Fibrillar lining for prosthetic device

#This invention relates to the production of fibrillar products by the electrostatic spinning of organic materials.

#The technique of electrostatic spinning of liquids, including solutions containing a fibre-forming material is known and has been described in a number of patents as well as in the general literature.

#The process of electrostatic spinning involves the introduction of a liquid into an electric field, whereby the liquid is caused to produce fibres which tend to be drawn to an electrode. While being drawn from the liquid the fibres usually harden, which may involve mere cooling (where the liquid is normally solid at room temperature, for example), chemical hardening (for example by treatment with a hardening vapour) or evaporation of solvent (for example of dehydration). The product fibres may be collected on a suitably located receiver and subsequently stripped from it.

#The invention will be further understood from the following more detailed description taken with the drawings in which:

#FIG. 1 is a schematic perspective view of an apparatus for electrostatically spinning and collecting fibres;

#FIG. 2 is a schematic perspective view of a second embodiment of a spinning and collecting apparatus;

#According to one embodiment of the present invention we provide a shaped mat of electrostatically spun fibres in a form appropriate for use as a wound dressing. A particular advantage of the use of materials made from the electrostatically spun fibres is that the fibres may be of very small diameter, to give a mat with small interstices and consequently a high surface area. Where the dressing is formed from a wettable polymer, blood or serum escaping from the wound tends to penetrate the dressing and the high surface area encourages clotting. Such dressings may be used as emergency dressings to halt bleeding. As examples of suitable polymers we may mention polyurethanes. Where the dressing is formed from a non-wetting polymer a particular advantage is that if the interstices between the fibres are sufficiently small, averaging, say 1 to 100 .mu., tissue fluids, including blood, tend not to permeate the dressing, so that the fluids are retained adjacent to the wound, where clotting will occur. Subsequent removal of such a dressing is facilitated by the absence of blood clot permeating the dressing material. Furthermore such dressings have the advantage that they are usually sufficiently porous to allow interchange of oxygen and water vapour between the atmosphere and the surface of the wound. As examples of suitable non-wetting polymers we may mention saturated polyesters e.g. polyethylene terephthalate, fluorinated compounds, particularly fluorinated hydrocarbons, e.g. PTFE, and silicones.

#Such dressings may, of course, be associated with suitable supports or reinforcement, with mats of, say, woven fibres which may have other desirable properties, or with surface or other treatment with materials having antiseptic or wound-healing properties. Blood clotting, for example, may be encouraged by incorporating clotting accelerators or inducers in or on the mat and/or on materials associated therewith in a wound dressing. Other components with which the mat may be associated include water-proof layers intended to protect the mat from undesirable effects of moisture, dirt etc.

#Preferably the wound dressing of the invention comprises a mat of flexible non-absorbent, porous, hydrophobic material, together with a non-absorbent backing layer. Such a backing layer is preferably made of hydrophobic material, but this is not essential. The dressing may also include means for applying pressure to the mat. Such means may be, for example, a stretchable elastic bandage.