Surface Of Microfibers Research Articles

Oligoether grafting on cellulose microfibers for dispersion in poly(propylene glycol) and fabrication of reinforced polyurethane composite

Application of cellulose microfibers as a reinforcing agent for high-performance polyurethane composites is rarely mentioned because the inherent hydrophilicity combined with the adverse aspect ratio of the fibers cause difficulties in dispersion within and compatibility with the polymer matrix. Here, we propose a feasible approach to graft oligoethers synthesized by ring-opening polymerization in a heterogeneous reaction to the cellulose microfiber surface. The oligomers composed of ether linkages and flexible hydroxyl groups provide cellulose fibers with good dispersity in poly(propylene glycol) and potential physical and chemical cross-linking points in reaction with isocyanates to form good interfacial adhesion between the fibers and the polyurethane matrix. Consequently, the tensile properties and viscoelasticity of the oligomer-grafted cellulose-filled polyurethane composite were enhanced compared with those of the neat elastomer and composite containing pristine cellulose microfibers. This reinforcement effect is attributed to the natural stiffness of the fiber bundles and the cross-linking network generated by the oligomers grafted on the fiber surface.

Investigate the Drag Resistance of Antifouling Self-Adhesive Film

Fouling has always been a common issue for ships as fouling drastically increases the surface roughness and ship resistance. The microfiber self-adhesive antifouling film is claimed to be effective up to 5 years and is environmentally friendly. However, there is lack of information about the drag characteristics of the antifouling material. Thus, this project is conducted based on an experimental study to determine the drag characteristics of the surface installed with microfiber self-adhesive antifouling film. The rotor apparatus is used to study the coefficient of friction of the microfiber surface. From the experimental results, a flat plate simulation using ANSYS-Fluent is conducted to further estimate the coefficient of friction up to Reynolds number of 109 and to evaluate the total ship resistance for the Semi-SWATH (fast vessel) and KVLCC (slow trading ships). The results show that the percentage increase in total ship resistance for the KVLCC is about 80%, which is more than the Semi-SWATH of 30%, as frictional resistance has high significance for slow trading ships. The speed drop experienced by the ship model installed with the microfiber antifouling is 2 knots for the KVLCC and 1 knot for the Semi-SWATH if the power remained the same for both models.

Effect of Cellulose Microfiber Silylation Procedures on the Properties and Antibacterial Activity of Polydimethylsiloxane

In this study, the liquid phase and vapor phase procedures for silylating cellulose microfibers by hexamethyldisilazane (HMDS) were compared in terms of efficiency. The influence of functionalization degree on the morphology of microfibers and their interaction with polydimethylsiloxane (PDMS) matrix has been investigated. The antibacterial properties of silylated cellulose microfibers hybridized with Ag nanoparticles, obtained by in situ chemical reduction, were also studied. Sample morphology investigations were carried out using spectroscopy and microscopy techniques (FTIR, XPS, TEM, SEM, EDS, XPS). Trimethylsilyl moieties appear on the surface of the cellulose microfibers after modification and improve the dispersibility of the microfibers, allowing strong interaction with the PDMS matrix and favoring its crosslinking density. Microfibers functionalized by the vapor phase of HMDS show smoother surfaces with higher concentrations of Si-containing groups, resulting in a more hydrophobic wetting behavior and a greater influence on the mechanical properties of the polymer. The silylated cellulose microfiber–Ag nanohybrid shows stronger antimicrobial activity towards Gram-positive and Gram-negative bacteria strains compared to that of the untreated hybrid. A PDMS composite loaded with this hybrid exhibits the ability to inhibit bacterial growth.

