Robotic lightning bugs take flight

Fireflies that light up dusky backyards on warm summer evenings use their luminescence for communication — to attract a mate, ward off predators, or lure prey.

These glimmering bugs also sparked the inspiration of scientists at MIT. Taking a cue from nature, they built electroluminescent soft artificial muscles for flying, insect-scale robots. The tiny artificial muscles that control the robots’ wings emit colored light during flight.

This electroluminescence could enable the robots to communicate with each other. If sent on a search-and-rescue mission into a collapsed building, for instance, a robot that finds survivors could use lights to signal others and call for help.

The ability to emit light also brings these microscale robots, which weigh barely more than a paper clip, one step closer to flying on their own outside the lab. These robots are so lightweight that they can’t carry sensors, so researchers must track them using bulky infrared cameras that don’t work well outdoors. Now, they’ve shown that they can track the robots precisely using the light they emit and just three smartphone cameras.

“If you think of large-scale robots, they can communicate using a lot of different tools — Bluetooth, wireless, all those sorts of things. But for a tiny, power-constrained robot, we are forced to think about new modes of communication. This is a major step toward flying these robots in outdoor environments where we don’t have a well-tuned, state-of-the-art motion tracking system,” says Kevin Chen, who is the D. Reid Weedon, Jr. Assistant Professor in the Department of Electrical Engineering and Computer Science (EECS), the head of the Soft and Micro Robotics Laboratory in the Research Laboratory of Electronics (RLE), and the senior author of the paper.

Blood Pressure E-Tattoo Promises Continuous, Mobile Monitoring

Credit: University of Texas at Austin

Blood pressure is one of the most important indicators of heart health, but it’s tough to frequently and reliably measure outside of a clinical setting. For decades, cuff-based devices that constrict around the arm to give a reading have been the gold standard. But now, researchers at The University of Texas at Austin and Texas A&M University have developed an electronic tattoo that can be worn comfortably on the wrist for hours and deliver continuous blood pressure measurements at an accuracy level exceeding nearly all available options on the market today.

“Blood pressure is the most important vital sign you can measure, but the methods to do it outside of the clinic passively, without a cuff, are very limited,” said Deji Akinwande, a professor in the Department of Electrical and Computer Engineering at UT Austin and one of the co-leaders of the project, which is documented in a new paper published today in Nature Nanotechnology.

High blood pressure can lead to serious heart conditions if left untreated. It can be hard to capture with a traditional blood pressure check because that only measures a moment in time, a single data point.

“Taking infrequent blood pressure measurements has many limitations, and it does not provide insight into exactly how our body is functioning,” said Roozbeh Jafari, a professor of biomedical engineering, computer science and electrical engineering at Texas A&M and the other co-leader of the project.

The continuous monitoring of the e-tattoo allows for blood pressure measurements in all kinds of situations: at times of high stress, while sleeping, exercising, etc. It can deliver thousands of measurements, more than any device thus far.

Photon twins of unequal origin

The quantum dots of the Basel researchers are different, but send out exactly identical light particles.
Credit: University of Basel, Department of Physics

Researchers have created identical light particles with different quantum dots - an important step for applications such as tap-proof communication.

Many technologies that take advantage of quantum effects are based on exactly the same photons. However, it is extremely difficult to manufacture them. Not only must the wavelength (color) of the photons exactly match, but also their shape and polarization.

A team of researchers from the University of Basel around Richard Warburton, in collaboration with colleagues from the Ruhr University in Bochum, has now succeeded in producing identical photons that come from different, widely separated sources.

Individual photons from quantum dots

In their experiments, physicists use so-called quantum dots, i.e. structures a few nanometers in semiconductor materials. Electrons are trapped in these quantum dots, which only assume very specific energy levels and can emit light when moving from one level to another. With the help of a laser pulse that triggers such a transition, individual photons can be produced at the push of a button.

