📌 TOPINDIATOURS Update ai: New laser-powered optofluidics enable 3D microprinting

Scientists working at microscopic scales have relied on a single dominant fabrication technique to build complex 3D structures. Two-photon polymerization made it possible to sculpt objects far thinner than a human hair, pushing precision manufacturing into the micro- and nanoscale.

Despite its accuracy, the method locked researchers into using mostly polymer-based materials.

That restriction has limited what microscopic devices can do. Applications in medicine, engineering, and robotics often require metals, semiconductors, or other functional materials.

Until now, combining such materials with complex 3D microstructures remained out of reach.

Researchers from the Max Planck Institute for Intelligent Systems and the National University of Singapore now report a method that changes those constraints.

Their new approach enables micro- and nanoscale 3D fabrication using a wide range of materials, moving beyond polymers and opening new design possibilities.

The technique relies on optofluidic assembly, which uses light to control fluid motion inside a liquid.

Researchers suspend microscopic particles in a fluid and focus a femtosecond laser on a precise point. The laser creates a localized temperature difference that drives fluid flow.

This flow actively guides particles toward a defined location. Scientists position the laser next to a prefabricated polymer micromold with a small opening.

Particles move through that opening and collect inside the mold, gradually forming a solid structure.

“The key idea of this study is to manipulate optofluidic interactions (light-driven flow) precisely, guiding 3D assembly of various micro- or nanoparticles within a confined 3D space,” says the co-corresponding author, Mingchao Zhang, who is an Assistant Professor at National University of Singapore.

The micromold determines the final geometry. After assembly, researchers remove the polymer mold in a post-processing step. This leaves a free-standing object made entirely from the selected material.

Laser-driven particle assembly

The laser does not chemically bind the particles together. Instead, physical forces stabilize the final structure. The researchers report strong control over where particles move and how they accumulate.

“The femtosecond laser induces a localized thermal gradient which generates a strong flow that propels particles towards and into the template exactly where we want them to be,” says the first author of the publication, Xianglong Lyu.

He conducted the research at MPI-IS and now works as a postdoctoral researcher at the Karlsruhe Institute of Technology.

“Meanwhile, the mold can be any shape: from a cube structure to spheres, a croissant shape, or other,” Lyu says. Once researchers remove the mold, the assembled particles retain their shape and size.

Van der Waals forces hold the particles together. These forces provide enough strength to keep the structures mechanically stable without chemical bonding.

Micro-robots and devices

To demonstrate practical applications, the team fabricated several working devices. These include microvalves that sort particles by size inside extremely narrow channels. The researchers also built micro-robots composed of multiple materials.

The robots respond differently depending on how researchers actuate them. Some move when exposed to light.

Others react to external magnetic fields. This flexibility allows designers to combine multiple functions in a single microscopic system.

“Optofluidic assembly overcomes the material limitations of traditional two-photon polymerization,” says Metin Sitti, who led the Physical Intelligence Department at MPI-IS. “Our new technology allows us to form tiny 3D objects from almost any material.”

The findings point toward broader possibilities in microscale robotics and advanced microfabrication.

The research is published in the journal Nature.

🔗 Sumber: interestingengineering.com

📌 TOPINDIATOURS Eksklusif ai: Neutrino detection may allow nuclear weapons testing

Scientists at Los Alamos National Laboratory say neutrinos could be used as a diagnostic tool to better understand what happens inside a nuclear weapon during a detonation.

The idea relies on detecting elusive subatomic particles released in large numbers during fission events, offering a new way to study nuclear performance without explosive testing.

The research explores whether an inverse beta decay, or IBD, neutrino detector could capture usable data from a nuclear detonation or a pulsed fission reactor.

Nuclear weapons produce a single, intense burst of fission that is difficult to replicate in controlled settings. Since the United States ended nuclear testing in 1992, researchers have relied heavily on simulations and indirect measurements.

Neutrinos, however, pass through matter almost unhindered. That makes them difficult to detect, but also valuable.

During a fission event, vast numbers of antineutrinos are released, carrying information about the reaction itself. Advances in detector technology are now making it realistic to capture those signals.

“With the great improvements in neutrino detection technology, the idea of using neutrinos as a diagnostic has come full circle,” said Richard Van de Water, lead researcher on the study.

“Because they’re produced so prolifically in a test event and in a pulsed fission reactor, neutrinos could offer a novel and complementary diagnostic tool for national security science.”

The team modeled a hypothetical nuclear yield and calculated the resulting antineutrino spectrum.

By combining those results with known interaction probabilities, they estimated how often antineutrinos would trigger inverse beta decay inside a detector positioned several kilometers away.

Proving detection feasibility

Their calculations show that an IBD detector could register enough interactions to provide meaningful diagnostic data from a fission event, even at a safe standoff distance.

The analysis supports the idea that neutrino-based diagnostics could complement existing tools used to evaluate nuclear weapons performance.

To test the concept without a weapons test, the researchers propose deploying a detector near a pulsed fission reactor. Pulsed reactors generate short, repeatable bursts of fission energy that mimic some characteristics of a nuclear detonation.

One candidate site is the TRIGA reactor at Texas A&M University. Data from such a setup could be used to refine simulations, reduce uncertainties in fission yield databases, and test assumptions used in weapons physics models.

The idea has deep historical roots at Los Alamos. Physicists Clyde Cowan and Frederick Reines first proposed detecting neutrinos using a nuclear weapons test in the 1950s.

Practical constraints pushed them to use a nuclear reactor instead, leading to the first confirmed detection of neutrinos in 1956.

Beyond weapons science

The proposed detector, called νFLASH, would be based on the Coherent CAPTAIN-Mills experiment at the Los Alamos Neutron Science Center.

Initial simulations using this design suggest the detector could capture antineutrino signals from pulsed fission bursts.

Such measurements have never been made before. Beyond weapons diagnostics, the setup could enable studies of sterile neutrinos, axions, or unexplained anomalies seen in reactor antineutrino spectra.

The short pulse structure and energy range may offer advantages not available in steady-state reactor experiments.

The researchers argue that pulsed-reactor measurements could provide data comparable to that from an actual weapons detonation, advancing both national security science and fundamental physics.

The study was published in Review of Scientific Instruments.

🔗 Sumber: interestingengineering.com