Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/0007—Electro-spinning
  • D01D5/0061—Electro-spinning characterised by the electro-spinning apparatus
  • D01D5/0076—Electro-spinning characterised by the electro-spinning apparatus characterised by the collecting device, e.g. drum, wheel, endless belt, plate or grid
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
  • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
  • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/02—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/02—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
  • D04H3/04—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments in rectilinear paths, e.g. crossing at right angles
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/02—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
  • D04H3/07—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments otherwise than in a plane, e.g. in a tubular way

Definitions

• This invention relates to nanometre fibres and provides an array of such fibres suitable for the filtration of particles, in particular for particles in the nanometre size range, such as viruses.
• the fibres may also be useful for example in tissue and other medical engineering, catalysis, microelectronics, textiles and materials engineering.
• fibres in the nanometre diameter range can be produced by an electrospinning technique and disposed in the form of a non-woven scaffold of randomly oriented fibres which may be used as a filtration medium.
• Electrospinning involves, in general terms, introducing a charged liquid polymer solution to an electric field, the solution being dispensed typically through a needle attached to a syringe at a voltage between 10-2OkV, and deposition of the solution on a conductive collector material at ground (OV) potential located between 10 and 30cm from the needle.
• OV ground
• the ejected polymer solution as it emerges from the needle in the form of a pendant droplet maintained by surface tension, is initially deformed to a conical shape and, once the voltage exceeds a critical value, dependent on the chemical nature of the polymer solution, the electrostatic forces overcome the surface tension and the solution forms a fine charged jet which is deposited on the collector material as a continuous nanofibre.
• the jet before deposition, the jet exhibits bending instabilities due to repulsive electrical forces within the jet, as a result of which the jet extends through spiralling loops which, as they increase in diameter, result in the jet growing longer and thinner until it eventually solidifies on the collector.
• the fibres Due to the bending instabilities, the fibres are deposited on the collector in a random manner and result in a fibrous mat having a random pore size between the individual fibres.
• the broad pore size distribution means that the mat is only efficient for filtration of micron and larger particles and, even then, there is no guarantee that individual particles will not be allowed to pass through the mat.
• the filtration media are therefore not totally reliable particularly for particles in the nanometer size range, such as viruses.
• the particle size of the H5N1 strain of bird flu virus is in the region of lOOnm.
• WO02/034986 describes an electrospinning technique to form non- woven materials made from hollow fibres (mesotubes and nanotubes), the fibres being oriented in a single direction, in which the fibres are deposited on a flexible substrate which is subsequently stretched in one direction to align the fibres in the stretch direction.
• the fibres are oriented in one direction, the separation distance between the aligned fibres cannot be readily controlled, and the resultant array of fibres is still not appropriate for filtration and other purposes.
• An object of the present invention is to provide nanometre fibres in a form suitable for use as a filtration means for nanometre-size particles and which avoids the problems of currently- available filters using mats formed from randomly deposited nanometre-size fibres.
• the present invention provides a spatially-ordered matrix array of nanometre fibres with nanometre-size voids therebetween.
• the nanometre fibres may be deposited on a substrate support or may be essentially self- supporting.
• spatially-ordered matrix array of nanometre fibres is meant that the fibres define between them regular geometric shapes, for example squares or other rectangles, diamonds or hexagons, preferably as a fibre matrix monolayer, with nanometre-scale spaces or voids between the individual fibres.
• the matrix array of nanometre fibres is preferably produced by an electrospinning process in which the fibres are deposited on a substrate disposed on a collector including a plurality of electrically-conductive discrete nodes disposed thereon.
• the fibre matrix may subsequently be removed from the substrate. Depending, however, on the nature of the substrate and the intended end use, the matrix array may be left remaining on the substrate.
• the invention provides a process for producing an array of nanometre fibres, the process comprising electrospinning a fibre material to become deposited on a substrate disposed on a conductive collector means, in which the conductive collector means comprises a plurality of discrete electrically-conductive nodes, whereby the array of nanometre fibres constitutes a spatially-ordered matrix array with nanometre voids therebetween.
• the invention provides electrospinning apparatus for forming a spatially-ordered array of nanometre fibres, the apparatus including injection means for a liquid polymer material and collector means for the nanometre fibres, in which the collector means comprises an array of discrete electrically-conductive nodes arranged in a grid pattern.
• the fibre material forming the nanometre fibres comprises either a molten polymeric material, any thermoplastic polymer being potentially suitable, or a solution of a soluble thermoplastic polymer in a suitable solvent.
• the electrically-conductive nodes formed on the collector comprise discrete target points for attraction of the electrospun fibre material, the individual points being disposed at desired locations on the collector in order to control the geometry and size of the pores.
• the individual nodes may, for example, be constituted by clusters of electrically conductive nanoparticles.
• the nanoparticles may be positioned on the collector by various means including an atomic force microscope probe.
• the nodes may be formed on a silicon or other suitable conductive wafer to constitute an array of regularly aligned nodes by nonlinear laser lithography techniques.
• mechanical means such as the textile technique of carding may be used as basis for providing a matrix of conductive nodes.
• the fibre material is attracted either to a discrete node and settles laterally thereof or, where the nodes are arranged in aligned rows, the fibre material under deposition becomes attracted to the nearest node points and settles accordingly.
