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Self-powered photodetector achieves 20-fold sensitivity boost using novel device structure

Silicon semiconductors used in existing photodetectors have low light responsivity, and the two-dimensional semiconductor MoS₂ (molybdenum disulfide) is so thin that doping processes to control its electrical properties are difficult, limiting the realization of high-performance photodetectors.

A KAIST research team has overcome this technical limitation and developed the world’s highest-performing self-powered photodetector, which operates without electricity in environments with a light source. This paves the way for precise sensing without batteries in , biosignal monitoring, IoT devices, autonomous vehicles, and robots, as long as a is present.

Professor Kayoung Lee’s research team from the School of Electrical Engineering developed the self-powered photodetector, which demonstrated a sensitivity up to 20 times higher than existing products, marking the highest performance level among comparable technologies reported to date. The work is published in the journal Advanced Functional Materials.

Unique fingerprints in 3D printing may foil adversaries

3D printing is a simple way to create custom tools, replacement pieces and other helpful objects, but it is also being used to create untraceable firearms, such as ghost guns, like the one implicated in the late 2024 killing of UnitedHealthcare CEO Brian Thompson.

Netanel Raviv, assistant professor of computer science & engineering in the McKelvey School of Engineering at Washington University in St. Louis, led a team from the departments of Computer Science & Engineering and Biomedical Engineering that has developed a way to create an embedded fingerprint in 3D-printed parts that would withstand the item being broken, allowing authorities to gain information for forensic investigation, such as the identity of the printer or the person who owns it and the time and place of printing.

The research will be presented at the USENIX Security Symposium Aug. 13–15, 2025, in Seattle. The first authors of the paper are Canran Wang and Jinweng Wang, who earned doctorates in computer science in 2024 and 2025, respectively. The research is published on the arXiv preprint server.

Carbon nanotube ‘smart windows’ offer energy savings by modulating near-infrared light transmission

Half of the sun’s radiant energy falls outside of the visible spectrum. On a cold day, this extra infrared light provides additional warmth to residential and commercial buildings. On a warm day, it leads to unwanted heating that must be dealt with through energy-intensive climate control methods such as air-conditioning.

Triangle structured illumination microscopy developed for sustained live-cell super-resolution imaging

Structured illumination microscopy (SIM) is the most preferable system for live-cell super-resolution imaging. It enables the observation of intricate subcellular dynamics. However, conventional SIM has long relied on the complex rotation of one-dimensional stripe illumination at three angles, requiring nine exposures to reconstruct a uniform super-resolution image. This greatly hinders imaging speed and causes unnecessary photobleaching, limiting the available information flux in live-cell imaging.

Professor Xi Peng’s team from the College of Future Technology at Peking University has developed a triangle-beam interference SIM (3I-SIM) that enables gentler, sustained super-resolution live-cell imaging. This novel method upgrades the super-resolution imaging to an unprecedented kilo-Hz speed and half-day-long duration, enabling the study of complex and rapid biological processes with higher data throughput.

The work is published in Nature Photonics.

An alphabet for hand actions in the human brain

Using a corkscrew, writing a letter with a pen or unlocking a door by turning a key are actions that seem simple but actually require a complex orchestration of precise movements. So, how does the brain do it?

According to a new study, published in Proceedings of the National Academy of Sciences, by researchers from Carnegie Mellon University and the University of Coimbra, the has a specialized system that builds these actions in a surprisingly systematic way.

Analogous to how all of the words in a language can be created by recombining the letters of its alphabet, the full repertoire of human hand actions can be built out of a small number of basic building block movements.

A smart accelerator for qubits: Spin-orbit approach boosts both speed and stability

There are high hopes for quantum computers: they are supposed to perform specific calculations much faster than current supercomputers and, therefore, solve scientific and practical problems that are insurmountable for ordinary computers. The centerpiece of a quantum computer is the quantum bit, qubit for short, which can be realized in different ways—for instance, using the energy levels of atoms or the spins of electrons.

When making such qubits, however, researchers face a dilemma. On the one hand, a qubit needs to be isolated from its environment as much as possible. Otherwise, its quantum superpositions decay in a short time and the quantum calculations are disturbed. On the other hand, one would like to drive qubits as fast as possible in analogy with the clocking of classical bits, which requires a strong interaction with the environment.

Normally, these two conditions cannot be fulfilled at the same time, as a higher driving speed automatically entails a faster decay of the superpositions and, therefore, a shorter coherence time.

Sensing single ballistic electrons: High-speed method tracks fleeting quantum events

Researchers at NPL have reported a novel high-speed charge sensing method for ballistic electrons, a potentially useful technique in the fields of electron quantum optics, quantum electrical metrology, flying qubit technology, and signal sensing.

The study, published in Physical Review Letters, reveals that the presence of a single ballistic electron can be revealed by tracking the path of another fast-moving “sensing” electron. By steering the paths of these electrons close to each other, the tiny repulsion between them can redirect the sensing electron, like a train switching tracks or cars diverting off a freeway.

When charge sensors are used in quantum devices, they are measured continuously, with each sample long enough to resolve a signal from the noise. The NPL sensing system leverages synchronization between the detector and sensing electrons to achieve extreme time selectivity, only sampling within a minuscule time window and detecting interactions that occur in just 1–2 picoseconds.

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