Magnetic soft fibers (MSFs) have emerged as a promising class of stimuli-responsive materials that combine magnetic functionality, mechanical compliance, programmable magnetization, and multifunctional performance within fiber-based architectures. Their ability to enable wireless actuation, adaptive deformation, sensing, and electrical energy generation has attracted growing interest in wearable electronics, biomedical devices, and soft robotic systems. This review aims to provide a comprehensive overview of the fundamental principles, material systems, fabrication methods, magnetization strategies, and emerging applications of MSFs. The review highlights that recent advances in material design, scalable fabrication technologies, and programmable magnetization have enabled MSFs to evolve from simple magnetic composites into multifunctional platforms capable of actuation, sensing, and energy harvesting within a single fiber system. Furthermore, the integration of electrical, optical, and fluidic functionalities has expanded their potential in wearable monitoring, minimally invasive biomedical devices, adaptive soft actuators, and remotely actuated robotic systems. Key challenges associated with material optimization, scalable manufacturing, and long-term reliability are also identified, along with emerging opportunities in intelligent design and adaptive control. By consolidating recent progress, identifying critical challenges, and outlining future research directions, this review provides a roadmap for the development of next-generation multifunctional magnetic soft-fiber technologies.

Flexible electronic fibers that combine scalable manufacturability with multimodal physiological sensing remain challenging due to the conflicting requirements of conductivity, porosity, mechanical compliance, and environmental robustness. Here an in-situ thermally induced phase separation (TIPS) strategy integrated into thermal fiber drawing (TFD) was proposed to produce continuous flexible and stretchable porous graphene-polymer nanocomposite fibers with independently tunable pore architecture and electrical properties. Starting from a solvent-borne graphene/polyvinylidene fluoride slurry within an elastomeric cladding, our process yields tens of meters of fiber from a compact preform while accommodating high graphene loadings, enabling a percolated conductive network embedded in a phase-separated matrix. The fiber exhibited a conductivity of (1.35 ± 0.96) × 10− 3 S m− 1, reflecting a moderately percolated network formed within the polymeric matrix that balances electrical transport and structural porosity. The resulting fibers operate as multimodal wearable sensors, namely, a temperature sensor with a stable output and high temperature sensitivity with a negative temperature coefficient of resistance (TCR = 0.558 °C− 1), a pressure sensor with reliable cyclic response, and a dry-electrode cardiovascular data monitoring interface whose impedance/phase behavior closely matches commercial electrodes at low frequencies and captures fundamental features on human skin. The removable elastomeric cladding imparting water resistance supports textile integration and stable operation under humid exposure. This single-step, generalizable manufacturing route decouples porosity and conductivity to co-design fiber mechanics and device performance, advancing scalable fiber-/textile-grade platforms for continuous health and motion monitoring.

Terahertz (THz) frequencies, ranging from 0.1 to 10 THz, offer unique sensing, imaging, and high-speed communications applications. However, these electromagnetic radiations experience high attenuation in free-space transmission, emphasizing the need for a low-loss waveguiding solution, often limited by material absorption. Negative curvature hollow-core fibers offer a promising solution by confining the light within an air core region, further reducing material absorption losses. This study presents the design, fabrication, and characterization of a simple bar-nested tubular hollow core fiber tailored for operation in the THz regime. The bar nested four-tube fiber design parameters are numerically optimized using finite element simulations. The cyclic olefin copolymer-based fiber is fabricated through fused deposition modeling in a 3D printer, enabling rapid prototyping and intricate fiber designs. The experimental results demonstrated a measured transmission loss of 7.6 dB/ m for the fabricated fiber at 750 GHz with a bandwidth of 100 GHz. The differences observed between numerical and experimental losses are attributed to the fabrication imperfections, surface scattering losses, and coupling losses, highlighting the challenges and potential of 3D printing for THz waveguide development.

Negative-curvature hollow-core fibers (NCFs) offer strong potential not only for ultra-low loss transmission but also for spectral filtering. However, precise control over frequency selectivity remains challenging in NCFs. Here, a unique design strategy for controlling wavelength-selective transmission in NCFs is demonstrated. A silica-based six-tube NCF with pole-supported concentric nested elements induces pole-mediated mode coupling and decoupling, resulting in filtering and transmitting of specific frequency bands in the near-IR spectrum, respectively. This spectral filtering response is extended to orthogonal polarizations by introducing transverse asymmetry through the form of nested tubes. The filtering bands for both polarization modes exhibit an approximately linear dependence on structural asymmetry, enabling independent tuning of polarization-resolved filtering bands at targeted wavelengths. An overall tuning span of 1.402 µm to 1.652 µm is achieved within the telecommunication window, and a filtering band centered at 1.500 µm is independently red-shifted to 1.550 µm for both vertical- and horizontal-polarization modes. These results demonstrate promising spectral filtering control in NCFs and have great potential for applications including sensing, lasers, and spectroscopy.

