Machine and method for producing porous membranes for medical use

Abstract

The machine ( 1 ) for producing porous membranes ( 2 ) for medical use comprises a plurality of reserves ( 25 a , 25 b , 25 c , 26 a , 26 b , 26 c ) of components ( 18 a , 18 b , 18 c , 19 a , 19 b , 19 c ) which constitute fluid substances, first and second guns ( 16, 17 ) supplied from the reserves ( 25 a , 25 b , 25 c , 26 a , 26 b , 26 c ) for spraying the fluid substances onto an element ( 37 ) on which the substances are deposited and build up, the element ( 37 ) and the guns ( 16, 17 ) being mobile relative to one another for substantially even distribution of the fluid substances designed to form the membrane ( 2 ).

What is claimed is:  
     
         1 . A machine for producing porous membranes ( 2 ) for medical use, starting with fluid substances consisting of mixtures ( 18 ,  19 ) of two or more components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ), the machine being of the type comprising: 
 reserves ( 25   a ,  25   b ,  25   c ,  26   a ,  26   b ,  26   c ) of said components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ),    spray means ( 36 ) for the fluid substances, connected to the reserves ( 25   a ,  25   b ,  25   c ,  26   a ,  26   b ,  26   c ),    a support ( 11 ) constituting an element ( 37 ) on which the fluid substances sprayed by the means ( 36 ) are deposited and build up, the element ( 37 ) and the spray means ( 36 ) being mobile relative to one another for substantially even distribution of the fluid substances designed to form the membrane ( 2 ), the machine further comprising, upstream of the spray means ( 36 ), mixer means ( 23 ,  24 ) for mixing together the components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ) which form the fluid substances, in the desired relative mixing quantities, these relative quantities providing the membrane ( 2 ) with given chemico-physical properties.    
     
     
         2 . The machine according to  claim 1 , further comprising a central control unit ( 35 ) designed to act upon the mixer means ( 23 ,  24 ) to alter the relative quantities for mixture of the components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ) of the fluid substances, according to the desired values set on the control unit ( 35 ).  
     
     
         3 . The machine according to  claim 1  or  2 , wherein the spray means ( 36 ) comprise at least a first nozzle ( 16   a ) and a second nozzle ( 17   a ) for spraying a first mixture ( 18 ) and a second mixture ( 19 ) at the support ( 11 ).  
     
     
         4 . The machine according to  claim 3 , further comprising at least one pump ( 21 ,  22 ) for supplying the fluid substances to the nozzles ( 16   a ,  17   a ).  
     
     
         5 . The machine according to  claim 3  or  4 , further comprising at least one source ( 27 ) of pressurized gas for activating the nozzles ( 16   a ,  17   a ).  
     
     
         6 . The machine according to any of the foregoing claims from  1  to  5 , wherein the support ( 11 ) comprises a cylindrical element ( 12 ,  12   c ) for producing tubular porous membranes ( 2 ), the cylindrical element ( 12 ,  12   c ) being designed to turn about an axis of rotation (A).  
     
     
         7 . The machine according to any of the foregoing claims from  1  to  5 , wherein the element ( 37 ) on which the fluid substances sprayed are deposited and build up is a stent ( 40 ) designed to be covered by the substances, the stent ( 40 ) being supported by the machine using a wire ( 41 ) passing inside it and made to rotate about an axis of rotation (A).  
     
     
         8 . The machine according to  claim 7 , further comprising a heating element ( 46 ) designed to heat a given zone ( 48 ) close to the stent ( 40 ).  
     
     
         9 . The machine according to  claim 6 , wherein the spray means ( 36 ) comprise a first carriage ( 13 ) supporting the nozzles ( 16   a ,  17   a ), the first carriage ( 13 ) and the cylindrical element ( 12 ,  12   c ) being mobile relative to one another in a direction (D) substantially parallel with the axis of rotation (A) of the cylindrical element ( 12 ,  12   c ).  
     
     
         10 . The machine according to  claim 9 , wherein the first carriage ( 13 ) is driven by drive means so that it slides in the direction (D) substantially parallel with the axis of rotation (A) of the cylindrical element ( 12 ,  12   c ).  
     
     
         11 . The machine according to any of the foregoing claims from  6  to  10 , further comprising a second carriage ( 29 ) supporting an extractor hood ( 31 ), the second carriage ( 29 ) sliding in the direction (D) substantially parallel with the axis of rotation (A) and the extractor hood ( 31 ) being positioned over the nozzles ( 16   a ,  17   a ).  
     
     
         12 . The machine according to any of the foregoing claims from  1  to  11 , wherein one of the mixtures ( 18 ,  19 ) comprises a polymer and the other mixture ( 18 ,  19 ) comprises a non-solvent for the polymer.  
     
     
         13 . The machine according to any of the foregoing claims from  1  to  12 , further comprising means ( 43 ) for the insertion of membrane ( 2 ) stiffening elements ( 45 ) during membrane ( 2 ) formation.  
     
     
         14 . The machine according to  claim 13 , wherein the stiffening elements ( 45 ) comprise a filament ( 42 ) designed for insertion in the membrane ( 2 ).  
     
     
         15 . The machine according to  claim 13 , wherein the stiffening elements ( 45 ) comprise a tubular mesh ( 44 ) designed for insertion in the membrane ( 2 ).  
     
     
         16 . A method for producing porous membranes ( 2 ) for medical use starting with fluid substances consisting of mixtures ( 18 ,  19 ) of two or more components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ), comprising the steps of: 
 supplying the fluid substances to spray means ( 36 ),    depositing and building up the fluid substances sprayed by the spray means ( 36 ) on a supporting means ( 11 ),    providing drive means for the spray means ( 36 ) and the supporting means ( 11 ) for substantially even distribution of the substances designed to form the membrane ( 2 ), wherein the supply step comprises the further step of changing the relative quantities for mixture of the components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ), according to the desired values, relative to the chemico-physical properties required of the membrane ( 2 ).    
     
     
         17 . The method according to  claim 16 , wherein the step of changing the relative quantities for mixture of the components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ) occurs substantially instantaneously according to a stepped function.  
     
     
         18 . The method according to  claim 16 , wherein the step of changing the relative quantities for mixture of the components ( 18   a ,  18   b ,  18   c ,  19   a ,  19   b ,  19   c ) occurs continuously according to a gradual function.  
     
     
         19 . The method according to any of the foregoing claims from  16  to  18 , wherein the chemico-physical properties comprise the level of porosity of the membrane ( 2 ).  
     
     
         20 . The method according to any of the foregoing claims from  16  to  19 , further comprising the step of inserting stiffening elements ( 45 ) in the membrane ( 2 ) during membrane ( 2 ) formation.  
     
     
         21 . The method according to any of the foregoing claims from  16  to  19 , further comprising the step of heating a zone ( 48 ) close to a support ( 11 ) forming an element ( 37 ) on which the fluid substances sprayed are deposited and build up.