The study, published in Advanced Composites and Hybrid Materials by Yuchen Gu, Zili Wang, Shuyou Zhang, Xiwen Gu, Liangyou Li, Jianrong Tan and Mengyu Fu, with affiliations at Zhejiang University and a Zhejiang-based equipment company, proposes an architected TPU interlayer for aluminium pipe-in-pipe systems. Rather than relying on the intrinsic softness of the polymer alone, the design exploits geometry. When the interlayer is compressed, its internal structure deforms in a way that keeps the resisting force nearly constant over a wide range of displacement. In the language of structural mechanics, the effective tangent stiffness, the rate at which force increases with displacement, drops close to zero across that plateau. This is the quasi-zero stiffness (QZS) regime, and it is the sweet spot where a structure can support a static load while offering almost no resistance to small dynamic disturbances superimposed on that load.

Quasi-zero stiffness is not a new idea in isolation theory. Classic QZS vibration isolators combine a positive-stiffness spring with a negative-stiffness mechanism, such as two oblique springs or buckled beams, so that the positive and negative contributions cancel near the equilibrium point. What makes the new work distinctive is that the cancellation is achieved entirely through the geometric deformation of a single moulded polymer component, with no separate mechanisms, springs or moving parts. That matters for PIP systems, where space between the pipes is tight, assembly must be simple, and any loose hardware inside the annulus would be a liability over decades of service.

To understand and predict the behaviour of the interlayer, the researchers built analytical models describing both its quasi-static force-displacement response and its dynamic displacement transmissibility, the ratio of the vibration amplitude transmitted to the inner pipe relative to the outer pipe. The analytical treatment, elaborated in the paper’s appendix, is notably careful. The authors derive the effective interlayer tangent stiffness from the elastic energy of the deformed structure, accounting for the relaxation of internal coordinates at fixed interface displacement. They then embed that stiffness in an idealized two-degree-of-freedom model, in which effective masses represent the outer and inner pipes, tangent stiffness terms represent the pipes and the interlayer coupling, and a viscous damping coefficient captures energy dissipation. From this model they obtain an explicit expression for the absolute displacement transmissibility as a function of frequency, mass and stiffness parameters.

The team was equally candid about the limits of the model. The appendix states that a small coupling stiffness is not, by itself, proof of quasi-zero stiffness in the assembled system, and that a candidate QZS interval on a compression curve alone does not establish that a vibration experiment operates at a stable QZS equilibrium. Stability, they note, depends on the complete tangent matrix and the admissible vibration modes, and damping of relative motion alone does not guarantee decay of every relevant mode. The two-coordinate idealization also breaks down near local resonances, where the eliminated internal degrees of freedom of the interlayer cease to follow equilibrium quasi-statically and their inertia produces frequency-dependent behaviour that a constant-stiffness model cannot represent. This kind of explicit boundary-drawing is rare in engineering papers and gives readers a precise map of where the predictions can be trusted.

With the analytical framework in place, the researchers turned to finite element simulations and physical experiments. Compression tests assessed the plateau force, the width of the quasi-zero stiffness plateau, and the specific energy absorption, a normalized measure of how much mechanical energy the structure can absorb per unit mass. Vibration experiments measured how much of the outer pipe’s motion reached the inner pipe through the interlayer. Parametric studies then swept through the material properties and the geometric parameters of the architecture, identified in the paper as parameters l1 through l6, h1 and h2, and r1, along with the number of circumferential and axial arrays of the repeating units. The results showed that these parameter variations could widen the QZS plateau by 200 to 300 percent relative to the baseline configuration, while also tuning the plateau force. A wider plateau means the isolator keeps its near-zero stiffness over a larger range of compression, which is crucial because the static load on the interlayer varies along a real pipeline and with installation conditions.

Three representative configurations were then fabricated and tested experimentally, allowing the team to check the predicted compression and vibration responses against reality. The comparison between numerical prediction and measurement revealed differences that the authors attribute to three familiar culprits: the actual viscoelastic behaviour of the TPU, which departs from the idealized constitutive assumptions; manufacturing variability in the printed or moulded architecture; and boundary conditions in the test setup that differ from the idealized constraints of the model. None of these discrepancies undermines the approach, but they underline a lesson that recurs throughout the architected materials literature: the gap between a simulation and a specimen is where most engineering risk lives, and honest quantification of that gap is more valuable than a perfect-looking curve.

The multifunctional promise of the design is what elevates it beyond a routine vibration study. Because the interlayer is a single TPU component, it simultaneously serves as the mechanical spacer that keeps the pipes concentric, the energy absorber that crushes progressively under impact or overload, and the vibration isolator that decouples the inner tube from disturbances on the outer wall. TPU itself brings practical advantages: it is tough, abrasion-resistant, chemically robust and thermoplastic, meaning it can be processed by additive manufacturing or moulding and potentially recycled. For aluminium PIP systems in offshore and subsea applications, where corrosion resistance and weight savings already motivate the use of aluminium, a polymer interlayer that adds isolation without adding hardware is an attractive package.

The analytical machinery developed in the paper also has implications beyond this specific geometry. By defining the effective interlayer tangent stiffness through a rigorous condensation of the full elastic energy, the authors provide a template for connecting quasi-static compression data to dynamic vibration models, a connection that is often made loosely or not at all. Their derivation shows that the derivative of the full compression force between plates does not generally equal the derivative of the interlayer restoring force, because pipe deformation and contact effects intervene. An explicit mapping between coordinates and forces is required before compression measurements can supply coupling parameters for a dynamic model. For engineers designing any layered or sandwiched structure, from automotive mounts to aerospace panels, that distinction is a useful corrective against the tempting shortcut of reading isolation performance directly off a load-deflection curve.

Looking forward, the study positions architected interlayers as a design space rather than a single product. The parametric results demonstrate that geometry is a genuine tuning knob: the same material can be reshaped to trade plateau force against plateau width, shifting the isolator’s operating window to match a particular pipe weight or excitation environment. The authors describe their work as a basis for further development of architected interlayers for tubular assemblies, and the open-access publication, funded by the National Natural Science Foundation of China and several regional Chinese research programs, makes the models and methods available to other groups. If subsequent work closes the remaining gap between idealized models and manufactured parts, pipelines of the future may carry their own silence inside the wall, one geometrically clever polymer layer at a time.

