Microfluidic Spinning Technology Research Articles

Flexible ordered MnS@CNC/carbon nanofibers membrane based on microfluidic spinning technique as interlayer for stable lithium-metal battery

In this work, the novel flexible ordered carbon nanofibers membrane including cellulose nanocrystal (CNC) and MnS nanoparticles (MnS@CNC/CNFs) were prepared through the microfluidic spinning technology (MST) and carbonization process. Then the application of the prepared MnS@CNC/CNFs as the interlayer between the separator and lithium (Li) anode for lithium-metal battery (LMBs) was systematically investigated. The ordered carbon nanofibers framework with a regular arrangement structure could induce more uniform deposition of Li ions. Moreover, the MnS@CNC/CNFs interlayer possessed remarkable electrical conductivity and large specific surface area, which not only provided a high transmission channel for ions and electrons but also enhanced the interfacial compatibility between the Li anode or separator and interlayer. The doped MnS in the interconnected CNFs skeleton could provide more active sites to trigger the analogous alloying reaction with Li, and the polar hydroxyl groups (-OH) in the CNC could also induce strong chemical interactions toward Li ions. These comprehensive effects brought out the more homogeneous distribution of Li ions flux and the dendrite-free electrode. The assembled Li|LiFePO4 (LFP) batteries with the freestanding interlayer achieved an initial discharge capacity of 148.2 mAh g−1 and retention rate of 83.1% after 600 cycles at 1 C. The Li/Li symmetric batteries further indicated that the flexible ordered MnS@CNC/CNFs membrane could effectively inhibit the Li dendrite growth and enhance the cycling stability. The design of the MnS@CNC/CNFs based on MST offered a facile method for preparing CNFs and a potential solution for highly safe LMBs.

Independent dual-responsive Janus chromic fibers

Daily exposure under solar ultraviolet (UV) and infrared (IR) is prone to cause skin cancer and photoaging. Real-time monitoring of the environmental UV index and IR radiation temperature during outdoor activities can enhance awareness and strengthen personal protection. It is a challenge to design flexible, wearable devices (with measurement capabilities) that can be integrated with apparels. Here, microfluidic spinning technology (MST) was used for the continuous and large-scale fabrication of eco-friendly coresheath Janus fibers with a well-defined axially symmetric Janus core. One side of the core was sensitive to UV light and the opposite was sensitive to IR radiation. Textiles woven with Janus fibers showed excellent independent reversible color responses to dual-wavelength stimulation. Such textiles switched among four colors under UV and IR irradiation, both individually and in combination. The color gradient of the textiles changed significantly with increasing UV intensity (UV index). After 60 cycles of UV/IR stimulation and 50 washes, the change rate of the comprehensive chromatic aberration (ΔE*ab) of the textiles under different conditions was only 0.42%–4.71%. This was attributed to the unique structure of the fibers. The three-line striped textiles demonstrated the potential of the fibers to be used as wearable energy-free real-time visual monitors of the UV index and IR radiation temperature.

Bioinspired Helical Micromotors as Dynamic Cell Microcarriers.

Micromotors have exhibited great potential in multidisciplinary nanotechnology, environmental science, and especially biomedical engineering due to their advantages of controllable motion, long lifetime, and high biocompatibility. Marvelous efforts focusing on endowing micromotors with novel characteristics and functionalities to promote their applications in biomedical engineering have been taken in recent years. Here, inspired by the flagellar motion of Escherichia coli, we present helical micromotors as dynamic cell microcarriers using simple microfluidic spinning technology. The morphologies of micromotors can be easily tailored because of the highly controllable and feasible fabrication process including microfluidic generation and manual dicing. Benefiting from the biocompatibility of the materials, the resultant helical micromotors could be ideal cell microcarriers that are suitable for cell seeding and further cultivation; the magnetic nanoparticle encapsulation imparts the helical micromotors with kinetic characteristics in response to mobile magnetic fields. Thus, the helical micromotors could be applied as dynamic cell culture blocks and further assembled to complex geometrical structures. The constructed structures out of cell-seeded micromotors could find practical potential in biomedical applications as the stack-shaped assembly embedded in the hydrogel may be used for tissue repairing and the tube-shaped assembly due to its resemblance to vascular structures in the microchannel for organ-on-a-chip study or blood vessel regeneration. These features manifest the possibility to broaden the biomedical application scope for micromotors.

