Abstract
A semipermeable arrangement for use in clinical, agricultural, industrial and/or environmental settings. The semipermeable arrangement has a structural arrangement formed from a material such as ePTFE that has an affinity to a lubricating fluid such as perfluorocarbon. The structural arrangement may be infused with a lubricating fluid such that the semipermeable arrangement resists fouling. The semipermeable arrangement is further arranged with barriers to prevent or limit the movement of the lubricating fluid through at least part of the structural arrangement. The semipermeable arrangement further has passageways that are free from the presence of, and/or cannot be infused with, lubricating fluid. The passageways permit the movement of fluids such as air, water and dissolved substances through the structural arrangement. The semipermeable arrangement is thereby both self-cleaning and porous and has a wide range of uses.
Claims
1.-39. (canceled)
40. A semipermeable arrangement for use in clinical, agricultural, industrial and/or environmental settings comprising a porous structural means formed from one or more layers, the structural means being formed at least partially from a material having an affinity to a lubricating fluid, the lubricating fluid being perfluorocarbon liquid, and being adapted such that it can be infused with a lubricating fluid, the semipermeable arrangement being arranged with means to prevent or limit the movement of the lubricating fluid through at least part of the structural means such that when the lubricating fluid is applied to the structural means, the movement of lubricating fluid through the structural means is restricted, and there are areas on the semipermeable arrangement that are completely or substantially free from the presence of lubricating fluid, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means further being arranged having one or more passageways to permit the movement of fluids such as air, water and dissolved substances through the structural means.
41. The semipermeable arrangement as claimed in claim 40, wherein the structural means comprises PTFE.
42. The semipermeable arrangement as claimed in claim 41, wherein the means to prevent or limit movement of the lubricating fluid through at least part of the structural means includes barriers located within the pores of the structural means.
43. The semipermeable arrangement as claimed in claim 42, wherein the barriers are provided by pressing and/or heat-melting a polymer such as PU or FEP into the pores of the structural means.
44. The semipermeable arrangement as claimed in claim 43, wherein the means to prevent or limit movement of the lubricating fluid through at least part of the structural means is retained within the structural means.
45. The semipermeable arrangement as claimed in claim 44, wherein the means to prevent or limit movement of the lubricating fluid through at least part of the structural means extends out from a main plane of the structural means in at least one direction.
46. The semipermeable arrangement as claimed in claim 45, wherein the means to prevent or limit movement of the lubricating fluid through at least part of the structural means is disposed between first and second layers of the structural means.
47. The semipermeable arrangement as claimed in claim 46, wherein the means to prevent or limit the movement of the lubricating fluid through at least part of the structural means comprises at least one substantially hollow member, the substantially hollow member having a first opening arranged at one side of the structural means and a second opening arranged at another side of the structural means.
48. The semipermeable arrangement as claimed in claim 47, wherein the substantially hollow member is formed at least partially from one or more polymeric substances, for example polyurethane (PU), fluorinated ethylene propylene (FEP) and/or PTFE.
49. The semipermeable arrangement as claimed in claim 48, wherein the substantially hollow member is a tube.
50. The semipermeable arrangement as claimed in claim 49, wherein the structural means comprises a plurality of fibrils and wherein the spacing between the fibrils is equal to or less than 1.0 μm.
51. The semipermeable arrangement as claimed in claim 47, wherein the means to prevent or limit movement of the lubricating fluid through at least part of the structural means comprises at least one porous member.
52. The semipermeable arrangement as claimed in claim 51, wherein the porous member is spherical, roughly spherical, or a flattened sphere, spherical cap, hemisphere, ovoid, cube or cuboid in shape.
53. The semipermeable arrangement as claimed in claim 40, comprising lubricating fluid.
54. The semipermeable arrangement as claimed in claim 53, comprising perfluorocarbon liquid.
55. The semipermeable arrangement as claimed in claim 40, wherein the passageways of the means to prevent or limit movement of the lubricating fluid through at least part of the structural means comprises additives.
56. The semipermeable arrangement as claimed in claim 55, wherein the additives comprise soluble antimicrobial substances or medicaments, and/or a water and/or air-purifying substance.
Description
[0497] The invention will now be described with reference to the accompanying drawings which shows by way of example only twelve embodiments of an apparatus in accordance with the invention.
[0498] FIG. 1 is a perspective view of a first embodiment of a semipermeable arrangement according to the invention wherein no lubricant is present. The semipermeable arrangement is shown in expanded view with the lower filter web located away from the structural frame with arrows indicating the assembly direction.
[0499] FIG. 2 is a perspective view of the structural frame of the semipermeable arrangement of FIG. 1.
[0500] FIG. 3 is a front elevation view of a first embodiment of a porous member of the semipermeable arrangement of FIG. 1.
[0501] FIG. 4 is a perspective view of a second embodiment of a porous member.
[0502] FIG. 5 is a perspective view of a third embodiment of a porous member.
