Joshua Damien Cordle

New virtual reality-tested system shows promise in aiding navigation of people with blindness or low vision

A new study offers hope for people who are blind or have low vision (pBLV) through an innovative navigation system that was tested using virtual reality. The system, which combines vibrational and sound feedback, aims to help users navigate complex real-world environments more safely and effectively.

The research from NYU Tandon School of Engineering, published in JMIR Rehabilitation and Assistive Technology, advances work from John-Ross Rizzo, Maurizio Porfiri and colleagues toward developing a first-of-its-kind wearable system to help pBLV navigate their surroundings independently.

"Traditional mobility aids have key limitations that we want to overcome," said Fabiana Sofia Ricci, the paper's lead author and a Ph.D. candidate in NYU Tandon Department of Biomedical Engineering (BME) and NYU Tandon's Center for Urban Science + Progress (CUSP). "White canes only detect objects through contact and miss obstacles outside their range, while guide dogs require extensive training and are costly. As a result, only 2 to 8 percent of visually impaired Americans use either aid."

In this study, the research team miniaturized the earlier haptic feedback of its backpack-based system into a discreet belt equipped with 10 precision vibration motors. The belt's electronic components, including a custom circuit board and microcontroller, fit into a simple waist bag, a crucial step toward making the technology practical for real-world use.

The system provides two types of sensory feedback: vibrations through the belt indicate obstacle location and proximity, while audio beeps through a headset become more frequent as users approach obstacles in their path.

"We want to reach a point where the technology we're building is light, largely unseen and has all the necessary performance required for efficient and safe navigation," said Rizzo, who is an associate professor in NYU Tandon's BME department, associate director of NYU WIRELESS, affiliated faculty at CUSP and associate professor in the Department of Rehabilitation Medicine at NYU Grossman School of Medicine.

"The goal is something you can wear with any type of clothing, so people are not bothered in any way by the technology."

The researchers tested the technology by recruiting 72 participants with normal vision, who wore Meta Quest 2 VR headsets and haptic feedback belts while walking around NYU's Media Commons at 370 Jay Street in Downtown Brooklyn, an empty room with only side curtains.

Through their headsets, the participants experienced a virtual subway station as someone with advanced glaucoma would see it -- with reduced peripheral vision, blurred details, and altered color perception. The environment, created with Unity gaming software to match the room's exact dimensions, allowed the team to determine how well participants could navigate using the belt's vibrations and audio feedback when their vision was impaired.

"We worked with mobility specialists and NYU Langone ophthalmologists to design the VR simulation to accurately recreate advanced glaucoma symptoms," says Porfiri, the paper's senior author, CUSP Director and an Institute Professor in NYU Tandon's Departments of BME and Mechanical and Aerospace Engineering. "Within this environment, we included common transit challenges that visually impaired people face daily -- broken elevators, construction zones, pedestrian traffic, and unexpected obstacles."

Results showed that haptic feedback significantly reduced collisions with obstacles, while audio cues helped users move more smoothly through space. Future studies will involve individuals with actual vision loss.

The technology complements the functionality of Commute Booster, a mobile app being developed by a Rizzo-led team to provide pBLV navigation guidance inside subway stations. Commute Booster "reads" station signage and tells users where to go, while the haptic belt could help those users avoid obstacles along the way.

In December 2023, the National Science Foundation (NSF) awarded Rizzo, Porfiri, and a team of NYU colleagues a $5 million grant via its Convergence Accelerator, a program whose mission includes supporting the development of assistive and rehabilitative technologies. That grant, along with others from NSF, funded this research and also supports Commute Booster's development. In addition to Ricci, Rizzo and Porfiri, Lorenzo Liguori and Eduardo Palermo are the paper's authors, both from the Department of Mechanical and Aerospace Engineering of Sapienza University of Rome, Italy.

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Wireless, battery-free electronic 'stickers' gauge forces between touching objects

Engineers at the University of California San Diego have developed electronic "stickers" that measure the force exerted by one object upon another. The force stickers are wireless, run without batteries and fit in tight spaces. That makes them versatile for a wide range of applications, from arming robots with a sense of touch to elevating the immersive experience of VR and AR, making biomedical devices smarter, monitoring the safety of industrial equipment, and improving the accuracy and efficiency of inventory management in warehouses.

They could be used, for example, in knee implants to measure the forces that implants exert on the joint. Having the ability to sense changes in these forces can be useful for monitoring an implant's fit, as well as wear and tear. Force stickers could also be placed on the bottom of warehouse packages to measure the weight of their contents, acting as miniature scales for checking inventory.

"These force stickers could make technology more intelligent, interactive and intuitive," said Dinesh Bharadia, professor of electrical and computer engineering at the UC San Diego Jacobs School of Engineering. "Humans, by nature, possess an inherent ability to sense force. This allows us to interact seamlessly with our surroundings and enables clinicians to perform delicate surgical procedures. Providing this force-sensing ability to electronic devices and medical implants could be a game-changer for many industries."

A team led by Bharadia will present the new force stickers at the UbiComp 2023 conference, which will take place from Oct. 8 to 12 in Cancun, Mexico.

The force stickers consist of two main components. One is a tiny capacitor that is just a few millimeters thin and about the size of a grain of rice. The other component is a radiofrequency identification (RFID) sticker, which is a device that functions like a barcode that can be read wirelessly using radio signals. The researchers found a clever way to integrate these two components together so that they can measure the force applied by an object and communicate that information wirelessly to an RFID reader.

The capacitor is made of a soft polymer sheet sandwiched between two conductive copper strips. When an external force is applied, the polymer compresses, drawing the copper strips closer together, thereby increasing the electric charge in the capacitor.

This increase in electric charge as a result of applied force is key, the researchers show, because it creates changes in the signal transmitted by the RFID sticker. An RFID reader remotely measures these changes and translates them into a specific magnitude of applied force. This particular technique of creating changes in RFID signal enables the components within the force sticker to be miniaturized. In comparison, previous methods to create changes in RFID signal required components that are a thousand times larger in size.

Meanwhile, the RFID sticker runs on extremely low power by transmitting radio signals via a technique called backscattering. It takes incoming radio signals from an RFID reader, modifies the signals via electric changes induced by the capacitor, and then reflects the modified signals back to the reader, which deciphers and translates them into applied force.

As a result, the force stickers run on essentially no power. "The design is really simple with minimal electronics," said study first author Agrim Gupta, an electrical and computer engineering Ph.D. student in Bharadia's lab.

Another design feature is that the capacitor can be customized for various force ranges. By replacing the polymer layer with a softer or stiffer one, the capacitor can be tailored to measure smaller or larger forces, respectively.

To demonstrate, the researchers built and tested two types of force stickers. In one sticker, the capacitor was built with a super soft polymer to measure smaller forces, making it suitable for use in experiments in a model knee joint. Placed within the joint, the force sticker accurately measured different applied forces as the researchers pushed on the joint. The second sticker, in which the capacitor was constructed with a stiffer polymer, was tested in a warehouse packaging experiment. Attached to the underside of a box, it accurately measured the weight of varying quantities of objects placed in the box.

In tests, the force stickers were extremely durable. They withstood more than 10,000 force applications and remained consistently accurate. Additionally, they can be fabricated at low cost, with each sticker amounting to less than $2, the researchers noted.

"If we can commercialize this technology, we imagine that in the future a box of them could be sold inexpensively, like a box of Band-Aids," said Gupta.

However, it is worth noting a limitation: these force stickers require a static environment to function effectively and do not perform optimally in highly dynamic surroundings. The researchers are actively addressing this issue as they seek to further improve the technology.

Moving forward, the researchers aim to make the force stickers readable by smartphones, which would eliminate the need for RFID readers.

This work was supported in part by the National Science Foundation (grant 1935329).

