Method for forming hollow fibers

A method for forming a thin walled microtube, comprising the steps of:

• forming a continuous elongated member from a water soluble polyvinyl alcohol, the elongated member having a central axis and a cylindrical outer surface, the outer surface being uninterrupted with all portions of the outer surface being substantially equidistant from the central axis;
• providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non-porous silicone;
• providing a coating die having an orifice and a coating reservoir;
• filling the coating reservoir with the coating material and continuously passing the elongated material through the orifice and the coating reservoir such that a substantially uniform layer of coating material is deposited on the outer surface of the elongated member, the layer forming an outer tube encasing the elongated member;
• providing a curing device;
• continuously passing the coated member through the curing device so as to cure the layer and form a substantially uniform and continuous tube of substantially non-porous silicone encasing the member;
• exposing the elongated member to water so as to at least partially dissolve the elongated member;
• and
• purging the at least partially dissolved member from the outer tube;
• whereby an elongated microtube of substantially non-porous silicone is formed.

A method of forming a portion of a gas exchange device having a plurality of thin walled microtubes, comprising the steps of:

• forming a plurality of coated members, each coated member being formed by the steps of:
• providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;
• providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially nonporous silicone;
• coating the outer surface of the elongated member with the coating material so as to form a substantially uniform and continuous layer of coating material on the outer surface;
• curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non-porous silicone on the outer surface;
• grouping the plurality of coated members into a bundle having a first end and a second end with a bundle body extending therebetween;
• potting the first end of the bundle with a potting material so as to form a first potted end interconnecting and sealing the coated members to each other;
• potting the second end of the bundle with a potting material so as to form a second potted end interconnecting and sealing the coated members to each other;
• cutting off a portion of each of the first and second potted ends such that the coated members are cut and the elongated members are at least partially exposed;
• at least partially dissolving the elongated members using water;
• and
• purging the at least partially dissolved members from the silicone layers.

A method for forming a thin walled microtube comprising the steps of:

• providing a continuous elongated member having a outer surface providing a coating material;
• coating the outer surface of the elongated member with the coating material so as to form a tubular coating;
• and
• removing the elongated member from the tubular coating such that the tubular coating forms a tube.

A method for forming a thin walled microtube, comprising the steps of:

• providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;
• providing a coating material, the coating material being curable such that the material becomes a solid;
• coating the outer surface of the elongated member with the coating material so as to form a substantially uniform and continuous layer of coating material on the outer surface;
• curing the layer of coating material so as to form a substantially uniform and continuous solid layer on the outer surface;
• at least partially dissolving the elongated member using water;
• and
• purging the at least partially dissolved member from the solid layer;
• whereby an elongated tube of solid material is formed.