The solitons at the heart of the study are torons and skyrmion tubes, particle-like configurations of the director field—the local orientation of rod-like molecules—in chiral nematic liquid crystals. In these materials, the director twists with a characteristic pitch set by the molecular chirality, and defects or twisted regions can lock together into stable, localized structures that behave in many ways like particles. Torons, in particular, are triple-twisted, particle-like excitations confined between two bounding glass plates of a liquid-crystal cell. Because their topology is conserved, they cannot simply dissolve into the uniform background; instead, they persist as mobile objects that can be created, moved, and manipulated, for example with laser tweezers.

The experimental team, led by Smalyukh’s group at the University of Colorado Boulder, created individual torons in thin cholesteric cells and then imposed a controlled shear flow by translating one glass plate relative to the other. Using polarization optical microscopy, the researchers tracked the soliton trajectories as the shear rate varied. At low driving speeds, the torons moved essentially along the shear direction, but as the flow intensified, they acquired an increasingly pronounced transverse velocity component, deflecting away from the shear plane much as charged particles deflect in a magnetic field or magnetic skyrmions deflect under current. The team quantified this deflection with a Hall angle, which grew with the Ericksen number, a dimensionless parameter comparing viscous and elastic stresses in the liquid crystal.

Crucially, the experiments revealed that the solitons are not passive tracers of the surrounding fluid. The researchers simultaneously tracked small tracer particles—melamine resin spheres and alumina nanoplates—suspended in the liquid crystal. These tracers, which sample the local flow field, showed no detectable transverse motion across a wide range of shear rates. The torons, by contrast, drifted sideways far more strongly than any underlying transverse mass flow could explain. This discrepancy between the motion of the soliton and the motion of the fluid around it is the central puzzle that the theoretical and numerical parts of the study set out to resolve.

On the theory side, the Lisbon-based team performed a systematic perturbation analysis of the Ericksen–Leslie equations, the continuum description of nematic liquid-crystal hydrodynamics. Treating the shear as a weak perturbation of the static toron configuration, they computed the corrections to the director and velocity fields order by order. Their analysis predicts a weak net transverse mass flow that emerges only at third order in the perturbation parameter, meaning its magnitude scales as the cube of the shear rate. This cubic scaling reflects the nonlinear coupling between director distortion and flow that is characteristic of liquid-crystal rheology, where backflow effects link molecular orientation and fluid motion.

Numerical simulations based on a lattice Boltzmann implementation of the coupled director and flow dynamics confirmed and extended the analytical picture. The simulations reproduced the transverse drift of torons under steady shear, captured the deformation of the soliton as it elongates into finger-like shapes at higher shear rates, and even showed the instability and eventual destruction of torons at very large Ericksen numbers. Importantly, the simulations revealed that in certain parameter regimes the soliton’s transverse motion occurs opposite to the direction of the net transverse mass current predicted by the perturbation theory—a striking result that rules out any simple explanation in which the soliton is merely carried along by a secondary flow.

To rationalize these observations, the authors adapted the Thiele equation, a classical framework developed in the 1970s to describe the steady-state motion of magnetic domains. In its original form, the Thiele equation balances the driving force on a topological soliton against dissipative drag and a gyroscopic term that produces the transverse deflection responsible for the magnetic skyrmion Hall effect. The liquid-crystal version developed in this work replaces the magnetic gyrovector with a term tied to the flow vorticity—the local rotational component of the shear flow surrounding the soliton. This formulation provides a compact physical explanation: it is the vorticity of the backflow generated around the distorted director texture, rather than any net transverse current, that pushes the soliton sideways.

The generality of the effect was tested in several ways. Simulations of skyrmion tubes—solitons that extend through the cell thickness—showed Hall angles comparable to those of torons under identical conditions, and even more complex objects such as skyrmion bags containing multiple antiskyrmions exhibited the same qualitative behavior, with Hall angles of roughly nine to twelve degrees depending on their internal structure. The researchers also examined how boundary conditions at the glass plates influence the effect: tilting the surface anchoring of the director changes both the magnitude and, in some regimes, the sign of the Hall angle. Experiments under a sinusoidal electric field, which stabilizes the solitons against flow-induced distortion, showed torons with Hall angles of about ten degrees, and occasionally small negative angles corresponding to deflection in the opposite transverse direction.

Beyond its fundamental interest, the discovery suggests practical possibilities. Because the transverse drift is controllable—through shear rate, cell geometry, surface anchoring, and applied electric fields—topological solitons in liquid crystals could serve as functional building blocks in microfluidic technologies, acting as self-propelled carriers or as reconfigurable elements whose trajectories are steered by flow rather than by external fields alone. The effect also deepens the analogy between soft matter and magnetic systems, showing that Hall-like dynamics of topological excitations is not tied to electromagnetism or spin, but follows generally from the interplay of topology, dissipation, and vorticity in driven media.

