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Google Search Patterns Could Track MRSA Spread

Records of Google searches could be used to track the spread of drug-resistant staph infections, filling a gap in existing surveillance for the bugs. With near-real-time, city-by-city information about the spread of MRSA, or methicillin-resistant staphylococcus aureus, public health experts may be better able to fight it. 

“Potentially, we can get from Google a more timely measure of trends” than other surveillance systems provide, said epidemiologist Diane Lauderdale of the University of Chicago. 

MRSA causes hard-to-treat skin infections that can turn septic, potentially invading organs and the bloodstream. It became widespread in U.S. hosptials during the 1980s, and in the 1990s a second strain emerged outside hospitals, spreading among healthy people. In 2007 the Centers for Disease Control and Prevention estimated that MRSA killed 18,650 Americans in 2005, or more people than were killed by AIDS. In a paper published in the June issue of Emerging Infectious Diseases, Lauderdale’s group compared records of Google searches for MRSA between 2004 and 2008 with MRSA-related hospitalization records. Except for a search burst after that 2007 CDC report, the numbers tracked, suggesting that search data is a reliable indicator of infection.

Patterns of MRSA-related hospitalizations (above, dark red) with patterns of searchers for MRSA and staph (below, blue and green). Emerging Infectious Diseases

The methodology is similar to that used by Google Flu Trends, which caught researchers’ attention after flu symptom-related searches in Mexico preceded the 2009 swine flu outbreak. But whereas Flu Trends was seen as a potential source of early warning signs, better methods of MRSA surveillance are necessary to understand what’s already happening. 

“If we had a comprehensive, linked electronic health records system that researchers had access to, we wouldn’t need it. There are systems like that in Scandinavian countries, where you can analyze disease factors in all kinds of ways. But you can’t do that in the U.S,” said Lauderdale.

Added study co-author Michael David, a University of Chicago MRSA specialist, “Right now, in the U.S., there is no surveillance system to track MRSA infections overall.” 

The CDC tracks MRSA through the Active Bacterial Core surveillance program, which gathers supports from nine regions. The program is useful, but it leaves large areas unanalyzed and can’t give the fine-grained, city-by-city numbers. 

“If we knew the rate was two or three times higher in one city than another, that could be an influence on public health campaigns,” said Lauderdale. Such numbers could also help frame questions about MRSA trends, helping researchers investigate its spread. 

More tests of the new method are needed to be certain it works, said Lauderdale. In the meantime, it’s revealed a phenomenon of cultural rather than clinical interest: the evolution of disease-related search terms. 

Between 2004 and 2007, people tended to search for both “staph” and “MRSA.” After the CDC’s report, MRSA left staph behind, replacing it in public consciousness. But even as MRSA searches became more common, so did searches for “mersa” — the bug’s phonetic spelling. In a few decades, perhaps, MRSA will be replaced by mersa. 

By Brandon Keim
From wired

A Virtual View beneath the Skin

Microsoft researchers have developed a handheld device that gives physical-therapy patients a virtual view beneath the skin to see what an injury looks like inside. The hope is that this will make them a little more eager to keep doing their therapies.  

 What lies beneath: A device developed at Microsoft projects images bone structure, muscle, tendons and nerves onto a patient’s skin.

"People are notoriously bad at sticking to their physical therapy regimens," says Amy Karlson, of Microsoft Research's Computational User Experiences Group in Redmond, Washington. Between 30 and 50 percent of patients with chronic conditions fail to comply with their recommended therapies, she says. As a result, conditions can take longer to heal or can get even worse.

Karlson says the more information that patients have about their injuries, the more likely they are to comply with physical therapy regimens. The new tool, called AnatOnMe, aims to give patients that extra bit of information. The device projects an image of the underlying bone structure, muscle tissue, tendons, or nerves onto the skin, giving patients a better understanding of the injury, and of what they need to do to help the healing process, says Karlson.

The prototype device comes in two parts. The first contains a handheld, or pico, projector, an ordinary digital camera, and an infrared camera. The second contains a laser pointer and the control buttons. "The technology is somewhat low-tech," says Karlson, who presented the device this week in Vancouver at CHI 2011, the Association for Computing Machinery's Conference on Human Factors in Computing Systems.

Instead of using a complicated autocorrection system to map the image of the internal injury precisely onto the patient's exterior, the therapist simply points the projector and lines it up by eye. And with the prototype, the images displayed are not actually taken from scans of the patients but come from stock graphical images used to show one of six different types of injury. 

