Microporous filter membrane, method of making microporous filter membrane and separator employing microporous filter membranes
AssigneeBaxter International Inc.
InventorJames D. Jacobson
Life of this patent
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Abstract
A filter membrane, methods of making such filter membrane and apparatus employing such filter membrane are disclosed, in which the filter membrane is a monolithic polymeric membrane that includes a polymeric filter layer including a micron-scale precision-shaped pores and a polymeric support layer that has a precision-shaped porous support structure for the filter layer. Several methods are disclosed for making such a membrane using micromachining techniques, including lithographic, laser ablation and x-ray treatment techniques. Several filter apparatus employing such a membrane are also disclosed.
Claims23
A method for making a monolithic polymeric filter membrane comprising at least a filter layer including micron-scale precision-shaped pores and a support layer including a precision-shaped support structure for the filter layer, the method comprising:
- providing a polymeric film having first and second sides;
- forming the filter membrane layer by removing selected material from the first side of the polymeric film to define the precision-shaped micron-scale pores of the filter layer;
- and
- forming the support structure layer by removing selected material from the second side of said polymeric film to define the precision-shaped porous support structure, the pores communicating with the porous support structure to allow the passage of filtrate therethrough, and further comprising
- at least one of said filter layer and support layer being formed by:
- providing a polymeric film that is of polyimide material
- applying a metallic film to one surface of said polyimide film,
- applying a photoresist material to said metallic film,
- creating a first pattern on said photoresist layer to define micron scale pores or support structure and removing selected material from said photoresist layer;
- removing material from said metallic film in the areas where said photoresist material has been removed;
- and
- removing selected material from the polyimide film in the areas where the metallic film has been removed to define the pores or support structure;
- removing any remaining photoresist material and the metallic film from the polyimide film.
A method for making a monolithic polymeric filter membrane of a predetermined thickness, the filter membrane comprising at least one filter layer with micron-scale precision-shaped pores and a support layer including a precision-shaped support structure for said filter layer, the method comprising:
- providing a substrate;
- spinning a first polyimide layer onto the substrate;
- applying a metal layer to the first polyimide layer;
- applying photoresist to the metal layer;
- developing the photoresist to define a first pattern of one of the micron-scale pores or support structure;
- transferring the first pattern from said photoresist to said metal layer;
- transferring the first pattern from the metal layer to said first polyimide layer so as to create one of said micron-scale pores or said support structure;
- sequentially removing the photoresist and the metal layer;
- spinning a second polyimide layer onto the first layer polyimide so as to create an interface therebetween;
- creating a second pattern on the second polyimide layer to define the other of the micron-scale pores or the support structure;
- removing selected material from the second polyimide layer to define the other of the micron-scale pores or support structure;
- curing the first and second polyimide layers so as to remove the interface therebetween and create a monolithic filter layer-support structure;
- and
- removing the integral filter layer-support structure from said substrate.
Dependencies are inferred from the claim text.