The study, which received support from the Portuguese Foundation for Science and Technology, FAPERJ, CNPq, and the US Department of Energy, establishes a new arena in which the concepts of topological transport can be explored in a soft, transparent, and easily manipulated medium. As the authors show, a simple equation inspired by magnetism, combined with detailed experiments and large-scale simulations, is enough to capture the essence of the phenomenon: when you shear a chiral liquid crystal, its topological solitons refuse to follow the flow—they sidestep it.

Subject of Research: Hall-like transverse drift of topological solitons in sheared chiral liquid crystals

Article Title: A liquid-crystal analogue of the skyrmion Hall effect

Article References: Coelho, R. C. V., Zhao, H., Amaral, G. N. C., Smalyukh, I. I., Telo da Gama, M. M., & Tasinkevych, M. (2026). A liquid-crystal analogue of the skyrmion Hall effect. Nature Physics. https://doi.org/10.1038/s41567-026-03379-0

Image Credits: AI Generated

DOI: 10.1038/s41567-026-03379-0

Keywords: liquid crystals, skyrmions, topological solitons, torons, shear flow, Hall effect, Ericksen-Leslie theory, Thiele equation, microfluidics, soft matter, lattice Boltzmann simulations, cholesteric liquid crystals

The appeal of MXenes lies in a rare combination of properties. These atomically thin sheets, first reported in 2011, are typically produced by etching layered ceramics such as the titanium carbide Ti3C2Tx, whose surface terminations can be chemically tuned. The review highlights electrical conductivities on the order of 10^3 to 10^4 S cm^-1, an exceptionally high aspect ratio and tunable surface chemistry, all of which make MXenes natural candidates for reinforcing the long-range molecular order that defines the liquid crystalline state while adding the fluidity and responsiveness that liquid crystals already possess.

When MXene nanosheets are dispersed into liquid crystal hosts, the electro-optical characteristics improve markedly. The review documents polymer-dispersed liquid crystal films reaching a transmittance of roughly 74 percent at a bias of 50 volts in 13 micrometer-thick cells, with switching speeds below one millisecond in the ON state. Perhaps most striking for practical display and smart-window applications, the doped films retained about 71 percent transmittance after 180 days, evidence that the nanosheet-liquid crystal interface can remain stable over months rather than degrading within days as many earlier nanodopants did.

The mechanisms behind these gains are traced in detail. MXene sheets carry surface charges and functional groups that interact with the dipolar liquid crystal molecules, anchoring them and raising the effective dielectric anisotropy of the mixture. This lowers the threshold voltage needed to reorient the director field and accelerates the relaxation dynamics once the field is removed. The high conductivity of the MXene network also screens internal fields more efficiently, reducing ion-driven image sticking that has long plagued conventional liquid crystal devices.

Beyond doped thermotropic systems, the review devotes substantial attention to MXenes that form liquid crystalline phases on their own. When sufficiently concentrated in solution, MXene nanosheets align into lyotropic nematic phases with a relatively low viscosity of about 0.14 Pa s and an excellent orienting ability, producing residual dipolar couplings of up to 37 Hz in nuclear magnetic resonance measurements. These intrinsic liquid crystalline phases open a route to ordered MXene films and fibers without needing a separate liquid crystal host, and they suggest that the two-dimensional sheets can self-organize into macroscopic aligned architectures suitable for electrodes, membranes and photonic structures.

Nonlinear optical behavior also benefits from the partnership. Certain MXene-based liquid crystal formulations exhibit Kerr coefficients as high as 4.9 × 10^-6 m V^-2 at a concentration of 4 mg per milliliter, values that compare favorably with conventional liquid crystals and point toward low-voltage optical modulators and beam-steering elements. The Kerr effect, in which a liquid crystal becomes birefringent under an applied electric field, scales with the square of the field, so a larger Kerr coefficient translates directly into stronger optical response at lower drive voltages, a key requirement for energy-efficient photonic devices.

Soft actuation represents another frontier. MXene-liquid crystal soft actuators bend to angles as high as roughly 67 degrees under near-infrared irradiation while remaining stable across 100 actuation cycles, exploiting the strong photothermal conversion of the MXene sheets to drive reversible shape changes. Liquid crystal elastomers incorporating MXenes generate actuation strains up to about 42 percent and stresses near 1.56 MPa under 400 mW of 808 nm near-infrared light, combining the large deformation of elastomer networks with the rapid, localized heating that MXenes provide. These numbers approach the performance regime needed for artificial muscles, soft robotics and adaptive optical components.

The review maps these laboratory results onto a broad application landscape. Smart windows that modulate transparency on demand, camouflage systems that adapt their appearance, wearable textiles that respond to body heat or light, biosensors that exploit the ordered MXene-liquid crystal interface for molecular recognition, and energy storage devices that benefit from the aligned conductive pathways all appear as realistic targets. The common thread is that the MXene-liquid crystal hybrid is not merely a better display material but a multifunctional platform whose optical, electrical, mechanical and thermal responses can be tuned independently.