Even so, it appears to be very effective, says Karlson. Controlled experiments of the device carried out by two physical therapists suggest that the device encourages patients to stick to their therapies. 

A doctor or therapist could also use AnatOnMe to project images onto a nearby wall. The user interface also works this way, says Karlson, with the menu options projected onto a surface. Options are selected using the laser pointer, which is detected by the infrared camera. 

E. Anne Reicherter, a member of the American Physical Therapy Association at the University of Maryland-Baltimore School of Medicine, says physical therapy compliance is a major problem, partly because it usually involves exercise, and partly because it involves changing a habit or forgoing a behavior that may have caused the injury in the first place. 

"But most patients are very interested in understanding what's going on in their body, so something like this that can visually assist them in truly understanding would be a real benefit," says Reicherter. Although, she adds, a certain portion of the population, particularly older patients, may find such visceral detail a bit of a turn off. 

By Duncan Graham-Rowe
From Technology Review

A Nanotube Patch to Help Heal the Heart

A conductive patch of carbon nanotubes can regenerate heart tissue growing in a dish, according to preliminary research from Brown University. The patch, made of tiny chains of carbon atoms that fold in on themselves, forming a tube, conducts electricity and mimics the rough surface of natural tissue. The more nanotubes the Brown researchers added to the patch, the more cells around it were able to regenerate.

 Have a heart: Brown University researchers have created a tiny patch made out of carbon nanotubes that they hope will someday help regenerate heart cells.

During a heart attack, areas of the heart are deprived of oxygen, killing muscle and nerve cells used to keep the heart beating strongly and rhythmically. The tissue cannot regenerate on its own, which disrupts the heart's rhythm, weakens it, and sometimes leads to a repeat heart attack. Tissue engineers around the globe are searching for ways to regenerate or repair this damaged tissue using different types of scaffolds and stem cells.
Thomas Webster, an associate professor of engineering and orthopedics at Brown and senior author of the study, says his work is distinctive because he examined not just the muscle cells that beat, but also the nerve cells that help them contract and the endothelial cells that line the blood vessels leading to and from the heart. The fact that the patch helped regenerate all three types of cells, which function interdependently in the heart, suggests the newly grown tissue is similar to normal heart tissue. The research was published today in Acta Biomaterialia.

Jeff Karp, codirector of the Regenerative Therapeutics Research Center at Brigham and Women's Hospital, says he's impressed by Webster's idea. But Karp cautions that the work is still preliminary. "It will be some time before we know how promising this approach truly is," he says, because it has not yet been tested in animals.

Webster's nanotube patch is just one of many approaches underway to help repair the heart. Many involve injecting stem cells collected from the patient into the damaged heart or implanting patches of muscle derived from these stem cells. He says the nanotubes could be used on their own, or as scaffolds for stem cells.

Webster's team is now fine-tuning the nanomaterial to create a linear pattern to more closely mimic the pattern in natural tissue. Others have shown that creating this kind of structure can provide a natural scaffold that supports tissue strength and growth. The team is also working to make the patch as precisely as conductive as heart tissue, to see if that improves its function. The next step will be to figure out how to deliver the patch, which could be rolled up and transported to the heart via a catheter.

Of course, researchers need to do extensive safety testing before the technology can be used in patients. Unlike other materials used in tissue engineering, the carbon nanotube patch would not naturally degrade in the body. "The idea would be that the heart tissue would grow around these carbon nanotubes and they would continue to provide electrical stimulus to the heart," Webster says.

To avoid regulatory delays, Webster says, he may try his carbon nanotube patch first on pets. Right now, heart attacks are usually fatal for the family dog, Webster says, because most animals don't get diagnostic medical care or treatment, and have smaller hearts that have a harder time than human hearts compensating for damage. Treating pets "could be a way to get this technology out earlier," he says. 

By Karen Weintraub
From Technology Review

Sensing Brain Pressure without Surgery

One of the most important things to monitor in patients who've sustained a severe blow to the head or a serious hemorrhage is pressure in the brain. This can reveal an increase in the brain's volume, thanks to bleeding, swelling, or other factors, which can compress and damage brain tissue and starve the organ of blood. Increases in pressure have also been implicated in other, less critical neurological problems, such as migraines and repeated concussions. But current methods for monitoring intracranial pressure are highly invasive—a neurosurgeon drills a hole in the skull and inserts a catheter, which carries a risk of infection.

 Under pressure: Researchers have developed a noninvasive way to assess high levels of pressure in the brain (as seen in this MRI), which often result from brain injury.

