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Silicon metasurfaces boost optical image processing with passive intensity-based filtering

Of the many feats achieved by artificial intelligence (AI), the ability to process images quickly and accurately has had an especially impressive impact on science and technology. Now, researchers in the McKelvey School of Engineering at Washington University in St. Louis have found a way to improve the efficiency and capability of machine vision and AI diagnostics using optical systems instead of traditional digital algorithms.

Mark Lawrence, an assistant professor of electrical and systems engineering, and doctoral student Bo Zhao developed this approach to achieve efficient processing performance without high energy consumption. Typically, all-optical image processing is highly constrained by the lack of nonlinearity, which usually requires high light intensities or external power, but the new method uses nanostructured films called metasurfaces to enhance optical nonlinearity passively, making it practical for everyday use.

Their work shows the ability to filter images based on light intensity, potentially making all-optical neural networks more powerful without using additional energy. Results of the research were published online in Nano Letters on Jan. 21, 2026.

A new microscope for the quantum age: Single nanoscale scan measures four key material properties

Physicists in Leiden have built a microscope that can measure no fewer than four key properties of a material in a single scan, all with nanoscale precision. The instrument can even examine complete quantum chips, accelerating research and innovation in the field of quantum materials. The study is published in the journal Nano Letters.

Temperature, magnetism, structure, and electrical properties. These are the material characteristics that this new microscope reveals. “It almost feels like having a superpower,” says Matthijs Rog, a Ph.D. student in Kaveh Lahabi’s research group. “You look at a sample and see not only its shape but also the electrical currents, heat, and magnetism within it.”

Kaveh Lahabi, who leads the group, says, “This microscope removes the experimental bottlenecks that have long limited the study of quantum materials. This is not an idealized technique—it works on the systems we actually want to understand. Furthermore, the sensitivity of our measurements tends to impress a lot of my physicist colleagues.”

Driven electrolytes are agile and active at the nanoscale

Technologies for energy storage as well as biological systems such as the network of neurons in the brain depend on driven electrolytes that are traveling in an electric field due to their electrical charges. This concept has also recently been used to engineer synthetic motors and molecular sensors on the nanoscale or to explain biological processes in nanopores. In this context, the role of the background medium, which is the solvent, and the resulting hydrodynamic fluctuations play an important role. Particles in such a system are influenced by these stochastic fluctuations, which effectively control their movements.

“When we imagine the environment inside a driven electrolyte at the nanoscale, we might think of a calm viscous medium in which ions move due to the electric field and slowly diffuse around. This new study reveals that this picture is wrong: the environment resembles a turbulent sea, which is highly nontrivial given the small scale,” explains Ramin Golestanian, who is director of the Department of Living Matter Physics at MPI-DS, and author of the study published in Physical Review Letters.

The research uncovers how the movement of the ions creates large-scale fluctuating fluid currents that stir up the environment and lead to fast motion of all the particles that are immersed in the environment, even if they are not charged.

A New Model for Particle Charging

As flour, plastic dust, and other powdery particles get blown through factory ducts, they become charged through contact with each other and with duct walls. To avoid discharges that could ignite explosions, ducts are metallic and grounded. Still, particles remain an explosive threat if they reach a silo while charged. The microphysics of contact charging is an active area of research, as is the quest to understand the phenomenon as it plays out on larger scales in dust storms, volcanic plumes, and processing plants. Now Holger Grosshans of the German National Metrology Institute in Braunschweig and his collaborators have developed a contact-charging model that can cope with particles and walls made of different materials [1]. What’s more, the model is compatible with computational approaches used to analyze large-scale turbulent flows.

The model treats particles’ acquisition of electric charge from each other and their surroundings as a stochastic process—one that involves some randomness. The resulting charge distributions depend on the amount of charge transferred per impact and other nanoscale parameters that would be tedious to measure for each system. Fortunately, Grosshans and his collaborators found that if they determined all parameters for one system in a controlled experiment, they could readily adjust the parameters to suit other systems.

To test their model, the researchers coupled it to a popular fluid-dynamics solver and simulated 300,000 polymer microparticles stirred by a turbulent flow while confined between four walls. The combination reproduced the complex charging patterns observed in lab experiments—and it did so efficiently: The charging model added less than 0.01% to the simulation’s computational cost.

Ammonia leaks can be spotted in under two seconds using new alveoli-inspired droplet sensor

Researchers from Guangxi University, China have developed a new gas sensor that detects ammonia with a record speed of 1.4 seconds. The sensor’s design mimics the structure of alveoli—the tiny air sacs in human lungs—while relying on a triboelectric nanogenerator (TENG) that converts mechanical energy into electrical energy. The sensor uses a process that is driven by A-droplets, which are tiny water droplets containing a trapped air bubble. These droplets exploit ammonia’s affinity for water to rapidly capture NH₃ when it is present.

When an ammonia-laden droplet falls onto the sensor, its mechanical impact completes an electrical circuit, generating signals that are converted into accurate gas measurements at a speed that exceeds existing ammonia gas sensors.

