A material that normally blocks the flow of electricity can suddenly begin behaving like a metal when exposed to remarkably weak light, according to a new experiment involving one of the strangest forms of graphene ever created. The breakthrough reveals that an unusual quantum effect could eventually provide a new way to detect some of the faintest radiation around us.

Researchers working with “magic-angle” twisted bilayer graphene found that faint, long-wavelength radiation can effectively melt the material’s fragile correlated insulating state, causing its electrical resistance to plummet. Remarkably, the experiments showed that even relatively weak radiation could trigger a dramatic transition from an insulator to a metal.

Beyond revealing an unusual way that light can manipulate matter, the discovery could provide the foundation for extremely sensitive detectors capable of spotting faint terahertz and far-infrared radiation.

With further development, detectors operating at these wavelengths could have applications ranging from security imaging and material inspection to astronomy and environmental sensing.

The study, published in Nature Communications, centers on magic-angle twisted bilayer graphene, or MATBG—a material produced by stacking two sheets of graphene and rotating them relative to one another at a carefully controlled angle.

Under the right conditions, interactions between electrons can cause magic-angle graphene to enter exotic collective states, including superconducting and insulating phases.

“Here we show that this expectation does not apply to magic-angle twisted bilayer graphene (MATBG) and demonstrate giant photoresponse of MATBG to low-intensity long-wavelength photons when it is tuned to half filling of the moiré band,” researchers write. “Far-infrared photons selectively overheat the low-heat-capacity electronic subsystem, driving a collapse of the correlated order and producing a giant photoresistive response.”

Ordinarily, changing an insulator into a conductor with light requires supplying enough energy to alter how electrons can move through the material fundamentally. Previous experiments involving light-induced insulator-to-metal transitions have frequently depended on intense, ultrafast excitation.

Magic-angle graphene offers another route.

Twisting graphene sheets at carefully controlled angles creates a larger repeating structure known as a moiré superlattice, dramatically changing how electrons within the material interact. Those interactions have already produced some remarkable results.

As The Debrief reported last year, researchers studying magic-angle twisted trilayer graphene uncovered new evidence of unconventional superconductivity, including unusually tightly bound electron pairs and a distinctive superconducting energy gap.

That work was part of a greater effort to understand whether these exotic materials could eventually help scientists design superconductors capable of operating at much higher temperatures.

In the new study, researchers exploited another unusual state that can emerge in magic-angle graphene. At certain electron densities, interactions between electrons become unusually important, allowing them to organize into what physicists call a “correlated insulator.”

That collective state is extremely fragile. The correlated insulating gap exists at an energy scale of only a few millielectronvolts. Previous measurements cited by the researchers indicate that a gap of approximately 1 millielectronvolt at very low temperatures gradually closes as the material warms and disappears around 10 kelvin.

The researchers realized that weakness could become an advantage.

Their experimental device consisted of magic-angle graphene sandwiched between layers of hexagonal boron nitride and configured as a field-effect transistor. A graphite back gate allowed them to precisely control the number of charge carriers and tune the graphene into its correlated insulating state.

They then exposed it to millimeter-wave and far-infrared radiation.

Instead of needing to inject large numbers of charge carriers, the incoming photons heated the graphene’s low-heat-capacity electronic system. That relatively small temperature increase was enough to destabilize the cooperative electronic order, retaining the insulating state.

The gap collapsed, resistance dropped dramatically, and the material became metallic.

Measurements in darkness and under illumination reinforced that interpretation. Without radiation, the graphene displayed the temperature-sensitive resistance expected from an insulator. Under millimeter-wave illumination, it instead exhibited behavior representative of a metal.

Researchers compare the mechanism to superconducting bolometers, highly sensitive radiation detectors in which incoming energy interrupts a superconducting state. But their graphene device essentially operates in reverse: instead of destroying a zero-resistance state, approaching photons destroy a high-resistance correlated insulating state and turn it metallic.

That makes the insulator-to-metal transition more than an unusual demonstration of quantum physics. It becomes the detector’s signal.

The team found that the device responded across wavelengths ranging from 85 to 2,140 micrometers, encompassing far-infrared and millimeter-wave radiation.

