Security: Computer scientists develop tool to make the Internet of Things safer

 

June 2, 2014

University of California - San Diego

Computer scientists have developed a tool that allows hardware designers and system builders to test security -- a first for the field. There is a big push to create the so-called Internet of Things, where all devices are connected and communicate with one another. As a result, embedded systems -- small computer systems built around microcontrollers -- are becoming more common. But they remain vulnerable to security breaches. Some examples of devices that may be hackable: medical devices, cars, cell phones and smart grid technology.

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From left: Ph.D. student Jason Oberg, computer science professor Ryan Kastner and postdoctoral research Jonathan Valamehr.

Computer scientists at the University of California, San Diego, have developed a tool that allows hardware designers and system builders to test security- a first for the field. One of the tool's potential uses is described in the May-June issue of IEEE Micro magazine.

"The stakes in hardware security are high," said Ryan Kastner, a professor of computer science at the Jacobs School of Engineering at UC San Diego.

There is a big push to create the so-called Internet of Things, where all devices are connected and communicate with one another. As a result, embedded systems -- small computer systems built around microcontrollers -- are becoming more common. But they remain vulnerable to security breaches. Some examples of devices that may be hackable: medical devices, cars, cell phones and smart grid technology.

"Engineers traditionally design devices to be fast and use as little power as possible," said Jonathan Valamehr, a postdoctoral researcher in the Department of Computer Science and Engineering at UC San Diego. "Oftentimes, they don't design them with security in mind."

The tool, based on the team's research on Gate-level Information Flow Tracking, or GLIFT, tags critical pieces in a hardware's security system and tracks them. The tool leverages this technology to detect security-specific properties within a hardware system. For example, the tool can make sure that a cryptographic key does not leak outside a chip's cryptographic core.

There are two main threats in hardware security. The first is confidentiality. In some types of hardware, one can determine a device's cryptographic key based on the amount of time it takes to encrypt information. The tool can detect these so-called timing channels that can compromise a device's security. The second threat is integrity, where a critical subsystem within a device can be affected by non-critical ones. For example, a car's brakes can be affected by its CD player. The tool can detect these integrity violations as well.

Valamehr, Kastner, and Ph.D. candidate Jason Oberg started a company named Tortuga Logic to commercialize this technology. The company is currently working with two of the top semiconductor companies in the world. Their next step is to focus on medical devices, computers in cars, and military applications.

The team recently were awarded a $150,000 grant from the National Science Foundation to grow their business and further their research.

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Story Source:

The above story is based on materials provided by University of California - San Diego. Note: Materials may be edited for content and length.

How an Amateur Built the World's Biggest Dome

 

https://www.youtube.com/watch?v=_IOPlGPQPuM

Modern castle

Proteins 'ring like bells': Quantum mechanics and biochemical reactions

 

June 3, 2014

University of Glasgow

As far back as 1948, Erwin Schrödinger -- the inventor of modern quantum mechanics -- published the book 'What is life?' In it, he suggested that quantum mechanics and coherent ringing might be at the basis of all biochemical reactions. At the time, this idea never found wide acceptance because it was generally assumed that vibrations in protein molecules would be too rapidly damped. Now, scientists have shown that he may have been on the right track after all.

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Dr David Turton, the ultrafast laser expert who carried out the laser experiments.

As far back as 1948, Erwin Schrödinger -- the inventor of modern quantum mechanics -- published the book "What is life?"

In it, he suggested that quantum mechanics and coherent ringing might be at the basis of all biochemical reactions. At the time, this idea never found wide acceptance because it was generally assumed that vibrations in protein molecules would be too rapidly damped.

Now, scientists at the University of Glasgow have demonstrated he was on the right track after all.

Using modern laser spectroscopy, the scientists have been able to measure the vibrational spectrum of the enzyme lysozyme, a protein that fights off bacteria. They discovered that this enzyme rings like a bell with a frequency of a few terahertz or a million-million hertz. Most remarkably, the ringing involves the entire protein, meaning the ringing motion could be responsible for the transfer of energy across proteins.

