Field of the Invention

Filter media for filtering blood components is frequently encased in a hard plastic housing. Alternatively, the housing for the layered or foam filter media may be made of soft or flexible thermoplastic resin sheets resulting in what may be called a soft filter. It is to such a soft filter or soft housing filter that embodiments of the instant invention are directed.

Background

One of the challenges of manufacturing a soft housing filter is the attachment between the soft thermoplastic housing sheets and the filter media layers or filter or media pack itself. Some of the challenges relate to the inability or difficulty in bonding diverse or incompatible, (for bonding purposes), materials, e.g., plastics. A further challenge may be the bonding of filter media (which may be sheets of porous or fibrous material) to inlet and outlet tubes of the filter. Past solutions have included sealing the filter media layers or media pack by heat or thermal welding directly between the soft thermoplastic sheets on all edges of the soft housing sides. Such sealing would then bond the filter layers to the inlet and outlet tubes. This solution may not solve the binding compatibility issues depending on the materials utilized.

Another past solution includes providing a frame all around the edges of the filter media pack and sealing such edges of the media pack to the frame. The frame is then sealed, such as by heat or thermal welding, between the soft thermoplastic housing sheets and to the inlet and outlet tubes. Such frame may present extra construction costs as well as extra construction steps. The frame may also reduce the overall effective filtering surface within the housing in that it may reduce the overall surface available for filtering.

Filtering for removing leukocytes in blood components can be achieved through using a gravity drain procedure wherein the fluid to be filtered is allowed to drain by gravity from a container, through the filter inlet, through the filter media from one side to the other or through layers of the filter media, and out through the filter outlet. Alternatively, in some systems the fluid to be filtered may be pushed through the filter using a pump or an expressing device. The fluid to be filtered can also be pushed through the filter using a force, such as centrifugal force, to move the fluid.

Summary of the Invention

In embodiments of the present invention are directed to a filter. The filter may include an inlet tube; an outlet tube; an outer housing attached to the inlet tube and outlet tube; a first attachment element attached to one of the inlet or outlets tubes; and filter media in the outer housing, wherein the filter media may be attached to the first attachment element. In one embodiment, the first attachment element may attach the filter media to the outlet tube but not the inlet tube. In this embodiment, the first attachment element may include a first wing with a tip and a second wing with a tip with such attachment element being between the filter media and one of the inlet and outlet tubes. A second attachment element may be attached to the same one of the inlet and outlet tubes as the first attachment element. The second attachment element may include a third wing with a tip and a fourth wing with a tip and the second filter media may be further attached to the third and fourth wings. Filter media may be attached to the side of first, second, third and fourth wings, each of the tips of the wings may contact the outer housing to direct the blood or blood component through the filter media. The filter media may comprise layers, and the layers may be sealed together at a second end opposite the first end of the filter media. At least one of the inlet and outlet tubes may extend between the first and second attachment elements and between the filter media.

Brief Description of the Drawings

FIG. 1 illustrates a soft housing filter according to one embodiment.

FIG. 2 illustrates the soft housing filter of FIG. 1 with a portion of an outer housing removed.

FIG. 3 is a cross-sectional view of the filter illustrated in FIG. 2.

FIG. 4 is a perspective view of an embodiment of an attachment element.

FIG. 5 is a perspective view of another embodiment of an attachment element. FIG. 6 is a bottom perspective view of another embodiment of an attachment element.

FIG. 7 is a flow chart illustrating a method of manufacturing a filter according to embodiments.

Detailed Description

For purposes of illustration, embodiments of the present invention will be described with respect to a blood filter, for example a leukoreduction filter, for removing leukocytes from blood components or blood products. The embodiments of a leukoreduction filter include media encased in housing. It is noted that although the description may refer to leukoreduction, the present invention is not limited to this specific use, and may in other embodiments, be used to filter other fluid, of blood.

The media for filtering may be formed of any suitable material including, without limitation, woven material, non-woven material, or fibers oriented in specific ways.

