Engineering researchers have developed a device the size of a wristwatch that can monitor an individual’s body chemistry to help improve athletic performance and identify potential health problems. The device can be used for everything from detecting dehydration to tracking athletic recovery, with applications ranging from military training to competitive sports.
“This technology allows us to test for a wide range of metabolites in almost real time,” says Michael Daniele, co-corresponding author of a paper on the work and an assistant professor of electrical and computer engineering at North Carolina State University and in the Joint Department of Biomedical Engineering at NC State and the University of North Carolina at Chapel Hill.
Metabolites are markers that can be monitored to assess an individual’s metabolism. So, if someone’s metabolite levels are outside of normal parameters, it could let trainers or health professionals know that something’s wrong. For athletes, it could also be used to help tailor training efforts to improve physical performance.
“For this proof-of-concept study, we tested sweat from human participants and monitored for glucose, lactate, pH and temperature,” Daniele says.
A replaceable strip on the back of the device is embedded with chemical sensors. That strip rests against a user’s skin, where it comes into contact with the user’s sweat. Data from the sensors in the strip are interpreted by hardware inside the device, which then records the results and relays them to a user’s smartphone or smartwatch.
“The device is the size of an average watch, but contains analytical equipment equivalent to four of the bulky electrochemistry devices currently used to measure metabolite levels in the lab,” Daniele says. “We’ve made something that is truly portable, so that it can be used in the field.”
While the work for this paper focused on measuring glucose, lactate and pH, the sensor strips could be customized to monitor for other substances that can be markers for health and athletic performance — such as electrolytes.
“We’re optimistic that this hardware could enable new technologies to reduce casualties during military or athletic training, by spotting health problems before they become critical,” Daniele says. “It could also improve training by allowing users to track their performance over time. For example, what combination of diet and other variables improves a user’s ability to perform?”
The researchers are now running a study to further test the technology when it is being worn by people under a variety of conditions.
“We want to confirm that it can provide continuous monitoring when in use for an extended period of time,” Daniele says.
“While it’s difficult to estimate what the device might cost consumers, it only costs tens of dollars to make. And the cost of the strips — which can last for at least a day — should be comparable to the glucose strips used by people with diabetes.
“We’re currently looking for industry partners to help us explore commercialization options for this technology,” Daniele says.
- Murat A. Yokus, Tanner Songkakul, Vladimir A. Pozdin, Alper Bozkurt, Michael A. Daniele. Wearable multiplexed biosensor system toward continuous monitoring of metabolites. Biosensors and Bioelectronics, 2020; 153: 112038 DOI: 10.1016/j.bios.2020.112038
Smart technology keeps getting smaller. There are smartphones, smartwatches and now, smart rings, devices that allow someone to use simple finger gestures to control other technology.
Researchers at the University of Washington have created AuraRing, a ring and wristband combination that can detect the precise location of someone’s index finger and continuously track hand movements. The ring emits a signal that can be picked up on the wristband, which can then identify the position and orientation of the ring — and the finger it’s attached to. The research team published these results Dec. 11 in Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies.
“We’re thinking about the next generation of computing platforms,” said co-lead author Eric Whitmire, who completed this research as a doctoral student at the Paul G. Allen School of Computer Science & Engineering. “We wanted a tool that captures the fine-grain manipulation we do with our fingers — not just a gesture or where your finger’s pointed, but something that can track your finger completely.”
AuraRing is composed of a coil of wire wrapped 800 times around a 3D-printed ring. A current running through the wire generates a magnetic field, which is picked up by three sensors on the wristband. Based on what values the sensors detect, the researchers can continuously identify the exact position of the ring in space. From there, they can determine where the user’s finger is located.
“To have continuous tracking in other smart rings you’d have to stream all the data using wireless communication. That part consumes a lot of power, which is why a lot of smart rings only detect gestures and send those specific commands,” said co-lead author Farshid Salemi Parizi, a doctoral student in electrical and computer engineering. “But AuraRing’s ring consumes only 2.3 milliwatts of power, which produces an oscillating magnetic field that the wristband can constantly sense. In this way, there’s no need for any communication from the ring to the wristband.”