Size effect-inspired fabrication of konjac glucomannan/polycaprolactone fiber films for antibacterial food packaging

The exploration of new methods to produce food packaging with excellent physicochemical and antibacterial properties is of great scientific and technological interest. Here, we successfully prepare the food packaging films that are composed of konjac glucomannan (KGM), poly(ε-caprolactone) (PCL) and silver nanoparticles (AgNPs) via microfluidic spinning technology (MST). The obtained fiber films (average fiber diameter: 7.8 ± 0.2 μm) exhibit excellent antibacterial activities against S. aureus (34 ± 0.71 mm) and E. coli (39 ± 5.66 mm), which is ascribed to the good swelling of KGM in KGM/PCL/AgNPs fiber films (SD: 37.86 ± 6.87%). Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) are employed to study the interactions between polymers. Thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), water vapor permeability (WVP), and mechanical property measurements are conducted to evaluate the thermal properties, hydrophilicity and mechanical performances of the films. The results show that the films are thermal stable and relatively hydrophobic (WVP: 5.8 × 10−6 ± 1.44 g/(m·h·kPa), WCA: 101.0°) as well as have terrific elongation at break (EB: 223.59 ± 98.14%), which is beneficial for food packaging. This strategy provides a facile and green pathway for the construction of promising antibacterial food packaging.

Polymorphic calcium alginate microfibers assembled using a programmable microfluidic field for cell regulation.

Effectively guiding and accurately controlling cell adhesion and growth on the surfaces of specific morphological materials are key issues and hot research topics for optimizing biomaterials. Herein, novel polymorphic alginate microfibers formed through microfluidic spinning technology in a single microchip are presented. Through programming the flow and reaction kinetics in microchannels, other than self-modified micromorphic channel geometry, polymorphic microfibers with precisely tuned curvature-adjustable morphology can be obtained. Finite element (FE) simulations of the flow field (unidirectional fluid-solid coupling) proved the efficacy of the proposed control strategy. Moreover, the specific disordered-ordered cell arrangements showed a linear relationship between bioinspired alginate microfibers with different curvatures and the orientation angle of L929 cells, and diversified growth morphologies, including oblate ellipse, star, tree and strip shapes, occurred on the customizable interface curvature of the calcium alginate microfibers, providing a paradigm for using specific structured natural biomedical materials for cell regulation. This work represents a new design concept for manufacturing polymorphic fibrous biomedical materials through a unique marriage of the fields of green chemistry, hydromechanics, and biomaterials, which should be very useful for guiding the controllable construction of alginate materials for use in structural materials for biomedical and engineering purposes.

Microfluidic Printing of Three-Dimensional Graphene Electroactive Microfibrous Scaffolds.

Graphene materials have attracted special attention because of their electrical conductivity, mechanical properties, and favorable biocompatibility. Although various methods have been developed for fabricating micro/nano conductive fibrous scaffolds, it is still challenging to fabricate the three-dimensional (3D) graphene fibrous scaffolds. Herein, we developed a new method, termed as microfluidic 3D printing technology (M3DP), to fabricate 3D graphene oxide (GO) microfibrous scaffolds with an adjustable fiber length, fiber diameter, and scaffold structure by integrating the microfluidic spinning technology with a programmable 3D printing system. GO microfibrous scaffolds were then transformed into conductive reduced graphene oxide (rGO) microfibrous scaffolds by hydrothermal reduction. Our results demonstrated that the fabricated 3D fibrous graphene scaffolds exhibited tunable structures, maneuverable mechanical properties, and good electrical conductivity and biocompatibility, as reflected by the adhesion and proliferation of SH-SY5Y cells on the graphene microfibrous scaffolds in an obviously oriented manner. The developed M3DP would be a powerful tool for fabricating 3D graphene microfibrous scaffolds for electroactive tissue regeneration and drug-screening applications.

Strontium ion substituted alginate‐based hydrogel fibers and its coordination binding model

ABSTRACTSr‐alginate and Ca‐alginate hydrogel fibers were fabricated via microfluidic spinning technology, and various analytical methods were adopted to characterize fibers and disclose the coordination model of Sr2+ binding with alginate molecule chain. For both fibers, the more crosslinking sites of Sr2+ with alginate molecule were illustrated in comparison with that of Ca2+. The more robust mechanical performance of Sr‐alginate fibers than Ca‐alginate counterpart was a strong indication of the more strong binding of Sr2+ with alginate molecular chain. FTIR and electric conductivity disclosed the chelation type of Sr2+ with alginate macromolecule being similar to that of Ca2+, which was core‐shell of the analogous “egg‐box” structure. Circular dichroism spectroscopy further certified the extra coordination sites for Sr2+ with alginate molecule than Ca2+. Research on the coordination model will be more beneficial to optimizing the physicochemical properties of alginate fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48571.