Subject of Research: Quasi-zero stiffness thermoplastic polyurethane interlayers for vibration-isolating aluminium pipe-in-pipe systems

Article Title: Quasi-zero stiffness TPU interlayer for aluminium–polymer pipe-in-pipe systems: design, modeling and multifunctional performance

Article References: Gu, Y., Wang, Z., Zhang, S., Gu, X., Li, L., Tan, J., & Fu, M. (2026). Quasi-zero stiffness TPU interlayer for aluminium–polymer pipe-in-pipe systems: design, modeling and multifunctional performance. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02123-9

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02123-9

Keywords: quasi-zero stiffness, thermoplastic polyurethane, pipe-in-pipe systems, vibration isolation, architected materials, finite element analysis, energy absorption, aluminium structures, structural mechanics, soft materials, interlayer design, displacement transmissibility

The technique, called continuous chaotic printing, relies on static mixers: passive elements with no moving parts that are inserted into extrusion printheads. As two or more inks flow through these elements under laminar conditions, the flow is repeatedly split, stretched, and reoriented. Each mixing element duplicates existing material interfaces, so the number of internal layers grows exponentially along the length of the mixer. Unlike approaches that demand microstructured nozzles, optical patterning systems, or external electric, magnetic, or acoustic fields, chaotic printing is inexpensive, scalable, and mathematically predictable—and it is gentle enough to handle fragile mammalian cells.

In the new study, the researchers pushed the platform beyond the traditional Kenics static mixer, testing three additional geometries borrowed from industrial chemical engineering: the Ross mixer, the Mini-SMX, and the full SMX. Each geometry stamps a distinctive microarchitectural fingerprint onto the printed filament. Kenics elements produce the familiar aligned, multilayered lamellae, reaching feature sizes of about 60 micrometers with four elements yielding 16 layers within roughly a millimeter. Ross-based constructs display asymmetric, wave- or flame-like architectures, while the Mini-SMX generates symmetric motifs reminiscent of flowers or radiant forms. The SMX mixer, evaluated with one and two elements, produces flame-like structures with pronounced segregation of the two ink phases toward opposite sides of the cross-section.

Critically, these patterns are not accidents. Computational fluid dynamics simulations of the flow at each mixer outlet closely mirrored the experimentally observed cross-sections of printed hydrogel fibers, confirming that chaotic advection under laminar flow is deterministic rather than stochastic. Complex spatial patterns emerge from repeated stretching and folding of fluid streams despite the absence of turbulence or any moving mechanical components. Under the printing conditions used—fluid viscosities close to that of water—the resulting microarchitectures are dictated primarily by mixer geometry and topology, not by random perturbations. That predictability means researchers can design an internal structure on a computer and expect to see it materialize in the printed filament.

The team also demonstrated the flexibility of the approach across three distinct deposition modes. In continuous wet-printing, filaments are extruded directly into a calcium chloride bath that crosslinks alginate. In dripping, discrete spherical constructs form by droplet detachment, yet the internal architecture survives the formation process intact. In direct ink writing, viscoelastic materials are patterned by pressure-driven extrusion into grid-like constructs, each filament retaining discernible internal microstructure. Reproducing such interleaved architectures by conventional extrusion printing would require ultra-fine nozzles and sequential layer-by-layer deposition of distinct domains, which is impractical for continuous filament fabrication. Chaotic printing achieves the same result in a single, high-throughput step.

Because the goal of chaotic printing differs fundamentally from classical mixing, the researchers reframed how mixer performance should be judged. In conventional applications, a static mixer is judged by how completely it homogenizes fluids, and mixers with higher Lyapunov exponents—measures of how rapidly neighboring fluid elements separate—such as the SMX are considered superior. In chaotic printing, the objective is not homogenization but the rapid generation of controlled interfacial area over short residence lengths. Quantifying the intermaterial perimeter separating red and green domains in printed cross-sections, the team found that interface growth is often approximately linear over the few mixing elements relevant to biofabrication, rather than exponential. The Kenics mixer was a notable exception, showing clear exponential growth consistent with its deterministic 2-to-the-n lamellar multiplication mechanism.

The fluid dynamics analysis revealed a fundamental trade-off. SMX-type mixers, with their intersecting baffle structures, generate the highest instantaneous rates of interface proliferation and the finest features, but they impose significantly larger pressure drops due to repeated obstruction and redirection of flow. The Ross mixer produces the sharpest velocity transitions and localized zones of accelerated flow near blade edges, which promote strong interface stretching but also create aggressive shear peaks. The Kenics geometry achieves effective flow reorientation with comparatively moderate pressure penalties and smoother shear distributions, making it particularly attractive for shear-sensitive living cells. The Mini-SMX emerged as a compelling middle ground, capable of high interface densities with a lower pressure cost than the full SMX design. The choice of mixer, the authors argue, should follow the architectural objective—feature size, structural regularity, energetic efficiency—rather than classical mixing metrics alone.

To prove the concept has biological teeth, the team turned to living systems. Caco-2 intestinal epithelial cells were printed within a blend of alginate and GelMA using a hollow tube, a three-element Kenics mixer, and a one-element SMX mixer. Cell viability remained high across all conditions at day one and day twenty after printing. More strikingly, constructs printed with the single-element SMX spontaneously developed organized multicellular clusters over three weeks, and immunofluorescence staining revealed expression of tissue-relevant markers including Villin and Vimentin, along with F-actin and nuclei. The chaotic microenvironment was permissive enough to support long-term culture, self-organization, and functional marker expression—from a minimal setup with no external fields or complex optics.

Bacteria provided an even more vivid demonstration of spatial control. Using a Mini-SMX printhead with two inlets and a single mixing element, the researchers printed Escherichia coli, a facultative anaerobe expressing green fluorescent protein, in the outer regions of fibers while confining Bifidobacterium bifidum, a strict anaerobe, to the core. The peripheral E. coli shielded the oxygen-sensitive B. bifidum from ambient oxygen, and after 48 hours the anaerobe reached approximately ten to the ninth colony-forming units per gram in structured constructs—significantly higher than in pre-mixed controls, where populations homogenized completely. This rational compartmentalization of a synthetic microbial consortium points toward gut-mimetic systems, controlled cross-feeding platforms, and engineered biofilms in which gradients of nutrients, metabolites, or mechanical properties can be designed into the material itself.