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Materials provided by University of California - San Diego. Original written by Liezel Labios. Note: Content may be edited for style and length.

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Ultrathin nanotech promises to help tackle antibiotic resistance.

Researchers have invented a nano-thin superbug-slaying material that could one day be integrated into wound dressings and implants to prevent or heal bacterial infections.

The innovation -- which has undergone advanced pre-clinical trials -- is effective against a broad range of drug-resistant bacterial cells, including 'golden staph', which are commonly referred to as superbugs.

Antibiotic resistance is a major global health threat, causing about 700,000 deaths annually, a figure which could rise to 10 million deaths a year by 2050 without the development of new antibacterial therapies.

The new study led by RMIT University and the University of South Australia (UniSA) tested black phosphorus-based nanotechnology as an advanced infection treatment and wound healing therapeutic.

Results published in Advanced Therapeutics show it effectively treated infections, killing over 99% of bacteria, without damaging other cells in biological models.

The treatment achieved comparable results to an antibioticin eliminating infection and accelerated healing, with wounds closing by 80% over seven days.

The superbug-killing nanotechnology developed internationally by RMIT was rigorously tested in pre-clinical trials by wound-healing experts at UniSA. RMIT has sought patent protection for the black phosphorus flakes including its use in wound healing formulations, including gels.

RMIT co-lead researcher, Professor Sumeet Walia, said the study showed how their innovation provided rapid antimicrobial action, then self-decomposed after the threat of infection had been eliminated.

"The beauty of our innovation is that it is not simply a coating -- it can actually be integrated into common materials that devices are made of, as well as plastic and gels, to make them antimicrobial," said Walia from RMIT's School of Engineering.

A previous study led by RMIT revealed that black phosphorus was effective at killing microbes when spread in nano-thin layers on surfaces used to make wound dressings and implants such as cotton and titanium, or integrated into plastics used in medical instruments.

How the invention works

Black phosphorus is the most stable form of phosphorus -- a mineral that is naturally present in many foods -- and, in an ultra-thin form, degrades easily with oxygen, making it ideal for killing microbes.

"As the nanomaterial breaks down, its surface reacts with the atmosphere to produce what are called reactive oxygen species. These species ultimately help by ripping bacterial cells apart," Walia said.

The new study tested the effectiveness of nano-thin flakes of black phosphorus against five common bacteria strains, including E. coli and drug-resistant golden staph.

"Our antimicrobial nanotechnology rapidly destroyed more than 99% of bacterial cells -- significantly more than common treatments used to treat infections today."

The global war on superbugs

Co-lead researcher Dr Aaron Elbourne from RMIT said healthcare professionals around the world were in desperate need of new treatments to overcome the problem of antibiotic resistance.

"Superbugs -- the pathogens that are resistant to antibiotics -- are responsible for massive health burdens and as drug resistance grows, our ability to treat these infections becomes increasingly challenging," Elbourne, a Senior Research Fellow in RMIT's School of Science at RMIT, said.

"If we can make our invention a commercial reality in the clinical setting, these superbugs globally wouldn't know what hit them."

Treatment efficacy in preclinical models of wound infection

Lead researcher from UniSA, Dr Zlatko Kopecki, and his team performed the pre-clinical trials to show how daily topical application of the black phosphorus nanoflakes significantly reduced infection.

"This is exciting as the treatment was comparable to the ciprofloxacin antibiotic in eradicating wound infection and resulted in accelerated healing, with wounds closing by 80% over seven days," Dr Kopecki said.

Dr Kopecki, who is also a Channel 7 Children's Research Foundation Fellow in Childhood Wound Infections, said antibiotic treatments are becoming scarce.

"We urgently need to develop new alternative non-antibiotic approaches to treat and manage wound infection," he said.

"Black phosphorus seems to have hit the spot and we look forward to seeing the translation of this research towards clinical treatment of chronic wounds."

The team wants to collaborate with potential industry partners to develop and prototype the technology.

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Better cybersecurity with new material

Digital information exchange can be safer, cheaper and more environmentally friendly with the help of a new type of random number generator for encryption developed at Linköping University, Sweden. The researchers behind the study believe that the new technology paves the way for a new type of quantum communication.

In an increasingly connected world, cybersecurity is becoming increasingly important to protect not just the individual, but also, for example, national infrastructure and banking systems. And there is an ongoing race between hackers and those trying to protect information. The most common way to protect information is through encryption. So when we send emails, pay bills and shop online, the information is digitally encrypted.

To encrypt information, a random number generator is used, which can either be a computer programme or the hardware itself. The random number generator provides keys that are used to both encrypt and unlock the information at the receiving end.

Different types of random number generators provide different levels of randomness and thus security. Hardware is the much safer option as randomness is controlled by physical processes. And the hardware method that provides the best randomness is based on quantum phenomena -- what researchers call the Quantum Random Number Generator, QRNG.

"In cryptography, it's not only important that the numbers are random, but that you're the only one who knows about them. With QRNG's, we can certify that a large amount of the generated bits is private and thus completely secure. And if the laws of quantum physics are true, it should be impossible to eavesdrop without the recipient finding out," says Guilherme B Xavier, researcher at the Department of Electrical Engineering at Linköping University.

His research group, together with researchers at the Department of Physics, Chemistry and Biology (IFM), has developed a new type of QRNG, that can be used for encryption, but also for betting and computer simulations. The new feature of the Linköping researchers' QRNG is the use of light emitting diodes made from the crystal-like material perovskite.

Their random number generator is among the best produced and compares well with similar products. Thanks to the properties of perovskites, it has the potential to be cheaper and more environmentally friendly.

Feng Gao is a professor at IFM and has been researching perovskites for over a decade. He believes that the recent development of perovskite light emitting diodes (PeLEDs) means that there is an opportunity to revolutionise, for example, optical instruments.

"It's possible to use, for example, a traditional laser for QRNG, but it's expensive. If the technology is eventually to find its way into consumer electronics, it's important that the cost is kept down and that the production is as environmentally friendly as possible. In addition, PeLEDs don't require as much energy to run," says Feng Gao.

The next step is to develop the material further to make the perovskite lead-free and to extend its lifetime, which is currently 22 days. According to Guilherme B Xavier, their new QRNG could be available for use in cybersecurity within five years.

"It's an advantage if electronic components that are to be used for sensitive data are manufactured in Sweden. If you buy a complete randomness generator kit from another country, you can't be sure that it's not being monitored."

The study was funded by the Swedish Research Council, the Knut and Alice Wallenberg Foundation through the Wallenberg Centre for Quantum Technology and the European Research Council.

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Materials provided by Linköping University. Original written by Anders Törneholm. Note: Content may be edited for style and length.

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Scientists at Rice University in Houston, Texas have developed a fabric-based wearable device that "taps" a user's wrist with pressurized air, silently helping them navigate to their destination. The study, published August 29 in the journal Device, demonstrated that users correctly interpreted which direction the device was telling them to go an average of 87% of the time. Since the wearable embeds most of its control system within the fabric itself, using air instead of electronics, it can be built lighter and more compact than existing designs.

"We envision this device will be used by individuals who need or desire information to be transmitted to them privately and in a way that can be seamlessly integrated into clothing or other wearables," said Marcia O'Malley (@MarcieOMalley), Chair of the Department of Mechanical Engineering at Rice University and an author of the study.

The wearables may benefit amputees who use prosthetic limbs, people with hearing loss, and specialists such as surgeons, pilots, and soldiers who are inundated with visual and auditory information.

Visual and auditory cues like a flashing light on a dashboard or the ping of a new text message can effectively transmit information. However, many people are overwhelmed by such cues in their daily lives -- and with too many notifications conveyed the same way, information can get lost in the clutter. "Haptics," or touch-based stimuli, which include hot or cold sensations or cues based on pressure applied to the skin, can offer an alternative.