The experiments show that the ringing motion lasts for only a picosecond or one millionth of a millionth of a second. Biochemical reactions take place on a picosecond timescale and the scientists believe that evolution has optimised enzymes to ring for just the right amount of time. Any shorter, and biochemical reactions would become inefficient as energy is drained from the system too quickly. Any longer and the enzyme would simple oscillate forever: react, unreact, react, unreact, etc. The picosecond ringing time is just perfect for the most efficient reaction.

These tiny motions enable proteins to morph quickly so they can readily bind with other molecules, a process that is necessary for life to perform critical biological functions like absorbing oxygen and repairing cells.

The findings have been published in Nature Communications.

Klaas Wynne, Chair in Chemical Physics at the University of Glasgow said: "This research shows us that proteins have mechanical properties that are highly unexpected and geared towards maximising efficiency. Future work will show whether these mechanical properties can be used to understand the function of complex living systems."

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Story Source:

The above story is based on materials provided by University of Glasgow. Note: Materials may be edited for content and length.

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Journal Reference:

1. David A. Turton, Hans Martin Senn, Thomas Harwood, Adrian J. Lapthorn, Elizabeth M. Ellis, Klaas Wynne. Terahertz underdamped vibrational motion governs protein-ligand binding in solution. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4999

Vanishing da Vinci: Nondestructive way to determine state of degradation of ancient works of art

 

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This is Leonardo da Vinci's self-portrait as acquired during diagnostic studies carried out at the Central Institute for the Restoration of Archival and Library Heritage in Rome, Italy.

One of Leonardo da Vinci's masterpieces, drawn in red chalk on paper during the early 1500s and widely believed to be a self-portrait, is in extremely poor condition. Centuries of exposure to humid storage conditions or a closed environment has led to widespread and localized yellowing and browning of the paper, which is reducing the contrast between the colors of chalk and paper and substantially diminishing the visibility of the drawing.

A group of researchers from Italy and Poland with expertise in paper degradation mechanisms was tasked with determining whether the degradation process has now slowed with appropriate conservation conditions -- or if the aging process is continuing at an unacceptable rate.

To do this, as they describe in Applied Physics Letters, from AIP Publishing, the team developed an approach to nondestructively identify and quantify the concentration of light-absorbing molecules known as chromophores in ancient paper, the culprit behind the "yellowing" of the cellulose within ancient documents and works of art.

"During the centuries, the combined actions of light, heat, moisture, metallic and acidic impurities, and pollutant gases modify the white color of ancient paper's main component: cellulose," explained Joanna Łojewska, a professor in the Department of Chemistry at Jagiellonian University in Krakow, Poland. "This phenomenon is known as 'yellowing,' which causes severe damage and negatively affects the aesthetic enjoyment of ancient art works on paper."

Chromophores are the key to understanding the visual degradation process because they are among the chemical products developed by oxidation during aging and are, ultimately, behind the "yellowing" within cellulose. Yellowing occurs when "chromophores within cellulose absorb the violet and blue range of visible light and largely scatter the yellow and red portions -- resulting in the characteristic yellow-brown hue," said Olivia Pulci, a professor in the Physics Department at the University of Rome Tor Vergata.

To determine the degradation rate of Leonardo's self-portrait, the team created a nondestructive approach that centers on identifying and quantifying the concentration of chromophores within paper. It involves using a reflectance spectroscopy setup to obtain optical reflectance spectra of paper samples in the near-infrared, visible, and near-ultraviolet wavelength ranges.

Once reflectance data is gathered, the optical absorption spectrum of cellulose fibers that form the sheet of paper can be calculated using special spectroscopic data analysis.

Then, computational simulations based on quantum mechanics -- in particular, Time-Dependent Density Functional Theory, which plays a key role in studying optical properties in theoretical condensed matter physics -- are tapped to calculate the optical absorption spectrum of chromophores in cellulose.