With continuous tracking, AuraRing can pick up handwriting — potentially for short responses to text messages — or allow someone to have a virtual reality avatar hand that mimics what they’re doing with their actual hand. In addition, because AuraRing uses magnetic fields, it can still track hands even when they are out of sight, such as when a user is on a crowded bus and can’t reach their phone.
“We can also easily detect taps, flicks or even a small pinch versus a big pinch,” Salemi Parizi said. “This gives you added interaction space. For example, if you write ‘hello,’ you could use a flick or a pinch to send that data. Or on a Mario-like game, a pinch could make the character jump, but a flick could make them super jump.”
The researchers designed AuraRing to be ready to use as soon as it comes out of the box and not be dependent on a specific user. They tested the system on 12 participants with different hand sizes. The team compared the actual location of a participant’s finger to where AuraRing said it was. Most of the time, the system’s tracked location agreed with the actual location within a few millimeters.
This ring and wristband combination could be useful for more than games and smartphones, the team said.
“Because AuraRing continuously monitors hand movements and not just gestures, it provides a rich set of inputs that multiple industries could take advantage of,” said senior author Shwetak Patel, a professor in both the Allen School and the electrical and computer engineering department. “For example, AuraRing could detect the onset of Parkinson’s disease by tracking subtle hand tremors or help with stroke rehabilitation by providing feedback on hand movement exercises.”
The technology behind AuraRing is something that could be easily added to smartwatches and other wristband devices, according to the team.
“It’s all about super powers,” Salemi Parizi said. “You would still have all the capabilities that today’s smartwatches have to offer, but when you want the additional benefits, you just put on your ring.”
- Farshid Salemi Parizi, Eric Whitmire, Shwetak Patel. AuraRing. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, 2019; 3 (4): 1 DOI: 10.1145/3369831
The magnetic, conductive and optical properties of complex oxides make them key to components of next-generation electronics used for data storage, sensing, energy technologies, biomedical devices and many other applications.
Stacking ultrathin complex oxide single-crystal layers — those composed of geometrically arranged atoms — allows researchers to create new structures with hybrid properties and multiple functions. Now, using a new platform developed by engineers at the University of Wisconsin-Madison and the Massachusetts Institute of Technology, researchers will be able to make these stacked-crystal materials in virtually unlimited combinations.
The team published details of its advance Feb. 5 in the journal Nature.
Epitaxy is the process for depositing one material on top of another in an orderly way. The researchers’ new layering method overcomes a major challenge in conventional epitaxy — that each new complex oxide layer must be closely compatible with the atomic structure of the underlying layer. It’s sort of like stacking Lego blocks: The holes on the bottom of one block must align with the raised dots atop the other. If there’s a mismatch, the blocks won’t fit together properly.
“The advantage of the conventional method is that you can grow a perfect single crystal on top of a substrate, but you have a limitation,” says Chang-Beom Eom, a UW-Madison professor of materials science and engineering and physics. “When you grow the next material, your structure has to be the same and your atomic spacing must be similar. That’s a constraint, and beyond that constraint, it doesn’t grow well.”
A couple of years ago, a team of MIT researchers developed an alternate approach. Led by Jeehwan Kim, an associate professor in mechanical engineering and materials science and engineering at MIT, the group added an ultrathin intermediate layer of a unique carbon material called graphene, then used epitaxy to grow a thin semiconducting material layer atop that. Just one molecule thick, the graphene acts like a peel-away backing due to its weak bonding. The researchers could remove the semiconductor layer from the graphene. What remained was a freestanding ultrathin sheet of semiconducting material.
Eom, an expert in complex oxide materials, says they are intriguing because they have a wide range of tunable properties — including multiple properties in one material — that many other materials do not. So, it made sense to apply the peel-away technique to complex oxides, which are much more challenging to grow and integrate.
“If you have this kind of cut-and-paste growth and removal, combined with the different functionality of putting single-crystal oxide materials together, you have a tremendous possibility for making devices and doing science,” says Eom, who connected with mechanical engineers at MIT during a sabbatical there in 2014.
The Eom and Kim research groups combined their expertise to create ultrathin complex oxide single-crystal layers, again using graphene as the peel-away intermediate. More importantly, however, they conquered a previously insurmountable obstacle — the difference in crystal structure — in integrating different complex oxide materials.