But while devices that produce visual cues or sounds are prevalent in everyday life, devices that use haptic cues are still uncommon since they usually require bulky hardware that weighs down the wearer.

To overcome this obstacle, the Rice University researchers developed a light, comfortable wearable device from textile materials that can be worn on a user's arm. The team tested the device by measuring forces applied to the user as a function of pressure and the shape of the wearable -- a task that proved somewhat challenging since different users had different experiences with cues from the same device, said Barclay Jumet (@JUMETkinmecrazy), a PhD candidate in mechanical engineering and the lead author of the study.

"Every person has a differently shaped arm, a different perception of what "feels good" in terms of the forces applied and the timing of the forces, and different capabilities in responding to the type of haptic cues we delivered," said Jumet. "Fortunately, our textile-based platform is easily tailorable and adjustable to a range of body types and sizes."

After testing the performance of their haptic textile sleeves in a lab-based study involving human participants, the researchers set out to see how well these devices could help users navigate in a real-world scenario. They integrated two of the sleeves into a shirt and completed the ensemble with a textile belt where they attached auxiliary components, making the device portable. Next, an experimenter sent cues to the user wearing the device, directing them where to walk for one kilometer.

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"We were impressed that the user was able to navigate the streets of Houston and subsequently trace 50-meter-long Tetris pieces on an open field with 100% accuracy in receiving and interpreting navigational haptic cues," said Daniel Preston (@ProfDanPreston), an assistant professor of mechanical engineering and the corresponding author of the study.

In another navigation test, the participant again interpreted the cues with total accuracy, this time while riding an electric scooter over paved bricks, concrete sidewalks, and graveled paths.

"Further development will seek to improve the ability to convey even more complex cues that remain easily and naturally discerned by the user," said Preston.

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Materials provided by Cell Press. Note: Content may be edited for style and length.

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Discovery of a fundamental law of friction leads to new materials that can minimize energy loss

Professor of Chemical and Biomolecular Engineering Elisa Riedo and her team have discovered a fundamental friction law that is leading to a deeper understanding of energy dissipation in friction and the design of two-dimensional materials capable of minimizing energy loss.

Friction is an everyday phenomenon; it allows drivers to stop their cars by breaking and dancers to execute complicated moves on various floor surfaces. It can, however, also be an unwanted effect that drives the waste of large amounts of energy in industrial processes, the transportation sector, and elsewhere. Tribologists-those who study the science of interacting surfaces in relative motion-have estimated that one-quarter of global energy losses are due to friction and wear.

While friction is extremely widespread and relevant in technology, the fundamental laws of friction are still obscure, and only recently have scientists been able to use advances in nanotechnology to understand, for example, the microscopic origin of da Vinci's law, which holds that frictional forces are proportional to the applied load.

Now, Riedo and her NYU Tandon postdoctoral researcher Martin Rejhon have found a new method to measure the interfacial shear between two atomic layers and discovered that this quantity is inversely related to friction, following a new law.

This work-conducted in collaboration with NYU Tandon graduate student Francesco Lavini, and colleagues from the International School for Advanced Studies, the International Center for Theoretical Physics in Trieste Italy, as well as Prague's Charles University-could lead to more efficient manufacturing processes, greener vehicles, and a generally more sustainable world.

"The interaction between a single atomic layer of a material and its substrate governs its electronic, mechanical, and chemical properties," Riedo explains, "so gaining insight into that topic is important, on both fundamental and technological levels, in finding ways to reduce the energy loss caused by friction."

The researchers studied bulk graphite and epitaxial graphene films grown with different stacking orders and twisting, measuring the hard-to-access interfacial transverse shear modulus of an atomic layer on a substrate. They discovered that the modulus (a measure of the material's ability to resist shear deformations and remain rigid) is largely controlled by the stacking order and the atomic layer-substrate interaction and demonstrated its importance in controlling and predicting sliding friction in supported two-dimensional materials. Their experiments showed a general reciprocal relationship between friction force per unit contact area and interfacial shear modulus for all the graphite structures they investigated.

Their 2022 paper, "Relation between interfacial shear and friction force in 2D materials" was published online in Nature Nanotechnology and was funded by the U.S. Department of Energy Office of Science and the U.S. Army Research Office.

"Our results can be generalized to other 2D materials as well," Riedo, who heads NYU Tandon's PicoForce Lab, asserts. "This presents a way to control atomic sliding friction and other interfacial phenomena, and has potential applications in miniaturized moving devices, the transportation industry, and other realms."

"Elisa's work is a great example of NYU Tandon's commitment to a more sustainable future," Dean Jelena Kovačević says, "and a testament to the research being done at our newly launched Sustainable Engineering Initiative, which focuses on tackling climate change and environmental contamination through a four-pronged approach we're calling AMRAd, for Avoidance, Mitigation, Remediation and Adaptation."

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Can your phone tell if a bridge is in good shape?

A new study suggests mobile data collected while traveling over bridges could help evaluate their integrity.

Want to know if the Golden Gate Bridge is holding up well? There could be an app for that.

A new study involving MIT researchers shows that mobile phones placed in vehicles, equipped with special software, can collect useful structural integrity data while crossing bridges. In so doing, they could become a less expensive alternative to sets of sensors attached to bridges themselves.

"The core finding is that information about structural health of bridges can be extracted from smartphone-collected accelerometer data," says Carlo Ratti, director of the MIT Sensable City Laboratory and co-author of a new paper summarizing the study's findings.

The research was conducted, in part, on the Golden Gate Bridge itself. The study showed that mobile devices can capture the same kind of information about bridge vibrations that stationary sensors compile. The researchers also estimate that, depending on the age of a road bridge, mobile-device monitoring could add from 15 percent to 30 percent more years to the structure's lifespan.

"These results suggest that massive and inexpensive datasets collected by smartphones could play an important role in monitoring the health of existing transportation infrastructure," the authors write in their new paper.

The study, "Crowdsourcing Bridge Vital Signs with Smartphone Vehicle Trips," is being published in Nature Communications Engineering.

The authors are Thomas J. Matarazzo, an assistant professor of civil and mechanical engineering at the United States Military Academy at West Point; Daniel Kondor, a postdoc at the Complexity Science Hub in Vienna; Sebastiano Milardo, a researcher at the Senseable City Lab; Soheil S. Eshkevari, a senior research scientist at DiDi Labs and a former member of Senseable City Lab; Paolo Santi, principal research scientist at the Senseable City Lab and research director at the Italian National Research Council; Shamim N. Pakzad, a professor and chair of the Department of Civil and Environmental Engineering at Lehigh University; Markus J. Buehler, the Jerry McAfee Professor in Engineering and professor of civil and environmental engineering and of mechanical engineering at MIT; and Ratti, who is also professor of the practice in MIT's Department of Urban Studies and Planning.

Bridges naturally vibrate, and to study the essential "modal frequencies" of those vibrations in many directions, engineers typically place sensors, such as accelerometers, on bridges themselves. Changes in the modal frequencies over time may indicate changes in a bridge's structural integrity.

To conduct the study, the researchers developed an Android-based mobile phone application to collect accelerometer data when the devices were placed in vehicles passing over the bridge. They could then see how well those data matched up with data record by sensors on bridges themselves, to see if the mobile-phone method worked.

"In our work, we designed a methodology for extracting modal vibration frequencies from noisy data collected from smartphones," Santi says. "As data from multiple trips over a bridge are recorded, noise generated by engine, suspension and traffic vibrations, [and] asphalt, tend to cancel out, while the underlying dominant frequencies emerge."

In the case of the Golden Gate Bridge, the researchers drove over the bridge 102 times with their devices running, and the team used 72 trips by Uber drivers with activated phones as well. The team then compared the resulting data to that from a group of 240 sensors that had been placed on the Golden Gate Bridge for three months.