"Using our approach, we were able to evaluate the state of degradation of Leonardo da Vinci's self-portrait and other paper specimens from ancient books dating from the 15th century," said Adriano Mosca Conte, a researcher at the University of Rome Tor Vergata. "By comparing the results of ancient papers with those of artificially aged samples, we gained significant insights into the environmental conditions in which Leonardo da Vinci's self-portrait was stored during its lifetime."

Their work revealed that the type of chromophores present in Leonardo's self portrait are "similar to those found in ancient and modern paper samples aged in extremely humid conditions or within a closed environment, which agrees with its documented history," said Mauro Missori, a researcher at the Institute for Complex Systems, CNR, in Rome, Italy.

One of the most significant implications of their work is that the state of degradation of ancient paper can be measured and quantified by evaluation of the concentrations of chromophores in cellulose fibers. "The periodic repetition of our approach is fundamental to establishing the formation rate of chromophores within the self-portrait. Now our approach can serve as a precious tool to preserve and save not only this invaluable work of art, but others as well," Conte noted.

 

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Story Source:

The above story is based on materials provided by American Institute of Physics (AIP). Note: Materials may be edited for content and length.

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Journal Reference:

1. A. Mosca Conte, O. Pulci, M.C. Misiti, J. Łojewska, L. Teodonio, C. Violante, and M. Missori. Visual degradation in Leonardo da Vinci's iconic self-portrait: a nanoscale study. Applied Physics Letters, 2014 DOI: 10.1063/1.4879838

Spiders know the meaning of web music

 

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Silk during high-rate ballistic impact.

Spider silk transmits vibrations across a wide range of frequencies so that, when plucked like a guitar string, its sound carries information about prey, mates, and even the structural integrity of a web.

The discovery was made by researchers from the Universities of Oxford, Strathclyde, and Sheffield who fired bullets and lasers at spider silk to study how it vibrates. They found that, uniquely, when compared to other materials, spider silk can be tuned to a wide range of harmonics. The findings, to be reported in the journal Advanced Materials, not only reveal more about spiders but could also inspire a wide range of new technologies, such as tiny light-weight sensors.

"Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information," said Beth Mortimer of the Oxford Silk Group at Oxford University, who led the research. "The sound of silk can tell them what type of meal is entangled in their net and about the intentions and quality of a prospective mate. By plucking the silk like a guitar string and listening to the 'echoes' the spider can also assess the condition of its web."

This quality is used by the spider in its web by 'tuning' the silk: controlling and adjusting both the inherent properties of the silk, and the tensions and interconnectivities of the silk threads that make up the web. To study the sonic properties of the spider's gossamer threads the researchers used ultra-high-speed cameras to film the threads as they responded to the impact of bullets. In addition, lasers were used to make detailed measurements of even the smallest vibration.

"The fact that spiders can receive these nanometre vibrations with organs on each of their legs, called slit sensillae, really exemplifies the impact of our research about silk properties found in our study," said Dr Shira Gordon of the University of Strathclyde, an author involved in this research.

"These findings further demonstrate the outstanding properties of many spider silks that are able to combine exceptional toughness with the ability to transfer delicate information,' said Professor Fritz Vollrath of the Oxford Silk Group at Oxford University, an author of the paper. 'These are traits that would be very useful in light-weight engineering and might lead to novel, built-in 'intelligent' sensors and actuators."

Dr Chris Holland of the University of Sheffield, an author of the paper, said: "Spider silks are well known for their impressive mechanical properties, but the vibrational properties have been relatively overlooked and now we find that they are also an awesome communication tool. Yet again spiders continue to impress us in more ways than we can imagine."

Beth Mortimer said: "It may even be that spiders set out to make a web that 'sounds right' as its sonic properties are intimately related to factors such as strength and flexibility."