“Magnetic materials have one crystal structure, while piezoelectric materials have another,” says Eom. “So you cannot grow them on top of each other. When you try to grow them, it just becomes messy. Now we can grow the layers separately, peel them off, and integrate them.”
In its research, the team demonstrated the efficacy of the technique using materials such as perovskite, spinel and garnet, among several others. They also can stack single complex oxide materials and semiconductors.
“This opens up the possibility for the study of new science, which has never been possible in the past because we could not grow it,” says Eom. “Stacking these was impossible, but now it is possible to imagine infinite combinations of materials. Now we can put them together.”
“Improving our understanding of the catalyst-intermediary-reaction relationship could greatly expand the possibilities of catalytic reactions,” said Harold Kung, Walter P. Murphy Professor of Chemical and Biological Engineering at the McCormick School of Engineering, who led the research. “By learning that a chemical reaction can proceed without direct contact with a catalyst, we open the door to using catalysts from earth-abundant elements to perform reactions they normally wouldn’t catalyze.”
The study, titled “Noncontact Catalysis: Initiation of Selective Ethylbenzene Oxidation by Au Cluster-Facilitated Cyclooctene Epoxidation,” was published January 31 in the journal Science Advances. Mayfair Kung, a research associate professor of chemical and biological engineering, was a co-corresponding author on the paper. Linda Broadbelt, Sarah Rebecca Roland Professor of Chemical and Biological Engineering and associate dean for research, also contributed to the study.
The research builds on previous work in which the team investigated the selective oxidation of cyclooctene—a type of hydrocarbon—using gold (Au) as a catalyst. The study revealed that the reaction was catalyzed by dissolved gold nanoclusters. Surprised, the researchers set out to investigate how well the gold clusters could catalyze selective oxidation of other hydrocarbons.
Using a platform they developed called Noncontact Catalysis System (NCCS), the researchers tested the effectiveness of a gold catalyst against ethylbenzene, an organic compound prevalent in the production of many plastics. While ethylbenzene did not undergo any reaction in the presence of the gold clusters, the team found that when the gold clusters reacted with the cyclooctene, the resulting molecule provided the necessary intermediary to produce ethylbenzene oxidation.
Understanding the various molecular interactions and structures that arise among surface water molecules would enable scientists and engineers to develop all sorts of novel hydrophobic/hydrophilic materials or improve existing ones. For example, the friction caused by water on ships could be reduced through materials engineering, leading to higher efficiency. Other applications include, but are not limited to, medical implants and anti-icing surfaces for airplanes. However, the phenomena that occur in surface water are so complicated that Tokyo University of Science, Japan, has established a dedicated research center, called “Water Frontier Science and Technology,” where various research groups tackle this problem from different angles (theoretical analysis, experimental studies, material development, and so on). Prof Takahiro Yamamoto leads a group of scientists at this center, and they try to solve this mystery through simulations of the microscopic structures, properties, and functions of water on the surface of materials.
For this study in particular, which was published in the Japanese Journal of Applied Physics, the researchers from Tokyo University of Science, in collaboration with researchers from the Science Solutions Division, Mizuho Information & Research Institute, Inc., focused on the interactions between water molecules and graphene, a charge-neutral carbon-based material that can be made atomically flat. “Surface water on carbon nanomaterials such as graphene has attracted much attention because the properties of these materials make them ideal for studying the microscopic structure of surface water,” explains Prof Yamamoto. It had been already pointed out in previous studies that water molecules on graphene tend to form stable polygonal (2D) shapes in both surface water and “free” water (water molecules away from the surface of the material). Moreover, it had been noted that the probability of finding these structures was drastically different in surface water than in free water. However, the differences between surface and free water have to be established, and the transition between the two is difficult to analyze using conventional simulation methods.
Considering this situation, the research team decided to combine a method taken from data science, called persistent homology (PH), with simulations of molecular dynamics. PH allows for the characterization of data structures, including those contained in images/graphics, but it can also be used in materials science to find stable 3D structures between molecules. “Our study represents the first time PH was used for a structural analysis of water molecules,” remarks Prof Yamamoto. With this strategy, the researchers were able to obtain a better idea of what happens to surface water molecules as more layers of water are added on top.
