This application claims the benefit of U.S. Provisional Application Serial No. 63/176,426, filed April 19, 2021 , the disclosure of which is hereby incorporated by reference in its entirety.

Backqround

Field of the Disclosure

[0001] The present disclosure relates to blood filtration devices. More particularly, the present disclosure relates to blood filtration devices employing relatively rotating surfaces one of which carries a membrane for filtering a component from fluid passed between the surfaces.

Description of Related Art

[0002] Different types of blood collection procedures exist, including manual collection of whole blood from healthy donors through blood drives, donor visits to blood centers or hospitals and the like. In typical manual collection, whole blood is collected by simply flowing it, under the force of gravity and venous pressure, from the vein of the donor into a collection container. The amount of whole blood drawn is typically a "unit," which is about 450 to 550 ml.

[0003] Collection may employ a pre-assembled arrangement of tubing and containers or bags, including a flexible plastic primary container or bag for receiving a unit of whole blood from a donor and one or more "satellite" containers or bags. The blood may first be collected in the primary container, which also contains an anticoagulant (typically containing sodium citrate, phosphate and dextrose-often referred to as CPD). A preservative (often called an "additive solution" or AS, and commonly containing a saline, adenine and glucose medium- which is referred to as SAG) may be included as part of a larger assembly of containers and tubes that are used in processing after the blood is collected. [0004] After collection of a unit of whole blood, the unit of whole blood, with connected tubing and containers, may be transported to a blood component processing laboratory, commonly referred to as a "back lab," for further processing. Further processing may entail loading the primary container and associated tubing and satellite containers into a centrifuge to separate the whole blood into components such as concentrated red cells and platelet-rich or platelet- Attorney Docket No. F-6919 PCT (9362-0714) poor plasma. These components are then manually expressed from the primary container into other pre-connected satellite containers, and may again be centrifuged to separate the platelets from plasma.

[0005] Subsequently, the blood components may be leukoreduced by filtration for further processing or storage. The process may be time-consuming, labor intensive, and subject to possible human error.

[0006] Blood banks and transfusion centers may also perform the task of "cell washing," which removes and/or replaces the liquid medium (or a part thereof) in which the cells are suspended, to concentrate or further concentrate cells in a liquid medium, and/or to purify a cell suspension by the removal of unwanted cellular or other material.

[0007] Cell washing systems may involve centrifugation of a cell- suspension, decanting of the supernatant, re-suspension of concentrated cells in new media, and possible repetition of these steps until the cells of the suspension are provided at an adequately high or otherwise desirable concentration. Centrifugal separators used in the processing of blood and blood components may be used in such cell-washing methods.

[0008] Blood separation apparatus and procedures may employ a separation membrane to separate blood components instead of a centrifuge. This type of device includes relatively rotating surfaces, at least one or which carries a porous membrane. The device may have an outer stationary housing and an internal spinning rotor covered by a porous membrane. Although device designs of the prior art have proven adequate, there is room for improvement in the design of the grooves of the rotor for more efficient collection.

Summary

[0009] There are several aspects of the present subject matter which may be embodied separately or together in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto.

[00010] According to a first aspect, the present disclosure is directed Attorney Docket No. F-6919 PCT (9362-0714) to a blood filtration device comprising an outer housing having an interior wall. An internal member is mounted interior of the outer housing and comprises a rotor having an outer surface defining a circumference with a porous membrane disposed thereon and a hollow interior to separate blood into a filtrate that passes through the membrane onto the outer surface of the rotor and a retentate that does not pass through the membrane. The outer housing and internal member are relatively rotatable and define an annular gap between the outer housing and outer surface of the internal member. The blood filtration device also comprises an inlet for directing fluid into the annular gap, a first outlet for exiting filtrate passing through the porous membrane onto the outer surface of the rotor and into the interior of the rotor, and a second outlet for directing from the annular gap retentate remaining in the annular gap. The rotor has a first end adjacent the inlet and a second end adjacent the first outlet, the outer surface of the rotor further comprising a plurality of longitudinal grooves extending underneath the membrane and at least one circumferential groove adjacent the second end, with a bridge extending radially through the interior of the rotor and defining a flow path for the filtrate between the outer surface and the interior of the rotor.