Editor's Note: A video about the research is available on YouTube at http://www.youtube.com/watch?v=Kjh7bQSc8ag

Quest for the bionic arm: Advancements and challenges

 

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In the past 13 years, nearly 2,000 veterans returned from Iraq and Afghanistan with injuries requiring amputations; 14 percent of those injured veterans required upper extremity amputations. To treat veterans with upper extremity amputations, scientists continue to pursue research and development of bionic arms and hands with full motor and sensory function. An article appearing in the June issue of the Journal of the American Academy of Orthopaedic Surgeons (JAAOS) reviews the recent advancements in upper extremity bionics and the challenges that remain in creating a prosthesis that meets or exceeds the abilities of a human arm and hand.

During the next 50 years, "I truly believe we will be able to make artificial arms that function better than many injured arms that doctors are saving today," said article author Douglas T. Hutchinson, MD, associate professor of orthopaedics at the University of Utah Medical School, and chief of hand surgery at Primary Children's Medical Center, the Veterans Affairs Medical Center, and Shriners Intermountain Hospital. Advancements in prostheses technology will not only benefit injured veterans but also, eventually, the civilian population with upper extremity injuries that require amputations.

One of the most commonly used upper extremity prostheses continues to be the myoelectric prosthesis. Created more than 50 years ago, this prosthesis allows residual muscles to act as natural batteries to create transcutaneous signals (transmitted through the skin) to control the movements of the prosthetic arm and hand. However, the muscles used most often are the biceps and triceps, which do not naturally translate to the opening and closing of a hand. In addition, myoelectric prosthetics do not look natural and are heavy, hot, uncomfortable, and not waterproof. Sometimes the socket interface used to attach the prosthesis may interfere with the function of a residual joint such as the elbow.

Because of these challenges -- as well as the inability to "feel" the prosthesis -- the wearer never achieves fine motor control, the simultaneous use of multiple joints, or full rotation and use of the hand. The prosthesis also requires a long period of learning and adjustment. As a result, only about two thirds of patients properly fitted for upper extremity prosthesis use it daily, with many patients instead choosing to wear a body-operated "hook" device, invented during the Civil War and refined during World War I and World War II. Others choose not to use their prostheses because they prefer the ability to have physical sensation from their stump.

The 2014 federal budget for prostheses research alone is $2.5 billion. The U.S. Department of Defense Advanced Research Project (DARPA) has already invested more than $150 million into their Revolutionizing Prosthetics Program, which is charged with creating an upper extremity prosthesis that will function as a normal human arm does, complete with full motor and sensory functions. According to Dr. Hutchinson, the program has created several advanced upper extremity prostheses, "providing function and ease of learning superior to those of conventional myoelectric prostheses."

However, these prosthetic devices have a long way to go for effective and broad use in patients. Many are heavy and uncomfortable with short-life batteries. Current infection rates with osseous-integrated devices at the prosthesis-skin interface also remain high at approximately 45 percent. Most challenging is the problem of efficiently and accurately sending brain signals through the muscles and peripheral nerves of the arm and hands, which may require the creation and use of a reliable wireless device or direct wiring through an osseous (bone tissue)-integrated implant.

Answers may be found in combining recent advancements in prosthetic devices with breakthroughs in maintaining nerve and muscle function in badly damaged limbs.

"Orthopaedic surgeons who do peripheral nerve surgery (hand surgeons) will be part of the team that puts these devices into patients, but perhaps more relevant than that will be the way we treat severe near amputations or complete amputations differently," said Dr. Hutchinson. "In an amputation surgery, we will need to preserve muscles and nerves even more than we already do to make this type of later reconstruction more successful."

"We currently spend a lot of time, energy, and money saving hands and arms that truly have a poor prognosis because the alternative, an amputation and an insensate myoelectric prosthesis attached by a socket, is even worse," Dr. Hutchinson added. "As we improve the prosthesis, the options for these severely injured upper extremities will increase."

In addition, the perfection of nerve utilization could potentially aid other conditions, such as cerebral palsy, chronic nerve pain, and brachial plexus injuries.