When a single layer of water molecules is laid on top of graphene, the water molecules align so that their hydrogen atoms form stable polygonal structures with different numbers of sides through hydrogen bonds. This “fixes” the orientation and relative position of these first-layer water molecules, which are now forming shapes parallel to the graphene layer. If a second layer of water molecules is added, the molecules from the first and second layers form 3D structures called tetrahedrons, which resemble a pyramid but with a triangular base. Curiously, these tetrahedrons are mostly pointing downwards (towards the graphene layer), because this orientation is “energetically favorable.” In other words, the order from the first layer translates to the second one to form these 3D structures with a consistent orientation. However, as a third and more layers are added, the tetrahedrons that form don’t necessarily point downwards and instead appear to be free to point in any direction, swayed by the surrounding forces. “These results confirm that the crossover between surface and free water occurs within only three layers of water,” explains Prof Yamamoto.
The researchers have provided a video of one of their simulations where these 2D and 3D structures are highlighted, allowing one to understand the full picture. “Our study is a good example of the application of modern data analysis techniques to gain new and important insights,” adds Prof Yamamoto. What’s more, these predictions should not be hard to measure experimentally on graphene through atomic-force microscopy techniques, which would, without a doubt, confirm the existence of these structures and further validate the combination of techniques used. Prof Yamamoto concludes: “Although graphene is a rather simple surface and we could expect more complicated water structures on other types of materials, our study provides a starting point for discussions of more realistic surface effects, and we expect it will lead to the control of surface properties.”
Bilingual children use as many words as monolingual children when telling a story, and demonstrate high levels of cognitive flexibility, according to new research by University of Alberta scientists.
“We found that the number of words that bilingual children use in their stories is highly correlated with their cognitive flexibility — the ability to switch between thinking about different concepts,” said Elena Nicoladis, lead author and professor in the Department of Psychology in the Faculty of Science. “This suggests that bilinguals are adept at using the medium of storytelling.”
Vocabulary is a strong predictor of school achievement, and so is storytelling. “These results suggest that parents of bilingual children do not need to be concerned about long-term school achievement, said Nicoladis. “In a storytelling context, bilingual kids are able to use this flexibility to convey stories in creative ways.”
The research examined a group of French-English bilingual children who have been taught two languages since birth, rather than learning a second language later in life. Results show that bilingual children used just as many words to tell a story in English as monolingual children. Participants also used just as many words in French as they did in English when telling a story.
Previous research has shown that bilingual children score lower than monolingual children on traditional vocabulary tests, meaning this results are changing our understanding of multiple languages and cognition in children.
“The past research is not surprising,” added Nicoladis. “Learning a word is related to how much time you spend in each language. For bilingual children, time is split between languages. So, unsurprisingly, they tend to have lower vocabularies in each of their languages. However, this research shows that as a function of storytelling, bilingual children are equally strong as monolingual children.”
This research used a new, highly sensitive measure for examining cognitive flexibility, examining a participant’s ability to switch between games with different rules, while maintaining accuracy and reaction time. This study builds on previous research examining vocabulary in bilingual children who have learned English as a second language.
Princeton researchers have uncovered new rules governing how objects absorb and emit light, fine-tuning scientists’ control over light and boosting research into next-generation solar and optical devices.
The discovery solves a longstanding problem of scale, where light’s behavior when interacting with tiny objects violates well-established physical constraints observed at larger scales.
“The kinds of effects you get for very small objects are different from the effects you get from very large objects,” said Sean Molesky, a postdoctoral researcher in electrical engineering and the study’s first author. The difference can be observed in moving from a molecule to a grain of sand. “You can’t simultaneously describe both things,” he said.
The problem stems from light’s famous shapeshifting nature. For ordinary objects, light’s movement can be described by straight lines, or rays. But for microscopic objects, light’s wave properties take over and the neat rules of ray optics break down. The effects are significant. In important modern materials, observations at the micron scale showed infrared light radiating at millions of times more energy per unit area than ray optics predicts.
The new rules, published in Physical Review Letters on Dec. 20, tell scientists how much infrared light an object of any scale can be expected to absorb or emit, resolving a decades-old discrepancy between big and small. The work extends a 19th-century concept, known as a blackbody, into a useful modern context. Blackbodies are idealized objects that absorb and emit light with maximum efficiency.