Thomas Heldt, a research scientist at the Research Laboratory of Electronics at MIT, and collaborators Faisal Kashif and George Verghese, also at MIT, hope to change that with a new, noninvasive method for monitoring intracranial pressure. While the technology is still in its early stages of development, initial studies on data from comatose patients show that it is about as accurate as intracranial monitoring with a catheter and more accurate than other, less invasive options, which involve inserting a catheter into the tissue layers between the inner skull and the brain. Heldt presented the research at the Next-Generation Medical Electronic Systems workshop at MIT earlier this month.

"If we had a way of determining pressure in the field, even a simple heuristic, like whether pressure is greater than 20 mmHg (millimeters of mercury—the standard measure at which physicians intervene), it would be hugely helpful," says Rajiv Gupta, director of the Ultra-High-Resolution Volume CT Lab at Massachusetts General Hospital, in Boston. "Triage is based on that." Gupta was not involved in the research.

To assess pressure noninvasively, Heldt's team started by creating a simple circuit model of pressure in the brain using knowledge of brain anatomy and how blood and cerebrospinal fluid flow through the organ. They then developed an algorithm to calculate intracranial pressure for a given level of arterial blood pressure and cerebral blood flow. Arterial blood pressure can be measured either with a catheter inserted into the wrist, or indirectly with a finger cuff, a device similar to an arm blood-pressure cuff but which provides continuous readings of blood pressure. A noninvasive ultrasound technique known as transcranial Doppler can detect velocity of cranial blood flow, which is directly related to the flow itself. Researchers validated the approach using previously collected data from 45 comatose patients. The estimate matched the gold standard measure with a deviation of about eight to nine mmHg. Other methods for measuring pressure, such as catheters inserted into the space between the skull and brain tissue, vary by 10 mmHg from reading to reading in the same brain.

Heldt says the goal is to achieve accuracy within four to five mmHg, which will enable physicians to distinguish between a safe pressure—a healthy person's intracranial pressure ranges from about seven to 15 mmHg—and one that requires intervention. When pressure rises to between 20 to 25 mmHg, physicians try to bring it down to a safer range, either through steps as simple as making the patient sit up, or as severe as taking away a piece of the skull to relieve pressure.

Researchers are about to begin a new test of the technology with collaborators at Beth Israel Deaconess Medical Center in Boston using data collected in real time from intensive care unit (ICU) patients. They hope that better-quality data will improve the accuracy of the measure. (The previous data set was collected more than a decade ago, with older equipment.) They also hope to show that a noninvasive method of collecting arterial pressure will work as well as intra-arterial monitoring.

While the researchers are initially focused on validating the technology in ICU patients, where they can compare the measure to intracranial catheters, they say the biggest potential for the tool is in examining patients with mild traumatic brain injury, recurrent migraine, and certain vestibular disorders.

The cumulative effect of mild brain injury is of great concern to both athletes and the military, given growing evidence that repetitive damage can have serious long-term effects. "For mild traumatic brain injury, we don't know what intracranial pressure does," says Heldt. Recent research in rats has shown that exposure to a blast, which generates a pressure wave, triggers an increase in intracranial pressure; the bigger the blast, the bigger the increase in pressure. Eventually, the researchers plan to develop miniaturized devices that could be deployed on the battlefield or the sports field.

Heldt adds that his team isn't the first to try to assess intracranial pressure based on arterial and cerebral blood flow. But previous efforts used data mining or machine learning approaches to create the algorithm. Such approaches require a database of previous measures. If a new patient is substantially different from those in the database, the algorithm fails. By incorporating simple physiological knowledge of the brain, his team could create a model that doesn't require any previous knowledge of the patient or anyone else. 

By Emily Singer
From Technology Review

Simpler Genome Sequencing

A Massachusetts startup called Noblegen is developing a simplified version of nanopore genome-sequencing technology—a technique that promises high speed and low costs but that usually requires complex instruments to carry out. Noblegen, founded last spring, says its technology's ability to directly and rapidly read DNA sequences could make it economically feasible to bring sequencing technology into clinical labs to diagnose cancer and other diseases.

 Nanopore chip: This silicon chip is the core of a DNA-sequencing instrument being developed by startup Noblegen. At the center of the chip is an array of hundreds of nanoscale holes through which long sequences of DNA travel while being imaged.

Noblegen CEO Frank Feist says the company's goal is to sequence at a rate of 1000 bases per second. The company won't divulge details of its current prototypes, but says the technology could be scaled up to arrays of 400 by 400 nanopores that sequence over 500 gigabases an hour—or about one genome, covered 30 times, in 15 minutes.