Wearable self-powered sensors enable continuous health and activity monitoring, yet scalable fiber-based systems capable of delivering stable electrical output for real-time physiological sensing remain limited. In this work, we report the first thermally drawn polymer fiber-based piezoelectric-triboelectric hybrid nanogenerator (PT-HNG) integrated with graphene nanoplatelets (GNPs) for wearable sensing applications. The hybrid fiber was fabricated via thermal drawing, with controlled incorporation of GNPs into the PVDF matrix to enhance interfacial polarization and dielectric properties, while maintaining mechanical flexibility suitable for textile integration. At an optimal GNP loading of 5 wt%, the fiber exhibits a 118% increase in open-circuit voltage and a 151% increase in short-circuit current compared to pristine PVDF fibers, delivering a peak power output of 21 & micro;W at a 5 M Omega load and a power density of 266.27 mW m(-2). These results demonstrate a scalable and durable fiber-based hybrid nanogenerator capable of self-powered, wireless monitoring of respiration, arterial pulse, and upper-limb muscle activity, offering a practical route toward next-generation smart textiles and continuous wearable physiological monitoring systems.

The development of self-powered and sustainable tactile sensors requires scalable materials that integrate electromechanical coupling, environmental compatibility, and high precision. Here, we report a universal electromechanical scaling law governing the voltage-force response in triboelectric nanogenerators (TENGs), established through sustainable SnO2 integrated polyvinylidene fluoride nanocomposite fibers fabricated via a thermal fiber drawing technique. The fibers exhibit enhanced crystallinity and interfacial polarization, yielding an open-circuit voltage of 37.2 V and a short-circuit current of 36.25 μA, with a corresponding peak power of 32.1 μW (243 mW m-2) under cyclic mechanical excitation. Beyond performance gains, the extracted force-dependent power law provides a transferable framework to benchmark and compare soft TENG fibers across loading conditions, addressing a major gap in standardized sensitivity metrics. Moreover, the resulting devices demonstrate long-term durability (>16,000 cycles) and exceptional sensitivity in robotic tactile and continuum actuation systems. Integration of the fibers into continuum robotic platforms enabled self-powered tactile sensing and rapid collision detection in free-space and in-pipe scenarios, achieving response times under 25 ms. This study establishes a physics-based framework for soft triboelectric systems, merging sustainable nanomaterials, scalable fiber processing, and universal electromechanical laws, paving the way toward self-powered, ecoconscious robotic and wearable interfaces.

Glass fibers are widely utilized as reinforcement materials in composites due to their substantial properties, including mechanical strength, impact resistance, high strength-to-weight ratio, and cost efficiency. Improving the properties of glass fiber directly impacts the performance of composites. In this study, the mechanical, chemical, and electromagnetic properties of zinc oxide (ZnO) nanoparticle-coated E-glass fibers were investigated. A thin ZnO nanoparticle layer was applied onto the fibers via the dip-coating method, forming thin coatings to improve the mechanical and chemical properties. The uniformly coated ZnO nanoparticles enhanced the tensile strength of glass fibers by up to 14.67 %, accompanied by a corresponding improvement in the Weibull modulus, indicating a reduced failure probability. Moreover, the coating provided adequate protection against acid corrosion, maintaining surface integrity after 24 h of exposure to HCl solution. The coated fibers were further used to form fiber-reinforced composites. The electromagnetic response of the composites was evaluated in the X-band frequency range (8.2-12.4 GHz). While the ZnO layer slightly increased reflectance due to the presence of Zn-based nanoparticles, overall dielectric performance remained stable. These results demonstrate that ZnO nanoparticle coatings significantly enhance the mechanical and chemical durability of Eglass fibers while maintaining their desirable electromagnetic characteristics, providing a scalable and straightforward route for high-performance composite applications.