All-fiber spectral modulating device based on microfiber interferometer grown with tungsten disulfide

Here an integrated compact low-cost all-fiber optical spectrum control device based on a single fiber interferometer and tungsten disulfide is reported. Tungsten disulfide was deposited onto the surface of the non-adiabatic microfiber under the application of the radiation from an amplified spontaneous emission source. Next, the near-infrared light (NIR), which leaked through the strong evanescent field of the microfiber, excited the surrounding tungsten disulfide and generated heat due to the photothermal effect. Therefore, the phase shift of the interference spectrum was caused by the surrounding change in the refractive index (RI). In the experimental work at 1550 nm, a spectral shift equal to 0.8 nm was obtained following the use of a pump laser operating at 980 nm. In addition, the device can may be used as an all-optical switch with a modulation depth of 18.1%. The proposed tungsten disulfide-based all-fiber device has potential application in all-optical signal controllable devices.

Chalcogenide microfiber-assisted silica microfiber for ultrasound detection.

An ultra-compact ultrasound sensor with a chalcogenide (ChG) microfiber and a silica microfiber is fabricated. It can detect the ultrasound wave generated by a piezoelectric transducer peaked at 3.7MHz. The sensor shows the broadband ultrasound frequency response with a high signal-to-noise ratio (SNR), owing to the high refractive index and small Young's modulus of ChG material. A ChG (${{\rm As}_2}{{\rm Se}_3}$As2Se3) microfiber of 2µm diameter is adhered to the surface of a silica microfiber with a diameter of 5µm via Van der Waals force; the transmission spectrum has high contrast due to multi-mode interference in this hybrid structure. The SNR response could be up to 70dB, especially at low frequency due to the soft ChG microfiber as a sensing unit to magnify the ultrasound signal, along with an SNR over 12dB at ultrasound of 31.2MHz. As a comparison, a silica taper with the same size as the ChG microfiber is also placed on the silica microfiber with a diameter of 5µm to detect an ultrasound signal from 18kHz to 9.4MHz with an SNR lower than that based on the ChG microfiber up to 38.8dB, showing the high sensitivity of the ChG microfiber.

Ultrafast freestanding microfiber humidity sensor based on three-dimensional graphene network cladding.

An all-fiber humidity sensor is proposed and fabricated by depositing three-dimensional graphene network (3DGN) around the surface of a freestanding microfiber (MF). The high specific surface area and porosity of 3DGN enhances its interaction with water molecules, allowing high performance of the humidity sensor. The sensor can operate in a wide relative humidity (RH) range of 11.6%RH-90.9%RH with a high sensitivity of -2.841 dB/%RH in the RH range (80.3%RH - 90.9%RH). The response and recovery times of this type of microfiber sensor are measured respectively to be 57 ms and 55 ms, which are one order magnitude faster than those of other fiber RH sensors activated by two-dimensional materials coating. Such an all-fiber RH sensor with high sensitivity and fast response property possesses great potential of application in widespread fields, such as biology, chemical processing and food processing.

Label-free detection of breast cancer biomarker using silica microfiber interferometry

Sensitive detection of HER2 biomarkers is critical for clinical diagnostics of breast cancer while such detection is quite challenging due to the rapid detection of low concentration of HER2 biomarkers in complex biological media. A compact and label-free optical fiber sensor based on silica microfiber interferometry for detecting HER2 in serum has been proposed and experimentally demonstrated. The antibodies immobilized on the microfiber surface play the roles of the specific immuno-tentacles on catching the HER2 targets. The change of the surface refractive index attributed to the immunoreactions could be captured by the optical fiber sensor and transduced into a significant wavelength shift in the interferometric fringe. The proposed fiber-optic biosensor shows an improved sensitivity of 0.1 nm/(ng/mL), even in a serum matrix. The advantages of simple detection scheme and ease of miniaturization might make the biosensor a promising platform for clinical cancer diagnosis and prognosis.

Tuning of Titanium Microfiber Scaffold with UV-Photofunctionalization for Enhanced Osteoblast Affinity and Function.