Today, it takes about a month and $10,000 to $40,000 to sequence a human genome. The "next generation" sequencing technologies offered by companies including Illumina and Pacific Biosciences have come a very long way, says Jeffery Schloss, program director for technology development at the National Human Genome Research Institute, but "they leave a fair amount to be desired." These technologies vary, but in general, they require complex instrumentation. There are also limits on the length of the sequences they can read, and they don't read those sequences directly. This affects both the amount of time it takes to put the sequence together and the quality of the data.

For over a decade, researchers have been working on nanopore sequencing, which could eliminate these problems by directly reading off the sequence of long, unprocessed strands of DNA. The principle is to identify each base in the sequence as the molecule is threaded through a nanoscale hole (or nanopore) outfitted with a sensor. 

But integrating all the parts and making them work has been challenging. For example, some systems read out the bases by sensing their electrical field; this requires a processing circuit for each nanopore, and integrating large arrays of such systems is complex. One company, Oxford Nanopore, claims to have fully developed such a system, but has not named any product launch dates. 

Noblegen uses optical imaging to identify the bases. This adds a step at the beginning, but the trade-off is that the instrumentation needed for imaging is much simpler. First, the Noblegen researchers convert genomic DNA into a synthetic version that's labeled with four different fluorescent dyes, one for each type of base. Each base in the original sequence is represented by one fluorescently labeled segment in the synthetic one. 

The synthetic sequences are then directly read out by Noblegen's relatively simple instrument. It's based on a silicon chip that's drilled to create pores just a few nanometers in diameter; the chip is illuminated by an inexpensive laser. The long synthetic molecules, which are charged, are pulled through the hole by electrostatic forces. But they can't move too quickly, because the fluorescent labels are too big to fit through the pore. As the DNA moves through the pore one segment at a time, the labels pop off, creating a flash of light. This light is imaged by a simple CMOS sensor like the one in a digital camera.

Feist says Noblegen's goal is to aggressively drive down the cost and increase the speed of sequencing whole genomes to a point where it makes economic sense for hospital labs in the next three or four years. "We want to deliver whole genome sequencing in the [hospital] lab within the financial constraints of the health-care system," he says.

The Boston University lab of Amit Meller, whose technology NobleGen has licensed, received $4.2 million in funding from the National Human Genome Research Institute last September. Feist says that comes on top of $4.1m in funding that Prof. Meller has received since 2001 which has gone into developing the nanopore consumable and instrumentation. He adds that the company will need another $15 million to develop an industrial-scale prototype. 

By Katherine Bourzac
From Technology Review

The Future of Salt and Sugar Is Being Engineered in a PepsiCo Lab

The preferred way to think about the intersection of science and food lately is like this or this, when the reality is more like what's going on deep inside of PepsiCo, the largest food company in America.

The mission? To basically reinvent the way we taste food, with chemistry, biology, and even psychology. John Seabrook's amazing in-depth Pepsi profile in the New Yorker looks at the way Pepsi's trying to offer healthier food (not because they care about you, per se, but because healthier food is a huge, explosive market segment) while maintaining the indulgent tastes people love. Three interesting things make an appearance in the course of the piece:

• Pepsi's custom-designed a new type of type salt—"15 micron salt"—whose molecular structure is designed expressly to taste saltier (maintaining the "taste curve"), allowing Pepsi to douse Lay's potato chips with less sodium, while delivering the same salty kick. (Fun fact: You only taste about 20-25 percent of the salt on the chips. And no one knows how salt really works.) It's going to show up on Lay's in 2012.

• Pepsi's next major cola product looks to be a still-secret "mid-calorie" soda, with sixty percent less sugar than a regular can of Pepsi, but that still tastes exactly the same as the real thing. The secret? Flavor enhancements. "Biotech products that are not sweet themselves, but increase the intensity of sweeteners," so it tastes like real sugar.

• They've got a robot with genetically engineered tastebuds-it can taste sweet, sour, bitter and umami, though not salt-which is expressly designed to taste hundreds of thousands of compounds in their search for "the holy grail, a natural zero-calorie sweetener that tastes exactly like sugar." Before the robot honed in on things that tasted good to humans, narrowing down the field for human tasters, real people had to do all the work-and Pepsi has looked into tasting everything from beetles to bee larvae.

From gizmodo

Robotics: A Tiltable Head Could Improve the Ability of Undulating Robots to Navigate Disaster Debris

Researchers at the Georgia Institute of Technology recently built a robot that can penetrate and "swim" through granular material. In a new study, they show that varying the shape or adjusting the inclination of the robot's head affects the robot's movement in complex environments.