[0503] FIG. 6 is a perspective view of the structural frame and the plurality of porous members of the semipermeable arrangement of FIG. 1.
[0504] FIG. 7 is a cross-sectional view of a second embodiment of a semipermeable arrangement according to the invention wherein the self-cleaning web is not extended over the surface of the porous member and wherein the lubricant is present on one side of the semipermeable arrangement, further illustrating crystallized antimicrobial particles within the porous member.
[0505] FIG. 8 is a cross-sectional view of a third embodiment of a semipermeable arrangement according to the invention wherein the porous member is a spherical cap.
[0506] FIG. 9 is a cross-sectional view of a fourth embodiment of a semipermeable arrangement according to the invention wherein the porous member is disc-shaped.
[0507] FIG. 10 is a cross-section view of a fifth embodiment of a semipermeable arrangement according to the invention wherein the self-cleaning web is extended over the surface of the porous member and wherein the lubricant is present on one side of the semipermeable arrangement.
[0508] FIG. 11 is a cross-sectional view of a sixth embodiment of a semipermeable arrangement according to the invention wherein the self-cleaning web is not extended over the surface of the porous member and wherein the lubricant is present on both sides of the semipermeable arrangement and throughout the structural frame.
[0509] FIG. 12 is a cross-sectional view of a seventh embodiment of a semipermeable arrangement according to the invention wherein the porous member is a spherical cap.
[0510] FIG. 13 is a cross-sectional view of a eighth embodiment of a semipermeable arrangement according to the invention wherein the porous member is disc-shaped.
[0511] FIG. 14 is a cross-sectional view of a ninth embodiment of a semipermeable arrangement according to the invention wherein the self-cleaning web is extended over the surface of the porous member and wherein the lubricant is present on both sides of the semipermeable arrangement and throughout the structural frame.
[0512] FIG. 15 is a cross-sectional view of a tenth embodiment of a semipermeable arrangement according to the invention wherein the semipermeable arrangement is bent, showing redistribution of the lubricant through the structural frame.
[0513] FIG. 16 is a perspective view of a semipermeable arrangement having disc-shaped porous members.
[0514] FIG. 17 is a plan view of a filter web according to the invention as it would appear when used in an embodiment of the invention comprising spherical or hemispherical porous members.
[0515] FIG. 18 is a perspective view of the filter web in FIG. 17.
[0516] FIG. 19 is a side elevation view of the filter web in FIG. 17.
[0517] FIG. 20 is a plan view of a filter web according to the invention as it would appear when used in an embodiment of the invention comprising disc-shaped porous members.
[0518] FIG. 21 is a perspective view of the filter web in FIG. 20.
[0519] FIG. 22 is a side elevation view of the filter web in FIG. 20.
[0520] FIG. 23 is a plan view of the filter web and the self-cleaning web arranged on top of the filter web according to the invention and as present in the fifth and ninth embodiments of the semipermeable arrangement shown in FIGS. 10 and 14 respectively. The self-cleaning web is illustrated as dashed lines.
[0521] FIG. 24 is a perspective view of the filter web and self-cleaning web of FIG. 23.
[0522] FIG. 25 is a side elevation view of the filter web and self-cleaning web of FIG. 23.
[0523] FIG. 26 is a plan view of a self-cleaning web according to the invention.
[0524] FIG. 27 is a plan view of the self-cleaning web shown in FIG. 26 overlaying a filter web according to the invention and as present in the second and sixth embodiments of the semipermeable arrangement shown in FIGS. 7 and 11 respectively.
[0525] FIG. 28 is a perspective view of the self-cleaning web and filter web of FIG. 27.
[0526] FIG. 29 is a side-elevation view of the self-cleaning web and filter web of FIG. 27.
[0527] FIG. 30 is a side elevation, cross sectional view of a semipermeable arrangement according to an eleventh embodiment of the invention.
[0528] FIG. 31 is a side elevation, cross sectional view of a twelfth embodiment of a semipermeable arrangement according to the invention.
[0529] FIG. 32 is a perspective view the eleventh embodiment as shown in FIG. 30.
[0530] FIG. 33 is a rear perspective view of an envelope formed from a semipermeable arrangement for use with a MAVIED according to the invention, porous members have not been illustrated for clarity purposes.
[0531] FIG. 34 is a plan view of the envelope in FIG. 33.
[0532] FIG. 35 is a side elevation view of the envelope in FIG. 33.
[0533] FIG. 36 is a rear perspective view of the envelope in FIG. 33 in use containing a pulse generator, not sealed. The envelope is shown in low opacity for illustration purposes.
[0534] FIG. 37 is a plan view of the envelope as shown in FIG. 33.
[0535] FIG. 38 is a rear perspective view of the envelope in FIG. 33 after it has been sealed and a suture applied to the exit portion.
[0536] FIG. 39 is a cross section of sealing members according to the invention.
