Flexible Fiber Research Articles

High-performing fiber electrodes based on a gold-shelled silver nanowire framework for bioelectronics.

Flexible fiber electrodes offer new opportunities for bioelectronics and are reliable in vivo applications, high flexibility, high electrical conductivity, and satisfactory biocompatibility are typically required. Herein, we present an all-metal flexible and biocompatible fiber electrode based on a metal nanowire hybrid strategy, i.e., silver nanowires were assembled on a freestanding framework, and further to render them inert, they were plated with a gold nanoshell. Our fiber electrodes exhibited a low modulus of ∼75 MPa and electrical conductivity up to ∼4.8 × 106 S m-1. They can resist chemical erosion with negligible leakage of biotoxic silver ions in the physiological environment, thus ensuring satisfactory biocompatibility. Finally, we demonstrated the hybrid fiber as a neural electrode that stimulated the sciatic nerve of a mouse, proving its potential for applications in bioelectronics.

A flexible and energy independent fluorescence radiation fiber film dosimeter fabricated by electrostatic spinning.

Doping fluorescent substances in polymer matrices has shown promising applications in radiation dose sensing. In this work, quinoline dye based polyvinyl chloride fibrous films with fiber diameters of 123 nm, 540 nm and 864 nm were obtained by electrostatic spinning. The introduction of the fiber film structure makes the fluorescent film dosimeter flexible and lightweight compared to normal solid fluorescent films and further extends the linear range of X-ray detection to 0-350 Gy. Furthermore, the dosimeter shows energy and dose rate independence, and the sensitivity of the dosimeter can be improved by the application of fiber films with thinner diameters. This flexible fiber membrane provides a candidate material for wearable visual dosimeters.

Distributed and multimodal strain sensing performance of flexible hydrogel functional optical fibers

Flexible fiber enables large-scale, multi-mode, and distributed strain sensing and provides a versatile solution for wearable and implantable strain sensors.

Performance of low-cost fiber optic cables as leak detection sensors for water pipelines in unsaturated soil

Large volumes of potable water are lost from leaks in water distribution systems around the world. Such leaks may go undetected for a long time. A passive means of leak detection can be implemented by burying a suitable fiber optic cable in the pipe trench with water distribution pipes when they are installed. Water leaking from pipes into the ground results in a temperature change at the leak location. Leaks into unsaturated soil also cause changes in the bulk density and strength of the soil, resulting in significant soil deformation. Brillouin Frequency Shift (BFS) in optical fibers is sensitive to changes in both temperature and mechanical strain, allowing fiber optic cables to act as efficient leak detection sensors. Purpose-made fiber optic cables may be expensive, but telecommunication grade cables generally have a low cost and are readily available around the world. This paper investigates the performance of five different fiber optic cables, including communication grade fiber optic cables, to act as leak detection sensors in unsaturated ground. It was found that the most efficient leak detection sensors are flexible tight-buffered fiber optic cables.

Effect of morphology and microstructure of NiCo nanoparticles on the electromagnetic shielding behavior of flexible and durable NiCo-coated carbon fibers

Effect of morphology and microstructure of NiCo nanoparticles on the electromagnetic shielding behavior of flexible and durable NiCo-coated carbon fibers

In Situ Thermoelectric Property Characterization of Microscale Single Thermoelectric Fiber Based on Harmonic Detection

Exploring advanced thermoelectric materials, especially flexible thermoelectric fibers, is promising for wearable devices. The thermoelectric properties of these fibers are evaluated using the figure of merit ZT value. However, there is a lack of empirical research on the properties of microscale thermoelectric fibers, necessitating the development of precise measurement methods. In addition, since the properties of micro- and nanofiber materials can be affected by the microstructure, separate measurements of electrical conductivity, Seebeck coefficient, and thermal conductivity before calculating the ZT values can lead to large errors in the final calculations. In this study, Bi 2 Te 2.7 Se 0.3 thermoelectric fibers are prepared and measured by using a thermally drawn method and an in situ method, respectively. The in situ measurements are carried out using a self-developed instrument capable of measuring temperatures from room temperature up to 1,200 K, suitable for sample sizes ranging from micro- to nanoscale. The uncertainty of the measurement exhibits less than 6.36%. The results indicate that the thermal drawing process influences crystal growth, enhancing the Seebeck coefficient and reducing electrical conductivity and thermal conductivity. Moreover, the accuracy of the measurement method is verified by pure Pt wire. The integrated in situ measurement effectively reduces experimental errors due to sample differences when calculating parameters for multiple samples measured individually, and the maximum error that can be reduced is 19.5%. This research contributes a practical measurement method of thermoelectric fibers and advances the development of wearable thermoelectric devices.

Structurally oriented black phosphorus/MXene heterostructured fibers for flexible supercapacitors with enhanced ion transport and capacitive charge storage

Structurally oriented BP/Ti3C2Tx heterostructured fibers with high conductivity, excellent mechanical properties and high specific capacitance were fabricated via electrostatic assembly for high-performance flexible fiber supercapacitors.