Challenges remain before these systems reach commercial scale. The review notes that long-term colloidal stability of MXene nanosheets in liquid crystal hosts, oxidation of the sheets under ambient conditions, and the need for scalable, reproducible dispersion methods all require further work. Surface functionalization strategies and polymer-compatible MXene formulations are identified as promising directions, along with systematic studies of how nanosheet concentration, lateral size and surface chemistry govern the balance between enhanced order and increased viscosity that ultimately limits device speed.

What emerges from the survey is a coherent picture of a materials platform in rapid maturation. With electro-optical performance already meeting or exceeding key benchmarks for displays and smart windows, actuation strains approaching those of biological muscle, and nonlinear optical coefficients suitable for low-voltage photonics, MXene-doped liquid crystals are positioned as a candidate next-generation multifunctional material. The authors argue that continued progress in mechanism-level understanding, coupled with device-level engineering, could carry these hybrids from laboratory demonstrations into adaptable technologies spanning optics, wearables, sensing and energy within the coming decade.

Subject of Research: Materials Science

Article Title: Review: recent advances in MXene-doped liquid crystals—mechanisms to multifunctional applications

Article References: Chinky, Malik, P., & Kumar, P. (2026). Review: recent advances in MXene-doped liquid crystals—mechanisms to multifunctional applications. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13943-x

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13943-x

Keywords: MXene, liquid crystals, Ti3C2Tx, electro-optical materials, soft actuators, liquid crystal elastomers, smart windows, 2D nanomaterials, Kerr effect, polymer-dispersed liquid crystals, Review, recent

The work, led by Sachin Ashok Bhat and Channabasaveshwara V. Yelamaggad at the Centre for Nano and Soft Matter Sciences in Bengaluru, together with collaborators at BMS College of Engineering and the University of Mysore, describes a family of sixteen nonsymmetric liquid crystal dimers. Each dimer couples a rigid, chiral cholesteryl unit to a two-ring Schiff-base mesogenic core through a flexible alkylene spacer of systematically varied length. The two ends of the molecule play different roles: the cholesterol fragment carries the permanent molecular chirality, while the Schiff-base segment, with its azomethine linkage, provides the anisotropic shape and conjugation needed for liquid crystalline ordering. The chiral tail was drawn from one of two sources, either citronellol or octan-2-ol, giving two series of compounds, CSBC and CSBO, each containing matched R and S enantiomeric pairs.

All sixteen compounds proved to be enantiotropic liquid crystals, meaning they pass reversibly between crystalline, mesomorphic and isotropic states on heating and cooling. The phase behaviour, mapped by polarised optical microscopy and differential scanning calorimetry, was remarkably rich. Depending on spacer length and terminal substituent, the dimers formed chiral nematic phases, smectic A layers, tilted chiral smectic C phases, and, in several cases, the twist grain boundary phase, a frustrated mesophase that arises when the tendency of chiral molecules to twist conflicts with their drive to form flat, layered smectic order.

The spacer length emerged as the decisive variable in determining which phases appeared. Short spacers, such as the three-carbon and four-carbon linkers, enhanced conformational restriction and packing frustration, stabilising the twist grain boundary phase. In the CSBC series, for example, the three- and four-carbon dimers showed TGB phases adjacent to the isotropic liquid, while the five-carbon members favoured chiral nematic and smectic A phases with a metastable chiral smectic C phase on cooling. The seven-carbon dimers, by contrast, exhibited only the smectic A phase. This progression reflects a general principle in dimeric liquid crystals: as the spacer lengthens, molecular flexibility increases, packing becomes more efficient, and layered smectic organisation wins out over frustrated twist. The familiar odd-even effect, in which spacer parity modulates molecular bend and phase stability, was also evident across both series.

Variable-temperature X-ray diffraction provided the structural underpinning for these observations. For the representative dimer CSBC-(R)3, the smectic A phase showed a layer spacing of about 46 angstroms at 120 degrees Celsius, closely matching the calculated all-trans molecular length of 46.66 angstroms. The resulting d/L ratio of nearly one is the signature of a monolayer smectic A structure, in which each layer is one molecular length thick. For CSBO-(R)5, the smectic C phase told a different story: layer spacings fell well below the molecular length, with d/L ratios of 0.86 at 40 degrees and 0.83 at 30 degrees, corresponding to calculated tilt angles between roughly 31 and 34 degrees. These measurements confirmed that the molecules lean over as they enter the smectic C phase, a geometric change that turns out to be central to the chirality switching behaviour.

The most striking results came from temperature-dependent circular dichroism spectroscopy, a technique that measures how a material responds differently to left- and right-circularly polarised light. In the chiral nematic phase, the spectra displayed two distinct bands. A strong long-wavelength band centred near 550 nanometres arises from selective Bragg reflection by the periodic cholesteric helix, probing the long-range supramolecular architecture. A second band near 350 nanometres originates from the pi-to-pi-star transition of the Schiff-base chromophore and reflects the local chiral arrangement of neighbouring mesogenic units through excitonic coupling. The presence of both bands demonstrates that chirality is transferred hierarchically, from the stereogenic centres of the cholesterol unit to the local chromophore packing and onward to the macroscopic helix.