Real-time Imaging of Dynamic Atom-atom Interactions

In a breakthrough, Tokyo Tech researchers have managed to observe and characterize dynamic assembly of metallic atoms using an ingenious combination of scanning transmission electron microscopy and video-based tracking. By visualizing short-lived molecules, such as metallic dimers and trimers, that cannot be observed using traditional methods, the researchers open up the possibility of observing more such dynamic structures predicted by simulations.

Chemistry is the study of bond formation (or dissociation) between atoms. The knowledge of how chemical bonds form is, in fact, fundamental to not just all of chemistry but also fields like materials science. However, traditional chemistry has been largely limited to the study of stable compounds. The study of dynamic assembly between atoms during a chemical reaction has received little attention. With recent advances in computational chemistry, however, dynamic, short-lived structures are gaining importance. Experimental observation and characterization of dynamic bonding predicted between atoms, such as the formation of metallic dimers, could open up new research frontiers in chemistry and materials science.

However, observing this bond dynamics also requires the development of a new methodology. This is because conventional characterization techniques only provide time-averaged structural information and are, thus, inadequate for observing the bonds as they are formed.

A Fresh Take on Fat: Nanoparticle Technology Provides Healthy Trans, Saturated Fat Alternative

Yangchao Luo, an associate professor in the College of Agriculture, Health and Natural Resources.
 Credit: Jason Shelton/UConn Photo

The old adage that oil and water don’t mix isn’t entirely accurate. While it’s true that the two compounds don’t naturally combine, turning them into one final product can be done. You just need an emulsifier, an ingredient commonly used in the food industry.

Yangchao Luo, an associate professor in the College of Agriculture, Health and Natural Resources, is using an innovative emulsification process for the development of a healthier shelf-stable fat for food manufacturing.

Luo is working with something known as high internal phase Pickering emulsions (HIPEs). High internal phase means the mixture is at least 75% oil. Pickering emulsions are those that are stabilized by solid particles.

Previous research in Pickering emulsions has focused on non-edible particles, but Luo is interested in bringing HIPEs to the food industry as an alternative to trans and saturated fats.

This new approach could have a major impact on how food is produced and could make it easier for food manufacturers to include healthier fats.

Many processed foods are loaded with saturated and trans fats for flavor and to extend a product’s shelf life. Consuming these fats can increase the risk of cardiovascular disease, type 2 diabetes, and LDL cholesterol.

International team visualizes properties of plant cell walls at nanoscale

Scattering-type scanning near-field optical microscopy, a nondestructive technique in which the tip of the probe of a microscope scatters pulses of light to generate a picture of a sample, allowed the team to obtain insights into the composition of plant cell walls.
Credit: Ali Passian/ORNL, U.S. Dept. of Energy

To optimize biomaterials for reliable, cost-effective paper production, building construction, and biofuel development, researchers often study the structure of plant cells using techniques such as freezing plant samples or placing them in a vacuum. These methods provide valuable data but often cause permanent damage to the samples.

A team of physicists including Ali Passian, a research scientist at the Department of Energy’s Oak Ridge National Laboratory, and researchers from the French National Centre for Scientific Research, or CNRS, used state-of-the-art microscopy and spectroscopy methods to provide nondestructive alternatives. Using a technique called scattering-type scanning near-field optical microscopy, the team examined the composition of cell walls from young poplar trees without damaging the samples.

But the team still had other obstacles to overcome. Although plant cell walls are notoriously difficult to navigate due to the presence of complex polymers such as microfibrils — thin threads of biomass that Passian describes as a maze of intertwined spaghetti strings — the team reached a resolution better than 20 nanometers, or about a thousand times smaller than a strand of human hair. This detailed view allowed the researchers to detect optical properties of plant cell materials for the first time across regions large and small, even down to the width of a single microfibril. Their results were published in Communications Materials.

