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A novel device enabling high-resolution observation of liquid phase dynamic processes at nanoscale

Phys.org - Scientific News Websites

In situ observation and recording of important liquid-phase electrochemical reactions in energy devices is crucial for the advancement of energy science.

Jan 31, 2023

Converting temperature fluctuations into clean energy with novel nanoparticles and heating strategy

Nanowerk - Nanotechnology Websites

Researchers triggered a significantly faster and more efficient pyro-catalytic reaction using localized plasmonic heat sources to rapidly and efficiently heat up the pyro-catalytic material and allow it to cool down. The findings open up new aven...

Jan 31, 2023

New Faraday Cages Can Be Switched Off and On ",plain_text=" Advanced new Faraday cages—the metal mesh enclosures that can block wireless signals—can also be switched on and off for reversible protection against noise, a new study finds.In addition, these new shields can be easily fabricated through a technique akin to spray-painting, which could help them find use in electronics, researchers say.Similarly to the way window blinds adjust how much visible light enters a room, engineers want dynamic control over the electromagnetic waves used in wireless communications. This ability would let devices receive and transmit signals when desired but also protect them against electromagnetic interference, such as static and jamming, and help them avoid being spied on.However, developing thin films that can tunably shield against electromagnetic interference is challenging when it comes to electromagnetic wavelengths that are much longer in scale than the materials used in the coatings—for example, microwaves with frequencies measured in gigahertz. Coatings that can shield against electromagnetic interference typically provide only static protection.Previously, researchers came up with foams they could mechanically compress or decompress to dynamically control the reflection or absorption of microwaves. However, these foams are several millimeters thick, hindering their potential use in microchips.Now, using materials discovered just over a decade ago that are only a few atoms thick, scientists have created shields less than a micrometer thick that can block microwaves in an electrically switchable manner.“This is the first demonstration of dynamic electrical modulation of electromagnetic interference shielding,” says study senior author Yury Gogotsi, a materials scientist at Drexel University, in Philadelphia.In the new study, researchers investigated two-dimensional materials known as MXenes, which are made of materials abundant on Earth’s surface. Previous research has found that MXenes may find use in a wide range of applications, such as energy storage, printable electronics, spray-on antennas, flexible transparent electrodes, water purification, lubricating space rovers, light-emitting quantum dots, and sensors. “There are more than 50 reported and more than a hundred compositions possible,” Gogotsi says.MXenes each possess a structure like a sandwich. The middle layer is composed of atoms of a conductive metal and either carbon, nitrogen, or carbon and nitrogen. On either side of that middle layer is an oxide layer.Shields against electromagnetic interference are presently made of highly electrically conductive materials that can reflect electromagnetic waves. These include metals and carbon materials such as graphene. However, it’s generally not possible to alter the electrical conductivity of metals, and graphene’s electrical conductivity can be modified by chemical means only so much before it loses its shielding capability.MXenes are highly conductive, and recent work found they could be even better shields against electromagnetic waves than metals and graphene. Researchers now show that when they combine MXenes with electrolyte solutions, they could temporarily electrically make these combinations transparent to electromagnetic radiation.A cross-section of MXene film used in the study. The film is about 1/50 to 1/100 as thick as a human hair. DrexelAn electric field can make ions flow within each film to expand or compress the space between its layers. This in turn can tune its conductivity and shielding properties.“Properties of MXenes can be modulated similar to properties of semiconductors, by applying a small potential,” says Gogotsi, who helped discover MXenes in 2011.In experiments, by applying less than a volt, the scientists found they could quickly and reversibly switch how much these films were either transparent to or shield against the X-band (8.2 to 12.4 gigahertz), the most common radar frequency range. These films could sustain their performance through more than 500 cycles of discharging and recharging.In the future, the researchers aim to increase the strength of the change in shielding and explore blocking other wavelengths of light, such as infrared, terahertz, and radio frequencies.“There is no reason to believe that a couple of MXene tested are the best ones for this application—we need to search for the best MXene,” Gogotsi says. “There is plenty of room for improvement.”The scientists detailed their findings online 16 January in the journal Nature Nanotechnology.