“There’s been a lot of research done to try to understand in practice, for a given material, how one can approach these blackbody limits,” said Alejandro Rodriguez, an associate professor of electrical engineering and the study’s principal investigator. “How can we make a perfect absorber? A perfect emitter?”
“It’s a very old problem that many physicists — including Planck, Einstein and Boltzmann — tackled early on and laid the foundations for the development of quantum mechanics.”
A large body of previous work has shown that structuring objects with nanoscale features can enhance absorption and emission, effectively trapping photons in a tiny hall of mirrors. But no one had defined the fundamental limits of the possible, leaving open major questions about how to assess a design.
No longer confined to brute-force trial and error, the new level of control will allow engineers to optimize designs mathematically for a wide range of future applications. The work is especially important in technologies like solar panels, optical circuits and quantum computers.
Currently, the team’s findings are specific to thermal sources of light, like the sun or like an incandescent bulb. But the researchers hope to generalize the work further to agree with other light sources, like LEDs, fireflies, or arcing bolts of electricity.
The research was supported in part by the National Science Foundation, the Cornell Center for Materials Research, the Defense Advanced Research Projects Agency and the National Science and Engineering Research Council of Canada.
A new study led by Simon Fraser University’s Dean of Science, Prof. Paul Kench, has discovered new evidence of sea-level variability in the central Indian Ocean.
The study, which provides new details about sea levels in the past, concludes that sea levels in the central Indian Ocean have risen by close to a meter in the last two centuries.
Prof. Kench says, “We know that certain types of fossil corals act as important recorders of past sea levels. By measuring the ages and the depths of these fossil corals, we are identifying that there have been periods several hundred years ago that the sea level has been much lower than we thought in parts of the Indian Ocean.”
He says understanding where sea levels have been historically, and what happens as they rise, will provide greater insights into how coral reefs systems and islands may be able to respond to the changes in sea levels in the future.
Underscoring the serious threat posed to coastal cities and communities in the region, the ongoing study, which began in 2017, further suggests that if such acceleration continues over the next century, sea levels in the Indian Ocean will have risen to their highest level ever in recorded history.
The solar wind that pummels the Earth’s dayside magnetosphere causes turbulence, like air over a wing. Physicists at Rice University have developed new methods to characterize how that influences space weather on the nightside.
It’s rarely quiet up there. The solar wind streams around the Earth and cruises off into the night, but closer to the planet, parcels of plasma get caught in the turbulence and sink back toward Earth. That turbulence causes big ripples in the plasma.
With the help of several spacecraft and computational tools developed over the past decade, Rice scientists led by space plasma physicist Frank Toffoletto can now assess the ripples, called buoyancy waves, caused by the turbulence.
These waves, or oscillations, have been observed in the thin layer of magnetic flux along the base of the plasma sheet that tails away from the planet’s nightside. The Rice theory is the first to quantify their motion.
The theory adds another element to the Rice Convection Model, an established, decades-in-the-making algorithm that helps scientists calculate how the inner and middle magnetosphere will react to events like solar storms that threaten satellites, communications and power grids on Earth.
The new paper in JGR Space Physics by Toffoletto, emeritus professor Richard Wolf and former graduate student Aaron Schutza starts by describing the bubbles — “bursty bulk flows” predicted by Wolf and Rice alumnus Duane Pontius in 1990 — that fall back toward Earth through the plasma tail.
Functionally, they’re the reverse of buoyant air bubbles that bob up and down in the atmosphere because of gravity, but the plasma bubbles respond to magnetic fields instead. The plasma bubbles lose most of their momentum by the time they touch down at the theoretical, filamentlike boundary between the inner plasma sheet and the protective plasmasphere.
That sets the braking boundary into a gentle oscillation, which lasts mere minutes before stabilizing again. Toffoletto compared the motion to a plucked guitar string that quickly returns to equilibrium.
“The fancy name for this is the eigenmode,” he said. “We’re trying to figure out the low-frequency eigenmodes of the magnetosphere. They haven’t been studied very much, though they appear to be associated with dynamic disruptions to the magnetosphere.”
Toffoletto said the Rice team has in recent years discovered through simulations that the magnetosphere doesn’t always respond in a linear fashion to the steady driving force of the solar wind.