[0537] In the drawings there is a shown a semipermeable arrangement according to the invention. FIGS. 1 to 3 show a first embodiment of a semipermeable arrangement and components thereof indicated generally by reference numeral 1. The semipermeable arrangement has a structural frame 2 and a plurality of porous members 3 that are arranged within the structural frame 2. The structural frame 2 is a single layered frame formed from a plurality of structural rods 4. The structural rods 4 are arranged as a first group of structural rods and a second group of structure rods 6, wherein each group of structural rods 5, 6 have a plurality of structural rods arranged in a spaced apart, parallel relationship. The spacing between the structural rods 4 in the first group of structural rods 5 and the second group of structural rods 6 is 3 mm. The first group of structural rods 5 is arranged perpendicular to the second group of structural rods 6 and the they are woven together to form a mesh network 8 with square-shaped openings 9 having an area of around 9 mm.sup.2 each (see FIG. 2). The structural rods 2 have a circular cross-section and a diameter of around 1 mm and are formed from ePTFE.
[0538] FIG. 3 shows an expanded view of a porous member 3. The porous members 3 are roughly spherical and have a diameter of around 3 mm enabling them to be located in the openings 9 within the mesh network 8. When they are located in openings 9 of the mesh network 8 the structural rods 4 press against, hold and retain the porous members 3 in the structural frame. The porous members 3 are formed from polypropylene and are manufactured by sintering together small, loosely compacted particles 10 of polypropylene. This provides gaps between the particles which act as pores to permit passage of water and dissolved substances into and through the porous members 3. The pore size of the porous members 3 is varied but they are less than or equal to 50 μm. The porous members 3 are arranged in the structural frame 3 and extend out of the plane of the structural frame by 1 mm each side of the structural frame.
[0539] FIG. 4 shows an alternative porous member indicated by reference numeral 103. The porous member 103 is a truncated sphere or spherical cap. The porous member 103 can be formed, for example, in the same way as the spherical porous member 3 and then removing a portion. The porous member 103 is arranged in a structural frame with the plane of the flat surface of the porous member 103 being parallel with the plane of the frame, and the rounded surface extending beyond the plane of the structural frame at the opposing surface of the frame. The flat, circular surface has a radius of 1.4 mm.
[0540] FIG. 5 shows a further alternative porous member indicated by reference numeral 203. The porous member 203 is disc-shaped and can be formed, for example, by producing a spherical porous member as in FIG. 3 and removing two portions, or by producing a porous sheet and punching out round porous members having a radius of 1.5 mm and a thickness of 1 mm. When arranged in a structural frame, the plane of the flat surfaces are parallel with the plane of the structural frame.
[0541] As shown in FIG. 6, the plurality of porous members 3 are located interspersed within the structural frame 2 in rows within the structural frame 2 such that every other opening in the row of the mesh network 8 of the structural frame 2 contains a porous member 3 and that a row above or below this row contains a similar pattern but is offset relative to the row such that the plurality of porous members 3 are arranged in a diagonal relationship within the mesh network 8 but not laterally or longitudinally adjacent to one another.
[0542] The semipermeable arrangement 1 further has a filter arrangement 11 having two filter webs 12a, 12b with spacings (see FIG. 1). The filter webs 12a, 12b are formed by electrospinning polyurethane to form filter web fibres that are irregularly arranged, overlapping to and have spacings therebetween. The spacings are equal to or less than equal to or less than 0.2 μm, thereby filtering out any matter with a diameter larger than 0.2 μm. The filter webs 12a, 12b are arranged on the surface of the structural frame 2 and the porous members 3 and are stretched tight over them. The filter arrangement 11 is arranged on both sides of the structural frame 2 creating a bilayer effect. FIG. 1 shows an expanded view of the semipermeable arrangement 1 wherein the lower filter web 12b is located away from the structural frame 2 for illustration purposes.
[0543] In use, the semipermeable arrangement 1 can be used as a filter membrane in clinical, agricultural, industrial or environmental settings. For example, the semipermeable arrangement 1 can be positioned over a vessel and a fluid to be filtered can be added to one side of the semipermeable arrangement 1. The pores of the filter webs 12a, 12b are sized less than 1 μm so any matter greater than this will be retained on one side of the semipermeable arrangement 1 as the fluid filters through the semipermeable arrangement 1. The semipermeable arrangement 1 can be easily removed and cleaned and the porous members 3 provide a roughened texture to the surface of the semipermeable arrangement 1, preventing matter from settling across the surface of the semipermeable arrangement 1.