The third proof of concept moved from biology to chemistry. Phosphate-rich and calcium-rich gelatin inks were co-extruded through a printhead containing three Ross mixing elements, generating interdigitated domains with distinct ionic compositions embedded in a single continuous gelatin matrix. Calcium phosphate precipitated precisely at the internal interfaces between the domains, visualized by tetracycline-based fluorescence staining. Because both inks share the same polymeric matrix and are crosslinked throughout by transglutaminase, the construct remains mechanically integrated despite its chemically distinct microregions. This capacity to spatially program chemical transformations within soft materials opens routes to biomineralization, catalysis, and bioinspired composites with functional gradients or hybrid living-nonliving features.

Taken together, the work establishes static mixer geometry as a genuine design parameter—one that simultaneously controls microarchitecture, interface generation, shear exposure, and pressure loss. By expanding the chaotic printing toolbox beyond Kenics elements to Ross, Mini-SMX, and SMX geometries, and by validating the platform across wet-spinning, dripping, and direct writing, the researchers have broadened the design space available to bioprinting, soft matter, catalysis, and synthetic biology. The broader promise is seductive in its simplicity: complex, nature-like internal organization encoded passively within a printhead, in a single continuous fabrication step, using equipment that many laboratories already own. As the authors suggest, future directions may include interfacial reactivity for sensing, directed nutrient diffusion, and even the synthesis of inorganic phases within hydrogel scaffolds—turning chaos itself into a tool for structuring complexity.

Subject of Research: Chaotic bioprinting of microarchitected soft materials using different static mixer geometries

Article Title: From Flow to Function: Using Different Static Mixers to Fabricate Microarchitected Materials Via Chaotic Printing

Article References: Bolívar‐Monsalve, E. J., Ceballos‐González, C. F., Quevedo‐Moreno, D. A., Rendón‐Moreno, I. I., Cantoral‐Sánchez, A., Ambriz‐González, H., Alvarez, M. M., & Trujillo‐de Santiago, G. (2026). From Flow to Function: Using Different Static Mixers to Fabricate Microarchitected Materials Via Chaotic Printing. Advanced Science, 13(55), Article e76626. https://doi.org/10.1002/advs.76626

Image Credits: AI Generated

DOI: 10.1002/advs.76626

Keywords: chaotic printing, static mixers, bioprinting, microarchitecture, hydrogels, chaotic advection, computational fluid dynamics, synthetic microbial consortia, biomineralization, direct ink writing, soft materials, Caco-2 cells

The research, led by Yeeshu Kumar and Sungjune Park of Sungkyunkwan University together with colleagues at Jeonbuk National University and the University of Seoul, addresses a long-standing bottleneck in wearable bioelectronics. Hydrogels have long been attractive candidates for skin-mounted sensors because their softness and water content resemble biological tissue, making them comfortable and biocompatible. Yet in practice they have struggled to earn clinical trust. They dehydrate over time, they are mechanically fragile, and their adhesion to skin is inconsistent, all of which degrade the delicate electrical contact between device and body.

The physics of the problem is unforgiving. Human electrophysiological signals occupy a low-frequency band, roughly 0.1 to 100 Hz, which is precisely where the skin-electrode interface is most hostile. High impedance at that interface attenuates the tiny biosignals before they ever reach the amplifier, while motion artifacts and ambient electrical noise pile on top. The result is the familiar hiss and drift that plagues consumer fitness bands and, more seriously, undermines diagnostic-grade monitoring. Achieving high-quality signal acquisition in this lower frequency range is especially critical, the authors note, because signal quality deteriorates sharply when skin-electrode impedance rises.

The Korean team’s solution is a hybrid material they call PeLM-CH: a conductive hydrogel incorporating pectin-encapsulated liquid metal particles, subsequently doped with an ionically conductive salt solution. Each component plays a distinct role. The liquid metal, typically a gallium-based alloy, contributes metallic conductivity, while the doped hydrogel matrix supplies ionic conductivity. By embedding both conduction pathways in a single soft material, the electrode can shuttle charge efficiently across the skin boundary without the rigid, dry metal contacts that irritate skin and lose contact as the body moves.

The pectin wrapper is the clever part. Pectin, a polysaccharide naturally found in plant cell walls, serves as a biocompatible shell around each liquid metal nanoparticle. This encapsulation stabilizes the particles within the hydrogel matrix, preventing them from coalescing or leaching while preserving the tissue-friendly character of the gel. The combination yields an electrode that is simultaneously soft and stretchable like skin, electrically conductive like metal, and stable enough for extended wear. The dual conduction mechanism, metallic from the liquid metal cores and ionic from the salt-doped gel, produces what the researchers describe as an appreciable decrease in skin-electrode impedance across the electrophysiological bandwidth.

The payoff shows up directly in signal quality. When the PeLM-CH electrodes were used to record ECG, the signal-to-noise ratio reached 15.05 dB; for EMG recordings it climbed to 20.98 dB. Those figures matter because signal-to-noise ratio is the fundamental currency of biosignal acquisition: every additional decibel represents a cleaner waveform from which algorithms and clinicians can extract heart rhythms, muscle activation patterns, and early warning signs of pathology. The improved performance is attributed to the electrode’s excellent skin conformity and relatively low interfacial impedance, which together allow faint biosignals to pass through with minimal loss and contamination.

Conformability deserves particular attention. Rigid electrodes make point contact with the uneven, microscopically rough surface of skin, concentrating pressure and current into small spots. A hydrogel electrode, by contrast, can deform to follow the skin’s contours, spreading the contact area and lowering the effective impedance. The pectin-liquid metal particles reinforce this effect by keeping the material conductive even as it stretches and flexes. The authors highlight that the PeLM-CH gel electrodes excel in clean, high-precision electrophysiological monitoring precisely because of this combination of skin conformity and low interfacial impedance in the frequency band where biosignals live.

