Filter assembly having a flexible housing and method of making same

Abstract

A fluid filter assembly for filtering fluids such as blood. The assembly includes first and second filter housing elements formed by an injection molding process. Each element is flexible and includes a peripheral flange formed thereabout and a fluid communicating port formed therein. Filter media, such as a filter membrane, is sealed between the mating flanges of two elements. The fluid filter assembly is capable of collapsing and expanding during the filtration process depending upon the composition of the fluid passed there through. A method for making the filter assembly and systems for using the filter assembly are also disclosed.

What is claimed is:  
     
         1 . A filter device comprising: 
 a body defined by at least one injection molded, flexible housing element sealed to form an interior chamber having an inlet and an outlet;    an inlet port being integrally molded at said inlet;    an outlet port being integrally molded at said outlet; and    a filter medium, the filter medium being located within the chamber.    
     
     
         2 . The filter device of    claim 1    wherein said flexible housing element prevents foaming of said fluid.  
     
     
         3 . The filter device of    claim 1    wherein said flexible housing element is spaced a predetermined distance from the filter medium.  
     
     
         4 . The filter device of    claim 1    wherein the interior chamber volume increases and decreases with fluid flow.  
     
     
         5 . The filter device of    claim 1    wherein the flexible filter housing element is attached to a non-flexible filter housing member.  
     
     
         6 . The filter device of    claim 1    wherein two flexible, injection molded housing elements are sealed along respective edges thereof defining said interior chamber.  
     
     
         7 . A filter device comprising: 
 at least one injection molded filter housing element, said element having a flexible portion formed therein;    said filter housing element sealed along edges thereof to form a interior cavity;    a filter membrane being positioned within said interior cavity; and    at least one port integrally molded in said flexible portion of said filter housing element, said port in fluid communication with said interior cavity.    
     
     
         8 . The filter device of    claim 7    wherein said flexible portion prevents foaming of a fluid passed through said device.  
     
     
         9 . The filter device of    claim 7    wherein the flexible portion is spaced a predetermined distance from the filter media.  
     
     
         10 . The filter device of    claim 7    wherein the flexible portion is capable of contracting and expanding between a minimum volume condition and a maximum volume condition.  
     
     
         11 . The filter device of    claim 7    wherein said injection molded filter housing assembly is sealed to a non-flexible filter housing member.  
     
     
         12 . The filter device of    claim 7    wherein said port is positioned tangentially with respect to the flexible portion and said filter device is positioned horizontally with respect to said port.  
     
     
         13 . The filter device of    claim 7    wherein two injection molded filter housing elements are sealed along respective portions thereof defining said interior cavity.  
     
     
         14 . A blood filter device comprising: 
 first and second generally flexible injection molded filter housing elements, each element comprising a substantially flat outer flange about a periphery thereof, a domed interior wall located therein and a fluid port integrally molded therein;    a sheet of filter media, said sheet of filter media having an outer periphery;    said first and second housing elements being arranged to define an interior chamber and said sheet extending across said chamber on opposite sides of said ports; and    said first and second housing elements being sealed along said outer flanges.    
     
     
         15 . The filter device of    claim 14    wherein said flexible housing elements prevent foaming of said blood.  
     
     
         16 . The filter device of    claim 14    wherein said flexible housing elements are spaced a predetermined distance from the filter media.  
     
     
         17 . The filter device of    claim 14    wherein the interior chamber volume increases and decreases with blood flow.  
     
     
         18 . The filter device of    claim 14    wherein said molded ports are positioned tangentially with respect to the domed wall of each filter housing element.  
     
     
         19 . The filter device of    claim 14    wherein said filter housing elements are expandable and collapsible to prevent foaming of blood flowing through said device.  
     
     
         20 . A container comprising: 
 an injection molded sheet having a substantially flexible portion integrally molded therein;    said sheet being sealed along an edge thereof after injection molding forming an interior chamber;    at least one port integrally molded in said substantially flexible portion of said sheet, said port being in fluid communication with said interior chamber; and    filter media, said filter media being positioned within said interior chamber.    
     