Alternatively, a porous foam material can be used. Media may be stacked in layers to form a pack or packs and optionally and selectively calendared to form different shapes, and in some embodiments shapes that correspond to the shapes of the filter housing. In some embodiments, the shape may be disk shaped. The edges of the layers of media may be heat or thermally welded together or attached using some other bonding techniques, including without limitation, solvent welding, heat welding, high frequency welding (e.g., RF (radio frequency) welding or ultrasonic welding), and/or laser welding. FIG 2 illustrates bonding of layers of media at an edge 31. In embodiments, synthetic, semi-synthetic or natural fibers may be used for the media. For example, polyester fibers such as polyethylene

terephthalate, nylon, polypropylene, polyacrylnitrile and the like may be used. The media in embodiments may receive treatment to enhance wet-ability or filter functionality, e.g., chemical, heat, or other types of treatments.

FIG. 1 shows the front of an embodiment of a soft housing filter 25. For the filter 25, a first sheet 11 is sealed or bonded by heat or thermal sealing or other known sealing methods to a second sheet 10 around peripheral edge 12 to form an outer housing 120 made of soft material within which filter media is positioned (see FIG. 3). Sheets 10 and 11 are flexible in some embodiments and may in some embodiments be made of thermoplastic resin. Sheets 10 and 11 may optionally be textured to provide an uneven surface or have a surface treatment to prevent filter media packs 30 and 32 (described below) from adhering to such sheets 10 and 11.

A port 100 in the outer housing 120 is shown in FIG. 1 with tube 15 positioned in the port 100. The tube 15 attached to and between sheets 10 and 11. FIG. 1 also shows a second port 104 with tube 16 positioned in the port 104. Tube 16 is attached to and between the sheets 10 and 11. The ports 100 and 104, with tubes 15 and 16, are designated by the direction of flow and can serve as either inlets or outlets for the filter 25. For example, arrows 116 in FIG. 2 illustrate the flow of fluid when tube 15 is an inlet tube and fluid flows through the filter media from inlet tube 15 to outlet tube 16. In

embodiments where tube 16 is an inlet tube, filter 25 would be turned 180 degrees (from the illustration in FIG. 2) when used to filter fluid and the flow of fluid through the filter media would also be approximately 180 degrees from the flow shown in FIG. 2.

Filter media material for filtration is shown in FIG. 2 positioned within the outer housing 120 created by sheets 10 and 11. The filter media material is also shown in FIG. 3. The filter media may be in the form of packs 30 and 32 which include multiple layers of filter media and which may include calendared layers. In the example filter, the layers of the two filter packs 30 and 32 are welded together around their peripheral edges such as edge 31 for pack 30 as shown in FIG. 2. The filter media or packs 30 and 32 are attached to tube 16 by barriers or attachment elements 40 and 45 to create a filter assembly 108, as described below.

Tube 15 and tube 16 may be formed of soft or hard plastic tubing material a non- limiting example including, polyvinyl chloride (PVC). First attachment element 40 (as shown in FIG. 2 and FIG. 4), in embodiments includes first wing 41 and second wing 42. FIG. 2 shows first attachment element 40 and the first of filter media layers or pack 30 attached thereto. Second attachment element 45 is shown in FIG. 3 with the second of filter media layers or pack 32 adhered thereto. Wings 41 and 42 of the first barrier 40 and the third and fourth wings 46 and 47 of second barrier 45 (FIG. 4) assure the fluid to be filtered passes through the filter media packs 30 and 32. As shown in FIG. 2, first barrier or attachment element 40 and first and second barrier tips 43 and 44 extend toward the soft side wall sheet 10 and 11 forming the outer housing 120 of filter 25. Second barrier or attachment element 45 has similar third and fourth barrier tips 48, 49 which also extend to the sheets 10 and 11. When tube 16 is attached to attachment elements 40 and 45, tube 16 extends between the attachment elements.

Attachment elements or barriers 40 and 45 may also be constructed as a one piece element, prior to attachment to the filter media and the tube 16 as described below, with tip 43 attached to tip 48 and tip 44 attached to tip 49 by heat sealing, solvent bonding or other known sealing methods. The attachment elements may be made of suitable plastic material such as thermoplastic material. The attachment elements or barriers 40 and 45 may also be molded as a one piece construction. The combination of filter media packs 30 and 32, and the attachment elements 40 and 45 create a filter assembly 108 which is positioned within the outer housing.