The corresponding R and S enantiomers produced nearly perfect mirror-image CD spectra across the entire temperature range, with both bands inverting sign while retaining identical profiles and intensities. This confirms that molecular stereochemistry is faithfully translated into supramolecular helicity without racemisation or preferential aggregation. Notably, the absolute configuration had little effect on thermodynamics: each enantiomeric pair showed essentially identical phase sequences and transition temperatures, indicating that handedness governs the direction of the helix but not the stability of the phases themselves.

The pivotal discovery was what happened at the transition from the chiral nematic phase to the chiral smectic C phase. On cooling, both the selective reflection band and the chromophore absorption band reversed sign simultaneously and completely. Because the molecular stereochemistry is fixed throughout the thermal cycle, this inversion cannot reflect any change in the molecules themselves. Instead, it demonstrates a genuine reversal of the supramolecular helical sense. The authors propose a mechanistic picture: in the chiral nematic phase, molecular chirality is expressed through continuous rotation of the director, producing the cholesteric helix. On entering the smectic C phase, positional layering develops together with molecular tilt, and the azimuthal rotation of the tilt direction from one layer to the next generates a different chiral superstructure whose preferred helical sense is opposite to that of the cholesteric phase. The reorganisation of molecular packing, not any alteration of molecular configuration, drives the switch.

The team took care to rule out optical artefacts. Because liquid crystalline phases are anisotropic, apparent CD signals can in principle arise from linear dichroism, linear birefringence, reflection or scattering. Control experiments detected no measurable linear dichroism over the investigated spectral range, and rotating the samples about the incident light axis in 90-degree intervals left the spectral profiles, intensities and signs unchanged. Genuine circular dichroism is rotationally invariant, whereas artefactual contributions from linear optical effects are not, so the observed rotational invariance, together with the mirror-image behaviour of the enantiomeric pairs and the disappearance of the CD signal in the isotropic phase, establishes that the signals are intrinsic. The simultaneous, reversible inversion of both bands across the phase transition is characteristic of a real thermally driven reorganisation of the helical structure.

The researchers note that a similar thermally induced helicity inversion had previously been observed by their group in ferroelectric liquid-crystalline systems, suggesting that helicity inversion reflects a general competition between orientational twist and layered chiral ordering. However, the systematic observation of simultaneous inversion of both the selective reflection and chromophore CD bands across the nematic-to-smectic-C transition in cholesterol-based Schiff-base dimers has rarely been reported. The finding establishes thermally induced supramolecular chirality inversion, or TISCI, as a direct experimental manifestation of chirality transfer across multiple structural length scales, from local chromophore packing to the macroscopic helical superstructure.

The practical implications extend well beyond fundamental soft matter physics. Because the handedness of the supramolecular assembly can be switched reversibly with temperature while the molecular chirality stays constant, these dimers offer a design strategy for responsive chiroptical materials, circularly polarised photonic systems, optical information storage, smart sensors and temperature-controlled optical switching devices. The structure-property relationships uncovered here, in which spacer architecture regulates packing, conformational flexibility tunes phase stability, and terminal chirality sets the direction of helicity transfer, provide molecular design principles for next-generation chiral liquid crystals whose mesophases and optical responses can be tuned with precision. In a field where controlling light with chiral soft matter is a growing pursuit, a material that flips its entire helical handedness on command is a compelling addition to the toolkit.

Subject of Research: Thermally induced supramolecular chirality inversion in cholesteryl Schiff-base liquid crystal dimers

Article Title: Hierarchical chirality transfer and thermally induced supramolecular chirality inversion in cholesteryl schiff-base liquid crystal dimers

Article References: Bhat, S. A., P. N., R., Veerabhadraiah, S. R., & Yelamaggad, C. V. (2026). Hierarchical chirality transfer and thermally induced supramolecular chirality inversion in cholesteryl schiff-base liquid crystal dimers. Frontiers in Soft Matter, 6, Article 1928826. https://doi.org/10.3389/frsfm.2026.1928826

Image Credits: AI Generated

DOI: 10.3389/frsfm.2026.1928826

Keywords: liquid crystals, chirality, cholesterol, Schiff base, circular dichroism, supramolecular helicity, smectic phases, chiral nematic, twist grain boundary, phase transitions, chiroptical materials, self-assembly

The motivation behind the work is rooted in a growing tension of modern life. High-frequency electromagnetic fields are everywhere, emitted by power lines, communication systems, imaging technologies, and the dense infrastructure of 5G and 6G wireless networks and satellite communications. While short-term exposure within prescribed safety limits is generally considered minimal risk, long-term exposure to high-frequency radiation has been associated with detrimental effects on human health and ecosystems. In industrial settings, local field intensities can spike unexpectedly when multiple sources overlap or when equipment malfunctions, yet most monitoring today relies on bulky, powered instruments that cannot be worn or embedded cheaply in every device that might pose a hazard.