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Story Source:

The above story is based on materials provided by American Academy of Orthopaedic Surgeons. Note: Materials may be edited for content and length.

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Journal Reference:

1. D. T. Hutchinson. The Quest for the Bionic Arm. Journal of the American Academy of Orthopaedic Surgeons, 2014; 22 (6): 346 DOI: 10.5435/JAAOS-22-06-346

Carbon-capture breakthrough: Recyclable material absorbs 82 percent of its weight in carbon dioxide

 

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Particles of nitrogen-containing porous carbon are able to capture carbon dioxide from natural gas under pressure at a wellhead by polymerizing it, according to researchers at Rice University. When the pressure is released, the carbon dioxide returns to gaseous form.

Rice University scientists have created an Earth-friendly way to separate carbon dioxide from natural gas at wellheads.

A porous material invented by the Rice lab of chemist James Tour sequesters carbon dioxide, a greenhouse gas, at ambient temperature with pressure provided by the wellhead and lets it go once the pressure is released. The material shows promise to replace more costly and energy-intensive processes.

Results from the research appear today in the journal Nature Communications.

Natural gas is the cleanest fossil fuel. Development of cost-effective means to separate carbon dioxide during the production process will improve this advantage over other fossil fuels and enable the economic production of gas resources with higher carbon dioxide content that would be too costly to recover using current carbon capture technologies, Tour said. Traditionally, carbon dioxide has been removed from natural gas to meet pipelines' specifications.

The Tour lab, with assistance from the National Institute of Standards and Technology (NIST), produced the patented material that pulls only carbon dioxide molecules from flowing natural gas and polymerizes them while under pressure naturally provided by the well.

When the pressure is released, the carbon dioxide spontaneously depolymerizes and frees the sorbent material to collect more.

All of this works in ambient temperatures, unlike current high-temperature capture technologies that use up a significant portion of the energy being produced.

"If the oil and gas industry does not respond to concerns about carbon dioxide and other emissions, it could well face new regulations," Tour said, noting the White House issued its latest National Climate Assessment last month and, this week, set new rules to cut carbon pollution from the nation's power plants.

"Our technique allows one to specifically remove carbon dioxide at the source. It doesn't have to be transported to a collection station to do the separation," he said. "This will be especially effective offshore, where the footprint of traditional methods that involve scrubbing towers or membranes are too cumbersome.

"This will enable companies to pump carbon dioxide directly back downhole, where it's been for millions of years, or use it for enhanced oil recovery to further the release of oil and natural gas. Or they can package and sell it for other industrial applications," he said.

The Rice material, a nanoporous solid of carbon with nitrogen or sulfur, is inexpensive and simple to produce compared with the liquid amine-based scrubbers used now, Tour said. "Amines are corrosive and hard on equipment," he said. "They do capture carbon dioxide, but they need to be heated to about 140 degrees Celsius to release it for permanent storage. That's a terrible waste of energy."

Rice graduate student Chih-Chau Hwang, lead author of the paper, first tried to combine amines with porous carbon. "But I still needed to heat it to break the covalent bonds between the amine and carbon dioxide molecules," he said. Hwang also considered metal oxide frameworks that trap carbon dioxide molecules, but they had the unfortunate side effect of capturing the desired methane as well and they are far too expensive to make for this application.

The porous carbon powder he settled on has massive surface area and turns the neat trick of converting gaseous carbon dioxide into solid polymer chains that nestle in the pores.

"Nobody's ever seen a mechanism like this," Tour said. "You've got to have that nucleophile (the sulfur or nitrogen atoms) to start the polymerization reaction. This would never work on simple activated carbon; the key is that the polymer forms and provides continuous selectivity for carbon dioxide."

Methane, ethane and propane molecules that make up natural gas may try to stick to the carbon, but the growing polymer chains simply push them off, he said.