[0544] In the second embodiment of the invention illustrated in FIG. 7 there is shown a semipermeable arrangement indicated generally by reference numeral 201 having a structural frame 2 with a porous member 3 formed from particles 10. The semipermeable arrangement 201 further has soluble particles 70 of an antimicrobial located within the porous member 3. The semipermeable arrangement 201 further has two filter webs 12a, 12b and two self-cleaning webs 14a, 14b arranged at each side of the structural frame 2 to create a bilayer effect. The self-cleaning webs 14a, 14b are formed from electrospinning PTFE to form self-cleaning web fibres that are irregularly arranged, overlapping and have spacings therebetween. The self-cleaning webs 14a, 14b are adapted, through control of the spacings between the self-cleaning web fibres, to receive and uptake a lubricant via capillary action. The semipermeable arrangement 201 further has perfluorocarbon liquid 20 at one surface of the semipermeable arrangement 201. The perfluorocarbon liquid 20 is dispersed through the self-cleaning web 14a. The self-cleaning web 14a is formed from PTFE and so the perfluorocarbon liquid 20 has a natural affinity for the self-cleaning web 14a. In addition, the spacings of the self-cleaning web 14a are sized to allow capillary uptake of the perfluorocarbon liquid 20, dispersing it over the surface of the semipermeable arrangement 201. The filter web 12a, however, does not contain any fluorine atoms and the ionophilicity of the perfluorocarbon liquid prevents it from dispersing through the filter web 12a. The self-cleaning web 14a contains gaps at the location of the porous member 3. Therefore, none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. Water and dissolved substances can enter and pass through the filter webs 12a, 12b and the porous member 3 even when the perfluorocarbon liquid 20 is present within the self-cleaning web 14a.
[0545] In use, the semipermeable arrangement 201 can be used as a filter membrane in clinical, agricultural, industrial or environmental settings. For example, the semipermeable arrangement 201 can be positioned over a vessel with self-cleaning web 14a containing the perfluorocarbon liquid 20 facing out of the vessel. A fluid to be filtered can be added to this side of the semipermeable arrangement 201. The filter web 12a acts as a barrier to prevent matter sized less than 1 μm entering the semipermeable arrangement 201 and the omniphobicity of the perfluorocarbon liquid 20 repels the majority of substances from the surface of semipermeable arrangement 201; for example, hydrophilic and hydrophobic substances that contribute to fouling.
[0546] In the third embodiment of the invention illustrated in FIG. 8 there is shown a semipermeable arrangement indicated generally by reference numeral 301. The third embodiment 301 is similar to the second embodiment 201 but in that the porous member is a spherical cap porous member 103. In use, the surface of the semipermeable arrangement 301 with the flat surface of the porous members 103 can be orientated to abut a flat surface, such as that of a MAVIED, with the rounded portion of the porous members 103 arranged projecting out from the flat surface. The rounded portions help prevent fouling whereas the flat portion allows the semipermeable arrangement 301 to sit neat against the surface and can help anchor the semipermeable arrangement 301 to a surface. In addition, the porous member 103 has a larger internal void volume than the disc-shaped porous member 203. However, it may not be as technically straightforward as the disc-shaped porous member 203 to manufacture, which can simply be punched out of a porous sheet.
[0547] In the fourth embodiment of the invention illustrated in FIG. 9 there is shown a semipermeable arrangement indicated generally by reference number 401. The fourth embodiment 401 is similar to the second embodiment 201 but in that the porous member is a disc-shaped porous member 203. In use, both planar surfaces of the semipermeable arrangement 401 are identical with the exception that one surface has a layer of perfluorocarbon 20. Both planar surfaces of the porous member 203 are almost flush and just slightly outset from the planar surfaces of the structural frame 2. The thickness of the semipermeable arrangement 401 is close to being equal to the thickness of the structural frame 2.
[0548] In the fifth embodiment of the invention illustrated in FIG. 10 there is shown a semipermeable arrangement indicated generally by reference numeral 501 having a structural frame 2 with a porous member 3 formed from particles 10. The semipermeable arrangement 501 further has soluble particles 70 of an antimicrobial located within the porous member 3. The semipermeable arrangement 501 further has two filter webs 12a, 12b and two self-cleaning webs 514a, 514b arranged at each side of the structural frame 2 to create a bilayer effect. The semipermeable arrangement 501 further has a perfluorocarbon liquid 20 at one surface of the semipermeable arrangement 501. The perfluorocarbon liquid 20 is dispersed through the self-cleaning web 514a. In this embodiment, the self-cleaning webs 514a, 514b extend over the porous member 3. As a result of stretching, the spacings between the self-cleaning webs 514a, 514b are greater around the porous member 3 than the spacings between the self-cleaning webs 14a, 14b located at an opening of the structural frame 20. The increase in spacings of the self-cleaning webs 14a, 14b at the porous member 3 prevents dispersion of the perfluorocarbon liquid 20 through the self-cleaning webs 514a, 514b at the porous member 3 by capillary action. Therefore, none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. Water and dissolved substances can enter and pass through the filter webs 12a, 12b, the self-cleaning webs 514a, 514b and the porous member 3 even when the perfluorocarbon liquid is present within the self-cleaning web 514a.