 Using this robot, researchers at Georgia Tech were able to show that when its wedge-shaped head was set flat on the horizontal plane, negative lift force was generated and the robot moved downward into the medium. As the tip of the head was raised from zero to 7 degrees relative to the horizontal, the lift force increased until it became zero. At inclines above 7 degrees, the robot rose out of the medium.

"We discovered that by changing the shape of the sand-swimming robot's head or by tilting its head up and down slightly, we could control the robot's vertical motion as it swam forward within a granular medium," said Daniel Goldman, an assistant professor in the Georgia Tech School of Physics.

Results of the study will be presented on May 10 at the 2011 IEEE International Conference on Robotics and Automation in Shanghai. Funding for this research was provided by the Burroughs Wellcome Fund, National Science Foundation and Army Research Laboratory.

The study was conducted by Goldman, bioengineering doctoral graduate Ryan Maladen, physics graduate student Yang Ding and physics undergraduate student Andrew Masse, all from Georgia Tech, and Northwestern University mechanical engineering adjunct professor Paul Umbanhowar.

"The biological inspiration for our sand-swimming robot is the sandfish lizard, which inhabits the Sahara desert in Africa and rapidly buries into and swims within sand," explained Goldman. "We were intrigued by the sandfish lizard's wedge-shaped head that forms an angle of 140 degrees with the horizontal plane, and we thought its head might be responsible for or be contributing to the animal's ability to maneuver in complex environments."

For their experiments, the researchers attached a wedge-shaped block of wood to the head of their robot, which was built with seven connected segments, powered by servo motors, packed in a latex sock and wrapped in a spandex swimsuit. The doorstop-shaped head -- which resembled the sandfish's head -- had a fixed lower length of approximately 4 inches, height of 2 inches and a tapered snout. The researchers examined whether the robot's vertical motion could be controlled simply by varying the inclination of the robot's head.

Before each experimental run in a test chamber filled with quarter-inch-diameter plastic spheres, the researchers submerged the robot a couple inches into the granular medium and leveled the surface. Then they tracked the robot's position until it reached the end of the container or swam to the surface.

The researchers investigated the vertical movement of the robot when its head was placed at five different degrees of inclination. They found that when the sandfish-inspired head with a leading edge that formed an angle of 155 degrees with the horizontal plane was set flat, negative lift force was generated and the robot moved downward into the media. As the tip of the head was raised from zero to 7 degrees relative to the horizontal, the lift force increased until it became zero. At inclines above 7 degrees, the robot rose out of the medium.

"The ability to control the vertical position of the robot by modulating its head inclination opens up avenues for further research into developing robots more capable of maneuvering in complex environments, like debris-filled areas produced by an earthquake or landslide," noted Goldman.

The robotics results matched the research team's findings from physics experiments and computational models designed to explore how head shape affects lift in granular media.

"While the lift forces of objects in air, such as airplanes, are well understood, our investigations into the lift forces of objects in granular media are some of the first ever," added Goldman.

For the physics experiments, the researchers dragged wedge-shaped blocks through a granular medium. Blocks with leading edges that formed angles with the horizontal plane of less than 90 degrees resembled upside-down doorstops, the block with a leading edge equal to 90 degrees was a square, and blocks with leading edges greater than 90 degrees resembled regular doorstops.

They found that blocks with leading edges that formed angles with the horizontal plane less than 80 degrees generated positive lift forces and wedges with leading edges greater than 120 degrees created negative lift. With leading edges between 80 and 120 degrees, the wedges did not generate vertical forces in the positive or negative direction.

Using a numerical simulation of object drag and building on the group's previous studies of lift and drag on flat plates in granular media, the researchers were able to describe the mechanism of force generation in detail.

"When the leading edge of the robot head was less than 90 degrees, the robot's head experienced a lift force as it moved forward, which resulted in a torque imbalance that caused the robot to pitch and rise to the surface," explained Goldman.

Since this study, the researchers have attached a wedge-shaped head on the robot that can be dynamically modulated to specific angles. With this improvement, the researchers found that the direction of movement of the robot is sensitive to slight changes in orientation of the head, further validating the results from their physics experiments and computational models.

Being able to precisely control the tilt of the head will allow the researchers to implement different strategies of head movement during burial and determine the best way to wiggle deep into sand. The researchers also plan to test the robot's ability to maneuver through material similar to the debris found after natural disasters and plan to examine whether the sandfish lizard adjusts its head inclination to ensure a straight motion as it dives into the sand.