The barriers or attachment elements 40 and 45 of the filter assembly 108 are bonded by solvent or thermal bonding or other known methods to the tube 16 on either side of the tube 16 in an opposite relationship. As shown in FIG. 3, one side or inner layer 52 of the filter media or pack 30 is attached by heat, solvent or thermal bonding to first barrier or attachment element 40 along the wings 41 and 42. The other layers (if fibrous multi-layer media is used) are attached to the side or inner layer 52. Similarly, one side or inner layer 51 of filter media pack 32 is attached to second barrier or attachment element 45 along its wings by suitable bonding technique with other layers attached or welded to the side or inner layer 51. Alternatively, if appropriately sized, multiple layers of each of the filter media pack 30 and 32 of the filter 25, may be attached to the barriers or attachment elements 40 and 45. As shown in the embodiment of FIG. 3, the filter media layers of packs 30 and 32 are not directly attached to soft housing sheets 11 and 10 but are attached to barrier or attachment elements 40 and 45. Similarly the media layers or packs 30 and 32 are not directly attached to the tube 16. The tube 16, however, is attached to the barrier or attachment elements 40 and 45.

The barrier or attachment elements 40 and 45 prevent the fluid to be filtered from by-passing one of the filter media packs 30 or 32. Filter media packs 30 and 32 are sealed together at the top at 53 by welding so that fluid must go through filter media 30 or 32 to reach tube 16. In embodiments, the filter media packs 30 and 32 are not attached to the tube 15. Similarly the attachment of the filter packs 30 and 32 through the inner layer, and barrier or attachment element 40 or 45 prevents fluid from flowing directly to the tube 16 and bypassing the filter pack.

The barrier or attachment elements 40 and 45 are shown connecting the filter media packs 30 and 32 to the tube 16. In embodiments, the barrier or attachment elements 40 and 45 may optionally be used on the tube 15, with the filter packs 30 and 32 sealed to each other on the side of the filter 25 near the tube 16 but not attached thereto. In this instance, flow would be from the tube 15 between the two filter media packs 30 and 32, through the media of such packs and then to the tube 16. Tubes 15 and 16 may in embodiments be configured to serve as either inlet or outlet tubes of filter 25, allowing fluid to flow into and out of filter 25.

FIG. 5 illustrates another design of attachment elements. As shown in FIG. 5, the attachment elements 40A and 45A, and wings (41A, 42A, 46A, and 47 A) on the attachment elements, may have a different shape. The wings shown in FIG. 5 are larger and have a shallower angle, than the wings shown in FIGS. 1-4. In other embodiments, the tips (43A, 44A, 48A, and 49A) of the wings may be rounded, end in an edge instead of a tip, or have other designs or shapes. FIG. 5 is shown to illustrate other designs that are contemplated within the scope of the present invention. Other attachment elements with different wings or other structural features will be apparent to those of skill in the art and are within the scope of the present invention.

FIG. 6 shows a bottom perspective view of attachment elements that are consistent with another embodiment of the present invention. As shown in FIG. 6, some embodiments may include connecting material 112 that connects attachment elements 40B and 45B. As noted above, the tips of attachment elements, e.g., 40B and 45B may be connected;

connecting material 112 further connects attachment elements 40B and 45B. The connecting material 112 may be angled to serve as a funnel that further funnels filtered fluid to tube 16. The angle may be shallow or sharp and range from less than or equal to 180 degrees to greater than or equal to 10 degrees. The connecting material 112 may in embodiments be formed with the attachment elements 40B and 45B, such as during an injection molding process, or may be later added after the attachment elements have been formed. As shown in FIG. 6, connecting material 112 is positioned so that tube 16 may still be bonded to the attachment element, however in some embodiments, tube 16 may be attached only to the connecting material 112 and the attachment elements 40B and 45B do not physically contact tube 16. In these embodiment, the connecting material 112 is used to connect the attachment elements 40B and 45B to tube 16. FIG. 6 illustrates only one embodiment of using connecting material 112 with attachment elements 40B and 45B, other designs with different structures are contemplated within the scope of the present invention.

FIG. 7 shows a flow 700 that illustrates methods that may be performed to manufacture a filter. Although specific structures from FIGS 1-6 may be referred to below in describing the performance of methods, the present invention is not limited to these structures. For example, embodiments may include creating a filter assembly, which may be described below by referring to filter assembly 108 (FIGS. 1 and 2) but in other embodiments involve attachment elements different from attachment elements 40 and 45. The description below is provided merely for illustrative purposes, and flow chart 700 is not limited to manufacturing the structures shown in FIGS. 1-6, and may in other embodiments involve manufacturing structures that have features not described above with respect to FIGS. 1-6 above.