The researchers treated their carbon source with potassium hydroxide at 600 degrees Celsius to produce the powders with either sulfur or nitrogen atoms evenly distributed through the resulting porous material. The sulfur-infused powder performed best, absorbing 82 percent of its weight in carbon dioxide. The nitrogen-infused powder was nearly as good and improved with further processing.

Tour said the material did not degrade over many cycles, "and my guess is we won't see any. After heating it to 600 degrees C for the one-step synthesis from inexpensive industrial polymers, the final carbon material has a surface area of 2,500 square meters per gram, and it is enormously robust and extremely stable."

Apache Corp., a Houston-based oil and gas exploration and production company, funded the research at Rice and licensed the technology. Tour expected it will take time and more work on manufacturing and engineering aspects to commercialize.

The paper's co-authors are undergraduate Josiah Tour, research scientist Carter Kittrell and senior research scientist Lawrence Alemany, all of Rice, and Laura Espinal, an associate at NIST. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and nanoengineering and of computer science.

Hubble unveils new colorful view of the universe

 

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Astronomers using NASA's Hubble Space Telescope have assembled a comprehensive picture of the evolving universe -- among the most colorful deep space images ever captured by the 24-year-old telescope.

Astronomers using NASA's Hubble Space Telescope have assembled a comprehensive picture of the evolving universe -- among the most colorful deep space images ever captured by the 24-year-old telescope.

Researchers say the image, from a new study called the Ultraviolet Coverage of the Hubble Ultra Deep Field, provides the missing link in star formation. The Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken in 2003 to 2012 with Hubble's Advanced Camera for Surveys and Wide Field Camera 3.

Astronomers previously studied the Hubble Ultra Deep Field (HUDF) in visible and near-infrared light in a series of images captured from 2003 to 2009. The HUDF shows a small section of space in the southern-hemisphere constellation Fornax. Now, using ultraviolet light, astronomers have combined the full range of colors available to Hubble, stretching all the way from ultraviolet to near-infrared light. The resulting image -- made from 841 orbits of telescope viewing time -- contains approximately 10,000 galaxies, extending back in time to within a few hundred million years of the big bang.

Prior to the Ultraviolet Coverage of the Hubble Ultra Deep Field study of the universe, astronomers were in a curious position. Missions such as NASA's Galaxy Evolution Explorer (GALEX) observatory, which operated from 2003 to 2013, provided significant knowledge of star formation in nearby galaxies. Using Hubble's near-infrared capability, researchers also studied star birth in the most distant galaxies, which appear to us in their most primitive stages due to the significant amount of time required for the light of distant stars to travel into a visible range. But for the period in between, when most of the stars in the universe were born -- a distance extending from about 5 billion to 10 billion light-years -- they did not have enough data.

"The lack of information from ultraviolet light made studying galaxies in the HUDF like trying to understand the history of families without knowing about the grade-school children," said principal investigator Harry Teplitz of Caltech in Pasadena, California. "The addition of the ultraviolet fills in this missing range."

Ultraviolet light comes from the hottest, largest, and youngest stars. By observing at these wavelengths, researchers get a direct look at which galaxies are forming stars and where the stars are forming within those galaxies.

Studying the ultraviolet images of galaxies in this intermediate time period enables astronomers to understand how galaxies grew in size by forming small collections of very hot stars. Because Earth's atmosphere filters most ultraviolet light, this work can only be accomplished with a space-based telescope.

"Ultraviolet surveys like this one using the unique capability of Hubble are incredibly important in planning for NASA's James Webb Space Telescope," said team member Rogier Windhorst of Arizona State University in Tempe. "Hubble provides an invaluable ultraviolet-light dataset that researchers will need to combine with infrared data from Webb. This is the first really deep ultraviolet image to show the power of that combination."

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Story Source:

The above story is based on materials provided by Space Telescope Science Institute (STScI). Note: Materials may be edited for content and length.