“You get all kinds of wave modes in the system,” he said, explaining that bursty bulk flows are one such mode. “Every time one of these things come flying in, when they hit the inner region, they basically reach their equilibrium point and oscillate with a certain frequency. Finding that frequency is what this paper is all about.”
As measured by the THE MIS spacecraft, the periods of these waves are a few minutes and the amplitudes are often bigger than the Earth.
“Understanding the natural frequency of the system and how it behaves can tell us a lot about the physical properties of plasma on the night side, its transport and how it might be related to the aurora,” he said. “A lot of these phenomena show up in the ionosphere as auroral structures, and we don’t understand where these structures come from.”
Toffoletto said the models suggest buoyant waves may play a role in the formation of the ring current that consists of charged particles that flow around Earth as well as magnetospheric substorms, all of which are connected to the aurora.
He said that no more than a decade ago, many magnetosphere simulations “would look very uniform, kind of boring.” The Rice group is collaborating with the Applied Physics Laboratory to include the Rice Convection Model in a newly developed global magnetosphere code called “Gamera,” named after the fictional Japanese monster.
“Now, with such higher-resolution models and much better numerical methods, these structures are starting to show up in the simulations,” Toffoletto said. “This paper is one little piece of the puzzle we’re putting together of how the system behaves. All this plays a big role in understanding how space weather works and how that in turn impacts technology, satellites and ground-based systems.”
The Rice Convection Model itself was refreshed this month in a paper led by recent Rice alumnus Jian Yang, now an associate professor of Earth and space sciences at the Southern University of Science and Technology, Shenzhen, China.
Lithium-ion batteries are notorious for developing internal electrical shorts that can ignite a battery’s liquid electrolytes, leading to explosions and fires. Engineers at the University of Illinois have developed a solid polymer-based electrolyte that can self-heal after damage — and the material can also be recycled without the use of harsh chemicals or high temperatures.
The new study, which could help manufacturers produce recyclable, self-healing commercial batteries, is published in the Journal of the American Chemical Society.
As lithium-ion batteries go through multiple cycles of charge and discharge, they develop tiny, branchlike structures of solid lithium called dendrites, the researchers said. These structures reduce battery life, cause hotspots and electrical shorts, and sometimes grow large enough to puncture the internal parts of the battery, causing explosive chemical reactions between the electrodes and electrolyte liquids.
There has been a push by chemists and engineers to replace the liquid electrolytes in lithium-ion batteries with solid materials such as ceramics or polymers, the researchers said. However, many of these materials are rigid and brittle resulting in poor electrolyte-to-electrode contact and reduced conductivity.
“Solid ion-conducting polymers are one option for developing nonliquid electrolytes,” said Brian Jing, a materials science and engineering graduate student and study co-author. “But the high-temperature conditions inside a battery can melt most polymers, again resulting in dendrites and failure.”
Past studies have produced solid electrolytes by using a network of polymer strands that are cross-linked to form a rubbery lithium conductor. This method delays the growth of dendrites; however, these materials are complex and cannot be recovered or healed after damage, Jing said.
To address this issue, the researchers developed a network polymer electrolyte in which the cross-link point can undergo exchange reactions and swap polymer strands. In contrast to linear polymers, these networks actually get stiffer upon heating, which can potentially minimize the dendrite problem, the researchers said. Additionally, they can be easily broken down and resolidified into a networked structure after damage, making them recyclable, and they restore conductivity after being damaged because they are self-healing.
“This new network polymer also shows the remarkable property that both conductivity and stiffness increase with heating, which is not seen in conventional polymer electrolytes,” Jing said.
“Most polymers require strong acids and high temperatures to break down,” said materials science and engineering professor and lead author Christopher Evans. “Our material dissolves in water at room temperature, making it a very energy-efficient and environmentally friendly process.”
The team probed the conductivity of the new material and found its potential as an effective battery electrolyte to be promising, the researchers said, but acknowledge that more work is required before it could be used in batteries that are comparable to what is in use today.
“I think this work presents an interesting platform for others to test,” Evans said. “We used a very specific chemistry and a very specific dynamic bond in our polymer, but we think this platform can be reconfigured to be used with many other chemistries to tweak the conductivity and mechanical properties.”