That portion of the electromagnetic spectrum is particularly interesting because it can reveal things ordinary cameras cannot. Terahertz radiation can penetrate some materials opaque to visible light, while interactions between this radiation and matter can provide information about a material’s composition.

More capable detectors could therefore eventually contribute to technologies such as security scanners looking for concealed objects, systems inspecting manufactured components without cutting them open, or sensors identifying substances using characteristic spectral markers.

Astronomy offers another potential application. Cold dust, star-forming regions, and other objects that may be faint or obscured at visible wavelengths emit radiation in the far-infrared. Detecting those extremely weak signals requires exceptionally sensitive instruments, making improved detector technology valuable for future astronomical observatories.

The experimental graphene detector exhibited considerable intrinsic sensitivity. The researchers measured an internal voltage responsivity of approximately 17 million volts per watt of absorbed power. They note that its internal responsivity exceeds that of many commercial bolometers operating in the same spectral region.

However, researchers caution that practical external performance is presently limited partly by how efficiently radiation is absorbed, meaning the experimental device is not equivalent to a finished commercial detector. Better antennas, cavities, metamaterials, or other structures designed to funnel radiation into the graphene could potentially improve its performance considerably.

There are other hurdles. The effect currently requires ultra-low temperatures, and the unusually strong response depends upon generating high-quality magic-angle graphene structures. Those requirements mean practical security scanners or telescope cameras based on the technology remain prospective rather than imminent.

Still, there are encouraging characteristics. The photoresponse persisted at temperatures around 6 to 7 kelvin and remained robust in magnetic fields of several tesla, with substantial reduction appearing only above roughly 4 tesla. That magnetic-field tolerance could make the technology attractive for specialized scientific instruments where superconducting detectors may meet limitations.

The current device also has an estimated practical response time of roughly 50 nanoseconds, largely because of its electrical design. The underlying electron cooling occurs much faster, and researchers estimate that smaller devices could reduce that practical limit by at least an order of magnitude. They also envision twisted multilayer materials, wafer-scale growth, and large-format detector arrays as potential directions for future development.

For now, the experiment demonstrates that in certain quantum materials, changing electrical behavior does not necessarily require pumping large amounts of energy into individual electrons. Sometimes, a small amount of light only needs to destabilize the collective state that those electrons have constructed together.

For physicists, the discovery offers a new way to investigate how fragile collective states of matter collapse and recover. For engineers, that same fragility could become useful precisely because extraordinarily weak radiation can trigger an extraordinarily large electrical response.

“Our experiments can be further generalized for time-domain interrogation of the CI state itself,” researchers write. “Radiation-driven excitation confined within the flat band, combined with time-resolved monitoring of the CI photoresistance, would allow direct access to the intrinsic timescale of correlated-order suppression and recovery, thereby probing the collective dynamics within the ground state.”

Study: Elesin, L., Shilov, A. L., Kravtsov, M. et al. “Correlated Insulator Moiré Bolometer.” Nature Communications (2026).

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

Researchers have demonstrated an unusual new form of 3D printing capable of building entirely new structures directly onto—and even around—existing objects in just seconds. In a series of experiments, the technique printed microscopic fluid channels around embedded glass spheres, fabricated precision gears onto polished steel rods, and even built a miniature lens directly onto the surface of a working LED.

The breakthrough, described in a paper published in Nature Communications, relies on an advanced form of tomographic volumetric additive manufacturing (TVAM) that allows researchers to “overprint” new structures onto components made from a wide range of materials, including metal, glass, and preassembled microfluidic components. Instead of constructing objects layer by layer like conventional 3D printers, the system projects precisely calculated light patterns into a rotating vat of photosensitive resin, causing an entire three-dimensional object to solidify almost simultaneously within seconds.

The advancement could represent a major step toward making volumetric 3D printing practical in real-world manufacturing environments, where new components often must be integrated with parts that already exist.

It additionally highlights the growing sophistication of computational techniques that can accurately model how light behaves as it passes through materials that absorb, scatter, refract, or reflect light.

“Tomographic Volumetric Additive Manufacturing (TVAM) is a light-based 3D printing technique capable of producing centimeter-scale objects within seconds,” researchers write. “This work demonstrates a broad range of overprinting scenarios, where new structures are directly printed onto or around pre-existing components made from different materials.”