Multifunctional Micro/Nanoscale Fibers Based on Microfluidic Spinning Technology.

Superfine multifunctional micro/nanoscale fibrous materials with high surface area and ordered structure have attracted intensive attention for widespread applications in recent years. Microfluidic spinning technology (MST) has emerged as a powerful and versatile platform because of its various advantages such as high surface-area-to-volume ratio, effective heat transfer, and enhanced reaction rate. The resultant well-defined micro/nanoscale fibers exhibit controllable compositions, advanced structures, and new physical/chemical properties. The latest developments and achievements in microfluidic spun fiber materials are summarized in terms of the underlying preparation principles, geometric configurations, and functionalization. Variously architected structures and shapes by MST, including cylindrical, grooved, flat, anisotropic, hollow, core-shell, Janus, heterogeneous, helical, and knotted fibers, are emphasized. In particular, fiber-spinning chemistry in MST for achieving functionalization of fiber materials by in situ chemical reactions inside fibers is introduced. Additionally, the applications of the fabricated functional fibers are highlighted in sensors, microactuators, photoelectric devices, flexible electronics, tissue engineering, drug delivery, and water collection. Finally, recent progress, challenges, and future perspectives are discussed.

Robust microfluidic construction of konjac glucomannan-based micro-films for active food packaging

The objective of this study was to develop a novel active food packaging with high performance by using natural active compound. Here, a facile and green strategy was employed to construct the konjac glucomannan/polylactic acid/trans-cinnamic acid micro-films (KPTMF) via microfluidic spinning technology (MST). MST, a mild preparation approach, could remain the activities of natural compound during processing. Konjac glucomannan could drive the release of trans-cinnamic by using its hydrophilicity under our careful design. The results of fourier-transform infrared spectra and infrared images revealed that konjac glucomannan, polylactic acid, and trans-cinnamic acid had good compatibility through hydrogen bonds in the micro-films, which was consistent with the X-ray diffraction results. Also, the good swelling degree (81.36 ± 5.79%) of KPTMF could promote the release of trans-cinnamic. Besides, the KPTMF had excellent mechanical properties (Tensile strength: 14.09 ± 2.97 MPa, Elongation at break: 3.12 ± 0.57%), thermal stabilities and hydrophobicity (Water vapor permeability: 4.81 × 10−6 g/(m·h·kPa), Water contact angle: 99.2°). The obtained micro-films with large specific surface areas exhibited great antibacterial activities against Staphylococcus aureus and Escherichia coli, which suggested the potential applications in active food packaging.

Microfluidic spinning of poly (methyl methacrylate)/konjac glucomannan active food packaging films based on hydrophilic/hydrophobic strategy

Here, inspired by the hydrophilic/hydrophobic theory, a novel konjac glucomannan/poly (methyl methacrylate)/chlorogenic acid (KGM/PMMA/CGA) food packaging film was successfully fabricated via microfluidic spinning technology (MST). The results of fourier transform infrared spectroscopy and x-ray diffraction confirmed the formation of hydrogen bonds in the films, which lead to the enhanced mechanical properties. Thermogravimetric analysis and differential scanning calorimetry showed excellent thermal stability of the films. Water vapor permeability (1.47 × 10−5 ± 0.11 g/(m⋅h⋅kPa)) and water contact angle (89.2°) measurement proved that the films were hydrophobic. The good swelling degree (85.18 ± 15.65%) indicated film’s potentials in releasing CGA. More importantly, KGM played a key role in the antibacterial activities against Staphylococcus aureus (8.5 ± 3.5 mm) and Escherichia coli (6.5 ± 2.1 mm) by utilizing its hydrophilicity. Thus, our present work may provide a new idea for constructing active food packaging films with significant performances based on hydrophilic/hydrophobic strategy.