High stability of robust anti-thermal-quenching lead-free double perovskite crystals for optoelectronic devices and high-performance fibers

Sb3+-doped Cs2NaHoCl6 perovskite crystals were synthesized through an efficient and energy-saving method. The flexible luminescent fibers prepared from Sb3+-doped Cs2NaHoCl6 exhibit excellent luminescent stability in high-temperature environments.

Flexible carbon fibres with magnetic ZIF-67 as core layer and in-situ grown NiMn-LDH nanosheets as shell layer for microwaves absorption

Fabrication of high-performance microwaves absorbers by assembling multi-dimensional nanocomponents into core-shell electromagnetic structures has been shown to be a new manufacturing strategy. In this work, a novel core-shell carbon-fibres@ZIF-67@NiMn-Layered double...

Mid-Infrared Absorption Spectroscopy for NO and NO2 Detection in a Flexible Hollow Core Fiber (Invited)

Mid-Infrared Absorption Spectroscopy for NO and NO2 Detection in a Flexible Hollow Core Fiber (Invited)

A thermal evaporation–trapping strategy to synthesize flexible and robust oxygen electrocatalysts for rechargeable zinc–air batteries

A thermal evaporation–trapping strategy is developed to fabricate a flexible N-doped carbon fiber cloth loaded with both CoFe-oxide nanoparticles and atomic Co/Fe–Nx sites, showing outstanding oxygen electrocatalytic performance.

Slippery hydrogel surface on PTFE hollow fiber membranes for sustainable emulsion separation.

Establishing an efficient and sustainable membrane module is of great significance for practical oil/water emulsion separation. Superwetting membranes have been extensively studied but cannot meet long lasting separation owing to inevitable membrane fouling. Herein, we constructed a hydrogel-mediated slippery surface on polytetrafluoroethylene (PTFE) hollow fibers and then designed a flexible and swing hollow fiber membrane module inspired by fish gill respiration, which achieved sustainable emulsion separation. A vinyl silane-crosslinked polyvinylpyrrolidone (PVP) hydrogel was interpenetrated with nano-fibrils of the PTFE hollow fibers, thus facilitating fast water permeance while resisting oil intrusion. Liquid-like polydimethylsiloxane (PDMS) brushes were then grafted to promote oil aggregation-release from the membrane surface. Owing to the heterogeneous surface and gill-like structure, the designed PTFE hollow fiber membrane module could separate emulsion in a long-term filtration process, maintaining a high water permeability of 500 L m-2 h-1 bar-1 with a separation efficiency of over 99.9% for 5000 min. This novel technique shows its great potential to realize practical emulsion separation by solving the persistent problem of membrane fouling and permeance decay.

The Development of a Prototype Trainer Aircraft/Unmanned Aerial Vehicle

The use of generic unmanned aerial vehicle (UAV) is getting common as its small size can easily replace bulky aerial vehicle such as helicopters and airplanes in performing surveillance missions. Spacious room is need to store the UAV and the cost for a generic UAV is relatively high and seldom be owned by normal commercials and industries other than military. The study produced a detachable, light weight, hand launched and low-cost generic unmanned aerial vehicle (UAV). The UAV components were designed to be attachable for launching to perform surveillance activity and detachable for easy storage in small space after service. UAV was manufactured low-cost fiber materials to mold the fuselage. A pair of male and female mold was constructed and the shape of the fuselage was imitated using flexible fiber material. Epoxy cohesive and hardener were used to harden and sustain the shape of the fuselage during the molding process. Finishing was done on the new molded fuselage to refine the aerodynamics flow around the body. The UAV was tested and results showed a satisfactory stability performance.

Cross-streamline migration and near-wall depletion of elastic fibers in micro-channel flows.

The complex dynamics of elastic fibers in viscous fluids are central to many biological and industrial systems. Fluid-structure interactions underlying these dynamics govern the shape and transport of flexible fibers, and understanding these interactions can help tune flow properties in applications such as microfluidic separation, printing and clogging. In this work, we use slender-body theory to study micromechanical dynamics that arise from the coupling between the elastic backbone of a fiber and the local straining flow that contributes to filament flipping and cross-streamline migration. The resulting transverse drift is unbiased in either direction in simple shear flow. However, a non-uniform shear rate results in bias towards regions of high shear, which we connect to the shape transitions during flips. We discover a depletion layer that forms near the boundaries of pressure-driven channel flow due to the competition between such a cross-streamline drift and steric exclusion from the walls. Finally, we develop scaling laws for the curvature of filaments during flip events, demonstrating the origin of the drift bias in non-uniform flows, and confirm this behavior from our simulations. Put together, these results shed light on the role of a local and dominant coupling between elasticity and viscous resistance in dictating long-term dynamics and transport of elastic fibers in confined flows.