Unlike conventional stereolithography or fused-filament printers that gradually build an object from one direction, tomographic volumetric printing projects hundreds of two-dimensional light patterns into a rotating container filled with liquid resin.

As the resin accumulates enough light energy, the desired three-dimensional structure appears almost simultaneously throughout the volume rather than emerging layer by layer. The approach can produce centimeter-scale objects in mere seconds.

However, until now, one of the technology’s greatest challenges has been accurately calculating how light travels through complicated environments.

Existing objects inside the resin can block, scatter, or bend incoming light, degrading print quality. Conventional models often assume these objects are either completely transparent or completely opaque. This is an oversimplification that breaks down in realistic manufacturing scenarios.

To overcome those limitations, the team developed an upgraded computational framework called Dr.TVAM. Built upon physically based ray tracing, the software models how light propagates through materials with different optical properties while simultaneously optimizing the projected light patterns needed to create the desired object.

Because the framework accounts for reflection, refraction, scattering, absorption, and arbitrary container shapes, it can successfully print structures around components that previously would have interfered with the process.

One of the study’s most compelling demonstrations involved manufacturing microfluidic channels directly inside sealed, preassembled square chambers. Microfluidic devices contain microscopic channels that transport tiny volumes of liquids and are widely used in biomedical research, diagnostics, and organ-on-a-chip systems.

Instead of fabricating the channels separately and assembling the device afterward—a process that can introduce contamination or leaks—the researchers successfully printed perfusable channels directly inside an already assembled chamber while accounting for inlet and outlet structures that would otherwise obstruct the light.

They demonstrated straight channels, branching networks, and spiral geometries capable of carrying fluid after fabrication. Supplementary demonstrations showed colored dye successfully flowing through the finished structures.

The researchers then pushed the concept even further by creating what they describe as context-aware printing. In this experiment, they embedded two tiny glass spheres inside a hydrogel-filled chamber, rapidly determined each sphere’s three-dimensional position using two camera images, and generated customized print patterns in less than a minute.

Those optimized projections produced hollow channels connecting each sphere to inlet and outlet ports while simultaneously printing protective cavities around the spheres themselves. The complete workflow—from detecting the embedded objects to generating printing instructions and fabricating the final structure—required less than three minutes.

That ability could eventually enable highly customized biomedical manufacturing, where printers automatically adapt to the precise location of living tissues, organoids, or other biological materials rather than requiring perfect positioning beforehand.

Another experiment highlighted why precisely modeling light matters.

Previous demonstrations of volumetric overprinting treated metal components as though they completely absorbed incoming light. In reality, polished metal reflects and scatters significant amounts of light, creating distortions that reduce print quality.

Researchers tested both assumptions by printing a gear directly onto a polished steel rod. When the software ignored scattered light, the gear’s fine holes became over-polymerized and poorly defined.

After including realistic scattering behavior into the optical model, however, the resulting gear preserved those elaborate features far more accurately, increasing simulated print fidelity substantially. The improvement was confirmed experimentally.

Researchers even went as far as demonstrating that the process could print directly onto an electronic component.

Using an LED-based volumetric printing system, the researchers fabricated both a miniature lens and a small cross-shaped symbol directly onto the surface of a red LED. When illuminated, the printed lens projected the symbol onto a screen, successfully transforming the LED into a tiny optical projector without requiring additional assembly. The experiment showcased how optical elements themselves could potentially be integrated directly onto existing electronic hardware during manufacturing.

Beyond the individual demonstrations, the work additionally underscores an important trend in additive manufacturing: increasingly sophisticated software is becoming just as important as advances in hardware.

Instead of relying on simplified mathematical approximations, the new framework performs physically based optical simulations capable of modeling arbitrary geometries along with material properties.

The software has been released as open source, along with configuration files and experimental data, allowing other researchers to reproduce and expand upon the 3D printing work.

Although the current demonstrations remain laboratory-scale, the possible implications could extend well beyond experimental 3D printing. Biomedical researchers could eventually fabricate sterile microfluidic systems without multi-step assembly. Optical engineers may integrate lenses directly onto light sources. Manufacturers could add custom features to finished components without redesigning entire production processes.