Progress on detecting glucose levels in saliva: New biochip sensor

 

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A plasmonic interferometer can detect glucose molecules in water. Detection of glucose in a complex fluid is more challenging. Controlling the distance between grooves and using dye chemistry on glucose molecules allows researchers to measure glucose levels despite the 1 percent of saliva that is not water.

Researchers from Brown University have developed a new biochip sensor that can selectively measure concentrations of glucose in a complex solution similar to human saliva. The advance is an important step toward a device that would enable people with diabetes to test their glucose levels without drawing blood.

The new chip makes use of a series of specific chemical reactions combined with plasmonic interferometry, a means of detecting chemical signature of compounds using light. The device is sensitive enough to detect differences in glucose concentrations that amount to just a few thousand molecules in the sampled volume.

"We have demonstrated the sensitivity needed to measure glucose concentrations typical in saliva, which are typically 100 times lower than in blood," said Domenico Pacifici, assistant professor of engineering at Brown, who led the research. "Now we are able to do this with extremely high specificity, which means that we can differentiate glucose from the background components of saliva."

The new research is described in the cover article of the June issue of the journal Nanophotonics.

The biochip is made from a one-inch-square piece of quartz coated with a thin layer of silver. Etched in the silver are thousands of nanoscale interferometers -- tiny slits with a groove on each side. The grooves measure 200 nanometers wide, and the slit is 100 nanometers wide -- about 1,000 times thinner than a human hair. When light is shined on the chip, the grooves cause a wave of free electrons in the silver -- a surface plasmon polariton -- to propagate toward the slit. Those waves interfere with light that passes through the slit. Sensitive detectors then measure the patterns of interference generated by the grooves and slits.

When a liquid is deposited on the chip, the light and the surface plasmon waves propagate through that liquid before they interfere with each other. That alters the interference patterns picked up by the detectors, depending on the chemical makeup of the liquid. By adjusting the distance between the grooves and the center slit, the interferometers can be calibrated to detect the signature of specific compounds or molecules, with high sensitivity in extremely small sample volumes.

In a paper published in 2012, the Brown team showed that interferometers on a biochip could be used to detect glucose in water. However, selectively detecting glucose in a complex solution like human saliva was another matter.

"Saliva is about 99 percent water, but it's the 1 percent that's not water that presents problems," Pacifici said. "There are enzymes, salts, and other components that may affect the response of the sensor. With this paper we solved the problem of specificity of our sensing scheme."

They did that by using dye chemistry to create a trackable marker for glucose. The researchers added microfluidic channels to the chip to introduce two enzymes that react with glucose in a very specific way. The first enzyme, glucose oxidase, reacts with glucose to form a molecule of hydrogen peroxide. This molecule then reacts with the second enzyme, horseradish peroxidase, to generate a molecule called resorufin, which can absorb and emit red light, thus coloring the solution. The researchers could then tune the interferometers to look for the red resorufin molecules.

"The reaction happens in a one-to-one fashion: A molecule of glucose generates one molecule of resorufin," Pacifici said. "So we can count the number of resorufin molecules in the solution, and infer the number of glucose molecules that were originally present in solution."

The team tested its combination of dye chemistry and plasmonic interferometry by looking for glucose in artificial saliva, a mixture of water, salts and enzymes that resembles the real human saliva. They found that they could detect resorufin in real time with great accuracy and specificity. They were able to detect changes in glucose concentration of 0.1 micromoles per liter -- 10 times the sensitivity that can be achieved by interferometers alone.

The next step in the work, Pacifici says, is to start testing the method in real human saliva. Ultimately, the researchers hope they can develop a small, self-contained device that could give diabetics a noninvasive way to monitor their glucose levels.

There are other potential applications as well.

"We are now calibrating this device for insulin," Pacifici said, "but in principle we could properly modify this 'plasmonic cuvette' sensor for detection of any molecule of interest."

It could be used to detect toxins in air or water or used in the lab to monitor chemical reactions as they occur at the sensor surface in real time, Pacifici said.