We report a negative-curvature hollow-core waveguide for the terahertz (THz) band that employs ellipse-nested half-ellipse (ENHEF) cladding elements 3D-printed in cyclic olefin copolymer (COC). The five-ring elliptical structure supports anti-resonant guidance, resulting in low interaction between the guided field and the polymer, which reduces material absorption. Numerical optimization predicts a confinement loss of 0.041 dB/m and a total loss, including material absorption, of 0.35 dB/m at 0.412 THz, coincident with the frequency of the lowest measured propagation loss of 3.89 dB/m for a 6 mm-core fiber fabricated via fused deposition modeling (FDM). The design also achieves strong higher-order-mode (HOM) suppression, with an extinction ratio of 704 at 0.476 THz. Direct measurements of the COC filament provide the refractive index and bulk loss used in the simulations, ensuring model-experiment consistency. The bending loss was also evaluated numerically by introducing curvature-induced refractive-index modification into the simulation model. The ENHEF concept combines simple additive fabrication with low-loss and single-mode guidance, offering a scalable route to practical THz delivery fibers. (c) 2026 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Glass fibers are among the most widely used reinforcement materials in polymer composite systems because of their favorable strength-to-weight ratio, thermal stability, electrical insulation, corrosion resistance, and costeffective large-scale production. This review aims to provide an integrated understanding of glass fibers for advanced composites by linking glass chemistry, continuous fiber manufacturing, surface engineering, composite performance, application-driven material selection, and future research directions. The review critically examines the historical development, industrial manufacturing routes, major glass fiber types, sizing and chemistry, nanoparticle-based coatings, fiber-matrix interphase behavior, processing-microstructure-property relationships, and representative applications in the aerospace, automotive, construction, marine, electronics, and renewable energy sectors. The reviewed literature shows that the final performance of glass fiber-reinforced composites is governed not only by intrinsic fiber properties but also by melt-processing stability, fiber diameter, flaw distribution, sizing durability, matrix compatibility, processing route, and long-term environmental exposure. Recent developments in interphase engineering, nanoparticle coatings, recycling, remelting, re-sizing, and service-life prediction are also discussed as emerging routes to improve durability and sustainability. This review highlights that future progress in glass fiber composites will depend on stronger integration between composition design, scalable manufacturing, surface modification, performance-based material selection, and predictive lifetime modelling. These insights are expected to support the development of more reliable, durable, recyclable, and application-specific glass fiber-reinforced composites for high-performance engineering applications.

As specialized optical fibers, side-emitting optical fibers (SEOFs) are designed to emit light from their sides rather than their ends for possible applications in curved-surface lighting and sensing. In this study, we propose and demonstrate an in situ decoration of SEOFs with colloidal quantum wells (CQWs) for the first time. The proposed method enables the homogeneous distribution of CQWs in the polymeric matrix of the fiber with high side-emission efficiency, which is based on a simple yet effective method of CQW sheet coating. Two different structures of CQWs, a red-emitting CdSe/CdZnS core/shell and a green-emitting CdSe/CdS core/crown, were synthesized and employed in SEOFs. Accordingly, carefully tuned concentrations of CQWs were incorporated within the hollow-core optical fibers, and the side-scattered light from the fibers was systematically characterized and analyzed. The results confirm excellent side-emitting characteristics that are highly dependent on the optical fiber structure and CQW absorption spectrum. The average quantum yield values of 51 +/- 5% and 34.5 +/- 5% for different concentrations of red and green CQWs relative to their solution form were measured in our experiment, which is associated with polymeric medium, cluster formation, and fiber tower temperature. The findings pave the way for developing high-performance optical fiber devices based on CQW-doped SEOFs capable of efficient and precise light emission targeting a wide variety of applications ranging from three-dimensional curved-surface lighting to sensing.

AbstractTriboelectric nanogenerators (TENGs) are environmentally sustainable energy harvesting devices that can convert mechanical and biomechanical energy into electrical output through the synergistic process of triboelectrification and electrostatic induction. Incorporating polyvinylidene fluoride (PVDF) and its copolymers into flexible TENG is particularly advantageous because of the abundance of highly electronegative fluorine ions and high dielectric constant. MoS2 can interact with PVDF dipoles to improve PVDF's β phase content, thereby improving the triboelectric property of the polymer nanocomposite fibers. In this study, thermally drawn PVDF TENG fibers are fabricated, incorporating various concentrations of MoS2 for the first time. The enhanced β phase property in the nanocomposite fiber improves the triboelectric output where 3 wt.% MoS2 – PVDF fiber demonstrates a maximum peak power output of 17.64 µW, exhibiting a threefold increment compared to 0 wt.% MoS2 – PVDF fiber. Simultaneous integration of multiple nanomaterials (MoS2 and graphene) is also investigated to analyze the triboelectric fiber's β phase formation and electrical performance. Harnessing the superior sensitivity of the MoS2 integrated triboelectric fiber, a self‐powered wearable mask is designed for continuous human respiration monitoring.

