A method and an apparatus for fabricating nanofibrous articles is disclosed. The method may include providing a double-walled nozzle with an inner tube coaxially disposed within an outer tube. In addition, the double-walled nozzle is secured in front of a collector and an electrical field is applied between a tip of the double-walled nozzle and the collector. The method further includes preparing a spinning solution by dissolving a polymer in a solvent, mixing a vapor stream of the solvent with a stream of a pressurized gas with a predetermined ratio to obtain a pressurized solvent/gas stream feeding the spinning solution through the inner tube of the double-walled nozzle, and concurrently feeding the pressurized solvent/gas stream through the outer tube of the double-walled nozzle. The spinning solution and the pressurized solvent/gas stream may concurrently be discharged from the double-walled nozzle and drawn toward the collector being collected as nanofibrous articles on the collector.

An electrospinning device includes: a plurality of nozzles that discharge a spinning solution containing a resin; and a plurality of power sources for applying charge to the solution. The power sources are connected such that different charges are applied to the solutions discharged from the nozzles, respectively. The fiber sheet is a long fiber nonwoven fabric including first fibers and second fibers that are different from the first fibers. In a histogram based on fiber diameter distributions and frequencies of the numbers of fibers, the fiber sheet has a peak where a ratio P1 of a frequency of the number of fibers of the first fibers to a frequency of the number of fibers of the second fibers is 0.01 or more and 100 or less. Alternatively, the fiber sheet has two or more peaks in the histogram, in which a ratio P2 of a frequency of the number of fibers of the first fibers at a highest peak in a range of a fiber diameter of 3 μm or less to a frequency of the number of fibers of the second fibers at a highest peak in a range of a fiber diameter of more than 3 μm is 1 or more and 1 000 or less.

A fiber collection tool for collecting a fiber spun by electrospinning is described. The fiber collection tool has a size holdable by the hand of a user, and includes, in at least a portion of the surface thereof, an electroconductive section having a surface electrical resistivity of 10.sup.11 Ω/cm.sup.2 or less, or a hydrophilic section having a water contact angle of preferably from 15° to 90° at 25° C. A user collects, with the fiber collection tool, a fiber spun by the user by electrospinning using an electrospinning device having a size holdable by the hand of the user, and thereby produces a film including a deposit of the fiber on a surface of the fiber collection tool. The fiber collection tool, having the deposit formed thereon, is pressed against a surface of an object, and the deposit is transferred onto the surface of the object, to form a film including the fiber deposit on the surface of the object.

A fiber collection tool for collecting a fiber spun by electrospinning is described. The fiber collection tool has a size holdable by the hand of a user, and includes, in its interior, an electroconductive section. Preferably, the fiber collection tool further includes a surface section outside the electroconductive section. In a fiber deposit production method, a user collects, with the fiber collection tool, a fiber spun by the user by performing electrospinning using an electrospinning device having a size holdable by the hand of the user, and thereby produces a film including a deposit of the fiber on a surface of the fiber collection tool. The fiber collection tool, having the deposit formed thereon, is pressed against a surface of an object, and the deposit is transferred onto the surface of the object, to form a film including the fiber deposit on the surface of the object.

The present disclosure discloses a high-whiteness polyimide microfiber and a preparation method thereof and use. The polyimide fiber includes polyimide obtained from the reaction of wholly alicyclic dianhydride HTDA and an aromatic diamine monomer containing methyl or trifluoromethyl by chemical imidization. In the present disclosure, the polyimide microfiber has both excellent heat-resistant stability and spinning film-forming property, and the fabric has ultra-high whiteness. The microfiber fabric prepared from the polyimide fiber may be used as a component with high-temperature resistant and high-whiteness in personal protective equipment such as mask and protective clothing, and also may be used as an electronic component in the high-tech field such as aerospace, optoelectronic, microelectronic and automobile.

The present invention generally relates to a dual density air filtration media that comprises a plurality of nanofibers layers formed from nanofibers having different fiber diameters. Due to the presence of these multiple nanofiber layers with different nanofiber diameters, the resulting filtration media of the present invention comprises a gradient density. In particular, the present invention uses a novel combination of two or more layers of nanofibers made via an electrospinning process, wherein the nanofiber layers made up from different fiber sizes are strategically applied to a cellulose or synthetic base material or substrate, to thereby maximize the filtration efficiency and dust holding capacity of the resulting filtration media.

A multi-laminar electrospun nanofiber scaffold for use in repairing a defect in a tissue substrate is provided. The scaffold includes a first layer formed by a first plurality of electrospun polymeric fibers, and a second layer formed by a second plurality of electrospun polymeric fibers. The second layer is combined with the first layer. A first portion of the scaffold includes a higher density of fibers than a second portion of the scaffold, and the first portion has a higher tensile strength than the second portion. The scaffold is configured to degrade via hydrolysis after at least one of a predetermined time or an environmental condition. The scaffold is configured to be applied to the tissue substrate containing the defect, and is sufficiently flexible to facilitate application of the scaffold to uneven surfaces of the tissue substrate, and to enable movement of the scaffold by the tissue substrate.

The electrospinning method comprises the steps of providing a composition to be electrospun; providing an electrospinning device comprising an electrospinning head and a collector; applying an electric field between the electrospinning head and the collector; and feeding the composition to be electrospun through the electrospinning head, so that the electric field applied induces the formation of an electrospun fiber.

An electrospun nanofiber membrane and a method for preparing the electrospun nanofiber membrane are provided to solve problems of poor mechanical properties, short service life, poor uniformity and consistency of orientation of fibers and poor stability of fiber networks in current electrospun composite nanofiber materials. The electrospun nanofiber membrane is prepared by spinning solution through a high-voltage electrospinning device. The spinning solution is blending solution of regenerated silk fibroin: polyvinyl alcohol: polylactic acid with a mass ratio being 75-85:10-20:5 dissolved in a mixed solvent of trifluoroacetic acid and dichloromethane with a volume ratio being 7:3. The method establishes a reasonable mass ratio parameter of the regenerated silk fibroin, the polyvinyl alcohol and the polylactic acid to blending spinning to improve spinnability of silk fibroin, as well as prepare the electrospun composite nanofiber membrane with good mechanical properties.

Applications of electrospinning (ES) range from fabrication of biomedical devices and tissue regeneration scaffolds to light manipulation and energy conversion, and even to deposition of materials that act as growth platforms for nanoscale catalysis. One major limitation to wide adoption of electrospun materials is the ES hardware itself, which typically requires high voltage, electric isolation, and charged and flat deposition surfaces. In the past, fabrication of structures or materials with precisely determined mesoscale morphology has been accomplished through modification of electrode shape, use of multi-dimensional electrodes or pins, deposition onto weaving looms, hand held electrospinners that allow the user to guide deposition, or electric field manipulation by lensing elements or apertures. In this work, we demonstrate an ES system that contains multiple high voltage power supplies that are independently controlled. This system produces a novel electrostatic field that enables deposition of polymers in precise, mesoscale structures.