[0549] In use, the semipermeable arrangement 501 can be used as a filter membrane in clinical, agricultural, industrial or environmental settings. For example, the semipermeable arrangement 501 can be positioned over a vessel with self-cleaning web 14a containing the perfluorocarbon liquid 20 facing out of the vessel. A fluid to be filtered can be added to this side of the semipermeable arrangement 501. The filter web 12a and the self-cleaning web 514a acts as a physical barrier to prevent matter sized less than 1 μm entering the semipermeable arrangement 501 and the omniphobicity of the perfluorocarbon liquid 20 repels the majority of substances from the surface of semipermeable arrangement 501.
[0550] In the sixth embodiment of the invention illustrated in FIG. 11 there is shown a semipermeable arrangement indicated generally by reference numeral 601. The structural frame 2, filter webs 12a, 12b, self-cleaning webs 14a, 14b and porous member 3 are the same as that of the second embodiment 201 (FIG. 7). The sixth embodiment 601 differs in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 601 and throughout both self-cleaning webs 14a, 14b. The self-cleaning webs 14a, 14b contains gaps at the location of the porous member 3 so none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. The structural frame 2 acts as a reservoir to replenish perfluorocarbon liquid 20 at the surfaces of the semipermeable arrangement 601 when the perfluorocarbon liquid 20 is depleted.
[0551] In use, the semipermeable arrangement 601 can be used as a filter membrane in clinical, agricultural, industrial or environmental settings. For example, the semipermeable arrangement 601 can be positioned over a vessel with either the self-cleaning web 14a or self-cleaning web 14b facing out of the vessel. A fluid to be filtered can be added the surface of the semipermeable arrangement 601. The filter webs 12a or 12b act as a physical barrier to prevent matter sized less than 1 μm entering the semipermeable arrangement 301 and the omniphobicity of the perfluorocarbon liquid 20 repels all substances lacking an affinity to perfluorocarbon from the surfaces of the semipermeable arrangement 601.
[0552] In the seventh embodiment of the invention illustrated in FIG. 12 there is shown a semipermeable arrangement indicated generally by reference numeral 701. The seventh embodiment 701 is similar to the third embodiment 301 (FIG. 8) but in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 701 and throughout both self-cleaning webs 14a, 14b.
[0553] In the eighth embodiment of the invention illustrated in FIG. 13 there is shown a semipermeable arrangement indicated generally by reference number 801. The eighth embodiment 801 is similar to the fourth embodiment 401 (FIG. 9) but in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 801 and throughout both self-cleaning webs 14a, 14b. In use, the semipermeable arrangement 801 has self-cleaning properties on both planar surfaces and as such it may be orientated in either way, where self-cleaning is desired on both surfaces. The eight embodiment is further illustrated in FIG. 16.
[0554] In the ninth embodiment shown in FIG. 14 there is shown a semipermeable arrangement indicated generally by reference numeral 901. The semipermeable arrangement 901 is similar to that of the fifth embodiment 501 shown in FIG. 10, but differs in that the perfluorocabon liquid 20 extends throughout structural frame 2 and is present on both sides of the semipermeable arrangement 801 and throughout both self-cleaning webs 14a, 14b. In use, the semipermeable arrangement 901 can be used as a filter membrane in clinical, agricultural, industrial or environmental settings. For example, the semipermeable arrangement 901 can be positioned over a vessel with either the self-cleaning web 14a or self-cleaning web 14b facing out of the vessel. A fluid to be filtered can be added the surface of the semipermeable arrangement 901. The filter webs 12a or 12b and the self-cleaning webs 14a or 14b act as a physical barrier to prevent matter sized less than 1 μm entering the semipermeable arrangement 901 and the omniphobicity of the perfluorocarbon liquid 20 repels the majority of substances from the surface of semipermeable arrangement 901.
[0555] In the tenth embodiment of the invention illustrated in FIG. 15, there is shown a semipermeable arrangement 1001 with a structural frame 2 and perfluorocarbon liquid 20. The tenth embodiment is similar to the ninth embodiment (FIG. 14) but differs in that there are no soluble antimicrobial particles 70. As shown, when the structural frame 2 is bent the perfluorocarbon liquid is redistributed. The outer perimeter of the curve of the semipermeable arrangement 1001 is stretched in the direction of the arrow 30 whereas the inner perimeter of the curve contracts in the direction of the arrows 31. The contraction at the inner perimeter of the curve reduces the volume at this portion of the structural frame and forces redistribution of the perfluorocarbon liquid 20, in the direction of the arrows 32, to the outer perimeter of the curve, thus ensuring that the outer perimeter of the curve remains lubricated by the perfluorocarbon 20 even when the structural frame 20 is bent.
[0556] FIGS. 17 to 19 illustrate a filter web 12 according to the invention as it would appear in situ over a spherical or hemispherical porous member 3 for illustration purposes. The filter web 12 comprises a plurality of filter web fibres 35 formed from electrospun polyurethane with gaps defining pores 36. The pores are no greater than 1 μm in size and therefore prevent passage of matter with dimensions greater than 1 μm from passing through the filter web 12. FIGS. 20 to 22 illustrate the filter web 12 according to the invention as it would appear in situ over a disc-shaped porous member 203 for illustration purposes.