There is also a security dimension. High-frequency fields are the physical medium of electromagnetic pulse weapons, which can be used defensively but also maliciously in cyberterrorism. Real-time, in-situ detection of destructive electromagnetic fields would significantly enhance risk management for command-and-control systems and battlefield operations. Drone warfare, in particular, demands simple onboard microsensors capable of detecting and alarming potential electromagnetic attacks. Existing sensor technologies, from Hall effect devices and anisotropic magnetoresistance elements to giant magnetoresistance and spin-dependent tunneling sensors, offer compact designs with medium-to-high accuracy, but they all require detection electronics powered by external energy supplies, limiting their mobility and their usefulness in passive, wearable formats.

The new chip takes a radically different approach by exploiting a magnetothermal mechanism. At its heart is a thin, flat cell filled with the thermotropic liquid crystal 4-cyano-4′-pentylbiphenyl, better known as 5CB, a rod-like nematic compound that has served as a model material since its first synthesis in 1973. Embedded within the liquid crystal matrix is a network of thin ferromagnetic wires, a 50-mesh nickel gauze with wires roughly 50 micrometers in diameter. Both sides of the chip are laminated with polymer-based polarizer films aligned at 90 degrees to each other, forming crossed polarizers in direct contact with the liquid crystal. The assembled device measures about one centimeter square, weighs less than 0.3 grams, and has a Young’s modulus on the order of tens of kilopascals, making it flexible and light enough for integration into smart glasses or miniature unmanned aerial vehicles.

The physics of the sensing process unfolds in two coupled steps. First, when an external alternating magnetic field exceeds roughly 6 millitesla at the tested frequency of 125 kilohertz, the time-varying field induces eddy currents in the conductive nickel mesh, generating Joule heating. Because nickel has a high relative permeability, it concentrates the magnetic field, increasing the induced currents and heating efficiency compared with a non-magnetic mesh. A second mechanism, magnetic hysteresis loss, contributes additional heat that occurs only in ferromagnetic materials and is proportional to the area under the magnetization loop. The heating power scales with the square of the product of field strength and frequency, which means even modest increases in either parameter dramatically accelerate the response.

Second, the heat generated in the mesh diffuses into the surrounding liquid crystal. Once the local temperature surpasses the clearing point of 5CB at about 35 degrees Celsius, the material undergoes a reversible phase transition from the nematic phase, in which the rod-like molecules are quasi-one-dimensionally ordered, to the isotropic phase, in which they are globally disordered. This transition changes the optical properties of the film dramatically. In the nematic, field-off state, the unaligned liquid crystal exhibits strong birefringence between the crossed polarizers, so the chip transmits ambient light and appears bright. In the isotropic, field-on state, birefringence vanishes and transmittance drops to near zero, so the chip turns dark. No separate transducer is needed to convert temperature into an optical signal; the phase transition itself is the readout.

In experiments, the researchers placed the chip at the center of a Helmholtz coil driven by an induction heater power supply and filmed its response with a digital camera positioned about 1.5 meters away to shield the camera electronics from interference. When a field of 125 kilohertz and up to 30 millitesla was applied, optically dark domains appeared near the chip center, grew into a ring-like pattern, and rapidly spread to cover most of the display. When the field was switched off, the dark domain gradually shrank and disappeared as heat dissipated by natural convection, completing a full on-off cycle in roughly ten seconds at room temperature. The response time upon induction heating was as fast as 30 milliseconds, while recovery took tens of seconds. The chip showed remarkably high stability and repeatability over more than ten consecutive field pulses.

To understand and predict this behavior, the team built a finite element model in COMSOL Multiphysics that coupled electromagnetic induction with heat transfer and the latent-heat-mediated phase transition. The simulations closely matched the experimental data, predicting the characteristic transition times and optical switching behavior across a wide range of field strengths, generally falling within the standard deviation of the measurements. The model revealed that the onset of the nematic-to-isotropic transition follows a line of constant field-frequency product, suggesting the system operates in the low-frequency regime where heating power scales as the square of that product. The researchers also found that sensitivity increases with the volume fraction of the nickel mesh: a denser mesh generates heat faster and shortens response times, though it also stores more thermal energy and lengthens recovery. Skin-depth effects, estimated at about 30 micrometers at 125 kilohertz, comparable to the wire diameter, add a further frequency-dependent wrinkle to the design space.

The material choices are deliberately pragmatic. 5CB is cheap, easy to handle, and stable at room temperature thanks to long-term supercooling of its nematic melt, and its low viscosity, volatility, and toxicity make it practical for real devices. Its clearing temperature of 35 degrees Celsius suits temperate climates, but the authors note that alternative or blended liquid crystals with higher transition temperatures, such as MBBA at 47 degrees Celsius, could extend operation to warmer subtropical environments, while lower-transition materials could serve aerospace applications. Tuning the mesh geometry, wire diameter, or liquid crystal composition offers further control over sensitivity and response time, and coating the wires with anchoring agents could better align the liquid crystal molecules for improved performance.