Titanium (Ti) is an osteoconductive material that is routinely used as a bulk implant to fix and restore bones and teeth. This study explored the effective use of Ti as a bone engineering scaffold. Challenges to overcome were: (1) difficult liquid/cell infiltration into Ti microfiber scaffolds due to the hydrophobic nature of Ti; and (2) difficult cell attachment on thin and curved Ti microfibers. A recent discovery of UV-photofunctionalization of Ti prompted us to examine its effect on Ti microfiber scaffolds. Scaffolds in disk form were made by weaving grade 4 pure Ti microfibers (125 µm diameter) and half of them were acid-etched to roughen the surface. Some of the scaffolds with original or acid-etched surfaces were further treated by UV light before cell culture. Ti microfiber scaffolds, regardless of the surface type, were hydrophobic and did not allow glycerol/water liquid to infiltrate, whereas, after UV treatment, the scaffolds became hydrophilic and immediately absorbed the liquid. Osteogenic cells from two different origins, derived from the femoral and mandibular bone marrow of rats, were cultured on the scaffolds. The number of cells attached to scaffolds during the early stage of culture within 24 h was 3–10 times greater when the scaffolds were treated with UV. The development of cytoplasmic projections and cytoskeletal, as well as the expression of focal adhesion protein, were exclusively observed on UV-treated scaffolds. Osteoblastic functional phenotypes, such as alkaline phosphatase activity and calcium mineralization, were 2–15 times greater on UV-treated scaffolds, with more pronounced enhancement on acid-etched scaffolds compared to that on the original scaffolds. These effects of UV treatment were associated with a significant reduction in atomic carbon on the Ti microfiber surfaces. In conclusion, UV treatment of Ti microfiber scaffolds tunes their physicochemical properties and effectively enhances the attachment and function of osteoblasts, proposing a new strategy for bone engineering.

Generation of ultra-fast pulse based on bismuth saturable absorber

We demonstrate a bismuth (Bi) saturable absorber (SA) for generating ultrafast pulse. The Bi SA is fabricated by the Bi film deposited on the surface of microfibers through using magnetron sputtering. Its nonlinear optical properties are investigated. The as-prepared Bi SA has outstanding nonlinear absorption property demonstrated by the open aperture (OA) <i>Z</i>-scan system at 1500 nm and balanced twin-detector method at 1560 nm. The nonlinear optical property of Bi SA shows that the modulation depth, the nonsaturable losses, and the saturable intensity at 1.5 μm are 14% and 79%, and 0.9 MW/cm<sup>2</sup>, respectively. Besides, the closed aperture (CA) <i>Z</i>-scan measurement is also implemented to estimate the nonlinear refractive index of Bi film. The Bi film shows that the typical CA/OA curve possesses the feature of peak-valley profile, meaning that the sample with a negative nonlinear refractive index is self-defocusing. In our experiments, the parameters of the nonlinear absorption coefficient <i>β</i> and the nonlinear refractive index <i>n</i><sub>2</sub> are estimated at about 2.38 × 10<sup>–4</sup> cm/W and –1.47 × 10<sup>–9</sup> cm<sup>2</sup>/W according to the actual experimental data points, respectively. To further investigate its nonlinear optical property, the microfiber-based Bi SA is embedded into an erbium-doped fiber laser with a typical ring cavity structure. Based on the Bi SA device, the stable ultrafast pulses are generated at 1.5 μm with the pulse width of 357 fs, the output power of 45.4 mW, corresponding to the pulse energy of 2.39 nJ, and the signal-to-noise ratio is 84 dB. The stable soliton pulses emitting at 1563 nm are obtained with a 3-dB and 6-nm spectral bandwidth. The experimental results suggest that the microfiber-based Bi SA prepared by magnetron sputtering deposition (MSD) technique can be used as an excellent photonic device for ultrafast pulse generation in the 1.5 μm regime, and the MSD technique opens a promising way to produce high-performance SA with a large modulation depth, low saturable intensity, and high power tolerance, which are conducible to the generation of high power and ultrafast pulse with high stability.