     
         21 . The container of    claim 20    wherein said flexible portion prevents foaming of a fluid with said container.  
     
     
         22 . A blood processing system including: 
 an inlet tube adapted for connection to a source of blood,    a blood filter connected to said tube, the blood filter comprising a body defined by at least one injection molded, flexible housing element sealed to form an interior chamber having an inlet and an outlet; an inlet port being integrally molded at said inlet; an outlet port being integrally molded at said outlet; and a filter medium, said filter medium being located within the chamber.    
     
     
         23 . A blood processing system including: 
 an inlet tube adapted for connection to a source of blood and defining a fluid path from said source,    a blood filter connected in said fluid path, said blood filter comprising at least one injection molded filter housing element, said element having a flexible portion formed therein; said filter housing element sealed along edges thereof to form a interior cavity; filtration medium being positioned within said interior cavity; and at least one port integrally molded in said flexible portion of said filter housing element, said port in fluid communication with said interior cavity.    
     
     
         24 . A blood collection system including: 
 an inlet tube adapted for connection to a source of blood,    said inlet tube defining a fluid path from said source to a collection container;    a blood filter connected in the fluid path, the blood filter comprising first and second generally flexible injection molded filter housing elements, each element comprising a substantially flat outer flange about a periphery thereof, a flexible interior wall located therein and a fluid port integrally molded therein; filtration medium; said first and second housing elements being arranged to define an interior chamber and said medium extending across said chamber on opposite sides of said ports; and said housing element outer flanges being sealed.    
     
     
         25 . A method of forming a fluid filter from a thermoplastic material, the method comprising the steps of: 
 injection molding first and second substantially flexible filter housings, each housing having a port integrally formed therein and having a periphery thereabout;    placing a filter membrane between said first and second filter housing peripheries; and    sealing along the peripheries of the filter housings to form a fluid tight enclosure.    
     
     
         26 . The method of    claim 25    wherein the first and second filter housings are injection molded from polyvinyl chloride material.  
     
     
         27 . The method of    claim 25    wherein the sealing step is conducted by placing metallic dies on opposite sides of the filter housings and applying energy to the peripheries to dielectrically heat said peripheries to cause softening and sealing thereof.  
     
     
         28 . The method of    claim 27    wherein the sealing step is conducted by the application of radio frequency energy.  
     
     
         29 . The method of    claim 25    wherein at least two filter housings are injection molded at the same time and at least two filter assemblies are sealed at the same time.  
     
     
         30 . The method of    claim 29    further including the step of die cutting each filter assembly.  
     
     
         31 . A method of making a fluid filter assembly from thermoplastic material, the method comprising the steps of: 
 injection molding first and second filter housing elements, at least one housing element having a flexible portion;    arranging the housings to define an interior cavity;    placing a filter media within the cavity; and    heat fusing the filter housing elements to form a sealed filter chamber.    
     
     
         32 . The method of    claim 31    wherein at least one filter housing is formed from polyvinyl chloride material.  
     
     
         33 . The method of    claim 31    wherein the fusing step is conducted by placing metallic dies on opposite sides of the filter housing elements and applying energy to dielectrically heat said housing elements to cause softening and sealing thereof.  
     
     
         34 . The method of    claim 33    wherein the fusing step is conducted by the application of radio frequency energy.  
     
     
         35 . The method of    claim 31    wherein at least four filter housing elements are molded at the same time and at least two filter assemblies are fused at the same time.  
     
     
         36 . The method of    claim 35    further including the step of die cutting each filter assembly.  
     
     
         37 . A blood processing system comprising: 
 a first blood bag,    a second blood bag,    tubing establishing communication between the first and second blood bags, and;    a filter in the tubing to remove undesired materials from blood, the filter comprising a body defined by at least one flexible housing element sealed to form an interior chamber; a port integrally molded on said flexible housing element; and a filter medium located within the chamber.    
     
     
         38 . A system according to    claim 37    wherein the filter media removes leukocytes from blood.