The outcome was that the data from the phones converged with that from the bridge's sensors; for 10 particular types of low-frequency vibrations engineers measure on the bridge, there was a close match, and in five cases, there was no discrepancy between the methods at all.

"We were able to show that many of these frequencies correspond very accurately to the prominent modal frequencies of the bridge," Santi says.

However, only 1 percent of all bridges in the U.S. are suspension bridges. About 41 percent are much smaller concrete span bridges. So, the researchers also examined how well their method would fare in that setting.

To do so, they studied a bridge in Ciampino, Italy, comparing 280 vehicle trips over the bridge to six sensors that had been placed on the bridge for seven months. Here, the researchers were also encouraged by the findings, though they found up to a 2.3 percent divergence between methods for certain modal frequencies over all 280 trips, and a 5.5 percent divergence over a smaller sample. That suggests a larger volume of trips could yield more useful data.

"Our initial results suggest that only a [modest amount] of trips over the span of a few weeks are sufficient to obtain useful information about bridge modal frequencies," Santi says.

Looking at the method as a whole, Buehler observes, "Vibrational signatures are emerging as a powerful tool to assess properties of large and complex systems, ranging from viral properties of pathogens to structural integrity of bridges as shown in this study. It's a universal signal found widely in the natural and built environment that we're just now beginning to explore as a diagnostic and generative tool in engineering."

As Ratti acknowledges, there are ways to refine and expand the research, including accounting for the effects of the smartphone mount in the vehicle, the influence of the vehicle type on the data, and more.

"We still have work to do, but we believe that our approach could be scaled up easily -- all the way to the level of an entire country," Ratti says. "It might not reach the accuracy that one can get using fixed sensors installed on a bridge, but it could become a very interesting early-warning system. Small anomalies could then suggest when to carry out further analyses."

The researchers received support from Anas S.p.A., Allianz, Brose, Cisco, Dover Corporation, Ford, the Amsterdam Institute for Advanced Metropolitan Solutions, the Fraunhofer Institute, the former Kuwait-MIT Center for Natural Resources and the Environment, Lab Campus, RATP, Singapore-MIT Alliance for Research and Technology (SMART), SNCF Gares & Connexions, UBER, and the U.S. Department of Defense High-Performance Computing Modernization Program.

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Materials provided by Massachusetts Institute of Technology. Original written by Peter Dizikes. Note: Content may be edited for style and length.

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Magnetic molecules on surfaces: Advances and challenges in molecular nanoscience

In the field of molecular magnetism, the design of devices with technological applications at the nanoscale -- quantum computing, molecular spintronics, magnetic cooling, nanomedicine, high-density information storage, etc. -- requires those magnetic molecules that are placed on the surface to preserve their structure, functionality and properties. Now, a paper published in the journal Coordination Chemistry Reviews analyses the most updated knowledge on the processes of deposition and organization of magnetic molecules on surfaces (nanostructuring), a determining process for the progress of technologies that involve a miniaturisation of engines and a more efficient functioning in nanometric dimensions.

The study -- signed by the researchers Carolina Sañudo, Guillem Gabarró-Riera and Guillem Aromí, from the Group of Magnetism and Functional Molecules of the Faculty of Chemistry and the Institute of Nanosciences and Nanotechnology of the University of Barcelona (IN2UB) -- describes the global scenario of the progress of the research in this field, and it proposes new ways to make advances in the organization in two dimensions (2D) of magnetic molecules, regarding its technological applications.

The article includes recommendations to select the best deposition method for each molecule, a review of the used surfaces in these processes, apart from guidelines for an effective characterization and future perspectives based on bidimensional materials. Moreover, the authors provide a new critical perspective on how, in a near future, to reach the effective application of the molecular systems in a device to get a faster technology using less energy.

Molecular nanoscience and magnetic materials

In the process to select the top deposition method on surfaces for each magnetic molecule, we have to consider each molecule and its structure, as well as the surface and structure it has. "The selection of the top method depends on the system, but it will always be possible to find a proper combination to deposit the molecular systems," notes the lecturer Carolina Sañudo, from the Department of Inorganic and Organic Chemistry of the UB.

"The protocols vary in each case and the first step is to determine the desired characteristics of the surface," she continues. "For example, if we want to study spintronics, we will need a conducting surface. Once the surface and its nature have been determined, it is essential to determine the shape anisotropy of the molecule while looking at its crystalline structure, its properties -- can it sublimate? can it dissolve? in which solvents? -- and potential anchor points -- does it have functional groups that allow chemisorption, and if it doesn't, what are the options for physisorption? If not, what are the physisorption options? Once we have all these details, we can design a deposition protocol. For example, if our molecule has an available sulphur group, we can anchor it by chemisorption to a gold (Au) surface. If the molecule can undergo sublimation, we can do it by evaporation," she concludes.

Smaller and more efficient electronic devices

The synthesis of new molecules with better properties is an unstoppable process, "but stability does not always go hand in hand with magnetic properties. Right now, the molecule with the highest blocking temperature T -- below which the molecule behaves like a magnet -- is extremely unstable. In particular, it is an organometallic compound and this makes it very difficult (or impossible) to place it on the surface or use it in a technological device."

To improve the design of magnetic molecules and obtain more efficient surface deposition processes, the stability of new organometallic monomolecular magnets (SMMs) has to be improved if they are to be used effectively. On the other hand, magnetic molecules that are not so good SMMs or that are quantum bits (qubits), or molecules that have spin-allowed electronic transitions, have features that make them very difficult to use -- due to lack of or little anisotropy in their shape or multiple anchoring functional groups that make diverse depositions of the molecule on the surface possible.

"To avoid this, it is necessary to advance the organisation of D2 molecules. For example, by forming two-dimensional organometallic materials (MOFs) in which the nodule is the molecule, and depositing the nanolayers that are already implicitly ordered on a surface. A 2D MOF, where each nodule is a qubit, would allow us to obtain an array of ordered qubits on a surface. This is a very important challenge and some groups like ours are working on it," the researcher says.

Reducing the energy consumption of technological devices is another goal of surface deposition technology. "The designed devices -- she continues -- can have very low power consumption if we have a device that stores information in SMM, or we use qubits in a perfectly ordered 2D matrix, or a system with spin-enabled electronically transition -- enabled molecules on a surface by molecular spintronics. In addition, they would be faster and more miniaturised than current devices."

In this field, the synthesis of inorganic compounds has generated magnet molecules that can function at temperatures around liquid nitrogen, "and this has been a major breakthrough," says the researcher. Technologies such as tunnelling microscopy (STM) and atomic force microscopy (AFM) with functionalised tips are the techniques that have made it possible to identify the position of the molecules on the surface. In particular, AFM with functionalised tips can become a very useful technique to characterise surface molecules.

"The discovery that a magnesium oxide (MgO) layer of a few nanometres is needed to decouple the molecule from the surface to maintain the molecular properties once the molecule is deposited is a major breakthrough. It is also worth mentioning the coating of large surface areas by monolayers of molecules with a high percentage of order, since the arrangement of the molecule on the surface in different ways can produce different interactions and, therefore, cause not all molecules to maintain their properties. These two points are crucial for the future development of devices based on the use of molecules deposited on surfaces," says Carolina Sañudo.

Magnetic molecules: future challenges

For now, obtaining SMMs at elevated temperatures, or synthesising qubits with longer relaxation times (T1) and coherence times (T2) that facilitate use in larger devices, is a challenge for chemists. Being able to obtain large areas coated with monolayers of equal and ordered molecules will also represent a very relevant progress, and this challenge includes characterisation. For this reason, the application of synchrotron light techniques -- such as GIXRD, HAXPES and XMCD -- will be essential.

"In order to achieve this order of the molecules on the surface, the UB Group of Magnetism and Functional Molecules is considering using 2D MOFs, i.e. coordination polymers that extend in two dimensions and are made up of extremely thin layers stacked by Van der Waals forces. Our team also wants to address other challenges, such as measuring the T1 and T2 relaxation times for a qubit deposited on a surface and confirming that they maintain (or improve) the measured values," the researcher concludes.