The combination of extreme simplicity, millimeter-scale dimensions, lightweightness, passive operation, and a robust visual readout positions this chip as a promising candidate for ultra-low-power wearable technologies, mobile platforms, and electronic warfare systems. Because the sensor is fundamentally independent of electronics, it is also inherently resistant to external field-induced signal noise that plagues conventional detectors. The researchers caution that the thermally driven mechanism is slower than the millisecond intrinsic reorientation of the liquid crystal itself, spanning from several milliseconds at high fields to tens of seconds near the detection limit, and that future work will explore faster liquid crystal formulations inspired by electro-optical sensing modes. Even so, the demonstration that electromagnetic radiation can be caught, converted, and displayed by a chip with no power source of its own marks a striking step toward a world where hazard warnings are woven invisibly into the fabric of everyday objects.

Subject of Research: Passive liquid crystal sensor chip for detecting high-frequency electromagnetic fields

Article Title: Electronics-free, ultra-low-power, wearable sensor chip for high-frequency electromagnetic field detection

Article References: Mohizin, A., Abelmann, L., & Sung, B. (2026). Electronics-free, ultra-low-power, wearable sensor chip for high-frequency electromagnetic field detection. Communications Engineering, 5(1), Article 170. https://doi.org/10.1038/s44172-026-00800-7

Image Credits: AI Generated

DOI: 10.1038/s44172-026-00800-7

Keywords: liquid crystals, electromagnetic field sensor, wearable technology, magnetothermal effect, nickel mesh, 5CB, passive sensing, radio-frequency detection, phase transition, electronics-free, electromagnetic pulse, birefringence

The study, published in the journal Advanced Composites and Hybrid Materials, was led by Ki-Hyun Ryu and Sungju Lee of the Korea Institute of Science and Technology, together with colleagues across several KIST research centers. Their central insight is deceptively simple: instead of trying to push ions into a densely packed nanotube fiber after the fact, why not build molecular-scale breathing room into the material from the very beginning? The answer they arrived at relies on a thermodynamically driven co-assembly process borrowed from the world of liquid crystals, a field more often associated with display screens than with supercapacitors.

To understand why the problem matters, it helps to picture what happens inside a conventional carbon nanotube fiber. Individual nanotubes, each essentially a rolled-up sheet of graphene a few nanometers wide, are drawn together into bundles, and those bundles are packed into a fiber with inter-bundle spacing measured at the molecular scale. This ultra-dense arrangement maximizes the contact between tubes, which is exactly what you want for load transfer and for electrons hopping from one tube to the next. But for electrochemical applications, the picture inverts. Ions from an electrolyte can only access the outermost surfaces of the fiber; the deep internal channels between bundles remain inaccessible, so the enormous theoretical surface area of the nanotubes goes largely unused. Materials scientists have long described this as a packing-accessibility trade-off, and it has been a persistent bottleneck in translating the extraordinary properties of individual nanotubes into practical devices.

The Korean team’s strategy attacks the problem at the molecular level using soft poly(vinyl alcohol), or PVA, chains. PVA is a hydrophilic, water-soluble polymer, and the researchers exploited its strong non-covalent adsorption onto carbon nanotube surfaces to intercalate the polymer chains directly into the nanotube bundles during fiber formation. Because the process occurs during a lyotropic liquid crystalline co-assembly stage, the rigid nanotubes retain the high axial alignment that is essential for efficient electron transport along the fiber, while the flexible polymer chains wedge themselves between the bundles and hold the channels open. The researchers describe the resulting architecture as unlocked, in the sense that the interstitial channels that would normally collapse into dense packing are instead molecularly secured at a controlled spacing.

The thermodynamics of this intercalation are worth appreciating. When long, flexible polymer chains are confined between rigid nanotubes, they lose some conformational entropy, but the strong adsorption energy between the polymer and the carbon surface compensates for that loss, driving the hybrid structure to self-assemble spontaneously. Once in place, the entropic relaxation of the soft chains, their tendency to coil and spread, effectively props open the interstitial channels without any external scaffolding, template, or post-processing step. This bottom-up approach stands in contrast to more common strategies that graft bulky functional groups onto nanotube walls or hybridize the fibers with additional active materials, both of which can disrupt the intrinsic structure of the nanotubes or add complexity and cost to manufacturing.

The benefits of the unlocked architecture extend beyond simple spacing. Carbon nanotube surfaces are inherently hydrophobic, which impedes wetting by aqueous electrolytes and further limits ion access. The intercalated PVA chains, being hydrophilic, impart wettability to the composite fiber, so electrolyte ions are not only given physical pathways into the interior but are also chemically encouraged to penetrate. In effect, the polymer performs double duty: it acts as a molecular spacer that maintains the channels, and it converts the fiber’s internal environment from one that repels electrolytes to one that welcomes them. The dormant internal volume of the fiber, previously inaccessible, becomes an active participant in electrochemical processes.