Small caliber heparin loaded ultrafine microfiber woven graft achieved high patency rate in a preliminary study of canine carotid artery implantation

ObjectiveIn the past five decades, many small caliber vascular grafts have been developed as bypasses for infrapopliteal or coronary arteries. However, reliable grafts have not been obtained owing to poor patency, mainly caused by early thrombosis or neointimal hyperplasia in the intermediate period after implantation. We developed a novel small caliber heparin-loaded polyethylene terephthalate ultrafine microfiber (HL-PET) graft and evaluated the feasibility to overcome those main causes of graft failure in canine carotid artery implantation. MethodsThe HL-PET graft with a diameter of 3 mm and length of 30 mm was made with combination of three key technologies: (1) weaving with PET ultrafine microfiber with a high biological porosity allowing for cell ingrowth, (2) heparin loading on microfiber surfaces, and (3) an outer coating with a flexible bioabsorbable polymer for prevention of blood leakage and graft kinking. Kink resistance, water permeability, and loaded heparin were assessed. One HL-PET graft each was implanted into a carotid artery of six animals. Graft patency rate and healing were assessed 24 weeks after implantation. ResultsAmong the six grafts, five were deemed patent (patency rate of >83%), with one occluded 20 weeks after implantation. Histopathology of the patent grafts showed neointima formation with confluent endothelial cell lining (estimated mean endothelial cell coverage area, 89 ± 18%). Intimal hyperplasia at the anastomotic sites and severe chronic inflammatory responses were not observed. Immunohistochemistry with antibodies to endothelial nitric oxide synthase, alpha 2 smooth muscle actin and calponin 1 revealed luminal surface endothelial cell layer with expression of endothelial nitric oxide synthase and vascular smooth muscle cells with contractile phenotype in the subintimal layer. ConclusionsThe HL-PET graft showed no early postoperative thrombosis and was able to demonstrate a high patency rate with no severe biological response observed after 24 weeks. These results strongly suggest the potential of the HL-PET graft to be used for distal bypasses.

Generating Nanotopography on PCL Microfiber Surface for Better Cell-Scaffold Interactions

To understand the behavior of cells in natural environment, 3D scaffolds are needed to provide biomimetic environment for routine cell growth in vitro. Electrohydrodynamic jet (EHDJ) printing, one of the emerging 3D printing techniques, is capable of fabricating 3D scaffolds with oriented fibers and customized microscale structures. However, most of the EHDJ-printed scaffolds lack of hierarchical structures such as nanotopographies present in native tissues. In this study, we propose a novel approach that combine EHDJ printing of poly(ε-caprolactone) (PCL)/gliadin composite inks to produce scaffolds with oriented microfibers. The nanoscale pores and flaws (fiber nanotopography) could be generated on the printed fibers by simply leaching the gliadin phase from the printed PCL/gliadin scaffolds. The density and size of nanotopographical features could be controlled by adjusting the gliadin ratio. Furthermore, by seeding mouse embryonic fibroblasts (NIH/3T3) cells, it clearly manifested that such scaffolds are favorable to cell adhesion, migration and proliferation efficiently. Thus, the newly designed PCL scaffolds with both micro- and nano-scale topographies can be a promising 3D cell culture platform with improved cell-scaffold interactions.

Bacterial cellulose synthesized with apple pomace enhanced by ionic liquid pretreatment

Apple pomace was explored as alternative feedstock for producing bacterial cellulose (BC) by Gluconacetobacter xylinus following a cellulase saccharification performed after pretreatment of 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). The dissolving process of apple pomace cellulose was observed by polarized light microscopy (PLM). As FT-IR and XRD results demonstrated, the IL pretreatment proved to be a physical process and no changes in the crystalline structure occurred during the pretreatment. However, the SEM result showed that more fissures and breakages appeared on the surface of pomace microfibers after IL-pretreating, which increased the contact area with cellulase and improved the enzymatic hydrolysis efficiency. An enhancing effect on the BC yield has been observed, 27% higher yield of BC obtained from hydrolysate as compared to sucrose-based medium indicates efficiency of IL-treated apple pomace to serve as high quality feedstock in BC production.