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Materials provided by University of Barcelona. Note: Content may be edited for style and length.

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Quantum dots form ordered material

Quantum dots are clusters of some 1,000 atoms which act as one large 'super-atom'. It is possible to accurately design the electronic properties of these dots just by changing their size. However, to create functional devices, a large number of dots have to be combined into a new material. During this process, the properties of the dots are often lost. Now, a team led by University of Groningen professor of Photophysics and Optoelectronics, Maria Antonietta Loi, has succeeded in making a highly conductive optoelectronic metamaterial through self-organization. The metamaterial is described in the journal Advanced Materials, published on 29 October.

Quantum dots of PbSe (lead selenide) or PbS (lead sulphide) can convert shortwave infrared light into an electrical current. This is a useful property for making detectors, or a switch for telecommunications. 'However, a single dot does not make a device. And when dots are combined, the assembly often loses the unique optical properties of individual dots, or, if they do maintain them, their capacity to transport charge carriers becomes very poor', explains Loi. 'This is because it is difficult to create an ordered material from the dots.'

Ordered layer

Working with colleagues from the Zernike Institute for Advanced Materials at the Faculty of Science and Engineering, University of Groningen, Loi experimented with a method that allows the production of a metamaterial from a colloidal solution of quantum dots. These dots, each about five to six nanometres in size, show a very high conductivity when assembled in an ordered array, while maintaining their optical properties.

'We knew from the literature that dots can self-organize into a two-dimensional, ordered layer. We wanted to expand this to a 3D material', says Loi. To achieve this, they filled small containers with a liquid that acted as a 'mattress' for the colloidal quantum dots. 'By injecting a small amount onto the surface of the liquid, we created a 2D material. Then, adding a bigger volume of quantum dots turned out to produce an ordered 3D material.'

Superlattice

The dots are not submersed in the liquid, but self-orient on the surface to achieve a low energy state. 'The dots have a truncated cubic shape, and when they are put together, they form an ordered structure in three dimensions; a superlattice, where the dots act like atoms in a crystal', explains Loi. This superlattice that is composed by the quantum dot super atoms displays the highest electron mobility reported for quantum dot assemblies.

Detectors

It took special equipment to ascertain what the new metamaterial looks like. The team used an electron microscope which has atomic resolution to show the details of the material. They also 'imaged' the large-scale structure of the material using a technique called Grazing-incidence small-angle X-ray scattering. 'Both techniques are available at the Zernike Institute, thanks to my colleagues Bart Kooi and Giuseppe Portale, respectively, which was a great help', says Loi.

Measurements of the electronic properties of the material show that it closely resembles that of a bulk semiconductor, but with the optical properties of the dots. Thus, the experiment paves the way to create new metamaterials based on quantum dots. The sensitivity of the dots used in the present study to infrared light could be used to create optical switches for telecommunication devices. 'And they might also be used in infrared detectors for night-vision and autonomous driving.'

ERC Grant

Loi is extremely pleased with the results of the experiments: 'People have been dreaming of achieving this since the 1980s. That is how long attempts have been made to assemble quantum dots into functional materials. The control of the structure and the properties we have achieved was beyond our wildest expectations.' Loi is now working on understanding and improving the technology to build extended superlattices from quantum dots, but is also planning to do so with other building blocks, for which she was recently awarded an Advanced Grant from the European Research Council. 'Our next step is to improve the technique in order to make the materials more perfect and fabricate photodetectors with them.'

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Electron microscope images of ordered structures

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Scientists discover material that can be made like a plastic but conducts like metal

Breakthrough could point way to new class of materials for electronics, devices

Scientists with the University of Chicago have discovered a way to create a material that can be made like a plastic, but conducts electricity more like a metal.

The research, published Oct. 26 in Nature, shows how to make a kind of material in which the molecular fragments are jumbled and disordered, but can still conduct electricity extremely well.

This goes against all of the rules we know about for conductivity -- to a scientist, it's kind of seeing a car driving on water and still going 70 mph. But the finding could also be extraordinarily useful; if you want to invent something revolutionary, the process often first starts with discovering a completely new material.

"In principle, this opens up the design of a whole new class of materials that conduct electricity, are easy to shape, and are very robust in everyday conditions," said John Anderson, an associate professor of chemistry at the University of Chicago and the senior author on the study. "Essentially, it suggests new possibilities for an extremely important technological group of materials," said Jiaze Xie (PhD'22, now at Princeton), the first author on the paper.

'There isn't a solid theory to explain this'

Conductive materials are absolutely essential if you're making any kind of electronic device, whether it be an iPhone, a solar panel, or a television. By far the oldest and largest group of conductors is the metals: copper, gold, aluminum. Then, about 50 years ago, scientists were able to create conductors made out of organic materials, using a chemical treatment known as "doping," which sprinkles in different atoms or electrons through the material. This is advantageous because these materials are more flexible and easier to process than traditional metals, but the trouble is they aren't very stable; they can lose their conductivity if exposed to moisture or if the temperature gets too high.

But fundamentally, both of these organic and traditional metallic conductors share a common characteristic. They are made up of straight, closely packed rows of atoms or molecules. This means that electrons can easily flow through the material, much like cars on a highway. In fact, scientists thought a material had to have these straight, orderly rows in order to conduct electricity efficiently.

Then Xie began experimenting with some materials discovered years ago, but largely ignored. He strung nickel atoms like pearls into a string of of molecular beads made of carbon and sulfur, and began testing.

To the scientists' astonishment, the material easily and strongly conducted electricity. What's more, it was very stable. "We heated it, chilled it, exposed it to air and humidity, and even dripped acid and base on it, and nothing happened," said Xie. That is enormously helpful for a device that has to function in the real world.

But to the scientists, the most striking thing was that the molecular structure of the material was disordered. "From a fundamental picture, that should not be able to be a metal," said Anderson. "There isn't a solid theory to explain this."

Xie, Anderson, and their lab worked with other scientists around the university to try to understand how the material can conduct electricity. After tests, simulations, and theoretical work, they think that the material forms layers, like sheets in a lasagna. Even if the sheets rotate sideways, no longer forming a neat lasagna stack, electrons can still move horizontally or vertically -- as long as the pieces touch.

The end result is unprecedented for a conductive material. "It's almost like conductive Play-Doh -- you can smush it into place and it conducts electricity," Anderson said.

The scientists are excited because the discovery suggests a fundamentally new design principle for electronics technology. Conductors are so important that virtually any new development opens up new lines for technology, they explained.

One of the material's attractive characteristics is new options for processing. For example, metals usually have to be melted in order to be made into the right shape for a chip or device, which limits what you can make with them, since other components of the device have to be able to withstand the heat needed to process these materials.

The new material has no such restriction because it can be made at room temperatures. It can also be used where the need for a device or pieces of the device to withstand heat, acid or alkalinity, or humidity has previously limited engineers' options to develop new technology.

The team is also exploring the different forms and functions the material might make. "We think we can make it 2-D or 3-D, make it porous, or even introduce other functions by adding different linkers or nodes," said Xie.

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Materials provided by University of Chicago. Original written by Louise Lerner. Note: Content may be edited for style and length.

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Illustration of the structure of the material

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Would traffic noise from future flying cars cause stress?

Researchers from Nagoya University and Keio University in Japan have estimated a person's stress levels caused by the sound of a flying car passing overhead. The research was published in the Technical Journal of Advanced Mobility in September 2022.