[0557] FIGS. 23 to 25 illustrate a filter web 12 and a self-cleaning web 514 according to the invention as it would appear in situ over a porous member 3 for illustration purposes. In this arrangement, the self-cleaning web 514 extends over the filter web 12 in accordance with the first, fifth, ninth and tenth embodiments of the invention. The self-cleaning web 514 is formed from self-cleaning web fibres 38, which are formed from electrospun PTFE having pores 39. The pore size of the self-cleaning 514 is greater around the porous member and this prohibits uptake of a lubricant via capillary action, leaving the surface of the porous member free for passage of water and dissolved substances. FIGS. 26 to 29 illustrate a filter web 12 and a self-cleaning web 14 according to the invention as it would appear in situ over a porous member 3 for illustration purposes. In this arrangement, the self-cleaning web 14 has gaps sized to accommodate a porous member in accordance with the second, third, fourth, sixth, seventh and eighth embodiments of the invention.
[0558] FIGS. 30 and 32 illustrate an eleventh embodiment of the invention indicated by reference numeral 1101, and FIG. 32 shows a twelfth embodiment of the invention indicated by reference numeral 1201. Each of these semipermeable arrangements 1101, 1201 have a structural arrangement 1102, 1202 formed from a first layer 1102a, 1202a and a second layer 1102b, 1202b of ePTFE, pressed together. As illustrated in FIG. 32, the longitudinal direction of the fibrils—represented by solid black lines—in the first layer 1102a is orthogonal to that of the second layer 1102b and this provides a structural arrangement 1102 of uniform tensile strength. The spacings between fibrils of the ePTFE is equal to or less than 0.5 μm such that pathogenic bacteria are excluded from moving through the first or second layers 1102a, 1202a,1102b, 1202b. The semipermeable arrangements 1101, 1201 have a plurality of tubes 1103, 1203 that extend between the first layer 1102a, 1202a and the second layer 1102b, 1202b. The tubes 1103, 1203 provide a barrier to movement of lubricating fluid through the structural arrangement 1102, 1202 whilst permitting the movement of fluids such as air, water and dissolved substances across the structural arrangement 1102, 1202 via the interior of the tubes 1103, 1203.
[0559] Each tube 1103, 1203 is formed from an interior cylinder of PTFE 1180, 1280 and a coating of FEP 1181, 1281. In the eleventh embodiment, the tubes 1103 each have a flange 1182 that extends around the base of the tube 1103 and is sized to fit between the first layer 1102a and second layer 1102b of the structural arrangement 1102. During manufacture, the FEP coating 1181, 1281 extends into spacings between fibrils of the structural arrangement 1102 and this provides a barrier to movement of lubricating fluid through the structural arrangement 1102. The FEP coating can be extending into the spacings by pressing the first and second layers 1102a, 1102b into the FEP or by applying heat to melt the FEP into the spacings. Alternative materials to FEP may be used provided they can fill the gaps between fibrils of PTFE and create a barrier to lubricating fluid. The tubes 1103 of the eleventh embodiment are sized having a diameter of 3 mm and a height of 1 mm and are arranged to extend out of main plane of the first layer 1102a only. The second layer 1102b is thereby planar without any projections extending form the main plane of the second layer 1102b. In contrast the twelfth embodiment 1201 is arranged with tubes having a diameter of 3 mm and a height of 2 mm, wherein approximately 1 mm of the height of each tube extends out at either side of the structural arrangement 1202, creating a symmetrical semipermeable arrangement 1201.
[0560] The structural arrangement 1102, 1202 extends over the openings of the tubes 1103, 1203. However, the barrier provided by the coating 1181, 1281 of the tube 1103, 1203 prevents any lubricating fluid from tracking up the side of the tube 1103, 1203 and over the openings of the tube 1103, 1203. The openings thereby remain clear of any lubricating fluid when lubricating fluid is applied to the semipermeable arrangement 1101, 1201 and fluids such as water or air can pass freely through the semipermeable arrangement 1101, 1201. The portion of the structural means that extends over the tubes 1103, 1203 can be formed form chemically modified PTFE (e.g. with the addition of hydroxyl groups), heat-treated PTFE, or formed from an alternative polymeric, hydrophilic substance such as hydrophilic PU to ensure hydrophilicity and movement of water therethrough. The structural arrangement 1102, 1202 is further infused with perfluorocarbon liquid 20 to render the structural arrangement 1102, 1202 self-cleaning. The tubes 1103, 1203 contain soluble particles 70 of an antimicrobial substance but it should be noted that any desirable substance could be confined within the tubes 1103, 1203. For example, a medicament could be inserted were the semipermeable arrangement 1101, 1201 is to be used as a wound dressing or other clinical use, or activated charcoal could be inserted if the semipermeable arrangement 1101, 1201 is to be used as an air or water filter. The semipermeable arrangements 1101, 1201 can be used in a similar manner as described above.