This material is based on research sponsored by the Burroughs Wellcome Fund, the National Science Foundation (NSF) under Award Number PHY-0749991, and the Army Research Laboratory (ARL) under Cooperative Agreement Number W911NF-08-2-0004.

From sciencedaily

Electromechanics Also Operates at the Nanoscale

"We have been studying carbon nanotubes theoretically, in order to see how they behave when they are stimulated to behave according to the laws quantum mechanics. The results provide a completely new platform for scientists to stand on," says Gustav Sonne of the Department of Physics at the University of Gothenburg.

 A suspended carbon nanotube can be made to vibrate like a guitar string. Gustav Sonne has studied how these oscillations influence the properties of the system if a magnetic field (H) is used to couple the mechanical motion of the tube to the electric current through it.

Every day we use a number of different microelectromechanical components for various forms of detection, to determine whether a certain process has taken place or whether a certain substance is present. These cannot be detected without instruments. One example is the detection of rapid accelerations that is used to activate the airbag in a car during an accident. What all of these components have in common is that they combine mechanical and electronic properties in order to react to external stimuli.

Gustav Sonne has taken research down to a whole new dimension -- from the micrometer scale to the nanometer scale -- and he has studied the younger brothers of these components: nanoelectromechanical systems. The studies have been based on tiny nanotubes suspended between two electrical contacts. He has subsequently calculated how small vibrations in the suspended tubes can be coupled to a current that is led through them.

"Our research has focussed mainly on how these systems, which consist of a tiny, super-light mechanical oscillator (the suspended nanotube), can be described in quantum mechanical terms, and what effects this has on the measurements we can carry out. We have been able to demonstrate a number of new mechanisms for electromechanical coupling that should be possible to observe experimentally. This, in turn, may lead to extremely exotic physical phenomena in these structures, phenomena which may be of interest for research into quantum computers, and other fields."

Interest in nanotubes is based on their outstanding properties: they are among the strongest materials known, weigh next to nothing, and have extremely high conductivity for both electric currents and heat. Carbon nanotubes can be used to manufacture composite materials that are several orders of magnitude stronger than currently available materials.

The thesis "Mesoscopic phenomena in the electromechanics of suspended nanowires" was successfully defended in the Department of Physics. Supervisor: Associate professor Leonid Gorelik.

From sciencedaily

Ultracapacitors to Boost the Range of Electric Cars

A startup called Nanotune says its ultracapacitor technology could make electric cars cheaper and extend their range. The company, based in Mountain View, California, has developed a way to make electrodes that results in ultracapacitors with five to seven times as much storage capacity as conventional ones.

Conventional ultracapacitors, which have the advantage of delivering fast bursts of power and can be recharged hundreds of thousands of times without losing much capacity, are too expensive and store too little energy to replace batteries. 

 Energy sponge: A micrograph shows the porous structure of a new electrode material that helps increase the storage capacity of ultracapacitors.

Nanotune, however, which has raised $3 million from the venture capital firm Draper Fisher Jurvetson, says its ultracapacitors are close to competing with batteries in terms of energy storage, and could soon surpass them. Using a conventional electrolyte, the company has demonstrated energy storage of 20 watt-hours per kilogram, as opposed to roughly five watt-hours for a conventional ultracapacitor. Using a more expensive ionic-liquid electrolyte, it has made ultracapacitors that store 35 watt-hours per kilogram. By the end of the year, the company hopes to approximately double this storage capacity, says Nanotune CEO  Kuan-Tsae Huang. At 40 watt-hours per kilogram, the ultracapacitors would be an improvement over the batteries used in some hybrid vehicles. 

In recent months, several startups have announced that they're using nanotechnology to make better ultracapacitors. Each hopes to help solve one of the biggest problems with electric cars today: their batteries' high cost and limited storage capacity. Nissan, for example, to make its electric Leaf affordable, had to limit the size of the battery pack, resulting in a range of just 73 miles. 

Part of the reason battery systems are so expensive and bulky is that the batteries degrade as they're used, especially when exposed to extreme temperatures—so automakers often augment them with cooling and heating systems, and add extra battery cells to offset losses in performance over time. Ultracapacitors could sidestep this problem, because they can be recharged without degrading and can work well in a wide range of temperatures. 

Eventually, Huang says, it may be possible to make ultracapacitors that store 500 watt-hours per kilogram—about three to four times more than the lithium-ion batteries used in cars today. The practical benefit could be even greater. Cars are often engineered to use only half the storage capacity of their batteries, to keep them from degrading. But almost all of an ultracapacitor's storage capacity can be used. 