IEEE Spectrum - Scientific and Educational Websites

Advanced new Faraday cages—the metal mesh enclosures that can block wireless signals—can also be switched on and off for reversible protection against noise, a new study finds.In addition, these new shields can be easily fabricated through a tech...

Jan 30, 2023

Electrospun nanomaterial offers great protection against electromagnetic interference

Phys.org - Scientific News Websites

Engineers have employed "electrospinning," a new technique of manufacturing nanomaterials, to produce a novel fabric that offers high performance protection against electromagnetic interference, a phenomenon that can result in electronic...

Jan 30, 2023

New vaccine platform could ease development, delivery of antigens

Phys.org - Scientific News Websites

To many, EV stands for "electric vehicle." To researchers at Harvard University and the University of Nebraska–Lincoln, it's shorthand for another vehicle—this one nanoscopic—that might help streamline the development and delivery o...

Jan 30, 2023

Study: Superconductivity switches on and off in 'magic-angle' graphene

Phys.org - Scientific News Websites

With some careful twisting and stacking, MIT physicists have revealed a new and exotic property in "magic-angle" graphene: superconductivity that can be turned on and off with an electric pulse, much like a light switch.

Jan 30, 2023

Qubits on strong stimulants

ScienceDaily - General News Websites

In the global push for practical quantum networks and quantum computers, an international team of researchers has demonstrated a leap in preserving the quantum coherence of quantum dot spin qubits.

Jan 27, 2023

Quantum physicists make major nanoscopic advance

ScienceDaily - General News Websites

In a new breakthrough, researchers have solved a problem that has caused quantum researchers headaches for years. The researchers can now control two quantum light sources rather than one. Trivial as it may seem to those uninitiated in quantum, th...