The quantitative evidence for this internal activation is striking. When the researchers measured the electrochemical performance of their composite fibers, they found an 11.2-fold enhancement in specific capacitance compared with pristine carbon nanotube fibers. Specific capacitance is a direct measure of how much charge a material can store per unit mass, and an improvement of more than an order of magnitude indicates that ions are genuinely reaching the deep core of the fiber rather than merely decorating its surface. The composite fibers also showed superior rate performance, meaning they retained much of their charge-storage capability even when charged and discharged rapidly. Rate capability is a sensitive probe of ion diffusion resistance: if ions had to fight their way through dense packing, performance would collapse at high rates. The fact that it did not confirms that the engineered channels substantially mitigate diffusion resistance throughout the fiber’s cross-section.

What makes this work particularly significant is its generality. The authors frame their methodology as a universal design paradigm for next-generation composite materials that require dynamic ion transport. Dense assemblies of one-dimensional nanomaterials are not limited to carbon nanotubes; nanowires, nanofibers, and other elongated building blocks face the same packing-accessibility dilemma whenever they are assembled into macroscopic forms. A spacing strategy that works during co-assembly, requires no complex active-material hybrids, and preserves the intrinsic structure of the constituent nanomaterials could therefore be applied far beyond the supercapacitor context in which it was demonstrated here. The approach also avoids covalent modification of the nanotubes, which is important because covalent chemistry on carbon surfaces introduces defects that degrade the electrical conductivity that makes nanotubes valuable in the first place.

The research was carried out at the Advanced Conductive Materials Research Center, the Carbon Composite Materials Research Center, and the Functional Composite Materials Research Center of the Korea Institute of Science and Technology in Wanju, Republic of Korea. It was supported by the Nano and Material Technology Development Programs through the National Research Foundation of Korea, funded by the Ministry of Science and ICT, as well as by a KIST Institutional Program. The work was published as an open-access article on 10 September 2026, making the full technical details freely available to researchers worldwide.

For a field that has spent decades chasing ways to make carbon nanotube assemblies live up to their nanoscale promise, the message of this study is refreshingly constructive. Rather than treating dense packing as an unavoidable compromise, the researchers showed that molecular-level design, using nothing more exotic than a soft polymer and the thermodynamics of liquid crystalline assembly, can unlock the hidden interior of a nanotube fiber while keeping its celebrated strength and conductivity intact. If the strategy proves as transferable as the authors suggest, the dense-but-dead interiors of one-dimensional nanomaterial assemblies may soon become some of the most valuable real estate in materials science.

Subject of Research: Liquid crystalline co-assembly of carbon nanotube and poly(vinyl alcohol) hybrid fibers to open interstitial channels for enhanced interfacial ion transport

Article Title: Bottom-up co-assembly of carbon nanotube and soft polymer hybrids: unlocking interstitial channels for enhanced interfacial ion kinetics

Article References: Ryu, K.-H., Lee, S., Lim, S.-I., Kim, S. G., Kim, S. M., Kim, N. D., Hwang, J. Y., Moon, S. Y., Yu, H., Jeong, H. S., & Kim, D.-Y. (2026). Bottom-up co-assembly of carbon nanotube and soft polymer hybrids: unlocking interstitial channels for enhanced interfacial ion kinetics. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02076-z

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02076-z

Keywords: carbon nanotubes, poly(vinyl alcohol), liquid crystals, co-assembly, nanocomposites, composite fibers, interstitial channels, ion diffusion, specific capacitance, supercapacitors, soft matter, Korea Institute of Science and Technology

Birefringence is the engine behind virtually every liquid crystal optical device. When linearly polarized light passes through a birefringent material, its two orthogonal polarization components travel at different speeds, accumulating a controllable phase difference known as retardation. Voltage-driven liquid crystal retarders exploit this effect to rotate, modulate, and analyze polarization states on demand, and they are ubiquitous in displays, adaptive optics, and imaging systems operating in the visible spectrum. But pushing the same technology into the infrared has proved stubbornly difficult, and the new study offers one of the clearest explanations yet of why—along with a practical way around the problem.

The core issue is one of geometry. Infrared wavelengths are roughly ten times longer than visible wavelengths, and the phase retardation a device delivers is proportional to the product of its birefringence and its thickness. To achieve the same retardation at 3.85 micrometers as at visible wavelengths, a liquid crystal layer would need to be about ten times thicker. That would be an inconvenience on its own, but it becomes a fatal performance problem because the switching speed of a liquid crystal device scales with the square of the layer thickness. A tenfold thicker cell means roughly a hundredfold slower response—far too sluggish for real-time polarization imaging.

A team led by Tomoyuki Sasaki and Hiroshi Ono at Toyama Prefectural University, working with colleagues including Sora Ohara, Kohei Noda, Moritsugu Sakamoto, and Nobuhiro Kawatsuki, reasoned that the better route was to raise the birefringence itself rather than thicken the cell. Their motivation builds on years of work showing that carbon nanomaterials can enhance liquid crystal properties in the visible range. Previous studies had reported that graphene flakes can roughly double the dielectric anisotropy of a nematic liquid crystal at kilohertz frequencies, and that reduced graphene oxide can lift visible-light birefringence by about ten percent at low doping levels. Whether the same trick would work in the infrared, however, was far from obvious.