[0561] Also provided by the invention is a method of manufacturing a semipermeable arrangement 1. Manufacturing the first embodiment involves forming a structural frame 2 from structural rods 4. The structural rods 4 are first formed by stretching PTFE into elongate rods. The structural rods 4 are then weaved together to form a single-layered mesh network 8 with a first group of structural rods 5 being spaced apart and parallel to one another and a second group of structural rods 6 being spaced apart and parallel to one another, the first group of structural rods 5 being arranged perpendicularly to the second group of structural rods 6. The mesh network 8 has openings 9 for receiving a porous member 3.
[0562] The porous members 3 are formed by sintering together loosely compacted particles of polypropylene to form roughly spherical porous members 3 with a diameter of 3 mm and pores sized less than or equal to 50 μm. The porous members 3 are then inserted into the openings 9 of the mesh network 8 as shown in FIG. 6. The porous members 3 are arranged by pressing them into the openings 8 such that they are retained by the structural frame 2. They are inserted to the extent that a portion of each porous member 8 extends above and below the plane of the structural frame 2 by around 0.5 to 1 mm. The method involves arranged the porous members 3 in rows leaving every other opening 9 empty. The adjacent rows have the same pattern but offset in relation to the rows either side such that the porous members 8 are in a diagonal relationship but are not longitudinally or laterally adjacent.
[0563] Next the method involves manufacturing a filter web 12 by electrospinning polyurethane to produce irregularly arranged filter web fibres 35 with gaps 36 therebetween defining pores as shown in FIGS. 17 to 22. The manufacturing process is controlled to produce pore sizes equal to or less than 1 μm after the filter web 12 is applied to the structural frame 2. The filter web 12 is then placed over the structural frame 2 with the porous members 3. An additional filter web 12 is then made in the same way and placed over the structural frame 2 and the porous members on the mutually opposing side of the semipermeable arrangement 1 creating a bilayer effect.
[0564] The embodiments having a self-cleaning web 514 that extends over the porous members 3, 103, 203, namely the fifth, ninth and tenth embodiments, are produced by manufacturing a self-cleaning web 514 by electrospinning PTFE to produce irregularly arranged self-cleaning web fibres 38 with gaps 39 therebetween defining pores as shown in FIGS. 23 to 25. The manufacturing process is controlled to ensure that the spacing between the self-cleaning web fibres 38 is suitable to permit capillary uptake of lubricant. The self-cleaning web 514 is then placed over the filter web 12 and the structural frame 2 with the porous members 3. As the self-cleaning web 514 is stretched over the porous members 3 the spacings between the self-cleaning web fibres 38 increases, reducing or eliminating the possibility of lubricant being dispersed through the self-cleaning web 514 at the porous members 3 by capillary action. An additional self-cleaning web 514 is then made in the same way and placed over the filter web 514, the structural frame 2 and the porous members 3 on the mutually opposing side of the semipermeable arrangement 1 creating a bilayer effect.
[0565] Manufacturing the second embodiment as illustrated in FIG. 7 involves the same steps as manufacturing the first embodiment with the additional steps of cutting holes in the self-cleaning web 14a, 14b corresponding to the location of the porous members 3 in the structural frame 2. When the self-cleaning web 14a, 14b is added to the structural frame 2 it does not cover the porous members 3. A further step involves exposing the semipermeable arrangement 201 to a solution of antimicrobial substance and allowing to dry to the form the soluble particles 70. Yet a further step involves adding perfluorocarbon liquid 20 to the self-cleaning web 14a.
[0566] Manufacturing the third embodiment as illustrated in FIG. 8 involves the same steps as manufacturing the second embodiment but replacing the spherical porous member 3 with a spherical cap porous member 103. Manufacturing the fourth embodiment (FIG. 9) is the same as manufacturing the second and third embodiments (FIGS. 7 and 8 respectively) but using a disc-shaped porous member 203. Manufacturing the fifth embodiment as illustrated in FIG. 10 is discussed above with the additional step of adding perfluorocarbon liquid 20 to the self-cleaning web 514a on one surface of the semipermeable arrangement 501. Manufacturing the sixth embodiment in FIG. 11 involves the same steps as manufacturing the second embodiment (FIG. 7) but with saturating the arrangement 601 with perfluorocarbon liquid such that it is present throughout the structural frame 2 and the self-cleaning webs 14a, 14b and an both surfaces of the semipermeable arrangement 601. Manufacturing the seventh embodiment as illustrated in FIG. 12 involves the same steps as manufacturing the sixth embodiment but replacing the spherical porous member 3 with a spherical cap porous member 103. Manufacturing the eighth embodiment (FIG. 13) is the same as manufacturing the sixth and seventh embodiments (FIGS. 11 and 12 respectively) but using a disc-shaped porous member 203. Manufacturing the ninth embodiment as illustrated in FIG. 14 involves the same steps as manufacturing the fifth embodiment (FIG. 10) however the perfluorocarbon liquid 20 is added throughout the structural frame 2 and on both self-cleaning webs 514a, 514b. Manufacturing the tenth embodiment as illustrated in FIG. 15 involves the same steps as manufacturing the ninth embodiment (FIG. 14) however the soluble antimicrobial particles 70 are not included.