Nanotune's technology is very expensive now—between $2,400 and $6,000 per kilowatt-hour. (The Department of Energy has proposed a goal of $250 per kilowatt-hour to make electric vehicles competitive with conventional ones.) Nanotune says, however, that its costs could come down to less than $150 per kilowatt-hour if the prices of some key materials, such as electrolytes, continue to fall, and as manufacturing is scaled up. 

The company's energy-storage projections are based on several advances it is working on. Nanotune is currently making electrodes with pores that are about 4 to 5 nanometers across, but it says it can make them smaller (high porosity leads to high surface area, which makes it possible to store a large amount of charge) and tune them to match the needs of different electrolytes—the ion-conducting materials the electrodes are immersed in. 

The company is also looking into using ionic liquids rather than conventional organic electrolytes. These increase the voltage of the system, greatly increasing energy storage, but typically they aren't compatible with conventional ultracapacitor electrodes.  Finally, the company hopes to make use of recent academic findings that suggests that adding small amounts of ruthenium to the ultracapacitors can increase energy storage. 

Nanotune isn't the first company to claim it can make ultracapacitors with very high energy storage. Others have found this promise hard to deliver. Increasing surface area can improve storage capacity only so much, since at some point the storage is limited by the ions in the electrolyte. Ionic liquids help with this, but they have significant shortcomings, says Joel Schindall, a professor of electrical engineering and computer science at MIT. (A company called FastCap Systems, which is developing ultracapacitors using carbon nanotubes, was spun out of his lab.) They're very expensive, for one thing, and some operate well only in a limited temperature range, making them impractical for cars.

Schindall says, however, that Nanotune can fall short of its very high energy goals and still improve the competitiveness of electric vehicles and hybrids. Given the durability of ultracapacitors, even achieving energy storage of 100 watt-hours per kilogram—close to that of lithium-ion batteries—"would be fantastic."

By Kevin Bullis
From Technology Review

Talking to the Wall

Our lives are awash with ambient electromagnetic radiation, from the fields generated by power lines to the signals used to send data between Wi-Fi transmitters. Researchers at Microsoft and the University of Washington have found a way to harness this radiation for a computer interface that turns any wall in a building into a touch-sensitive surface.

 Up in the air: Using an experimental interface, a person acts as an antenna for stray electromagnetic radiation in the environment.

The technology could allow light switches, thermostats, stereos, televisions, and security systems to be controlled from anywhere in the house, and could lead to new interfaces for games.

"There's all this electromagnetic radiation in the air," says Desney Tan, senior researcher at Microsoft (and a TR35 honoree in 2007). Radio antennas pick up some of the signals, Tan explains, but people can do this too. "It turns out that the body is a relatively good antenna," he says. 

The ambient electromagnetic radiation emitted by home appliances, mobile phones, computers, and the electrical wiring within walls is usually considered noise. But the researchers chose to put it at the core of their new interface.

When a person touches a wall with electrical wiring behind it, she becomes an antenna that tunes the background radiation, producing a distinct electrical signal, depending on her body position and proximity to and location on the wall. This unique electrical signal can be collected and interpreted by a device in contact with or close to her body. When a person touches a spot on the wall behind her couch, the gesture can be recognized, and it could be used, for example, to turn down the volume on the stereo.

So far, the researchers have demonstrated only that a body can turn electromagnetic noise into a usable signal for a gesture-based interface. A paper outlining this will be presented next week at the CHI Conference on Human Factors in Computing Systems in Vancouver, BC.

In an experiment, test subjects wore a grounding strap on their wrist—a bracelet that is normally used to prevent the buildup of static electricity in the body. A wire from the strap was connected to an analog-to-digital converter, which fed data from the strap to a laptop worn in a backpack. Machine-learning algorithms then processed the data to identify characteristic changes in the electrical signals corresponding to a person's proximity to a wall, the position of her hand on the wall, and her location within the house.

"Now we can turn any arbitrary wall surface into a touch-input surface," says Shwetak Patel, professor of computer science and engineering and electrical engineering at the University of Washington (and a TR35 honoree in 2009), who was involved with the work. The next step, he says, is to make the data analysis real-time and to make the system even smaller—with a phone or a watch instead of a laptop collecting and analyzing data.

"With Nintendo Wii and Microsoft's Kinect, people are starting to realize that these gesture interfaces can be quite compelling and useful," says Thad Starner, professor in Georgia Tech's College of Computing. "This is the sort of paper that says here is a new direction, an interesting idea; now can we refine it and make it better over time." 