The work also positions itself as a direct answer to the limitations of conventional gel electrodes, the sticky, wet pads used in hospitals for decades. Standard clinical electrodes rely on abrasive skin preparation and conductive paste that dries out within hours, making them poorly suited to continuous ambulatory monitoring. By embedding both the conductive elements and the adhesive, conformable interface into a single hydrogel, the new design points toward electrodes that could be worn for longer periods without reapplication, a prerequisite for the continuous cardiac and neuromuscular monitoring that next-generation healthcare envisions.

The implications extend beyond cardiology and muscle monitoring. Electrophysiological sensing underpins brain-computer interfaces, sleep studies, rehabilitation feedback, and the growing ecosystem of remote patient monitoring. Any platform that depends on reading the body’s faint electrical language benefits from a quieter, more stable skin interface. A material that combines biocompatibility, mechanical softness, dual metallic and ionic conduction, and resistance to dehydration could become a foundational building block for such systems, particularly as wearable devices are asked to deliver clinical-grade data outside the clinic.

The study, which was supported by grants from the National Research Foundation of Korea funded by the Korean government’s Ministry of Science and ICT, was published open access, allowing researchers worldwide to build on the results. The authors declare no competing interests, and the work involved collaborators from Sungkyunkwan University’s School of Chemical Engineering and its SKKU National Lab for Intelligent Energy Solution Technology, the spin-off company Wearable Fluidic, Jeonbuk National University’s Department of Electronic Engineering, and the University of Seoul’s Department of Intelligent Semiconductor Engineering. As wearable bioelectronics race toward mainstream medicine, the humble electrode, the point where silicon meets skin, may prove to be the decisive frontier, and liquid metal nanoparticles wrapped in fruit-derived polysaccharide may be an unlikely but potent weapon in that fight.

Subject of Research: Liquid metal-pectin nanoparticle hydrogel electrodes for wearable electrophysiological signal acquisition

Article Title: Liquid metal‒pectin polysaccharide nanoparticles integrated hydrogel epidermal electrodes for enhanced electrophysiological signal acquisition

Article References: Kumar, Y., Li, X., Bhuyan, P., Zhang, Q., Singh, M., Bae, H., Kim, T., & Park, S. (2026). Liquid metal‒pectin polysaccharide nanoparticles integrated hydrogel epidermal electrodes for enhanced electrophysiological signal acquisition. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02077-y

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02077-y

Keywords: wearable bioelectronics, liquid metal nanoparticles, pectin, hydrogel electrodes, electrophysiological monitoring, ECG, EMG, skin-electrode impedance, signal-to-noise ratio, biomedical materials, soft materials, epidermal sensing

The material at the heart of the study is a double-network hydrogel, a class of soft solids in which two interpenetrating polymer architectures share the same water-rich matrix. The first network in this design is built from chitosan, a naturally derived polysaccharide prized for its biocompatibility and its abundance of chemically active terminal groups. The second is a modified polyethylene glycol network, which contributes elasticity and water retention. Suspended within this paired architecture are graphene nanosheets, the atomically thin carbon layers whose exceptional electrical conductivity makes them a favorite filler for flexible electronics. The logic of the design is straightforward: the polymer networks supply the mechanical toughness and stretchability that a skin-like sensor demands, while the graphene supplies a continuous conductive pathway whose resistance changes predictably when the material is deformed or heated.

Double-network hydrogels earn their reputation through a clever division of labor. When the material is stretched, the more brittle of the two networks sacrificially fractures at the molecular scale, dissipating energy that would otherwise tear the sample apart. The more ductile network survives, holding the structure together and allowing it to recover. This energy-dissipating mechanism is what allows the chitosan and modified polyethylene glycol composite to remain mechanically resilient at strains of up to 350 percent, a stretch ratio far beyond what ordinary rigid sensors can tolerate. In practical terms, the hydrogel can be wrapped around a finger, an elbow, or an ankle and endure the full range of human motion without losing its integrity or its electrical function.

The strain-sensing performance is quantified by the gauge factor, a dimensionless ratio that describes how strongly the electrical resistance responds to deformation. For this hydrogel, the researchers report a gauge factor of 13.8, a high value that indicates sharp sensitivity to even small movements. When the material is attached to the wrist, fingers, elbows, or ankles, it converts bending, stretching, and joint flexion into clean, dynamic changes in relative resistance, denoted ΔR/R₀. Crucially, these signals remain stable during motion, and the sensor maintained cyclic electromechanical stability over more than 500 stretching cycles, an endurance benchmark that matters enormously for any device expected to survive daily wear.

Temperature sensing is where the chitosan-based chemistry reveals an additional advantage. The hydrogel exhibits a thermoresistive response, meaning its electrical resistance changes with temperature, and the researchers measured a linear response across the fever-relevant window of 37.5 to 40 degrees Celsius. That linearity is a genuine asset: it means the sensor output can be translated into a temperature reading with simple calibration rather than complex curve fitting. Even more striking is the temperature coefficient of resistance, which the team reports as an ultrahigh negative 5.62 percent per degree Celsius. In plain terms, a one-degree rise in temperature changes the resistance by more than five percent, a sensitivity that allows the sensor to detect fever-range changes in real time. Most commercial thermistors and resistive temperature detectors operate with coefficients orders of magnitude smaller, so this figure represents a substantial leap in thermal resolution for a soft, wearable format.

The dual-mode capability raises an obvious engineering question: how does a single sensor distinguish a change in temperature from a change in strain, when both alter its resistance? The answer lies in the very different signatures the two stimuli produce. Strain-induced resistance changes are typically large, transient, and correlated with movement, while temperature changes produce slower, sustained shifts. By separating fast dynamic components from slow baseline drifts in the resistance signal, the sensor can deliver stable pulse waveforms from the wrist even while the wearer moves, and simultaneously flag a rising body temperature. This decoupling is precisely what a tactile healthcare patch would need: continuous pulse monitoring during exercise, for example, alongside early detection of a fever developing underneath the device.

Another practical hurdle for wearable hydrogels has always been adhesion. Soft gels tend to slide off skin or peel away from substrates after a few minutes of wear. The chitosan network in this material solves the problem chemically. Its terminal hydroxyl and amino groups are prolific hydrogen-bond donors and acceptors, allowing the hydrogel to form spontaneous adhesive contacts with a striking variety of surfaces, including plastic, rubber, glass, metal, and human tissue. This self-adhesion eliminates the need for separate tapes or medical adhesives, simplifying device assembly and improving comfort during extended wear on the skin. It also means the sensor conforms intimately to curved body surfaces, which improves both mechanical coupling for strain measurement and thermal contact for temperature measurement.