The drone market is booming, as several automobile companies and start-ups develop new personal aircraft. The long-awaited flying car, made famous in films like Blade Runner, may soon be a common sight in cities around the world. But while the automobile industry is busy developing technology to catch up to fantasy, few inventors or science fiction authors have thought much about how noise from the roaring and whirring of flying car engines might affect people's psychological state. Professor Susumu Hara of the Department of Aerospace Engineering, Graduate School of Engineering at Nagoya University, the lead author of the study, points out that in past industrial revolutions, people often prioritized technological advancement and economic demands over social and environmental issues, including noise and air pollution. "Unless technology is well-integrated in our daily lives," he argues, "we cannot expect it to make our society a better place." Therefore, his team conducted an experiment to estimate people's stress levels as if they were living in a world with flying cars.

In the research experiment, participants watched short videos that simulated cars flying in a city. The videos were designed so that the viewers felt like a car was flying 15 meters above them at a speed of 15.5 miles per hour (25 km per hour). To simulate such a scene, the videos used audio recordings of an industrial drone flying at a speed and height similar to the flying car depicted in the videos. Participants watched the video eight times, while the researchers changed the volume of the audio in each viewing to examine how the noise level would affect the participants. Participants' stress levels were assessed using two different measures. First, while watching the videos, a portable EEG device, called a Kansei Analyzer, recorded their brain activity. Second, after watching each video, the participants responded to a written questionnaire.

The researchers found that each person's self-reported stress level corresponded to the noise level of the flying car. As the noise increased, the participants reported greater stress. When the noise level decreased, they reported lower stress levels. However, brain activity data showed a different pattern. As predicted, when the noise level increased for the first time in the experiment, the EEG data showed higher levels of stress among the participants. But once the participants were exposed to loud noise, their stress levels did not decrease -- even after the noise level dropped. This may suggest that while most people think they can become accustomed to loud noise, it may actually be causing them stress without noticing it. To protect the health of residents, it is important to consider the long-term effects of exposure to chronic loud traffic noise in a world where flying cars are constantly landing, taking off, and whizzing above us. In addition to a self-reported assessment, checking brain activity might also be necessary to measure stress from noise.

When considering flying cars, an obvious solution is for aerospace engineers to prioritize making them quieter. But for now, we do not know how to determine the optimal sound level for protecting citizens' health. The researchers in this study hope that their measurement methods can help answer such questions.

"I am sure drones and flying cars will bring significant benefits to our society," said Professor Hara. At the same time, the study clearly shows that we cannot neglect noise pollution. "We believe that developing guidelines and regulations on flying cars is important so that we can better adapt them to our lives," he continued. "I hope this study provides some clues how to do that."

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

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New computing architecture: Deep learning with light

A new method uses optics to accelerate machine-learning computations on smart speakers and other low-power connected devices

Ask a smart home device for the weather forecast, and it takes several seconds for the device to respond. One reason this latency occurs is because connected devices don't have enough memory or power to store and run the enormous machine-learning models needed for the device to understand what a user is asking of it. The model is stored in a data center that may be hundreds of miles away, where the answer is computed and sent to the device.

MIT researchers have created a new method for computing directly on these devices, which drastically reduces this latency. Their technique shifts the memory-intensive steps of running a machine-learning model to a central server where components of the model are encoded onto light waves.

The waves are transmitted to a connected device using fiber optics, which enables tons of data to be sent lightning-fast through a network. The receiver then employs a simple optical device that rapidly performs computations using the parts of a model carried by those light waves.

This technique leads to more than a hundredfold improvement in energy efficiency when compared to other methods. It could also improve security, since a user's data do not need to be transferred to a central location for computation.

This method could enable a self-driving car to make decisions in real-time while using just a tiny percentage of the energy currently required by power-hungry computers. It could also allow a user to have a latency-free conversation with their smart home device, be used for live video processing over cellular networks, or even enable high-speed image classification on a spacecraft millions of miles from Earth.

"Every time you want to run a neural network, you have to run the program, and how fast you can run the program depends on how fast you can pipe the program in from memory. Our pipe is massive -- it corresponds to sending a full feature-length movie over the internet every millisecond or so. That is how fast data comes into our system. And it can compute as fast as that," says senior author Dirk Englund, an associate professor in the Department of Electrical Engineering and Computer Science (EECS) and member of the MIT Research Laboratory of Electronics.

Joining Englund on the paper is lead author and EECS grad student Alexander Sludds; EECS grad student Saumil Bandyopadhyay, Research Scientist Ryan Hamerly, as well as others from MIT, the MIT Lincoln Laboratory, and Nokia Corporation. The research will be published in Science.

Lightening the load

Neural networks are machine-learning models that use layers of connected nodes, or neurons, to recognize patterns in datasets and perform tasks, like classifying images or recognizing speech. But these models can contain billions of weight parameters, which are numeric values that transform input data as they are processed. These weights must be stored in memory. At the same time, the data transformation process involves billions of algebraic computations, which require a great deal of power to perform.

The process of fetching data (the weights of the neural network, in this case) from memory and moving them to the parts of a computer that do the actual computation is one of the biggest limiting factors to speed and energy efficiency, says Sludds.

"So our thought was, why don't we take all that heavy lifting -- the process of fetching billions of weights from memory -- move it away from the edge device and put it someplace where we have abundant access to power and memory, which gives us the ability to fetch those weights quickly?" he says.

The neural network architecture they developed, Netcast, involves storing weights in a central server that is connected to a novel piece of hardware called a smart transceiver. This smart transceiver, a thumb-sized chip that can receive and transmit data, uses technology known as silicon photonics to fetch trillions of weights from memory each second.

It receives weights as electrical signals and imprints them onto light waves. Since the weight data are encoded as bits (1s and 0s) the transceiver converts them by switching lasers; a laser is turned on for a 1 and off for a 0. It combines these light waves and then periodically transfers them through a fiber optic network so a client device doesn't need to query the server to receive them.

"Optics is great because there are many ways to carry data within optics. For instance, you can put data on different colors of light, and that enables a much higher data throughput and greater bandwidth than with electronics," explains Bandyopadhyay.

Trillions per second

Once the light waves arrive at the client device, a simple optical component known as a broadband "Mach-Zehnder" modulator uses them to perform super-fast, analog computation. This involves encoding input data from the device, such as sensor information, onto the weights. Then it sends each individual wavelength to a receiver that detects the light and measures the result of the computation.

The researchers devised a way to use this modulator to do trillions of multiplications per second, which vastly increases the speed of computation on the device while using only a tiny amount of power.

"In order to make something faster, you need to make it more energy efficient. But there is a trade-off. We've built a system that can operate with about a milliwatt of power but still do trillions of multiplications per second. In terms of both speed and energy efficiency, that is a gain of orders of magnitude," Sludds says.

They tested this architecture by sending weights over an 86-kilometer fiber that connects their lab to MIT Lincoln Laboratory. Netcast enabled machine-learning with high accuracy -- 98.7 percent for image classification and 98.8 percent for digit recognition -- at rapid speeds.

"We had to do some calibration, but I was surprised by how little work we had to do to achieve such high accuracy out of the box. We were able to get commercially relevant accuracy," adds Hamerly.

Moving forward, the researchers want to iterate on the smart transceiver chip to achieve even better performance. They also want to miniaturize the receiver, which is currently the size of a shoe box, down to the size of a single chip so it could fit onto a smart device like a cell phone.

The research is funded, in part, by NTT Research, the National Science Foundation, the Air Force Office of Scientific Research, the Air Force Research Laboratory, and the Army Research Office.

Story Source:

Materials provided by Massachusetts Institute of Technology. Original written by Adam Zewe. Note: Content may be edited for style and length.

Journal Reference:

New computing architecture: Deep learning with light

A new method uses optics to accelerate machine-learning computations on smart speakers and other low-power connected devices

Ask a smart home device for the weather forecast, and it takes several seconds for the device to respond. One reason this latency occurs is because connected devices don't have enough memory or power to store and run the enormous machine-learning models needed for the device to understand what a user is asking of it. The model is stored in a data center that may be hundreds of miles away, where the answer is computed and sent to the device.