Microfluidic fabrication of robust konjac glucomannan-based microfiber scaffolds with high antioxidant performance

The exploration of high-performance biological scaffolds with antioxidant properties and microstructures is of great scientific and technological interest. Here, we develop a facile and green strategy to construct robust konjac glucomannan/polyvinylpyrrolidone (KGM/PVP) microfiber scaffolds via microfluidic spinning technology. Epigallocatechin-3-gallate (EGCG) as a representative natural antioxidant was then loaded into the microfiber scaffolds. Then characterizations were done by scanning electron microscopy, Fourier transform-infrared spectra, IR images, X-ray diffraction, and thermogravimetric analysis, along with antioxidant characterization. The as-prepared microfiber scaffolds (the average width of the microfibers is 1 ± 0.1 μm) are of high order, transparency, thermostability, and excellent antioxidant activity (43% DPPH radical scavenging activity and 0.61 reducing force), conferring highly potential applications in wound dressing and contact lenses.

Facile Access to Wearable Device via Microfluidic Spinning of Robust and Aligned Fluorescent Microfibers.

Microfluidic spinning technology (MST) has drawn much attention owing to its ideal platform for ordered fluorescent fibers, along with their large-scale manipulation, high efficiency, flexibility, and environment friendliness. Here, we employed the MST to fabricate a series of uniform fluorescent microfibers. By adjusting the microfluidic spinning parameters, the as-prepared microfibers of different diameters are successfully obtained. For more practice, these regular arranged fibers could be formed to versatile fluorescent codes by using various microfluidic chips. Also, these versatile fluorescent fibers could be further weaved into a white fluorescent film via continuous and cross-spinning process, which could be applied in a white light emitting diode (WLED) and a wearable device. Besides, we investigated the MST-directed microreactors to carry out green synthesis of CdSe quantum dots (QDs) fibers by the knot of Y-type microfluidic chip. The as-prepared CdSe QDs show nice optical property and are good candidate as phosphors in WLED. This strategy offers a facile and environment-friendly route to fluorescent hybrid microfibers and might open their potential application in optical devices, security, and fluorescent coding.

Hydrodynamic alignment and microfluidic spinning of strength-reinforced calcium alginate microfibers

Microfluidic spinning technology (MST) employed for the fabrication of microfibers is an emerging material fabrication method of great scientific interest. To achieve high-strength properties of the fabricated reinforced microfibers, the nanostructure must be tunable. Herein we present a process combining hydrodynamic alignment (HA) and MST to synthesize microfibers with different diameters in a multiphase coaxial flow. The preferential macromolecule orientation along the microfiber forming direction and its diameter was tuned by varying the process parameters. The tensile test revealed that the maximum strength of the fabricated calcium alginate microfiber reached 185.1 MPa, whereas the microfibers were found to have consistent and uniform size with an average diameter of 31.3 μm. Successful HA at higher flow rates prior to gelation caused a decrease in the diameter of the microfiber.

Cell Attachment on Inside-Outside Surface and Cell Encapsulation in Wall of Microscopic Tubular Scaffolds for Vascular Tissue-Like Formation.

By using the microfluidic spinning technology we generated tiny hydrogel tubular scaffolds. Fibroblast (NIH/3T3) cell cultures were performed for seventeen days to demonstrate the potential of cell attachment on surfaces and encapsulation in the wall of he microscopic scaffolds for blood vessel-like structure forming. Over theculture period, the NIH/3T3 confluence reached around 80\%, and 100\% on the inside and outside scaffolds' surface respectively while cells proliferated and coalesced in cell group in the hydrogel wall. These results could further be applied to endothelial co-culturing for forming engineered blood vessel.

Fabrication of ordered konjac glucomannan microfiber arrays via facile microfluidic spinning method

The exploration of methods to produce biocompatible materials in ultrasmall scales is of great scientific and technological interest. We reported a microfluidic spinning technology (MST) for fabrication of microfibers with a novel biocompatible material, konjac glucomannan (KGM) as the main material combined with sodium polyacrylate (PAAS). These as-produced KGM/PAAS microfibers are consistent and uniform in size with an average width of 100μm. Also, these microfibers can easily arrange to microarrays and microgrids, facilely forming a useful platform for molecules recognition of amines. Moreover, the nontoxicity of KGM developed an ofloxacin loaded KGM microfibers present potential application in wound dressing. This strategy contributes a facile pathway on the construction of biomaterial microfibers by using polysaccharides as the precursors.

Fabrication of highly fluorescent CdSe quantum dots via solvent-free microfluidic spinning microreactors

The available method for in situ fabrication of highly fluorescent hybrid materials prepared via microfluidic spinning technology (MST) have been demonstrated.