Spray system and method of making phase separated polymer membrane structures

A method of fabricating a polymer membrane structure for use as an implantable medical prosthesis, the method comprising:

• providing a first fluid mixture;
• the first fluid mixture being a first polymer material dissolved in a first solvent;
• placing the first fluid mixture in communication with a first spray apparatus;
• providing a second fluid mixture;
• the second fluid mixture being one selected from the group of a second polymer material dissolved in the first solvent;
• the second polymer material dissolved in a second solvent;
• or the second solvent;
• placing the second fluid mixture in communication with a second spray apparatus;
• providing a mandrel having an outer surface and a longitudinal axis;
• applying the first fluid mixture to at least a portion of the outer surface of the mandrel by spraying said fluid mixture from the first spray apparatus;
• applying the second fluid mixture to at least a portion of the outer surface of the mandrel by spraying said fluid mixture from the second spray apparatus, such that the second fluid mixture contacts the first fluid mixture;
• allowing the second fluid mixture to interact with the first fluid mixture on the outer surface of the mandrel until a blended layer is formed;
• curing the blended layer;
• wherein during said curing, the blended layer undergoes phase separation to form a polymer membrane structure on the outer surface of the mandrel;
• and
• removing the polymer membrane structure from the outer surface of the mandrel;
• the polymer membrane having a defined thickness and length.