The implications for wearable healthcare devices are considerable. A single soft patch that tracks joint motion, captures pulse waveforms, and monitors fever-range temperature could serve applications ranging from postoperative recovery monitoring to athletic performance tracking to continuous screening in clinical settings. Because the material is water-rich and built partly from a biocompatible polysaccharide, it sits comfortably within the emerging paradigm of skin-interfaced electronics that prioritize softness and conformity over the rigid silicon packages of conventional devices. The combination of a 350 percent strain tolerance, a gauge factor of 13.8, more than 500 stable cycles, and a temperature coefficient of negative 5.62 percent per degree Celsius in one material is a rare confluence of specifications in the flexible sensor literature.

The work also illustrates a broader trend in materials science: the deliberate fusion of structural and functional design at the nanoscale. Rather than treating a sensor as a rigid chip attached to a flexible substrate, the researchers engineered the sensing function directly into a soft structural material. Graphene, the conductive filler, does double duty as both the electrical transducer and a mechanical reinforcement within the double-network matrix. The chitosan does double duty as a structural polymer and an adhesive. This multifunctional economy, where each component serves multiple roles, is increasingly recognized as the path toward devices that are simultaneously simpler to manufacture, more robust in use, and more comfortable to wear.

Challenges remain before such hydrogels reach the clinic or the consumer market. Long-term dehydration of the gel, biocompatibility over weeks of continuous wear, and scalable manufacturing all require further study, and the published work reports laboratory characterization rather than clinical deployment. Yet the demonstration stands as a compelling proof of concept. By marrying a tough double-network polymer architecture with the conductivity of graphene and the natural adhesivity of chitosan, the Khalifa University-led team has produced a material that behaves less like an electronic component and more like a piece of engineered skin, one that feels the body move and reads its temperature at the same time. As flexible electronics mature, designs of this kind, documented in the open-access literature and available for the wider community to build upon, may well define what the next generation of wearable health monitors looks like.

Subject of Research: A graphene-integrated double-network nanocomposite hydrogel for dual strain and temperature wearable sensing

Article Title: A multifunctional graphene-integrated double-network nanocomposite hydrogel for dual strain-temperature wearable sensing

Article References: A multifunctional graphene-integrated double-network nanocomposite hydrogel for dual strain-temperature wearable sensing. (n.d.). https://doi.org/10.1007/s42114-026-02106-w

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02106-w

Keywords: wearable sensor, hydrogel, graphene, double-network hydrogel, strain sensing, temperature sensing, nanocomposite, chitosan, flexible electronics, healthcare monitoring, soft materials, 2D materials

The core difficulty is familiar to anyone who has wrestled with wireless phone chargers. Conventional inductive coupling depends on two coils being tuned to the same resonant frequency, like two tuning forks sharing a pitch. When the coils are perfectly aligned and the load is steady, energy flows efficiently across the gap. But inside a body, nothing stays still. A patient moves, breathes, and shifts posture; the implant stretches with surrounding tissue; the electrical impedance at the implant’s output changes as it stimulates muscle. Each of these disturbances shifts the resonance of the system, and once transmitter and receiver drift out of tune, power transfer efficiency collapses. The result is an implant that works beautifully on the bench but fails unpredictably in the clinic, a problem engineers have documented since early analyses of radio-frequency coils in implantable devices in the 1980s.

The Korean team’s solution attacks the problem on two fronts simultaneously: the circuit architecture and the materials. On the circuit side, they built the power link around a nonlinear parity-time symmetric circuit, an approach first demonstrated for robust wireless power transfer by researchers at Stanford University in 2017. In a parity-time symmetric system, the transmitter and receiver form a symmetric resonator pair, and the transmitter continuously adjusts its own operating frequency to match whatever frequency the receiver settles at. Instead of demanding that the two coils stay perfectly tuned, the system lets the receiver’s resonance wander and follows it in real time. A feedback circuit in the wearable transmitter detects changes and provides automatic frequency adaptation, so that misalignment, mechanical deformation, or load impedance fluctuations no longer break the resonance that carries the power.

On the materials side, the implantable receiver is built from liquid metal. Rather than patterning the receiver’s coil and interconnects from rigid copper, the researchers used liquid metal conductors encapsulated in soft elastomers, fabricated through a multistep process involving photolithographically defined copper traces that guide liquid metal deposition, vertical interconnect vias etched through insulating elastomer layers, and off-the-shelf electronic components integrated onto liquid metal pads. Because the conductors are intrinsically stretchy, the receiver’s electrical resistance barely changes when the device deforms. That matters because resistance-induced losses are what erode efficiency in stretchable electronics: a conventional serpentine metal trace stretches by uncoiling and thinning, raising resistance and shifting the coil’s electrical properties. A liquid metal channel simply changes shape while keeping its cross-section and conductivity largely intact, minimizing resistance-induced power losses during deformation.

The performance numbers reported in the paper are striking. The system maintains power transfer efficiency above 50 percent even when the receiver is stretched by 30 percent or displaced laterally by 30 millimeters from the transmitter. For context, conventional inductively coupled systems can lose the bulk of their efficiency at a fraction of that misalignment. The team also tested the system under bending, tilting, and rotational misalignment, tracking both operating frequency and transfer efficiency through each disturbance, and compared the parity-time symmetric architecture against a conventional negative-impedance-converted system in simulations and in live animals. In those comparisons, the conventional system’s efficiency maps showed sharp drop-offs as separation and strain increased, while the parity-time symmetric system held a broad, stable operating range. A radar chart comparison against previously reported stretchable wireless bioelectronic devices, scored on efficiency, alignment tolerance, strain insensitivity, stretchability, and conductivity, placed the new system at the most balanced and superior overall performance among state-of-the-art devices.