Polypyrrole in-situ polymerized MXene/TPU fiber electrode for flexible supercapacitors

Ti3C2Tx-based flexible fibers have great potential and wide applications in the energy storage field of wearable electronic textiles and portable electronic devices. This work reports a Ti3C2Tx-MXene/TPU/polypyrrole(PPy) fiber in which PPy is grown on the surface of Ti3C2Tx/TPU fiber by in-situ polymerization. Through efficient wet spinning and in-situ polymerization, Ti3C2Tx/TPU/PPy fiber exhibit pore structure and abundant active sites, which significantly enhance charge transfer rate and conductivity. The fiber exhibits a capacitance of 41.2 F g−1(5 mV S−1) and excellent rate performance in 1 M H2SO4 electrolyte. Its symmetrical fiber-based flexible supercapacitors(SCs) can provide an energy density of 2.36 mW h g−1. At the same time, the fiber has good flexibility and can be woven into a fabric SCs as a wearable energy storage device to realize power supply applications such as electronic watches and LEDs, which provides a potential strategy for the application of flexible wearable energy storage devices.

A flexible precontact CNT-Al2O3 fiber sensor resistant to extreme temperatures.

As a new soft electronic product, a flexible precontact sensor provides spatial position sensing ability. However, the properties of traditional polymer materials change in industrial environments with extreme temperatures, which can cause the sensor function to decline or even fail. In this study, we propose a flexible fiber sensor based on the capacitor principle, which achieves a stable spatial positioning function and is not affected by a wide range of temperature changes. The fiber element of the sensor is obtained through the deposition of a flexible Al2O3 ceramic coating onto the surface of a carbon nanotube fiber (CNTF) via atomic layer deposition (ALD) technology. Coatings of different thicknesses (100 nm, 200 nm, and 300 nm) show different colors. The temperature resistance and flame retardancy of Al2O3 keep the morphology of the composite fiber unaffected by flame or high temperatures. Even at extreme temperatures (-78 °C to 500 °C), the sensor's sensing ability exhibits excellent stability. In addition, the spatial perception of the fibers remained viable after repeated bending (10 000 times). We demonstrate the potential of the sensor to acquire position information during high-temperature industrial pipe docking.

Stretchable flexible fiber supercapacitors for wearable integrated devices

PANI-TPU films were prepared by electrostatic spinning and in situ polymerization, and a fiber supercapacitor that maintains stable performance under large tensile deformation conditions can be realized by twisting.

Electrospun polarity-controlled molecular orientation for synergistic performance of an artifact-free piezoelectric anisotropic sensor.

Anisotropy in mechanical, optical and thermal sensors in a spatial direction has many applications in health care, robotics, aerospace, and tissue engineering. In particular, wearable and implantable sensors respond to stretching and bending strains that probe mechanical energy and track physiological signals. Hence, the development of anisotropic pressure sensors with true piezoelectric (PE) signals is of utmost importance to achieve efficient devices. Herein, a simple and efficient method is developed for high longitudinal and transverse responses, with an approach to isolating a true piezoelectric signal. The electrospun (ES) polarity of oriented dipoles inside flexible fibers gives rise to a high longitudinal/transverse PE response of both lateral and transverse strains. Nanofibers of poly(vinylidene-chlorotrifluoroethylene) copolymers contain poled dipoles, up to 86%, that promote an enhanced PE coefficient of 42 pm V-1 in the case of negative polarity-based electrospinning. It is 40% higher in composition than the commonly adopted positive polarity-biased electrospinning process. We demonstrated the advantage of such a high PE coefficient by the enhanced sensitivity of the longitudinal (VLs = 0.3 V kPa-1, ILs = 0.07 μA kPa-1) as well as transverse (VTs = 1.0 V kPa-1, ITs = 0.8 μA kPa-1) PE response. To counter the ambiguity of high transverse response as compared to longitudinal in electrospun fiber-based devices, a facile method is proposed to isolate the ferroelectret, triboelectric and piezoelectric signals in a fiber-based hybrid device with their independent charge generation mechanisms.

Fast-response fiber organic electrochemical transistor with vertical channel design for electrophysiological monitoring.

Fiber organic electrochemical transistors (OECTs) hold significant promise for in vivo bio-signal amplification due to their minimally invasive and seamless integration with biological tissues. However, their use in monitoring rapid physiological changes, such as electrophysiological signals, has been constrained by slow response time, arising from their extensive channel dimensions. Here, we introduce a novel fiber OECT designed with a micro-scale vertical channel (F-vOECT) that substantially reduces the response time by an order of magnitude to 12 ms and achieves a maximum transconductance of 16 mS at zero gate bias, marking a substantial improvement over previous fiber OECTs. This compact and flexible fiber device demonstrates robust performance under cyclic switching, dynamic deformation and exhibits excellent biocompatibility. When subcutaneously implanted in rats, the F-vOECT enables stable, continuous electrocardiogram monitoring for 7 days, successfully identifying episodes of atrioventricular block. These capabilities illustrate its potential for clinical electrophysiological diagnostics. The design strategy of F-vOECT opens new avenues for developing fast-responsive fiber bioelectronic devices.

Facile and effective synthesis strategy for terbium-doped hydroxyapatite toward photoelectric devices and flexible functional fibers

Facile and effective synthesis strategy for terbium-doped hydroxyapatite toward photoelectric devices and flexible functional fibers