Jan 26, 2023

Wearable Ultrasound Patch Images the Heart in Real-Time ",plain_text=" A wearable ultrasound imager for the heart that is roughly the size of a postage stamp, can be worn for up to 24 hours, and works even during exercise may one day help doctors spot cardiac problems that current medical technology might miss, a new study finds.Heart disease is the leading cause of death among the elderly, and is increasingly becoming a problem among those who are younger as well because of unhealthy diets and other factors. The signs of heart disease are often brief and unpredictable, so long-term cardiac imaging may help spot heart anomalies that might otherwise escape detection.For instance, patients with heart failure may at times seem fine at rest, “as the heart sacrifices its efficiency to maintain the same cardiac output,” says study colead author Hongjie Hu, a nanoengineer at the University of California, San Diego. “Pushing the heart towards its limits during exercise can make the lack of efficiency become apparent.”In addition, the heart can quickly recover from problems it may experience during exercise. This means doctors may fail to detect these issues, since cardiac imaging conventionally happens after exercise, not during it, Hu says.However, cardiac imaging techniques are often limited in terms of when they can analyze the heart, due in large part to the bulkiness of the equipment. For example, traditional cardiac ultrasound imaging “evaluates images of the heart right before and right after intensive exercise, as holding an ultrasound probe over the chest by hand and maintaining a stable position for it is impossible during this process,” Hu says. Previous wearable heart sensors could capture signals only on the skin.Now scientists have developed a wearableultrasound device that can enable safe, continuous, real-time, long-term, and highly detailed imaging of the heart. They detailed their findings online on 25 January in the journal Nature.“Potential applications include continuously monitoring the heart in daily life, during exercise, during surgery, and much more,” says study coauthor Ray Wu, a nanoengineer at UC San Diego. “This will open up the possibility to detect previously undetectable symptoms of disease, identify symptoms in their very early stages, and greatly improve patient outcomes.”The new device is a patch 1.9 centimeters long by 2.2 cm wide and only 0.9 millimeters thick. It uses an array of piezoelectric transducers to send and receive ultrasound waves in order to generate a constant stream of images of the structure and function of the heart. The researchers were able to get such images even during exercise on a stationary bike. No skin irritation or allergy was seen after 24 hours of continuous wear.“The most exciting result is that our patch performs well when an individual is moving,” Hu says. “Our patch allows us to evaluate heart performance throughout exercise, providing valuable information about the heart when it is under high stress.”The new patch is about as flexible as human skin. It can also stretch up to 110 percent of its size, which means it can survive far more strain than typically experienced on human skin. These features help it stick onto the body, something not possible with the rigid equipment often used for cardiac imaging.“The wearable imager removes much of the bulkiness of traditional imagers and adheres to the body on its own,” Wu says. “This enables the heart to be imaged in ways and scenarios that were never possible before while also freeing up the hands of the doctor from having to continuously operate a traditional ultrasound probe.”The wearable ultrasound sensor is roughly the size of a postage stamp, can be worn for up to 24 hours, and works even during strenuous exercise.Xu Laboratory/UC San Diego Jacobs School of EngineeringIn the new study, the researchers focused on imaging the left ventricle, the largest of the heart’s four chambers “and strongly considered to be the most important in terms of cardiovascular health, as it is responsible for pumping oxygenated blood to the entire body,” Wu says. Cardiac imaging generally focuses on the left ventricle, but the new device can image all of the heart’s four chambers simultaneously, “so it may be possible for future research to focus on other or multiple chambers,” he adds. In addition, “the imager can be applied to image various other organs, such as the stomach, kidney, or liver.”Traditional cardiac ultrasound imaging constantly rotates an ultrasound probe to analyze the heart in multiple dimensions. To eliminate the need for this rotation, the array of ultrasound sensors and emitters in the new device is shaped like a cross so that ultrasonic waves can travel at right angles to each other.The scientists developed a custom deep-learning AI model that can analyze the data from the patch and automatically and continuously estimate vital details, such as the percentage of blood pumped out of the left ventricle with each beat, and the volume of blood the heart pumps out with each beat and every minute. The root of most heart problems is the heart not pumping enough blood, issues that often manifest only when the body is moving, the researchers note.The scientists did not begin investigating heart imaging until after they developed a wearable ultrasound device.“After learning in a casual chat that one of our colleague’s relatives had died of a sudden heart attack, we realized our technology could make real impacts on people’s lives,” says study colead author Hao Huang, a nanoengineer at UC San Diego. “We did not expect the imaging quality of the imager to be very good. However, it turned out we could achieve a comparable quality to commercial probes after careful engineering. We knew we were onto something big when we saw the images full of details after many rounds of improvement, and we thought we should keep pursuing this path to not waste the capabilities of the imager.”In the beginning, “we were always struggling with focusing of the ultrasound beam,” Huang recalls. “Debugging involved intensive trial and error based on the readings. After many failures, we used an automatic alignment strategy to make the transducer array with a high uniformity and perfect alignment so that it guarantees beam focusing.”Another set of problems involved noise in the signals. “We did lots of trial and error to identify all the sources of noise and isolate the imager from all of them but were still left with the most major one, the human body,” Huang says. They ultimately developed a stretchable electromagnetic shield made of the same liquid metal used in the device’s electrodes “to remove the noise from the human body while maintaining the flexibility and stretchability of the imager. It turned out that the optimized shielding layer worked very well, and we could finally remove the noise from the images.”The researchers note that right now, the device is connected through cables to a computer. They have developed a wireless version of the patch, details of which are in a study currently under review, Hu says.The study’s senior author, Sheng Xu, a professor at UC San Diego, plans to commercialize this technology through Softsonics, a company cofounded with another of the study’s coauthors, Shu Xiang. Further work is needed to develop this device into a fully integrated wearable system with a built-in power source, Hu says.

IEEE Spectrum - Scientific and Educational Websites

A wearable ultrasound imager for the heart that is roughly the size of a postage stamp, can be worn for up to 24 hours, and works even during exercise may one day help doctors spot cardiac problems that current medical technology might miss, a ne...

Jan 26, 2023

Quantum technologies benefit from the bottom-up approach of synthetic chemistry – Physics World

Physics World - Nanotechnology Websites

This podcast features a chemist who creates molecular qubits The post Quantum technologies benefit from the bottom-up approach of synthetic chemistry appeared first on Physics World.

Jan 26, 2023