Coaxial double filter with integrated filter support

A method of producing a filter of a type having:

• an inner and outer filter portion each having
• a tubular filter element having upper and lower ends separated along a tube axis;
• thermoplastic upper and lower supports in-molded to respective upper and lower ends of the tubular filter element supporting the upper and lower ends against deformation inward toward the axis;
• and
• at least one thermoplastic pillar extending between the thermoplastic upper and lower supports and in-molded to the tubular filter medium element supporting the upper and lower ends in separation along the axis;
• wherein the thermoplastic lower support for the inner and outer filter portions join to provide a continuous fluid-blocking wall extending between the lower end of the tubular filter element of the inner filter portion and the lower end of the tubular filter element of the outer filter portion;
• the method comprising the steps of:
• (a) preparing the tubular filter elements for the inner and outer filter portions by rolling respective planar sheets of filter material into tubes;
• (b) placing the tubes in a thermoplastic injection mold having cavities to form the thermoplastic upper and lower supports and thermoplastic pillars;
• and
• (c) injecting molten thermoplastic into the cavities to produce the thermoplastic upper and lower supports and thermoplastic pillars in-molded into the filter material.

A method of filtering blood comprising the steps of:

• (a) providing a filter having:
• an inner and outer filter portion each having
• a tubular filter element having upper and lower ends separated along a tube axis;
• thermoplastic upper and lower supports in-molded to respective upper and lower ends of the tubular filter element supporting the upper and lower ends against deformation inward toward the axis;
• and
• at least one thermoplastic pillar extending between the thermoplastic upper and lower supports and in-molded to the tubular filter medium element supporting the upper and lower ends in separation along the axis;
• wherein the thermoplastic lower support for the inner and outer filter portions join to provide a continuous fluid-blocking wall extending between the lower end of the tubular filter element of the inner filter portion and the lower end of the tubular filter element of the outer filter portion;
• wherein the thermoplastic upper support for the tubular filter element of the inner filter portion blocks fluid flow through the upper end of its tubular filter element and the thermoplastic upper support for the tubular filter element of the outer filter portion is open to allow fluid flow through the upper end of its tubular filter element;
• and
• wherein an axial length of the tubular filter element for the inner filter portion is substantially less than the axial length of the tubular filter element for the outer filter portion;
• and
• (b) introducing blood above the thermoplastic upper support for the tubular filter element of the inner filter portion to fall against the upper support for the tubular filter element of the inner filter and be diverted in between the tubular filter elements of inner and outer filter portions.