MIT researchers have created a new method for computing directly on these devices, which drastically reduces this latency. Their technique shifts the memory-intensive steps of running a machine-learning model to a central server where components of the model are encoded onto light waves.

The waves are transmitted to a connected device using fiber optics, which enables tons of data to be sent lightning-fast through a network. The receiver then employs a simple optical device that rapidly performs computations using the parts of a model carried by those light waves.

This technique leads to more than a hundredfold improvement in energy efficiency when compared to other methods. It could also improve security, since a user's data do not need to be transferred to a central location for computation.

This method could enable a self-driving car to make decisions in real-time while using just a tiny percentage of the energy currently required by power-hungry computers. It could also allow a user to have a latency-free conversation with their smart home device, be used for live video processing over cellular networks, or even enable high-speed image classification on a spacecraft millions of miles from Earth.

"Every time you want to run a neural network, you have to run the program, and how fast you can run the program depends on how fast you can pipe the program in from memory. Our pipe is massive -- it corresponds to sending a full feature-length movie over the internet every millisecond or so. That is how fast data comes into our system. And it can compute as fast as that," says senior author Dirk Englund, an associate professor in the Department of Electrical Engineering and Computer Science (EECS) and member of the MIT Research Laboratory of Electronics.

Joining Englund on the paper is lead author and EECS grad student Alexander Sludds; EECS grad student Saumil Bandyopadhyay, Research Scientist Ryan Hamerly, as well as others from MIT, the MIT Lincoln Laboratory, and Nokia Corporation. The research will be published in Science.

Lightening the load

Neural networks are machine-learning models that use layers of connected nodes, or neurons, to recognize patterns in datasets and perform tasks, like classifying images or recognizing speech. But these models can contain billions of weight parameters, which are numeric values that transform input data as they are processed. These weights must be stored in memory. At the same time, the data transformation process involves billions of algebraic computations, which require a great deal of power to perform.

The process of fetching data (the weights of the neural network, in this case) from memory and moving them to the parts of a computer that do the actual computation is one of the biggest limiting factors to speed and energy efficiency, says Sludds.

"So our thought was, why don't we take all that heavy lifting -- the process of fetching billions of weights from memory -- move it away from the edge device and put it someplace where we have abundant access to power and memory, which gives us the ability to fetch those weights quickly?" he says.

The neural network architecture they developed, Netcast, involves storing weights in a central server that is connected to a novel piece of hardware called a smart transceiver. This smart transceiver, a thumb-sized chip that can receive and transmit data, uses technology known as silicon photonics to fetch trillions of weights from memory each second.

It receives weights as electrical signals and imprints them onto light waves. Since the weight data are encoded as bits (1s and 0s) the transceiver converts them by switching lasers; a laser is turned on for a 1 and off for a 0. It combines these light waves and then periodically transfers them through a fiber optic network so a client device doesn't need to query the server to receive them.

"Optics is great because there are many ways to carry data within optics. For instance, you can put data on different colors of light, and that enables a much higher data throughput and greater bandwidth than with electronics," explains Bandyopadhyay.

Trillions per second

Once the light waves arrive at the client device, a simple optical component known as a broadband "Mach-Zehnder" modulator uses them to perform super-fast, analog computation. This involves encoding input data from the device, such as sensor information, onto the weights. Then it sends each individual wavelength to a receiver that detects the light and measures the result of the computation.

The researchers devised a way to use this modulator to do trillions of multiplications per second, which vastly increases the speed of computation on the device while using only a tiny amount of power.

"In order to make something faster, you need to make it more energy efficient. But there is a trade-off. We've built a system that can operate with about a milliwatt of power but still do trillions of multiplications per second. In terms of both speed and energy efficiency, that is a gain of orders of magnitude," Sludds says.

They tested this architecture by sending weights over an 86-kilometer fiber that connects their lab to MIT Lincoln Laboratory. Netcast enabled machine-learning with high accuracy -- 98.7 percent for image classification and 98.8 percent for digit recognition -- at rapid speeds.

"We had to do some calibration, but I was surprised by how little work we had to do to achieve such high accuracy out of the box. We were able to get commercially relevant accuracy," adds Hamerly.

Moving forward, the researchers want to iterate on the smart transceiver chip to achieve even better performance. They also want to miniaturize the receiver, which is currently the size of a shoe box, down to the size of a single chip so it could fit onto a smart device like a cell phone.

The research is funded, in part, by NTT Research, the National Science Foundation, the Air Force Office of Scientific Research, the Air Force Research Laboratory, and the Army Research Office.

Story Source:

Materials provided by Massachusetts Institute of Technology. Original written by Adam Zewe. Note: Content may be edited for style and length.

Journal Reference:

Would traffic noise from future flying cars cause stress?

Researchers from Nagoya University and Keio University in Japan have estimated a person's stress levels caused by the sound of a flying car passing overhead. The research was published in the Technical Journal of Advanced Mobility in September 2022.

The drone market is booming, as several automobile companies and start-ups develop new personal aircraft. The long-awaited flying car, made famous in films like Blade Runner, may soon be a common sight in cities around the world. But while the automobile industry is busy developing technology to catch up to fantasy, few inventors or science fiction authors have thought much about how noise from the roaring and whirring of flying car engines might affect people's psychological state. Professor Susumu Hara of the Department of Aerospace Engineering, Graduate School of Engineering at Nagoya University, the lead author of the study, points out that in past industrial revolutions, people often prioritized technological advancement and economic demands over social and environmental issues, including noise and air pollution. "Unless technology is well-integrated in our daily lives," he argues, "we cannot expect it to make our society a better place." Therefore, his team conducted an experiment to estimate people's stress levels as if they were living in a world with flying cars.

In the research experiment, participants watched short videos that simulated cars flying in a city. The videos were designed so that the viewers felt like a car was flying 15 meters above them at a speed of 15.5 miles per hour (25 km per hour). To simulate such a scene, the videos used audio recordings of an industrial drone flying at a speed and height similar to the flying car depicted in the videos. Participants watched the video eight times, while the researchers changed the volume of the audio in each viewing to examine how the noise level would affect the participants. Participants' stress levels were assessed using two different measures. First, while watching the videos, a portable EEG device, called a Kansei Analyzer, recorded their brain activity. Second, after watching each video, the participants responded to a written questionnaire.

The researchers found that each person's self-reported stress level corresponded to the noise level of the flying car. As the noise increased, the participants reported greater stress. When the noise level decreased, they reported lower stress levels. However, brain activity data showed a different pattern. As predicted, when the noise level increased for the first time in the experiment, the EEG data showed higher levels of stress among the participants. But once the participants were exposed to loud noise, their stress levels did not decrease -- even after the noise level dropped. This may suggest that while most people think they can become accustomed to loud noise, it may actually be causing them stress without noticing it. To protect the health of residents, it is important to consider the long-term effects of exposure to chronic loud traffic noise in a world where flying cars are constantly landing, taking off, and whizzing above us. In addition to a self-reported assessment, checking brain activity might also be necessary to measure stress from noise.

When considering flying cars, an obvious solution is for aerospace engineers to prioritize making them quieter. But for now, we do not know how to determine the optimal sound level for protecting citizens' health. The researchers in this study hope that their measurement methods can help answer such questions.

"I am sure drones and flying cars will bring significant benefits to our society," said Professor Hara. At the same time, the study clearly shows that we cannot neglect noise pollution. "We believe that developing guidelines and regulations on flying cars is important so that we can better adapt them to our lives," he continued. "I hope this study provides some clues how to do that."