The demonstration that turns this from an elegant circuit exercise into a potential medical technology is cardiac pacing. The researchers packaged the liquid metal receiver as a wireless pacemaker with electrodes made from a silver-gold nanowire composite embedded in an elastomer, designed to be sutured onto the surface of the heart. The wearable transmitter, powered by an 11-volt lithium-ion battery and managed by a microcontroller-controlled power unit, was mounted on the outside of the body. The received power is rectified on the implant and used to deliver controlled electrical stimulation to the cardiac tissue. Because the entire power link tolerates the constant motion of a large animal, the pacing could continue under highly dynamic in vivo conditions that would destabilize a conventional link.

In experiments, the team first validated the system in rabbit models, implanting the liquid metal receiver subcutaneously and using an LED indicator on the receiver to visualize successful power transfer as the axial and lateral separation between transmitter and receiver coils increased. The parity-time symmetric system maintained consistent activation across the tested positions, whereas the conventional system failed to power the implant at increased distances and lateral misalignments. The team then moved to a porcine model, whose heart size and physiology are much closer to humans. Fully untethered pigs with wearable transmitters attached to their backs received wireless epicardial pacing, with electrodes sutured onto the heart surface. The system not only paced the heart reliably but also terminated tachyarrhythmias, dangerously fast heart rhythms, under those same dynamic conditions, demonstrating that the power link could support not just routine pacing but active intervention during cardiac events.

The control side of the system reflects a deliberate design for real-world use. The wearable power management unit regulates power from the battery and provides regulated outputs to the transmitter circuits through a microcontroller-controlled switch, and the microcontroller was programmed using the Arduino IDE, with source code available from the corresponding authors. Smartphone control was implemented using a commercially available Bluetooth Low Energy terminal application, meaning a clinician or patient could in principle adjust the system with ordinary consumer hardware rather than bespoke equipment. That kind of practical engineering detail, mundane as it sounds, often separates laboratory demonstrations from technologies that can actually be deployed and maintained outside a research environment.

The implications extend well beyond pacemakers. Fully implantable bioelectronic systems, from neuromodulation devices and brain-computer interfaces to bioresorbable stimulators and injectable sensors, all face the same power bottleneck, and many of the most exciting recent devices in the field, including millimetre-scale bioresorbable optoelectronic systems and programmable ultrasonic implants, depend on some form of wireless energy delivery. A power link that tolerates strain, misalignment, and load variation could serve as a general-purpose energy backbone for soft, body-conformal devices that move with organs rather than fighting them. The authors’ comparison framework, scoring devices on efficiency, alignment tolerance, strain insensitivity, stretchability, and conductivity, also gives the field a clearer yardstick for evaluating future designs.

Cautious optimism is warranted. The work was demonstrated in animal models, and the path to human devices will require the usual gauntlet of biocompatibility validation, long-term reliability testing, and regulatory review; the liquid metal, elastomers, and nanocomposite electrodes involved have strong precedents in the soft bioelectronics literature but must prove themselves in chronic implants. Still, the combination of a self-tuning nonlinear circuit and an intrinsically stretchable liquid metal receiver addresses the two failure modes, resonance drift and deformation losses, that have most reliably broken wireless implants. If the variation tolerance demonstrated in freely moving pigs carries through to clinical devices, the era of truly untethered, maintenance-free implantable medicine moves considerably closer, powered by a transmitter you wear and a receiver that bends with every beat of your heart.

Subject of Research: Variation-tolerant wearable-to-implant wireless power transfer for implantable bioelectronics such as wireless cardiac pacemakers

Article Title: A wearable-to-implant wireless power transfer technology with variation tolerance

Article References: Nam, S., Seo, T., Yoo, S., Park, C., Kim, T., Yu, M., Kim, Y., Kang, H., Yeom, D., Cho, Y., Cho, H., Lee, D., Kim, J. H., Sunwoo, S.-H., Lee, S., Moon, J., Lee, S.-P., Kim, S., & Kim, D.-H. (2026). A wearable-to-implant wireless power transfer technology with variation tolerance. Nature Electronics. https://doi.org/10.1038/s41928-026-01714-0

Image Credits: AI Generated

DOI: 10.1038/s41928-026-01714-0

Keywords: wireless power transfer, parity-time symmetry, liquid metal electronics, implantable bioelectronics, cardiac pacing, stretchable electronics, wearable devices, resonant inductive coupling, soft materials, biomedical engineering, Nature Electronics, tachyarrhythmia

The central problem the team set out to solve is one that has dogged electronic textiles for years: how to embed genuine circuit-level functionality into fibres without wasting the fibre itself or creating fragile connections. Previous strategies often attached discrete components onto the surface of a fibre or built devices that used only a small fraction of the fibre volume. Interconnects between components tend to be unstable under the repeated bending, stretching and abrasion that clothing endures. Poor fibre utilization means much of the material contributes nothing to the electronics, while unstable interconnects mean the circuits fail exactly when a garment is treated like a garment.

The Donghua group’s answer is to make the fibre itself the circuit. Their microfluidic spinning process flows different functional materials through the channels of a spinning device, combining conductive layers with layers that perform specific functions. By switching the flow rates of the incoming streams during spinning, the researchers can arrange distinct functional modules along the fibre axis in a programmable sequence, rather like writing code that the spinning apparatus executes in material form. The team supported this design step with fluid-encoding simulations, drawing on established understanding of how flow velocity governs behaviour in microfluidic channels, to control where each module forms within the continuously drawn fibre.

Crucially, the researchers designed their modules around four fundamental types of signal conversion. Electroluminescent modules handle electron-to-photon conversion, turning electrical drive signals into emitted light. Resistor and capacitor modules perform electron-to-electron conversion, providing the passive components needed for analogue signal processing such as filtering. Organic electrochemical transistor modules carry out electron-to-ion conversion, translating electronic currents into ionic motion within a semiconductor polymer and thereby enabling digital logic operations. Finally, electro-quasistatic modules provide electro-quasistatic modulation, which the team exploited for touchless sensing and control. Because all four module families can be produced and integrated within the same spinning process, a single fibre can combine them into a working circuit tailored to a specific task.