That uncertainty matters because liquid crystals behave quite differently in the infrared. The molecules absorb strongly at numerous vibrational frequencies across the infrared spectrum, and through the Kramers–Kronig relations those absorption bands reshape the refractive-index dispersion even at wavelengths where absorption itself is negligible. In other words, the optical behavior of a liquid crystal at 3.85 micrometers cannot be safely extrapolated from its behavior in the visible. No one had previously measured the birefringence of graphene-doped liquid crystals anywhere in the infrared, making the Japanese team’s measurements a genuine first.

The experimental recipe combined a commercial nematic mixture, MLC-1902 from Merck, with graphene flakes less than three atomic layers thick and up to a few micrometers across. The flakes were first dispersed in ethanol using a planetary ultrasonic mixer, then blended with the liquid crystal in precisely calculated proportions before the ethanol was evaporated by heating to 120 degrees Celsius. The doped material was loaded into cells made of rubbed polyimide-coated quartz plates, with gaps between roughly 17 and 21 micrometers determined from Fabry–Pérot interference fringes. Birefringence was then measured at two strategically chosen wavelengths—3.85 micrometers in the mid-infrared and 1.55 micrometers in the near-infrared band used by fiber-optic telecommunications—using polarized lasers and a rotating-analyzer technique that recovers the retardation from the polarization azimuth of transmitted light.

The results revealed a striking concentration dependence. At vanishingly small graphene loadings, the birefringence climbed steadily, reaching a maximum at around 4 times 10 to the minus 3 weight percent before declining as more flakes were added. The peak enhancement factors were approximately 1.5 at 3.85 micrometers and 1.4 at 1.55 micrometers, and the team found that birefringence was consistently higher at the longer wavelength across every concentration tested—an indication that the infrared dispersion is governed by nearby molecular vibrational absorption bands rather than a simple Cauchy-like trend. Optical microscope images added a crucial clue: at the lowest concentrations the flakes dispersed cleanly, while at higher loadings they began clustering into aggregates up to tens of micrometers across.

To make sense of this rise-and-fall behavior, the researchers constructed a phenomenological model capturing two competing effects. On one side, π–π stacking interactions between the aromatic rings of the liquid crystal molecules and graphene’s honeycomb lattice enhance the orientational order of the mesophase, and graphene may also modify the molecules’ effective polarizability anisotropy; together these boost birefringence in proportion to an effective order parameter that grows linearly with concentration. On the other side, aggregation at higher loadings carves out disordered regions where the ordering benefit is lost. Modeling the aggregate volume fraction with a nonlinear exponential function and combining the two populations through effective medium theory yielded a simple expression for birefringence versus concentration that fitted both infrared data sets closely, with fitting parameters of similar magnitude at the two wavelengths.

The practical implications are considerable. Because phase retardation depends on birefringence multiplied by thickness, a 50 percent birefringence boost translates directly into cells that are substantially thinner—and therefore dramatically faster—for the same optical function. Faster infrared retarders would in turn benefit infrared polarization imaging, a technique the same group has been developing for applications that include seeing through scattering media and imaging biological tissue, where many materials that scatter visible light strongly become more transparent in the infrared. Notably, the team observed no measurable scattering or absorption losses from the graphene doping at any concentration studied, suggesting the enhancement comes essentially for free.

The authors are appropriately careful about the limits of their findings. The fitted parameters are phenomenological rather than independently measured quantities, the birefringence values were obtained from single samples at each concentration, and the aggregation-based explanation, while consistent with the microscopy, remains a plausible interpretation rather than a quantitatively proven mechanism. The origin of the unusual wavelength dependence, they note, cannot be fully resolved without accompanying infrared absorption spectroscopy, which they flag as a priority for future work. Even so, the central message stands: an optimal, exquisitely small dose of graphene can measurably enhance liquid crystal birefringence in the infrared for the first time, pointing the way toward liquid crystal devices that are fast enough, thin enough, and efficient enough to bring sophisticated polarization control to the infrared frontier.

Subject of Research: Enhancement of infrared birefringence in liquid crystals by graphene flake doping

Article Title: Enhancement of birefringence in liquid crystals with graphene flakes in the infrared region

Article References: Sasaki, T., Ohara, S., Noda, K., Sakamoto, M., Kawatsuki, N., & Ono, H. (2026). Enhancement of birefringence in liquid crystals with graphene flakes in the infrared region. Results in Optics, 25, Article 101135. https://doi.org/10.1016/j.rio.2026.101135

Image Credits: AI Generated

DOI: 10.1016/j.rio.2026.101135

Keywords: liquid crystals, graphene, birefringence, infrared optics, polarization imaging, nematic liquid crystal, phase retardation, nanomaterials, order parameter, π–π stacking, optical retarders, Kramers–Kronig relations