To take detection precision a step further, the team integrated an AI model that analyzes electrical signals and converts them into time-frequency images. After training on these images, the system classified ammonia into five concentration levels (0–200 ppm), achieving up to 98.4% detection accuracy.

Physicists challenge a 200-year-old law of thermodynamics at the atomic scale

A long-standing law of thermodynamics turns out to have a loophole at the smallest scales. Researchers have shown that quantum engines made of correlated particles can exceed the traditional efficiency limit set by Carnot nearly 200 years ago. By tapping into quantum correlations, these engines can produce extra work beyond what heat alone allows. This could reshape how scientists design future nanoscale machines.

Two physicists at the University of Stuttgart have demonstrated that the Carnot principle, a foundational rule of thermodynamics, does not fully apply at the atomic scale when particles are physically linked (so-called correlated objects). Their findings suggest that this long-standing limit on efficiency breaks down for tiny systems governed by quantum effects. The work could help accelerate progress toward extremely small and energy-efficient quantum motors. The team published its mathematical proof in the journal Science Advances.

Traditional heat engines, such as internal combustion engines and steam turbines, operate by turning thermal energy into mechanical motion, or simply converting heat into movement. Over the past several years, advances in quantum mechanics have allowed researchers to shrink heat engines to microscopic dimensions.

New nanoparticles remove melanoma tumors in mice with low-power near-infrared laser

Researchers at Oregon State University have developed and tested in a mouse model a new type of nanoparticle that enables the removal of melanoma tumors with a low-power laser. After the systemically administered nanoparticles accumulate in cancerous tissue, exposure to near-infrared light causes them to heat up and destroy the melanoma cells, leaving healthy tissue unharmed.

The study led by Olena Taratula and Prem Singh of the Oregon State University College of Pharmacy represents a huge step toward solving a persistent problem with using photothermal therapy to treat melanoma, the deadliest form of skin cancer: Conventional nanoparticles require lasers with power densities that are unsafe for the skin. Findings were published in Advanced Functional Materials.

Taratula, associate professor of pharmaceutical sciences, and Singh, a postdoctoral researcher in Taratula’s lab, based their new theranostic platform —it can be used for both treatment and diagnosis—on gold nanorods. The nanorods are coated with an iron-cobalt shell and tightly loaded with a dye that heats up upon exposure to near-infrared light—invisible, low-frequency radiation able to penetrate deeply into human tissue.

Laser‑written glass chip pushes quantum communication toward practical deployment

As quantum computers continue to advance, many of today’s encryption systems face the risk of becoming obsolete. A powerful alternative—quantum cryptography—offers security based on the laws of physics instead of computational difficulty. But to turn quantum communication into a practical technology, researchers need compact and reliable devices that can decode fragile quantum states carried by light.

A new study from teams at the University of Padua, Politecnico di Milano, and the CNR Institute for Photonics and Nanotechnologies shows how this goal can be approached using a simple material: borosilicate glass. As reported in Advanced Photonics, their work demonstrates a high-performance quantum coherent receiver fabricated directly inside glass using femtosecond laser writing. The approach provides low optical loss, stable operation, and broad compatibility with existing fiber-optic infrastructure—key factors for scaling quantum technologies beyond the laboratory.

Microfluidic method boosts control and separation of tiny particles—a promising tool for medical research

In nanoscale particle research, precise control and separation have long been a bottleneck in biotechnology. Researchers at the University of Oulu have now developed a new method that improves particle separation and purification. The promising technique could be applied, for example, in cancer research.

Separating nanosized particles remains a persistent challenge in biotechnology. Once particle size drops below a few hundred nanometers, their behavior becomes dominated by diffusion—the random walk of particles. This weakens the forces used to guide them, causing separation accuracy to collapse.

A microfluidics research group led by Professor Caglar Elbuken at the University of Oulu has developed a new solution to the problem. The method significantly improves the separation and purification of both small synthetic particles and nanoscale vesicles secreted by living cells.

3D ‘polar chiral bobbers’ identified in ferroelectric thin films

A novel type of three-dimensional (3D) polar topological structure, termed the “polar chiral bobber,” has been discovered in ferroelectric oxide thin films, demonstrating promising potential for high-density multistate non-volatile memory and logic devices. The result was achieved by a collaborative research team from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences, the Songshan Lake Materials Laboratory, and other institutions. The findings were published in Advanced Materials on January 30.

Topological polar textures in ferroelectrics, such as flux-closures, vortices, skyrmions, merons, Bloch points, and high-order radial vortices discovered in recent years, have attracted wide interest for future electronic applications. However, most known polar states possess limited configurational degrees of freedom, constraining their potential for multilevel data storage.

In this study, the researchers used phase-field simulations and aberration-corrected transmission electron microscopy to predict and experimentally confirm the existence of polar chiral bobbers in (111)-oriented ultrathin PbTiO₃ ferroelectric films. This 3D topological structure is characterized by a nanoscale domain with out-of-plane polarization opposite to its surroundings, which starts from the film surface and terminates at a Bloch point inside the film.

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