[0567] The eleventh and twelfth embodiments are manufactured in a similar fashion. Initially, the tubes 1103, 1203 are prepared by forming an elongate tube of PTFE and heat shrinking an outer coating of FEP onto the PTFE tube. The tube has a diameter of 3 mm and is cut into a plurality of tubes 1103, 1203 of desired heights. Then the second layer 1102b, 1202b of ePTFE is set out and the tubes 1103, 1203 are arranged at desired locations on what will form part of the interior of the structural arrangement 1102, 1202. An ePTFE having a maximum pore size of 0.5 μm is selected as this is impermeable by pathogenic bacteria such as Staphylococcus aureus. Next, a soluble antimicrobial substance 70 is disposed in the tubes 1103, 1203. Then, the first layer 1102a, 1102b of ePTFE is applied over the second layer 1102b, 1202b and the tubes 1103, 1203 and is pressed onto the second layer 1102b, 1202b and the tubes 1103, 1203. The FEP of the tubes 1103, 1203 spreads into the pores of the structural arrangement (i.e. the gaps between fibrils of the ePTFE) and provides a barrier to movement of lubricating fluid. Finally, the structural arrangement 1102, 1202 is impregnated with perfluorocarbon liquid 20, rendering the structural arrangement 1102, 1202 self-cleaning.
[0568] An exemplary use of the semipermeable arrangement is illustrated in FIGS. 33 to 39 wherein two semipermeable arrangements of the eighth embodiment type 801a, 801b are arranged to form an envelope 50 formed for containing a MAVIED 52 and to be inserted into a recipient. The semipermeable arrangements 801a, 801b have a structural frame (not shown) and porous members (not shown) located within the structural frame. The envelope 50 is formed as a similar shape to a pulse generator, having a semicircular portion 53 and a rectangular portion 654 and a cavity 55 for receiving a pulse generator 56 as shown in FIGS. 36 to 38. The two semipermeable arrangements 801a, 801b are adjoined about their edges forming a side portion 57. The envelope 50 further has a seal arrangement 58 for sealing the envelope 50. The seal arrangement 58 extends along the rear edge portion of each of the semipermeable arrangements 51a, 51b and involves two mutually opposing seal members 59a, 59b—one situated on each semipermeable arrangement 801a, 801b—formed from ePTFE that can be pressed together to seal the envelope 50. One seal member 59a is a female sealing member with a groove extending along its length sized to receive male sealing member 59b (FIG. 39). The seal members 59a, 59b can be pressed together or pulled apart as required to seal and unseal the envelope 50 respectively.
[0569] The seal arrangement 58 further involves a reinforcement member 60 situated at one end of the two seal members 59a, 59b and holding them together. The reinforcement member 60 provides additional strength to the structure of the envelope 50 and prevents the two semipermeable arrangements 801a, 801b from easily being torn apart. The envelope 50 further has an exit point 61 located at the side portion 57 at the end of the two sealing members 59a, 59b to permit passage of a lead 62 from inside the cavity 55 to the outside of the envelope 50. The envelope 50 further has an extended portion 63 that extends out from the cavity 55 and is adapted for extending along a length of a lead 62.
[0570] In use, as shown in FIGS. 36 to 38, a pulse generator 56 is inserted into the cavity 55 of the envelope 50 and the redundant lead length of the pulse generator 56 is also folded into the cavity 55 on the top or the bottom of the pulse generator 56. The lead 62 is arranged extending along the extended portion 63 of the envelope 50 and out the exit point 61. The envelope 50 is sealed by operating the seal arrangement 58. Specifically, the two seal members 59a, 59b are pressed to close the seal arrangement 58. Finally, a suture 65 is tied around the extended portion 63 thereby sealing the envelope. The envelope 50 can then be inserted into a recipient. The semipermeability of the semipermeable arrangements 801a, 801b allows water and dissolved substances to enter the envelope but prevents entry of bacteria. The pulse generator can therefore provide electrical current across the envelope. The self-cleaning arrangement of the semipermeable arrangements 801a, 801b prevents adhesion of bacteria or formation of tissue on the surface of the envelope 50.
[0571] In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of the parameter, lying between the more preferred and the less preferred of the alternatives, is itself preferred to the less preferred value and also to each value lying between the less preferred value and the intermediate value.
[0572] The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof as defined in the appended claims.