The demonstrations span an impressive functional range. Electroluminescent IC fibres emit light, and a single fibre can encode a variety of luminescent colours along its length, suggesting displays or lighting elements woven directly into fabric. Resistor-capacitor IC fibres perform analogue signal processing, implementing functions such as tuneable filtering. Fibres built around organic electrochemical transistors execute digital logic, including inverter circuits, bringing Boolean operations into the thread itself. The electro-quasistatic IC fibres are perhaps the most striking: they sense the approach of a body or hand without contact, exploiting the quasistatic electric field coupling between the fibre and nearby conductors, and can translate that sensing into control signals.

To show that this touchless capability is more than a laboratory curiosity, the researchers connected their electro-quasistatic fibres to real machines. In supplementary demonstrations, the fibres controlled a virtual drone, a physical drone and a robotic arm, and a robotic arm equipped with the fibres automatically tracked a target object. The team even calibrated the relationship between applied voltage and sensing distance using a simple cardboard sheet wrapped in aluminium foil, and tested how nearby conductors interfere with the fibres’ operation, work that speaks to the practical engineering needed before such sensors can live inside clothing in the messy electromagnetic environment of daily life.

Durability, the historic weak point of e-textiles, receives serious attention. The IC fibres can be woven, sewn and arranged into textiles and, according to the researchers, withstand repeated deformation and washing. This mechanical resilience builds on the group’s earlier work on stretchable conductive fibres, in which a worm-shaped graphene microlayer enabled ultrahigh tensile strain and stable conductance, and on their broader research into soft fibre electronics based on semiconducting polymers. By embedding the functional layers within the fibre structure rather than coating them on top, the spinning process protects the electronics from the mechanical abuse that destroys surface-mounted devices.

The study situates itself within a rapidly maturing field. Recent years have seen large-area display textiles, fabric-based optical communication using diode fibres, digital electronics in fibres enabling fabric-based machine-learning inference, a single-fibre computer capable of textile networks and distributed inference, and a chipless textile electronics platform based on body-coupled fibres. Related work has produced fibre-integrated circuits through multilayered spiral architectures and axially encoded metafibers created by sequence spinning. What distinguishes the new approach is the programmability of the spinning process itself: rather than assembling pre-made components, the researchers encode circuit topology into the fluid flows that form the fibre, so the circuit design and the fibre manufacturing become a single continuous operation.

The implications reach toward what the authors frame through the lens of embodied intelligence, the idea that sensing, processing and feedback should be integrated into a physical platform rather than separated across devices. A textile based on IC fibres could, in principle, sense its environment, process the signals locally and respond with light, logic or actuation, all within the fabric. The researchers also point to applications in robotics, where their fibres already steer machines, and in wearable platforms that merge biosensing, computation and feedback. The fact that the team has released source data through Figshare and code through Code Ocean underscores the engineering orientation of the work, inviting others to reproduce the fluid-encoding process and build on the module library.

Challenges remain before IC fibres appear in commercial garments. The reported work demonstrates individual functional fibre types and their integration, but scaling production, achieving the transistor densities of conventional silicon, and managing power delivery through textile interconnects are all open problems. The electro-quasistatic sensing mode, while elegant, will require careful engineering to remain reliable around the conductors and interference sources that surround any wearer. Yet the core achievement stands: a spinning process in which the circuit is programmed into the fibre as it forms, yielding threads that glow, compute, filter and sense, and that survive the washing machine. If the module library continues to grow, the line between textile and computer may soon be measured in micrometres rather than millimetres.

Subject of Research: Programmable microfluidic spinning of fibres containing integrated circuit modules for smart textiles

Article Title: Programmable spinning of integrated circuit fibres

Article References: Sun, F., Chen, W., Jiang, F., Wang, K., Liu, F., Hong, Y., Han, X., Zhao, M., Zhu, Y., Sun, H., Wang, H., Wang, G., & Zhu, M. (2026). Programmable spinning of integrated circuit fibres. Nature Electronics. https://doi.org/10.1038/s41928-026-01712-2

Image Credits: AI Generated

DOI: 10.1038/s41928-026-01712-2

Keywords: electronic textiles, microfluidic spinning, integrated circuit fibres, organic electrochemical transistors, electroluminescence, wearable electronics, soft materials, touchless sensing, semiconducting polymers, flexible electronics, smart fabrics, Nature Electronics

The central idea is that a gel need not be a passive, homogeneous medium. In a multiphasic gel, the material is structured into distinct phases with different chemical compositions, ionic mobilities and interfacial properties. When an electrical signal is applied, ions do not simply drift through the material in a straight, Ohmic fashion. Instead, they accumulate, deplete and redistribute at the boundaries between phases, giving rise to transient behaviors that depend on the history of the applied voltage. This memory of past stimulation, embedded directly in the spatial distribution of ions, is precisely the property that neuromorphic engineers prize, because it allows a single material element to perform operations that would otherwise require many transistors.

To appreciate why this matters, it helps to consider the limitations of conventional electronics. Silicon transistors move electrons through crystalline semiconductors with extraordinary speed and reliability, but they are fundamentally decoupled from the chemistry of the environments in which they operate. Biological neural systems, by contrast, process signals in wet, soft, salt-laden surroundings, and they do so at energies orders of magnitude lower than digital hardware performing comparable tasks. The commentary by Peng and Zhang situates the new ionic gel work within a broader landscape of iontronic research that has been rapidly consolidating in recent years, including reviews of bioelectronic and iontronic technologies in Nature Reviews Bioengineering and a dedicated iontronics journal literature that has emerged to catalog the field’s accelerating progress.

The physics underlying ionic signal processing is rich and, in some respects, counterintuitive. Because ions are much heavier and slower than electrons, ionic currents respond to voltage changes on time scales ranging from microseconds to seconds, depending on the mobility of the charge carriers, the geometry of the channels and the viscosity of the medium. Far from being a defect, this slowness can be exploited. It introduces natural temporal dynamics, such as gradual charging of interfacial capacitances, diffusion-limited transport and concentration-polarization effects, that mimic the integration and decay behaviors of biological synapses. In a multiphasic gel, the interfaces between phases act as internal barriers and reservoirs, so the effective response of the device becomes a convolution of transport, partitioning and interfacial reaction processes, each with its own characteristic time constant.

