
Now researchers at Columbia University from James Hone lab, in cooperation with a team at Korea Research Institute of Standards and Science (KRISS), have taken this huge step forward by creating the first on-chip incandescent visible light source
what is essentially the world's thinnest light bulb, says Hone, a professor at Columbia Engineering,
in a press release. his new type of'broadband'light emitter can be integrated into chips and will pave the way towards the realization of atomically thin, flexible,
and transparent displays, and graphene-based on-chip optical communications. n work published in the journal Nature Nanotechnology researchers suspended graphene above a silicon substrate by attaching it to two metal electrodes
and then passed current through the graphene-based filament, causing it to heat up. In the video below you can see an animated depiction of how the graphene filament operate.
The aim of creating integrated circuits that use photons rather than electrons sometimes called integrated photonic circuits,
depends on being able to generate light on the chip itself. While a number of approaches have been developed for generating this light,
this research marks the first time that anyone has done it with the simplest artificial light source: incandescent light.
and often led to damaging the surrounding chip. But graphene makes all the difference. The international team demonstrated heating the graphene-based filament to 2500 Degree celsius,
Graphene unusual heat conduction was key to keeping the light emitter from destroying the chip it was built on.
Erik had no qualms about signing up for brain surgery, but his mother wasn happy about it. he was just being a mom,
our brain is the only part of your body that works just fine. Why would you mess with that?
the surgery gave Sorto superhuman abilities. In the experiments, Sorto simply imagines reaching out to grab an object
While a handful of paralyzed people have used previously brain-computer interfaces (BCIS) to control robotic limbs, those subjectsimplants recorded signals from the primary motor cortex,
a brain region involved in planning movements. human os iconlead researcher Richard Andersen, a neuroscience professor at Caltech,
To prepare for Sorto surgery in April 2013 the researchers first used functional magnetic resonance imaging to identify two precise regions of his parietal cortex that activated when he imagined reaching and grasping motions.
The surgeons implanted two tiny microelectrode arrays, each with 96 electrodes that could record the electrical activity of single neurons.
The grids linked to two metal edestalsthat jutted out of Sorto skull. Within one month of surgery, Sorto was ready to get to work.
The researchers connected cables to the pedestals, bringing the neural signals to a computer that analyzed them and sent commands to the robot arm.
In the first experiment a scientist made a simple twisting motion with his own wrist,
and Sorto imagined himself imitating the gesture. And that just what the robot arm did. t was pretty much effortless,
Sorto says. From the population of neurons tapped by those electrodes, the researchers could distinguish cells whose activity coded for the location that Sorto wanted to reach, movement trajectories,
and particular types of movement. Each day experiments began with system calibration, because the electrodes shifted slightly within Sorto head
and picked up different neurons. ur decoding algorithms took that into account, Andersen says. If a given electrode was no longer contributing useful information to the decoding of a goal location
for example, the algorithm would ignore its signal and substitute other inputs. Andersen thinks such adaptive algorithms may enable a wide range of BCIS to record reliably over time.
Most of the prior studies in which paralyzed people used implanted BCIS were conducted by John Donoghue, director of Brown University Institute for Brain science and a pioneer in the use of implants in the motor cortex.
Donoghue says that the new research advances our understanding of the parietal cortex role in generating movements
and proves that it can provide a useful control signal. However, he not convinced it inherently a better signal than that provided by the motor cortex. ou get pretty good control from all these places
but it not clear how to get really good control, he says. While Andersen has suggested that combining the signals from the parietal and motor cortices might yield clearer commands for a robotic limb,
More than two years after his surgery, his electrodes are still functioning and his enthusiasm is undimmed.
#Chemical Battery Can Recharge Itself With Light Batteries, by definition, convert chemical energy into electricity. Once youe sucked them dry,
you have to reverse the process to convert electricity into chemical energy, and for that, you need a source of electricity.
It not like it hard to do this, but it is certainly a minor annoyance that could do with a fix.
Researchers at the Indian Institute of Science Education and Research (IISER) in Pune, India, have skipped the annoying step by developing a battery that charges directly from light.
Wee not talking about a battery with a solar panel on it: it a hoto batterywhere the anode itself is made of titanium nitride and ambient light.
Under artificial light, this prototype battery has a capacity of 77.8 mah/g. Itl quite happily power a small fan or LED light for about 30 seconds,
and then if you give it a break for 30 seconds while shining a light on it,
itl be charged all up and good to go again. Over 100 cycles, the battery retained a bit over 70 percent of its discharge capacity,
which at least suggests some potential for longevity and usefulness. In addition to being charged directly by light which is pretty awesome,
this battery design offers other benefits, including sustainable and economical anode material which will not be consumed as a part of the discharge reactions,
and an anode material that is free from loss of active materials, irreversible structural deformations, spontaneous deinsertion reactions,
and safety concerns commonly encountered in the state of the art anode materials in aqueous rechargeable batteries. ccording to a press release from the American Chemical Society,
he researchers say their design is a promising first step toward a more sustainable and safer battery technology.
In other words, this is a thing that does cool stuff in a lab right now but getting your hopes up for a light-powered battery in your cell phone might be premature by a decade or so.
For now, the best youl be able to do is read the full paper here o
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