Polyimide-Coated Glass Microfiber as Polysulfide Perm-Selective Separator for High-Performance Lithium-Sulphur Batteries.

Although numerous research efforts have been made for the last two decades, the chronic problems of lithium-sulphur batteries (LSBs), i.e., polysulfide shuttling of active sulphur material and surface passivation of the lithium metal anode, still impede their practical application. In order to mitigate these issues, we utilized polyimide functionalized glass microfibers (PI-GF) as a functional separator. The water-soluble precursor enabled the formation of a homogenous thin coating on the surface of the glass microfiber (GF) membrane with the potential to scale and fine-tune: the PI-GF was prepared by simple dipping of commercial GF into an aqueous solution of poly(amic acid), (PAA), followed by thermal imidization. We found that a tiny amount of polyimide (PI) of 0.5 wt.% is more than enough to endow the GF separator with useful capabilities, both retarding polysulfide migration. Combined with a free-standing microporous carbon cloth-sulphur composite cathode, the PI-GF-based LSB cell exhibits a stable cycling over 120 cycles at a current density of 1 mA/cm2 and an areal sulphur loading of 2 mgS/cm2 with only a marginal capacity loss of 0.099%/cycle. This corresponds to an improvement in cycle stability by 200%, specific capacity by 16.4%, and capacity loss per cycle by 45% as compared to those of the cell without PI coating. Our study revealed that a simple but synergistic combination of porous carbon supporting material and functional separator enabled us to achieve high-performance LSBs, but could also pave the way for the development of practical LSBs using the commercially viable method without using complicated synthesis or harmful and expensive chemicals.

Optically functionalized microfiber Bragg grating for RH sensing.

Herein, a novel material functionalization of fiber components is proposed, which is based on optically induced film forming. The film formation of polymer around a microfiber is achieved only by injecting an ultraviolet laser through the microfiber. The evanescent field of an ultraviolet laser, propagating along the microfiber surface, provides activation energy for photopolymerization of polymer and film formation directly onto the surface of a microfiber. The thickness of the deposited film can be controlled by adjusting the irradiation time. Additionally, the potential application case demonstrates that fiber components can be endowed with a given function by this material functionalization method. Therefore, a fiber relative humidity sensor using a polymer film-functionalized microfiber Bragg grating fabricated by this functionalization technique is demonstrated. This proposed sensor has the advantages of relatively fast response, large measurement range, and high stability.

Microfluidics-Based Fabrication of Cell-Laden Hydrogel Microfibers for Potential Applications in Tissue Engineering.

Fibrous hydrogel scaffolds have recently attracted increasing attention for tissue engineering applications. While a number of approaches have been proposed for fabricating microfibers, it remains difficult for current methods to produce materials that meet the essential requirements of being simple, flexible and bio-friendly. It is especially challenging to prepare cell-laden microfibers which have different structures to meet the needs of various applications using a simple device. In this study, we developed a facile two-flow microfluidic system, through which cell-laden hydrogel microfibers with various structures could be easily prepared in one step. Aiming to meet different tissue engineering needs, several types of microfibers with different structures, including single-layer, double-layer and hollow microfibers, have been prepared using an alginate-methacrylated gelatin composite hydrogel by merely changing the inner and outer fluids. Cell-laden single-layer microfibers were obtained by subsequently seeding mouse embryonic osteoblast precursor cells (MC3T3-E1) cells on the surface of the as-prepared microfibers. Cell-laden double-layer and hollow microfibers were prepared by directly encapsulating MC3T3-E1 cells or human umbilical vein endothelial cells (HUVECs) in the cores of microfibers upon their fabrication. Prominent proliferation of cells happened in all cell-laden single-layer, double-layer and hollow microfibers, implying potential applications for them in tissue engineering.