Refining the system to make it more user-friendly will be important, says Pattie Maes, a professor in MIT's Media Lab who specializes in computer interfaces. "Many interfaces require some visual, tangible, or auditory feedback so the user knows where to touch." While the researchers suggest using stickers or other marks to denote wall-based controls, this approach might not appeal to everyone. "I think it is intriguing," says Maes, "but may only have limited-use cases."

Joe Paradiso, another professor in MIT's Media Lab, says, "The idea is wild and different enough to attract attention," but he notes that the signal produced could vary depending on the way a person wears the device that collects the signal.

Patel has previously used a building's electrical, water, and ventilation systems to locate people indoors. Tan has worked with sensors that use human brain power for computing and muscle activity to control electronics wirelessly. The two researchers share an interest in pulling useful information out of noisy signals.  With the recent joint project, Tan says, the researchers are "taking junk and making sense of it."

By Kate Greene
From Technology Review

Salty Solution for Energy Generation

The difference in salinity between freshwater and saltwater holds promise as a large source of renewable energy. Energy is required to desalinate water, and running the process in reverse can generate energy. Now a novel approach based on a conventional battery design that uses nanomaterials could provide a way to harvest that energy economically.  

 Saline solution: This device generates electricity using differences in salinity between fresh and salt water. The two foil-like structures serve as positive and negative electrodes; the glass bulb is a reference electrode.

The new device, developed by researchers at Stanford University, consists of an electrode that attracts positive sodium ions and one that attracts negative chlorine ions. When the electrodes are immersed in saltwater, they draw sodium and chlorine ions from the water, and the movement of the ions creates an electrical current. The electrodes are recharged by draining the saltwater, replacing it with freshwater, and applying a relatively low-voltage electrical current, which draws the ions back out of the electrodes. When the freshwater is drained, the electrodes are ready to attract more ions from the next batch of saltwater.  

"It is the opposite process of water desalination, where you put in energy and try to generate freshwater and more concentrated saltwater," says Yi Cui, a materials science and engineering professor at Stanford University and the study's lead author. "Here you start with freshwater and concentrated saltwater, and then you generate energy." 

Cui's group converted to electricity 74 percent of the potential energy that exists between saltwater and freshwater, with no decline in performance over 100 cycles. Placing the electrodes closer together, Cui says, could allow the battery to achieve 85 percent efficiency.  

A power plant using this technology would be based near a river delta where freshwater meets the sea. Drawing 50 cubic meters of river water per second, Cui says, a power plant could produce up to 100 megawatts of power. He calculates that if all of the freshwater from all of the world's coastal rivers were harnessed, his salinity-gradient process could generate 2 terawatts, or approximately 13 percent of the energy currently used around the world. 

Such wide-scale use, however, would seriously disturb sensitive aquatic environments. "I think you would only be able to utilize a very small fraction of this or it would be an ecological disaster," says Menachem Elimelech, director of the Environmental Engineering Program at Yale University. Elimelech says it would be necessary to pretreat the water to remove suspended material including living organisms. Such processing would require energy, add costs, and itself seriously disturb the ecosystem if done on a large scale. 

Prior efforts to harvest energy from the salinity differential between saltwater and freshwater have focused primarily on a process known as pressure-retarded osmosis. In this approach, freshwater and saltwater are housed in separate chambers, which are divided by an artificial membrane. The higher salinity of the saltwater draws freshwater through the membrane, increasing the pressure on the saltwater side. The pressurized water is then used to drive a turbine and generate electricity.

Norwegian electric company Statkraft is currently testing pressure-retarded osmosis at a pilot plant outside Oslo and also working to develop more efficient and durable membranes. Statkraft officials say their goal is to convert 80 percent of the available chemical energy to electricity. Cui says he doubts that the approach will be able to exceed an efficiency of 40 percent. "Efficiency-wise we are certainly much better," he says. 

To achieve high efficiency, Cui's group used manganese-dioxide nanorods for its battery's positive electrode. The material gives the sodium ions roughly 100 times more surface area to interact with than conventional electrode materials do. And the nanostructure allows the ions to quickly attach and detach from the electrode, making the entire battery more efficient. 

Cui's team used a silver electrode to bond with the negatively charged chlorine ions. Silver, however, is prohibitively expensive for large-scale deployments, and it's also toxic, capable of causing environmental harm if it dissolves into the water being cycled through the battery. Cui says his group is looking for a substitute, but an alternative may be hard to find. 

By Phil McKenna
From Technology Review