Bioinspired Anti-Plateau-Rayleigh-Instability on Dual Parallel Fibers

Continuous Homogeneous Thin Liquid Film on a Single Cross-Shaped Profiled Fiber with High Off-Circularity: Toward Quick-Drying Fabrics

Quick-drying fabrics, renowned for their rapid sweat evaporation, have witnessed various applications in strenuous exercise. Profiled fiber textiles exhibit enhanced quick-drying performance, which is attributed to the excellent wicking effect within fibrous bundles, facilitating the rapid transport of sweat. However, the evaporation process is not solely influenced by macroscopic liquid transport but also by microscopic liquid spreading on the fibers where periodic liquid knots induced by spontaneous fluidic instability significantly reduce the evaporation area. Here, a cross-shaped profiled fiber with high off-circularity, featured as multiple concavities along the fibrous longitude-axis, which enables the formation of a homogeneous thin liquid film on a single fiber without any periodic liquid knots, is developed. The high off-circularity cross-sections help overcoming Plateau-Rayleigh instability by tuning the Laplace pressure difference, further facilitated by capillary flow along the concave surface. The homogeneous thin liquid film on a single fiber is responsible for maximizing the evaporation area, resulting in excellent overall evaporation capacity. Consequently, fabrics made from such fibers exhibit rapid evaporation behavior, with evaporation rates ≈50% higher than those of cylindrical fabrics. It is envisioned that profiled fibers may provide inspiration for the manipulating homogeneous liquid films for applications in fluid coatings and functional textiles.

Scale-Bridging Mechanics Transfer Enables Ultrabright Mechanoluminescent Fiber Electronics

Mechanoluminescent (ML) fibers and textiles enable stress visualization without auxiliary power, showing great potential in wearable electronics, machine vision, and human-computer interaction. However, traditional ML devices suffer from inefficient stress transfer in soft-rigid material systems, leading to low luminescence brightness and short cycle life. Here, we propose a tendon-inspired scale-bridging mechanics transfer mechanism for ML composites, which employs molecular-scale copolymerized cross-linking and nanoscale inorganic nanoparticles as hierarchical stress transfer sites. This strategy effectively reduces the dissipation of stress in molecular chain segments and alleviates local stress concentration, increases luminescence by 9 times, and extends cycle life to more than 10,000 times. Furthermore, a scalable (kilometer-scale) anti-Plateau-Rayleigh instability manufacturing technology is developed for thermoset ML fibers, compatible with various existing textile techniques. We also demonstrate its system-level applications in motion capture, underwater interaction, etc., providing a feasible strategy for the next generation of smart visual textiles.

A Soft-Fiber Bioelectronic Device with Axon-Like Architecture Enables Reliable Neural Recording In Vivo under Vigorous Activities

Implantable neural devices that record neurons in various states, including static states, light activities such as walking, and vigorous activities such as running, offer opportunities for understanding brain functions and dysfunctions. However, recording neurons under vigorous activities remains a long-standing challenge because it leads to intense brain deformation. Thus, three key requirements are needed simultaneously for neural devices, that is, low modulus, low specific interfacial impedance, and high electrical conductivity, to realize stable device/brain interfaces and high-quality transmission of neural signals. However, they always contradict each other in current material strategies. Here, a soft fiber neural device capable of stably tracking individual neurons in the deep brain of medium-sized animals under vigorous activity is reported. Inspired by the axon architecture, this fiber neural device is constructed with a conductive gel fiber possessing a network-in-liquid structure using conjugated polymers and liquid matrices and then insulated with soft fluorine rubber. This strategy reconciles the contradictions and simultaneously confers the fiber neural device with low modulus (300 kPa), low specific impedance (579 kΩ µm2), and high electrical conductivity (32 700 S m-1) - ≈1-3 times higher than hydrogels. Stable single-unit spike tracking in running cats, which promises new opportunities for neuroscience is demonstrated.

Unidirectional transport of both wettable and nonwettable liquids on an asymmetrically concave structured surface

Unidirectional liquid transport (UDLT) has been widely used in various fields as an important process for transferring both mass and energy. However, UDLT driven by a structural gradient has been witnessed for a long time only in wettable liquids. For nonwettable liquids, UDLT can hardly proceed merely by a structural gradient. Herein, we propose an asymmetrically concave structured surface (AMC-surface), featuring tip-to-base periodically arranged pyramid-shaped concave structures with a certain degree of overlap, which enables the UDLT of both wettable and nonwettable liquids. For wettable liquids, the capillary force along each corner leads to the UDLT pointing toward the base side of the concave pyramid, while for nonwettable liquids, the UDLT is attributable to the static liquid pressure overwhelming the repulsive Laplace pressure induced by the asymmetric grooves and overlapping part. As a result, both wettable and nonwettable liquids transport spontaneously and unidirectionally on the AMC-surface with no energy input. Moreover, the concave structure endows good mechanical stability and can be easily prepared using a facile nail-punching approach over a large area. We also demonstrated its application in a continuous chemical reaction in a confined area. We envision that the unique UDLT behavior on the as-developed AMC-surface will shed new light on the programmable manipulation of various liquids.