Story Source:

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

Journal Reference:

'Smart plastic' material is step forward toward soft, flexible robotics and electronics

Inspired by living things from trees to shellfish, researchers at The University of Texas at Austin set out to create a plastic much like many life forms that are hard and rigid in some places and soft and stretchy in others. Their success -- a first, using only light and a catalyst to change properties such as hardness and elasticity in molecules of the same type -- has brought about a new material that is 10 times as tough as natural rubber and could lead to more flexible electronics and robotics.

The findings are published today in the journal Science.

"This is the first material of its type," said Zachariah Page, assistant professor of chemistry and corresponding author on the paper. "The ability to control crystallization, and therefore the physical properties of the material, with the application of light is potentially transformative for wearable electronics or actuators in soft robotics."

Scientists have long sought to mimic the properties of living structures, like skin and muscle, with synthetic materials. In living organisms, structures often combine attributes such as strength and flexibility with ease. When using a mix of different synthetic materials to mimic these attributes, materials often fail, coming apart and ripping at the junctures between different materials.

Oftentimes, when bringing materials together, particularly if they have very different mechanical properties, they want to come apart," Page said. Page and his team were able to control and change the structure of a plastic-like material, using light to alter how firm or stretchy the material would be.

Chemists started with a monomer, a small molecule that binds with others like it to form the building blocks for larger structures called polymers that were similar to the polymer found in the most commonly used plastic. After testing a dozen catalysts, they found one that, when added to their monomer and shown visible light, resulted in a semicrystalline polymer similar to those found in existing synthetic rubber. A harder and more rigid material was formed in the areas the light touched, while the unlit areas retained their soft, stretchy properties.

Because the substance is made of one material with different properties, it was stronger and could be stretched farther than most mixed materials.

The reaction takes place at room temperature, the monomer and catalyst are commercially available, and researchers used inexpensive blue LEDs as the light source in the experiment. The reaction also takes less than an hour and minimizes use of any hazardous waste, which makes the process rapid, inexpensive, energy efficient and environmentally benign.

The researchers will next seek to develop more objects with the material to continue to test its usability.

"We are looking forward to exploring methods of applying this chemistry towards making 3D objects containing both hard and soft components," said first author Adrian Rylski, a doctoral student at UT Austin.

The team envisions the material could be used as a flexible foundation to anchor electronic components in medical devices or wearable tech. In robotics, strong and flexible materials are desirable to improve movement and durability.

Henry L. Cater, Keldy S. Mason, Marshall J. Allen, Anthony J. Arrowood, Benny D. Freeman and Gabriel E. Sanoja of The University of Texas at Austin also contributed to the research.

The research was funded by the National Science Foundation, the U.S. Department of Energy and the Robert A. Welch Foundation.

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Materials provided by University of Texas at Austin. Note: Content may be edited for style and length.

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New plastic-like material

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Seeing electron movement at fastest speed ever could help unlock next-level quantum computing

New technique could enable processing speeds a million to a billion times faster than today's computers and spur progress in many-body physics

The key to maximizing traditional or quantum computing speeds lies in our ability to understand how electrons behave in solids, and a collaboration between the University of Michigan and the University of Regensburg captured electron movement in attoseconds -- the fastest speed yet.

Seeing electrons move in increments of one quintillionth of a second could help push processing speeds up to a billion times faster than what is currently possible. In addition, the research offers a "game-changing" tool for the study of many-body physics.

"Your current computer's processor operates in gigahertz, that's one billionth of a second per operation," said Mackillo Kira, U-M professor of electrical engineering and computer science, who led the theoretical aspects of the study published in Nature. "In quantum computing, that's extremely slow because electrons within a computer chip collide trillions of times a second and each collision terminates the quantum computing cycle.

"What we've needed, in order to push performance forward, are snapshots of that electron movement that are a billion times faster. And now we have it."

Rupert Huber, professor of physics at the University of Regensburg and corresponding author of the study, said the result's potential impact in the field of many-body physics could surpass its computing impact.

"Many-body interactions are the microscopic driving forces behind the most coveted properties of solids -- ranging from optical and electronic feats to intriguing phase transitions -- but they have been notoriously difficult to access," said Huber, who led the experiment. "Our solid-state attoclock could become a real game changer, allowing us to design novel quantum materials with more precisely tailored properties and help develop new materials platforms for future quantum information technology."

To see electron movement within two-dimensional quantum materials, researchers typically use short bursts of focused extreme ultraviolet (XUV) light. Those bursts can reveal the activity of electrons attached to an atom's nucleus. But the large amounts of energy carried in those bursts prevent clear observation of the electrons that travel through semiconductors -- as in current computers and in materials under exploration for quantum computers.

U-M engineers and partners employ two light pulses with energy scales that match that of those movable semiconductor electrons. The first, a pulse of infrared light, puts the electrons into a state that allows them to travel through the material. The second, a lower-energy terahertz pulse, then forces those electrons into controlled head-on collision trajectories. The crashes produce bursts of light, the precise timing of which reveals interactions behind quantum information and exotic quantum materials alike.

"We used two pulses -- one that is energetically matched with the state of the electron, and then a second pulse that causes the state to change," Kira said. "We can essentially film how these two pulses change the electron's quantum state and then express that as a function of time."

The two-pulse sequence allows time measurement with a precision better than one percent of the oscillation period of the terahertz radiation that accelerates the electrons.

"This is really unique and took us many years of development," Huber said. "It is quite unexpected that such high-precision measurements are even possible if you remember how ridiculously short a single oscillation cycle of light is -- and our time resolution is one hundred times faster yet."

Quantum materials could possess robust magnetic, superconductive or superfluid phases, and quantum computing represents the potential for solving problems that would take too long on classical computers. Pushing such quantum capabilities will eventually create solutions to problems that are currently out of our reach. That starts with basic observational science.

"No one has been able to build a scalable and fault-tolerant quantum computer so far and we don't even know what that would look like," said study co-first author Markus Borsch, U-M doctoral student in electrical and computer engineering. "But basic research like studying how electronic motion in solids works on the most fundamental levels might give us an idea that leads us in the right direction."

Josef Freudenstein, a doctoral student at the University of Regensburg, is also co-first-author. The study was supported by the German Research Foundation, Army Research Office, the W.M. Keck Foundation and Michigan Engineering's Blue Sky Research Program.

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Disposable electronics on a simple sheet of paper

Discarded electronic devices, such as cell phones, are a fast-growing source of waste. One way to mitigate the problem could be to use components that are made with renewable resources and that are easy to dispose of responsibly. Now, researchers reporting in ACS Applied Materials & Interfaces have created a prototype circuit board that is made of a sheet paper with fully integrated electrical components, and that can be burned or left to degrade.

Most small electronic devices contain circuit boards that are made from glass fibers, resins and metal wiring. These boards are not easy to recycle and are relatively bulky, making them undesirable for use in point-of-care medical devices, environmental monitors or personal wearable devices. One alternative is to use paper-based circuit boards, which should be easier to dispose of, less expensive and more flexible. However, current options require specialized paper, or they simply have traditional metal circuitry components mounted onto a sheet of paper. Instead, Choi and colleagues wanted to develop circuitry that would be simple to manufacture and that had all the electronic components fully integrated into the sheet.

The team designed a paper-based amplifier-type circuit that incorporated resistors, capacitors and a transistor. They first used wax to print channels onto a sheet of paper in a simple pattern. After melting the wax so that it soaked into the paper, the team printed semi-conductive and conductive inks, which soaked into the areas not blocked by wax. Then, the researchers screen-printed additional conductive metal components and casted a gel-based electrolyte onto the sheet.

Tests confirmed that the resistor, capacitor and transistor designs performed properly. The final circuit was very flexible and thin, just like paper, even after adding the components. To demonstrate the degradability of the circuit, the team showed that the entire unit quickly burned to ash after being lit on fire. The researchers say this represents a step toward producing completely disposable electronic devices.

The authors acknowledge funding from the National Science Foundation.

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An electronic circuit printed on paper burning

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