Researchers also note that future improvements could further increase realism through incorporating additional physical effects, including changes in refractive index during polymerization and the diffusion of chemical inhibitors during printing. Those refinements could expand the technology’s accuracy and enable even more complex manufacturing scenarios.

“In summary, Dr.TVAM, our computational framework, has shown to be capable of modeling different optical situations for TVAM,” researchers write. “We believe this significantly expands the application space for TVAM, enabling the creation of complex, functionalized, and multi-component devices from applications in mechanics, optics, or biofabrication.”

Study: Wechsler F, et al. “Overprinting with tomographic volumetric additive manufacturing.” Nature Communications (2026).

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

A new material, inspired by the frustratingly powerful strength of a tangled ball of staples, could represent the future of flexible, adaptable design.

Published in the Journal of Applied Physics, material scientists and engineers from the University of Colorado Boulder’s Paul M. Rady Department of Mechanical Engineering revealed an interlocking particle design that can be shaped into rigid structures, and then return to a pile of loose pieces with only a targeted movement or vibration.

The particles, the team says, could potentially be used as a building material with high strength and flexibility, capable of reshaping into new forms on command.

Staple Ball Strength

The difficulty of separating tangled metal, such as a cluster of standard office staples, intrigued the researchers enough to investigate how interlocking particles could be used in recyclable construction. Such techniques are found in nature, as birds weave together found objects to create strong structures to protect their young.

On the level of particles, interlocking such elements is called “entanglement,” and is a relatively new focus for material scientists.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

“We’ve been playing around with the idea of building blocks and geometry for many years, but we started looking at interlocking, entangled particles only recently,” said Professor Francois Barthelat, the leader of the Laboratory for Advanced Materials & Bioinspiration.

“We are excited about the combination of properties we can get out of these systems, and we believe this technology has the potential to go in many directions,” Barthelat said.

Manufacturing Entanglement

While entanglement occurs naturally, as in the combination of soft protein and hard minerals that interlock to form bones, producing it artificially requires a careful understanding of how these interactions work. According to the team, particle shape is the most foundational element to natural entanglement.

“Let’s take sand as an example,” says PhD student Youhan Sohn. “Sand is smooth and convex-shaped, meaning it cannot interlock from grain to grain.”

“However, we found that if we change the shape of a grain of sand, we can drastically affect its behavior and mechanical properties, including the particle’s ability to link with other particles,” Sohn adds.

With shape decided as the researcher’s primary focus, they began running computer models, called Monte Carlo simulations, to observe how various potential shapes would interact, aiming to identify the optimal entanglement geometry. The shape their research settled on was remarkably similar to that of a staple: a particle with two legs.

Laboratory Material Experiments

After achieving success in the digital realm, the researchers fabricated the shape in the real world to test its behavior under practical conditions. During these tests, the team discovered that their optimized shape contained even more beneficial qualities than they had initially understood.

Conventional materials typically experience a trade-off between toughness and tensile strength. Typically, materials that are extremely tough and can absorb large amounts of energy are also quite brittle, lacking the ability to stretch or bend. However, this staple-like particle design exhibits an unusually high amount of both properties simultaneously.

“Our entangled granular material using the staple-like particle demonstrates both high strength and toughness at the same time,” said PhD student Saeed Pezeshki.

Additionally, they discovered that applying different vibrational patterns would change the particles’ degree of entanglement, allowing the team to assemble and disassemble a shape instantly. Applying a light vibration caused the pieces to interlock, whereas a heavy vibration untangled them as a pile of loose particles.

Material Applications

“No binder is required, so particles can be rapidly assembled in an infinite number of shapes, which can be reconfigured with appropriate mechanical stimuli, making them attractive for lightweight and reversible materials and structures and aggregate architectures,” the authors recently wrote.

“The fundamental understanding of entanglement gained in this project is also relevant to other physical systems, including biological structures, ‘living’ entangled matter, robotic materials, as well as colloidal assemblies,” the authors add.

“It’s a strange material because it’s obviously not a liquid. However, it’s also not quite solid,” Barthelat said. “This opens new and intriguing engineering possibilities.”

“Handling a bundle of these entangled particles feels very remote and exotic,” he added.

The paper, “Combined Effects of Particle Geometry and Applied Vibrations on the Mechanics and Strength of Entangled Materials,” appeared in the Journal of Applied Physics on April 14, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.