Flow 700 begins at step 704 where a filter assembly is created. In one embodiment, the filter assembly may be assembly 108 shown in FIGS. 1 and 2 above. As shown in FIG. 7, step 704 may involve one or more sub-steps. In embodiments, the sub-steps include bonding first media to a first attachment element at sub-step 708 and bonding second media to a second attachment element at sub-step 712. The bonding of media to attachment elements may involve attaching one or more layers of filter media to the attachment element. The bonding may involve one or more common bonding techniques, including without limitation, solvent welding, heat welding, high frequency welding (e.g., RF (radio frequency) welding or ultrasonic welding), and/or laser welding. The bonding techniques may depend on a number of different factors including the type of material from which the filter media and the attachment elements are made.

Flow 700 passes from step 704 to step 716, where the filter assembly created in step 704 is positioned prior to forming an outer housing of a filter, e.g., outer housing 120. In one embodiment, step 716 involves positioning the filter assembly between two sheets that will form the walls of an outer housing. In some embodiments the two sheets may be partially bonded together when step 716 is performed. In other embodiments, the filter assembly may be positioned adjacent one sheet before the second sheet is positioned on an opposite side of the filter assembly from the first sheet.

At step 720, a first sheet may be bonded to a second sheet to form an outer housing 120 of the filter. In embodiments, the first sheet and second sheet may be formed by flexible material such as polymeric sheets, e.g., sheets 10 and 11 described above. The bonding may involve one or more common bonding techniques, including without limitation, solvent welding, heat welding, high frequency welding (e.g., RF (radio frequency) welding or ultrasonic welding), and/or laser welding.

In some embodiments, step 720 may be performed multiple times. For example, a portion of the two flexible sheets may be partially bonded (to at least partially create a soft outer housing) before the filter assembly is positioned at step 716. In these embodiments, the sheets may be further bonded to form the final outer housing, after the filter assembly is positioned.

At step 724, a first tube is bonded to the first sheet and the second sheet of the outer housing. The first tube may be used in embodiments as an input or output for the filter, allowing fluid to enter or exit the outer housing. In embodiments, the first tube is positioned within a first port in the outer housing, such as port 104 (FIG. 2) before performing step 724 to bond the first tube to the first sheet and the second sheet. Step 724 may involve any of the bonding techniques described above.

At step 728, a second tube is bonded to the first sheet and the second sheet of the outer housing. The second tube may be used in embodiments as an input or output for the filter, depending upon for example whether the first tube is used as the input or the output. In embodiments, the second tube is positioned within a second port in the outer housing, such as port 100 (FIG. 2) before performing step 728 to bond the second tube to the first sheet and the second sheet. Step 728 may involve any of the bonding techniques described above.

At step 732, the filter assembly is bonded to the first tube. This step ensures that the filter assembly is secured and does not move around within the outer housing. This step may involve one or more sub-steps, such as sub-steps 736 and 740, where the first attachment element and the second attachment element are bonded to the first tube. In other embodiments, the sub-steps may involve bonding or otherwise attaching a structure of the filter assembly to the first tube. The first tube may be designed as the inlet for the filter or the outlet of the filter. Step 732 may involve any of the bonding techniques described above, and the specific bonding technique used will depend upon the materials of the filter assembly and the tube.

Although flow 700 has been described with steps listed in a particular order, the present invention is not limited thereto. In other embodiments, steps may be performed in different order, in parallel, or any different number of times, e.g., before and/or after another step. For example, is some embodiments, the step 732 (described above as bonding the filter assembly to the first tube) may be performed as part of step 704, namely creating the filter assembly (see line 744). In these embodiments, the sub-steps of bonding the first attachment element to the first tube (736) and bonding the second attachment element to the first tube (740) are performed as part of creating the filter assembly. As a result, when the filter assembly is created, it will include the first tube. This is merely one alternative example of different embodiments of flow 700.

Also, as indicated above, flow 700 includes some optional steps. However, those steps above that are not indicated as optional should not be considered as essential to the invention, but may be performed in some embodiments of the present invention and not in others.

The above has been described with respect to fibrous media formed into layers for filtering. It is understood, however, that the same attachment principles can apply to porous filter media.

It will be apparent to those skilled in the art that various modifications can be made to the apparatus and method described herein. Thus, it should be understood that the invention is not limited to the subject matter discussed in the specification. Rather, the present invention is intended to cover modifications and variations.