Development of a selectively liquid-blocking and vapor-passage microfilter based on polyurethane-aerogel microfibers

In this study, we developed a liquid–vapor selective microfilter woven into a mesh using polyurethane (PU)–aerogel microfibers. The aerogel particles embedded on the surface of a PU microfiber provided liquid repellent properties, and the liquid–vapor selective microfilter allowed only vaporized chemical substances to pass through, while blocking liquid chemicals and water. An SnO2 nanowire transistor covered with the liquid–vapor selective microfilter was used as a chemical sensor to detect the concentration of chemical substances, such as nitric acid, benzene, and toluene, in water. The time-dependence response of the sensor depending on the type of chemical present in water showed reproducible response and recovery properties for multiple cycles.

Enhancement of the Spontaneous Emission Rate of Perovskite Nanowires Coupled into Cylindrical Hollow Nanocavities Formed on the Surface of Polystyrene Microfibers

Fluorescent CsPbBr3 nanowires are uniformly integrated into a porous polystyrene matrix in the form of microfibers to investigate the changes in their spontaneous emission rate. Cylindrical hollow ...

Durable superhydrophobic glass wool@polydopamine@PDMS for highly efficient oil/water separation

The application of superhydrophobic materials for oil/water separation is receiving increasing attention. Meanwhile, durable superhydrophobic/superoleophilic materials and simple preparation methods are highly desired. Here, inspired by nature, we report a simple method for preparation of durable superhydrophobic glass wool (GW) for highly efficient oil/water separation. The durable and low-cost GW was converted to superhydrophobic simply by polymerization of dopamine followed by chemical vapor deposition of polydimethylsiloxane (PDMS). The polymerization of dopamine generated a lot of polydopamine nanoparticles on the surface of GW microfibers, forming hierachical micro-/nanostructures. The chemical vapor deposition of PDMS efficiently reduced the surface energy. The combination of the hierachical micro-/nanostructure and the PDMS layer successfully made the GW superhydrophobic with a water contact angle of ∼156° and water drops could easily roll off. In addition, the superhydrophobic GW showed high chemical stability in corrosive solutions and oils and high thermal stability. Moreover, the superhydrophobic GW showed high efficiency in selective oil absorption and oil/water separation as well as high recyclability. We believe that the superhydrophobic GW may find application in practical oil/water separation because of its good performance in oil/water separation and high stability under diverse harsh conditions.

Electrochemical detection of adenine and guanine using a three-dimensional WS2 nanosheet/graphite microfiber hybrid electrode

In this work, a WS2 nanosheet/graphite microfiber hybrid electrode has been fabricated by in situ synthesis of WS2 nanosheets on the surface of graphite microfibers. The WS2 nanosheets possess an excellent electrocatalytic oxidation response towards adenine and guanine that encourages the adsorption of nucleobases and charge transfer at the surface of the microfibers. The WS2 nanosheet/graphite microfiber hybrid electrode shows high sensitivity and selectivity for the detection of adenine and guanine. This hybrid microfiber electrode represents an excellent candidate platform for development of an electrochemical biosensor due to its low cost, flexibility and 3D morphology.

Interface Sensitized Optical Microfiber Biosensors

Sensitivity is an important parameter to characterize the performance of sensors. Interfacial modification and functionalization is an effective strategy to improve the sensitivity of optical biosensors. This paper reports our recent development on interface sensitized fiber optic biosensors for the detection of ultra-low concentration of biological targets. We employ microfiber mode interferometer as transducer to sense the molecular binding interaction induced surrounding refractive index change. By modifying the microfiber surface to increase the assembling surface area and enhance the evanescent field energy density, ultra-low limit of detection of 1.65 × 10−15 M and 6.82 × 10−17 M, respectively, were realized for neurotransmitter γ-amino-butyric acid and cellular cytochrome c.