Full-Fiber Auxetic-Interlaced Yarn Sensor for Sign-Language Translation Glove Assisted by Artificial Neural Network

Yarn sensors have shown promising application prospects in wearable electronics owing to their shape adaptability, good flexibility, and weavability. However, it is still a critical challenge to develop simultaneously structure stable, fast response, body conformal, mechanical robust yarn sensor using full microfibers in an industrial-scalable manner. Herein, a full-fiber auxetic-interlaced yarn sensor (AIYS) with negative Poisson's ratio is designed and fabricated using a continuous, mass-producible, structure-programmable, and low-cost spinning technology. Based on the unique microfiber interlaced architecture, AIYS simultaneously achieves a Poisson's ratio of-1.5, a robust mechanical property (0.6 cN/dtex), and a fast train-resistance responsiveness (0.025 s), which enhances conformality with the human body and quickly transduce human joint bending and/or stretching into electrical signals. Moreover, AIYS shows good flexibility, washability, weavability, and high repeatability. Furtherly, with the AIYS array, an ultrafast full-letter sign-language translation glove is developed using artificial neural network. The sign-language translation glove achieves an accuracy of 99.8% for all letters of the English alphabet within a short time of 0.25 s. Furthermore, owing to excellent full letter-recognition ability, real-time translation of daily dialogues and complex sentences is also demonstrated. The smart glove exhibits a remarkable potential in eliminating the communication barriers between signers and non-signers.

Spheres Multiple Physical Network-Based Triboelectric Materials for Self-Powered Contactless Sensing

Non-contact mode triboelectric nanogenerators effectively avoid physical contact between two triboelectric materials and achieve long-term reliable operation, providing broad application prospects in the field of self-powered sensing. However, the low surface charge density of triboelectric materials restricts application of contactless sensing. Herein, by controlling Rayleigh Instability deformation of the spinning jet and vapor-induced phase separation during electrostatic spinning, a polyvinylidene fluoride@Mxene (Ti₃ C₂ T_x ) composite film with spheres multiple physical network structures is prepared and utilized as the triboelectric material of a self-powered contactless sensor. The structure of the composite film and high conductivity of Ti₃ C₂ T_x provide triboelectric materials with high output performance (charge output and power output up to 128 µC m^-2 and 200 µW cm^-2 at 2 Hz) and high output stability. The self-powered contactless sensor shows excellent speed sensitivity (1.175 Vs m^-1 ). Additionally, it could accurately identify the motion states such as running (55 mV), jumping (105 mV), and walking (40 mV) within the range of 70 cm, and present the signals in different pop forms. This work lays a solid foundation for the development and application of high-performance triboelectric materials, and has guiding significance for the research of self-powered contactless sensing.

Charged membranes based on spider silk-inspired nanofibers for comprehensive and continuous purification of wastewater

Creating a facile and efficient porous membrane for the comprehensive treatment of both insoluble and soluble pollutants from water is of great significance, yet remains challenging. Here, we present a facile strategy to prepare charged nanofibrous membranes assembled from spider silk-like humped SiO₂/polyamide 66 (PA66)/polyaniline (PANI) nanofibers by combing Plateau-Rayleigh instability-induced assembly andin situsynthesis. The obtained nanofibrous membranes possess micro/nanostructured surfaces with promising superhydrophilic and underwater superoleophobic property, which are attributed to the synergy of hierarchical roughness and hydrophilic matrix. Combined with the superwettability and the integrated property of submicron pore size, high porosity, and good pore interconnectivity, the membranes can separate various oil-in-water emulsions with a remarkable permeation flux of 5403 l m^-2h^-1and a high separation efficiency (total organic carbon content <5 mg l^-1). Moreover, attributed to the Laplace pressure difference and positive potential of the spindle-knotted nanofibers, the biomimetic nanofibrous membranes could remove the filter cake during separation. In addition, the membrane exhibits a remarkable adsorption-reduction capacity of hexavalent chromium. The synthesis of such attractive nanomaterials may provide new insights into the development of multifunctional separation materials for environmental applications.

Polymeric Microparticles Generated via Confinement-Free Fluid Instability

In-fiber fluid instability can be harnessed to realize scalable microparticles fabrication with tunable sizes and multifunctional characteristics making it competitive in comparison to conventional microparticles fabrication methods. However, since in-fiber fluid instability has to be induced via thermal annealing and the resulting microparticles can only be collected after dissolving the fiber cladding, obtaining contamination-free particles for high-temperature incompatible materials remains great challenge. Herein, confinement-free fluid instability is demonstrated to fabricate polymeric microparticles in a facile manner induced by the ultralow surface energy of the superamphiphobic surface. The polymer solution columns break up into uniform droplets then form spherical particles spontaneously in seconds at ambient temperature. This method can be applied to a variety of polymers spanning an exceptionally wide range of sizes: from 1 mm down to 1 µm. With the aid of microfluidic spinning instrument, a large quantity of microparticles can be obtained, making this method promising for scaling up production. Notably, through simple modification of the feed solution configuration, composite/structured micromaterials can also be produced, including quantum-dots-labeled fluorescent particles, magnetic particles, core-shell particles, microcapsules, and necklace-like microfibers. This method, with general applicability and facile control, is envisioned to have great prospects in the field of polymer microprocessing.