Polarization-maintaining properties for a nested tube negative curvature hollow-core fiber are numerically investigated when the whole fiber cross-section is subjected to physical deformation leading to elliptical fiber forms. The results indicate that ellipticity provides a useful fine-tuning mechanism for polarization maintaining operation of fiber.

In the contemporary era, self-powered sensors have gained significant attention, particularly in the domains of wearable devices, flexible electronics, healthcare monitoring devices, and the Internet of Things (IoT). Among the most promising technologies for mechanical energy harvesting are piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), both of which convert ambient mechanical energy into electrical energy. However, the electrical output from either PENGs or TENGs alone is often insufficient to meet the power requirements of electronic devices. To address this limitation, the integration of piezoelectric and triboelectric effects into a single system has led to the emergence of piezoelectric-triboelectric hybrid nanogenerators (PT-HNGs). These hybrid systems represent a new class of energy harvesting devices capable of significantly enhancing energy conversion efficiency and output performance. This review provides a comprehensive overview of recent progress in developing PT-HNGs, focusing on their underlying mechanisms, structural designs, coupling effects, performance optimization strategies, and diverse application potentials. It highlights the hybrid system's unique synergy and real-world applicability, aiming to fill a critical gap in the literature. In addition, the review discusses the existing challenges, future directions, and prospects for the commercialization of PT-HNG technology.

A negative curvature hollow-core fiber design with double pole-anchored cladding elements is numerically proposed for spectral filtering. The fiber structure is investigated for improvement in filtering ability through manipulation of the pole length. The findings reveal reduced confinement losses as low as 0.0003 dB/km for filtered and 0.0054 dB/km for unfiltered wavelengths yielding enhanced loss modulation depth.

This work demonstrates the enhancement of the electroactive phase of the nanocomposite, resulting in a high energy density storage and piezoelectricity. Low loading (<= 1 wt %) of synthesized nitrogen-doped carbon dots (N-CDs) reinforced in poly(vinylidene fluoride) (PVDF) accelerated the formation of electroactive phases with conformational changes in the polymer chain. The addition of 1 wt % N-CDs to the PVDF polymer matrix increased the dielectric constant by 2.18 times, and the maximum polarization reached a multiplication of 2.32 compared to pure PVDF films. Moreover, a 1.62 times enhancement in the piezoelectric coefficient d 33 resulted in a voltage sensitivity of 22.28 mV/N for as low as 1% filler reinforcement. The simulation results further confirmed the increase in dielectric constant and piezoelectric coefficient. The N-CD-integrated PVDF films are promising candidates for energy storage and harvesting applications.

A novel negative curvature hollow-core fiber is numerically designed capable of filtering specific frequencies. The six-tube silica fiber strongly favors fundamental mode transmission over higher order modes despite uneven positioning of cladding elements.

A numerical study on the multi-bar nested cladding design of chalcogenide glass-based negative curvature hollow-core fiber was carried out to achieve a low-loss light guidance in the mid-infrared spectrum centered at 5.4 mu m. Fiber design parameters were systematically optimized, and the effect of the nested bars on the confinement and total loss performance of a five-tubular cladding structure was investigated. An ultra-low transmission loss of 0.112 dB km-1 at 5.4 mu m was achieved with As2Se3 triple-bar negative curvature fiber while maintaining low bending sensitivity. The design is also suitable for high transmission performance with alternative infrared glasses and can be potentially used for low-loss light guidance in a wide mid-infrared spectrum.

Abstract Triboelectric nanogenerators (TENGs) utilize the synergetic effect of triboelectrification and electrostatic induction to guide electrons through an external circuit, enabling low‐frequency mechanical and biomechanical energy harvesting and self‐powered sensing. Integrating 2D material with a high specific surface area into flexible ferroelectric polymers such as polyvinylidene difluoride (PVDF) has proven to be an efficient strategy to improve the performance of TENG devices. Scalable fabrication of graphene‐integrated PVDF nanocomposite fiber using thermal drawing process is demonstrated for the first time in this study. The open‐circuit voltage and short‐circuit current show 1.41 times and 1.48 times improvement with the integration of 5% graphene in the PVDF fibers, respectively. The TENG fabric shows a maximum power output of 32.14 µW at a matching load of 7 MΩ and a power density of 53.57 mW m−2. The fibers exhibit excellent stability in harsh environmental conditions such as alkaline medium, high/low temperature, multi‐washing cycle, and long‐time usage.