Researchers in the field have assembled a substantial body of evidence that such dynamics can be harnessed for computation. A landmark demonstration published in Science in 2023 showed that nanofluidic systems, in which ions are forced through channels comparable in size to the electrical double layers that screen charged surfaces, can display memory and even long-term memory behaviors, providing a physical basis for memristive operation driven entirely by ions. The memristor, a circuit element whose resistance depends on the history of current flow through it, has become the canonical building block of neuromorphic hardware, and its ionic realization suggests that synapse-like elements could be fabricated from soft materials rather than rigid oxide films. Peng and Zhang’s commentary draws on this lineage, emphasizing that the cross-interface dynamics observed in multiphasic gels extend the same conceptual framework into a new class of soft, multiphase media.

Work published in Science in 2024 by Zhang, Tan, Toepfer, Lu and Bayley, several of whom are central figures in the bio-iontronics community, demonstrated that droplet-based ionic architectures can support sophisticated signal processing functions, pointing toward computational primitives built entirely from aqueous phases separated by lipid or polymer membranes. The multiphasic gel described in the Nature Electronics commentary represents a conceptual cousin of these droplet interfacial systems, but with the phases locked into a continuous solid-like scaffold. This distinction matters for applications. Droplet networks are exquisite for fundamental studies but fragile, whereas gels can be handled, patterned and potentially integrated with electrodes, wires and biological tissue, opening a route from laboratory curiosity toward practical soft devices.

The relationship between ionic transport and neuromorphic function can be made concrete by considering what happens when a voltage pulse crosses one of the internal interfaces in the gel. Initially, the ionic current is dominated by the mobile carriers in the phase connected to the driving electrode. As ions pile up at the interface, the local concentration rises, the interfacial electric field redistributes, and counter-diffusion begins to flatten the gradient. If the pulse ends before the system reaches equilibrium, some of the accumulated charge relaxes back, producing a short-term memory trace; if pulses arrive repeatedly, the accumulation can persist, strengthening the effective coupling across the interface in a manner analogous to synaptic facilitation. Two-terminal elements built on this principle naturally implement paired-pulse facilitation, temporal filtering and thresholded switching, all canonical operations of biological synapses.

Chemical reviews published over the past two years have begun to systematize this design space. A comprehensive survey in Chemical Reviews in 2025 examined ionic materials and devices for neuromorphic and bioelectronic applications, while a 2024 review in Chemical Society Reviews mapped the physics of ion transport and rectification in engineered nanostructures. Together with a further Chemical Society Reviews article in 2026 surveying the state of iontronic materials, these works chart a field that is moving from proof-of-concept demonstrations toward systematic design rules, in which the choice of polymer matrix, ionic species, phase composition and interface chemistry can be tuned to produce a desired dynamic response. The multiphasic gel strategy sits squarely within this trend, treating the internal structure of the material itself as an engineering variable.

The companion research article highlighted in the commentary, published by Wu and colleagues in Nature Electronics, provides the experimental substance behind the conceptual discussion. Although the full analytical details are available to readers of the journal, the commentary frames the work as demonstrating that ions in the multiphasic gel exhibit the complex cross-interface dynamics required for neuromorphic processing, and the accompanying figure, titled ‘Ion transporters based on multiphasic gels,’ illustrates the device concept in which ionic transporters, the structural and functional units that shuttle charge between phases, underpin the observed signal processing behavior. Framing a material platform in terms of transporters rather than passive channels reflects a shift in how the field describes ionic devices, emphasizing active, directed, history-dependent charge management rather than simple conduction.

The possible applications of soft ionic processors extend well beyond replacing silicon. Because ionic gels are mechanically compliant, chemically compatible with aqueous environments and operable at low voltages, they are natural candidates for integration with living tissue. Implantable and wearable bioelectronics could, in principle, incorporate local neuromorphic elements that preprocess electrophysiological signals in situ, reducing the bandwidth and power demands on external hardware. Artificial synapses built from multiphasic gels might one day interface directly with neurons, whose native signaling currency is the same ionic flux that the devices process. Researchers have also proposed ionic systems for reservoir computing, in which the rich internal dynamics of a physical medium perform temporal computation, with the gel itself serving as the reservoir. The commentary’s authors, based at a laboratory explicitly dedicated to bio-iontronics, underscore that the convergence of soft materials science, electrochemistry and neural engineering is what gives this direction its momentum.

Significant challenges remain before ionic gels can rival established technologies. Ionic devices are inherently slow compared with electronic ones, which limits their usefulness for high-frequency computation even as it suits them for biological time-scale tasks. Scaling from single junctions to large integrated networks requires reproducible fabrication of multiphase architectures, stable electrode contacts and materials that resist dehydration, fatigue and fouling over long lifetimes. The theoretical toolkit for describing coupled ionic transport across heterogeneous interfaces is still maturing, and researchers acknowledge that the field benefits from continued cross-disciplinary synthesis, as reflected in the breadth of the literature the commentary engages, spanning nanofluidics, memristive physics, droplet interfacial science and bioengineering. Peng and Zhang declare no competing interests, and their perspective, published in September 2026, arrives at a moment when iontronics is acquiring the journals, citations and design principles of a mature discipline.

What the multiphasic gel work ultimately illustrates is that computation need not be confined to crystalline silicon or even to electrons. Matter structured at the mesoscale, with phases that sort, store and release ions across their interfaces, can perform operations that look strikingly neural, and it can do so in a material that is soft, wet and biologically congenial. As the commentary concludes in spirit if not in a single sentence, the complex cross-interface dynamics of ions in such gels are not a nuisance to be engineered away but the very resource from which neuromorphic function is built. If the past decade belonged to memristive oxides and spintronic devices, the next may belong to materials that compute the way life does, one ion at a time, and the ionic gel now stands as one of the clearest demonstrations of that possibility.

Subject of Research: Neuromorphic signal processing using ionic transport across interfaces in a multiphasic gel

Article Title: Neural signal processing in an ionic gel

Article References: Peng, P., & Zhang, Y. (2026). Neural signal processing in an ionic gel. Nature Electronics. https://doi.org/10.1038/s41928-026-01684-3

Image Credits: AI Generated

DOI: 10.1038/s41928-026-01684-3

Keywords: iontronics, multiphasic gel, neuromorphic computing, ionic transport, memristor, soft materials, bioelectronics, nanofluidics, synaptic dynamics, Nature Electronics, Neural, signal