• the resulting matrix array of nanometre fibres avoids the need for multi-layer systems, for use in filtration, and can easily be incorporated in existing filtration apparatus, the mesh geometry of the array being readily altered to meet particular requirements.
• the substrate on which the matrix array is deposited comprises a skeletal material to ensure that the integrity of the array is maintained, while still allowing passage therethrough, and access to the matrix array of nanometre fibres, of a gaseous medium to be filtered or other medium to be processed, according to the end use required.
• the substrate may for example comprise a textile material which, although not necessarily being electrically conductive, will nevertheless permit transmission of attractive forces between the zero-potential nodes formed on the underlying collector and the charged polymer jet during the electrospinning process. Natural and/or synthetic materials may be used for the textile fabric, either woven or non-woven.
• the material exhibits an essential smooth deposition surface with a substantial absence of upstanding ends, whereby the matrix nanofibres are in supported contact with the substrate surface rather than being held spaced slightly apart therefrom on upstanding ends.
• the electrically-conductive nodes formed as an array on the collector means constitute a regular array pattern and preferably coincide with parallel and intersecting notional lines whereby the nodes define square, diamond or other regular geometric shapes to attract the nanofibres as they are formed from the liquid polymer under the influence of the applied electric field and as the polymer solidifies or the solvent evaporates.
• the resulting fibre array is controlled as to the orientation and spacing-apart of the individual fibres, as opposed to the fibres being randomly-oriented or randomly spaced apart, as in the known art. Control may be exercised by varying the speed of the substrate relative to the collector to alter the effective attractive forces applied to the nanometre fibres as they approach the substrate.
• the collector may comprise a cylindrical mandrel disposed for rotation about an essentially horizontal axis of rotation, the mandrel having an array of individual nodes disposed thereon and the substrate material being passed over the mandrel as the mandrel rotates while the liquid polymeric material is deposited thereon.
• the substrate material may thus be passed over the mandrel in a continuous process and wound on a receiving roll.
• Figure 1 is a diagram illustrating schematically an electrospinning process for manufacture of an array of nanofibres according to the invention
• Figure 2 shows a perspective view of the collector mandrel used in the process of Figure 1 to illustrate how the fibres are attracted to the collector;
• Figure 3 shows a fragment of a continuous substrate illustrating a square pattern of deposited fibres
• Figure 4 is similar to Figure 3 but illustrates a diamond pattern of deposited fibres.
• the liquid polymer either as a melt or as a solution, is contained in syringe 11 the needle 12 of which is maintained at a positive electrical potential.
• a horizontally-disposed cylindrical rotatable target collector mandrel 13 having surface- mounted nodes 14 is mounted beneath the syringe and is maintained at zero or ground voltage.
• a fabric substrate material 15 is passed from a supply roll 16, over guide rollers 17, 18, the upper arcuate surface of the collector 13, and onwards over guide roller 19 to form a take-up roll 20.
• the polymer liquid in the form of a nanofibre 21 is deposited on the surface of the substrate in a manner determined by the nodes 14 formed on the surface of the collector, as described in more detail with reference to Figure 2.
• the syringe needles may be provided on a cylinder which is rotatably mounted in a solvent/polymer reservoir to form thousands if not millions of individual fibres, the numbers of which may optionally be attenuated by the use of inert, for example, ptfe, baffle plates.
• a suitable apparatus for forming the nanometre fibres is the Elmarco Nanospider "NS Lab” electrospinner.
• Figure 2 shows an array of the nanofibre-scale nodes 14 formed for example by nonlinear laser lithography, a manufacturing process using a femtosecond laser (ultra fast or ultra short pulse lasers) enabling structure sizes of less than lOOnm to be achieved.
• the nodes are formed on a semiconductor silicon wafer, although other conductive materials could be used in place of silicon.
• the silicon wafer is applied to the surface of the collector mandrel 13 and the nanofibres 21 are attracted towards the nodes and settle on the substrate material in a grid pattern as illustrated in Figure 2.
• Figure 2 shows the grid pattern as though the fibres were deposited directly on the surface of the mandrel without the substrate being present; in practice, the fibres would be distributed on the surface of the substrate and would form a nanometre-scale matrix array disposed on and supported by the fabric substrate material, as shown in Figure 3, where the fibres define a square grid pattern, and in Figure 4, where the fibres form a diamond grid pattern.
• the nodes 14 are shown at the positions of the nodes on the mandrel 13, below the substrate 15 as the substrate passes over the mandrel in the direction of the arrows at a linear speed matched with the rotational speed of the surface of the mandrel or, alternatively, at a different (faster or slower) speed to influence the fibres to assume a particular orientation as they approach the substrate according to the desired configuration of the matrix array of fibres.
• the velocity of the nodes on the rotating mandrel will produce variable resultant attractive forces on the fibres.
• the rotary drum of a textile carding machine may be used as the collector, in which the fabric substrate is passed over the arcuate upper surface of the drum, from which the carding needles extend radially and act as attraction nodes for the polymer nanofibre in a manner analogous to that shown in Figure 2 for the laser-etched nodes.
• Arrays of nanometres fibres according to the invention may be used for filtration purposes and in fibre-reinforced plastics materials, application of pesticides to plants, biomedical applications including tissue engineering scaffolds, bandages and drug release systems, protective clothing especially for chemical and biological protection, catalyst supports and for solar and light sails and mirrors in space, for example.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38983105

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (7)

Citations (2)

Family Cites Families (5)

• 2007
  • 2007-12-06 GB GB0723895A patent/GB0723895D0/en not_active Ceased
• 2008
  • 2008-12-08 WO PCT/GB2008/004027 patent/WO2009071909A1/en active Application Filing
  • 2008-12-08 EP EP08856541A patent/EP2231301A1/de not_active Ceased

Patent Citations (2)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events