Yolk-Shell Nanocrystals with Movable Gold Yolk: Next Generation of Photocatalysts

The synthesis of yolk-shell nanostructures involves sulfidation on an Au@Cu2O core-shell nanocrystal template to convert the shell composition to various metal sulphides.
Credit: Tokyo Institute of Technology

Owing to their unique permeable, hollow shell structures with inner, movable cores, yolk-shell nanocrystals are suitable for a wide variety of applications. Yolk-shell nanocrystals consisting of a gold core with various semiconductor shells have been developed by Tokyo Tech researchers, using a novel sequential ion-exchange process. These metal-semiconductor yolk-shell nanocrystals can serve as highly effective photocatalysts for many applications.

Yolk-shell nanocrystals are unique materials with fascinating structural properties, such as a permeable shell, interior void space, and movable yolk. These nanocrystals are suitable for a variety of applications, depending on the choice of materials used for their fabrication.

For example, if the inner surface of their shells are reflective, yolk-shell nanocrystals can make for a reliable photovoltaic device. A mobile core can can act as a stirrer, capable of mixing solutions held within the shell. The inner and outer surfaces of the shell provide plenty of active sites for reactions, and the yolk-shell structure's fascinating properties (a result of electronic interactions and charge-transfer between the surfaces of the structure) make these nanocrystals ideal for photocatalysis applications. Understandably, yolk-shell nanocrystals have earned the attention of researchers worldwide.

New nanoparticles aid sepsis treatment in mice

Shaoqin “Sarah” Gong
Source: University of Wisconsin–Madison

Sepsis, the body’s overreaction to an infection, affects more than 1.5 million people and kills at least 270,000 every year in the U.S. alone. The standard treatment of antibiotics and fluids is not effective for many patients, and those who survive face a higher risk of death.

In new research published in the journal Nature Nanotechnology today, the lab of Shaoqin “Sarah” Gong, a professor with the Wisconsin Institute for Discovery at the University of Wisconsin–Madison, reported a new nanoparticle-based treatment that delivers anti-inflammatory molecules and antibiotics.

The new system saved the lives of mice with an induced version of sepsis meant to serve as a model for human infections, and is a promising proof-of-concept for a potential new therapy, pending additional research.

The new nanoparticles delivered the chemical NAD+ or its reduced form NAD(H), a molecule that has an essential role in the biological processes that generate energy, preserve genetic material and help cells adapt to and overcome stress. While NAD(H) is well known for its anti-inflammatory function, clinical application has been hindered because NAD(H) cannot be taken up by cells directly.

“To enable clinical translation, we need to find a way to efficiently deliver NAD(H) to the targeted organs or cells. To achieve this goal, we designed a couple of nanoparticles that can directly transport and release NAD(H) into the cell, while preventing premature drug release and degradation in the bloodstream,” says Gong, who also holds appointments in the Department of Biomedical Engineering and the UW School of Medicine and Public Health’s Department of Ophthalmology and Visual Sciences.

The interdisciplinary work was led by Gong along with Mingzhou Ye and Yi Zhao, two postdoctoral fellows in the Gong lab. John-Demian Sauer, a professor in the Department of Medical Microbiology and Immunology, also collaborated on the project.

Making colors out of gold and DNA

In this experiment, the gel is being activated by a red LED before the researchers measure the light it transmits.
Photo: Joonas Ryssy

Folk belief says there’s a pot of gold at the end of the rainbow, but a new technology is turning that idea on its head – using particles of gold to make colors. With further work, the method developed at Aalto University could herald a new display technology.

The technique uses gold nanocylinders suspended in a gel. The gel only transmits certain colors when lit by polarized light, and the color depends on the orientation of the gold nanocylinders. In a clever twist, a collaboration led by Anton Kuzyk’s and Juho Pokki’s research groups used DNA molecules to control the orientation of gold nanocylinders in the gel.

‘DNA isn’t just an information carrier – it can also be a building block. We designed the DNA molecules to have a certain melting temperature, so we could basically program the material,’ says Aalto doctoral candidate Joonas Ryssy, the study’s lead author. When the gel heats past the melting temperature, the DNA molecules loosen their grip and the gold nanocylinders change orientation. When the temperature drops, they tighten up again, and the nanoparticles go back to their original position.

A unique catalyst paves the way for plastic upcycling

Visual of two variations of the catalyst, with a segment of the shell removed to show the interior. The white sphere represents the silica shell, the holes are the pores. The bright green spheres represent the catalytic sites, the ones on the left are much smaller than the ones on the right. The longer red strings represent the polymer chains, and the shorter strings are products after catalysis. All shorter strings are similar in size, representing the consistent selectivity across catalyst variations. Additionally, there are smaller chains produced by the smaller catalyst sites because the reaction occurs more quickly.
Credit: Ames Laboratory

A recently developed catalyst for breaking down plastics continues to advance plastic upcycling processes. In 2020, a team of researchers led by Ames Laboratory scientists developed the first processive inorganic catalyst to deconstruct polyolefin plastics into molecules that can be used to create more valuable products. Now, the team has developed and validated a strategy to speed up the transformation without sacrificing desirable products.

The catalyst was originally designed by Wenyu Huang, a scientist at Ames Lab. It consists of platinum particles supported on a solid silica core and surrounded by a silica shell with uniform pores that provide access to catalytic sites. The overall amount of platinum needed is quite small, which is important because of platinum's high cost and limited supply. During deconstruction experiments, the long polymer chains thread into the pores and contact the catalytic sites, and then the chains are broken into smaller sized pieces that are no longer plastic material (see image for more details).

Secret to treating ‘Achilles’ heel’ of alternatives to silicon solar panels revealed

Solar panels 
Credit: Alachua County

The researchers used a combination of techniques to mimic the process of aging under sunlight and observe changes in the materials at the nanoscale, helping them gain new insights into the materials, which also show potential for optoelectronic applications such as energy-efficient LEDs and X-ray detectors, but are limited in their longevity.

Their results, reported in the journal Nature, could significantly accelerate the development of long-lasting, commercially available perovskite photovoltaics.

Perovksites are abundant and much cheaper to process than crystalline silicon. They can be prepared in liquid ink that is simply printed to produce a thin film of the material.

While the overall energy output of perovskite solar cells can often meet or – in the case of multi-layered ‘tandem’ devices – exceed that achievable with traditional silicon photovoltaics, the limited longevity of the devices is a key barrier to their commercial viability.

A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses.

In the heat of the wound

Empa researcher Fei Pan is working on a membrane made of nanofibers that releases medication only when the material heats up. Such a membrane could, for example, become active in a bandage as soon as inflammation starts.
Image: Empa

A bandage that releases medication as soon as an infection starts in a wound could treat injuries more efficiently. Empa researchers are currently working on polymer fibers that soften as soon as the environment heats up due to an infection, thereby releasing antimicrobial drugs.

It is not possible to tell from the outside whether a wound will heal without problems under the dressing or whether bacteria will penetrate the injured tissue and ignite an inflammation. To be on the safe side, disinfectant ointments or antibiotics are applied to the wound before the dressing is applied. However, these preventive measures are not necessary in every case. Thus, medications are wasted and wounds are over-treated.

Even worse, the wasteful use of antibiotics promotes the emergence of multi-resistant germs, which are an immense problem in global healthcare. Empa researchers at the two Empa laboratories Biointerfaces and Biomimetic Membranes and Textiles in St. Gallen wants to change this. They are developing a dressing that autonomously administers antibacterial drugs only when they are really needed.

The idea of the interdisciplinary team led by Qun Ren and Fei Pan: The dressing should be "loaded" with drugs and react to environmental stimuli. "In this way, wounds could be treated as needed at exactly the right moment," explains Fei Pan. As an environmental stimulus, the team chose a well-known effect: the rise in temperature in an infected, inflamed wound.