[00011] According to a second aspect, the present disclosure is directed to a blood filtration device comprising an outer housing having an interior wall. An internal member is mounted interior of the outer housing and comprises a rotor having an outer surface defining a circumference with a porous membrane disposed thereon with a hollow interior to separate blood into a filtrate that passes through the membrane onto the outer surface of the rotor and a retentate that does not pass through the membrane. The outer housing and internal member are relatively rotatable and define an annular gap between the outer housing and outer surface of the internal member. The blood filtration device also comprises an inlet for directing fluid into the annular gap, a first outlet for exiting filtrate passing through the porous membrane onto the outer surface of the rotor and into the interior of the rotor, and a second outlet for directing from the annular gap retentate remaining in the annular gap. The rotor has a first end adjacent the inlet and a second end adjacent the first outlet, the outer surface of the rotor further comprising at least one groove extending helically between the first and second Attorney Docket No. F-6919 PCT (9362-0714) ends of the rotor underneath the membrane and at least one circumferential groove adjacent the second end, with a bridge extending radially through the interior of the rotor and defining a flow path for the filtrate between the outer surface and the interior of the rotor.

[00012] These and other aspects of the present subject matter are set forth in the following detailed description of the accompanying drawings.

Brief Description of the Drawings

[00013] Fig. 1 is a first front view of a blood filtration device, according to an exemplary embodiment, with portions removed to show detail;

[00014] Fig. 2 is a second front view of the blood filtration device of Fig. 1 , according to an exemplary embodiment, with portions removed to show detail; [00015] Fig. 3 is perspective view of the rotor of the blood filtration device of Figs. 1 and 2;

[00016] Fig. 4 is an enlarged fragmentary perspective view of the surface of the rotor within circle 4 of Fig. 3.

[00017] Fig. 5 is an exploded perspective view of the blood filtration device of Figs. 1 and 2, according to an exemplary embodiment;

[00018] Fig. 6 is a cross-sectional of the rotor of a blood filtration, taken along line 6-6 of Fig. 5;

[00019] Fig. 7 is a perspective view of the rotor of Fig. 6;

[00020] Fig. 8 is a cross-sectional view of the rotor of a blood filtration device taken along line 8-8 of Fig. 5;

[00021] Fig. 9 is a perspective view of the rotor of Fig. 8;

[00022] Fig. 10 is a cross-sectional view of the rotor of a blood filtration device taken along line 10-10 of Fig. 5;

[00023] Fig. 11 is a perspective cross-sectional of the rotor of Fig. 10;

[00024] Fig. 12 is a longitudinal cross-sectional view of an exemplary embodiment of a rotor of a blood filtration device;

[00025] Fig. 13 is a longitudinal cross-section of the blood filtration device of Fig. 12;

[00026] Fig. 14 shows a pair of cross-sectional portions of a rotor having varying groove depths; and Attorney Docket No. F-6919 PCT (9362-0714)

[00027] Fig. 15 is a perspective view of a rotor of a blood filtration device with helical grooves.

Description of the Illustrated Embodiments [00028] The embodiments disclosed herein are for the purpose of providing a description of the present subject matter, and it is understood that the subject matter may be embodied in various other forms and combinations not shown in detail. Therefore, specific designs and features disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims. [00029] Some embodiments may increase the efficiency of separation devices, systems, and methods applicable to blood collection and processing. [00030] A description of a spinning membrane separator may be found in U.S. Pat. No. 5,194,145 to Schoendorfer, which is incorporated by reference herein in its entirety, and describes a membrane-covered internal member having an interior collection system disposed within a stationary shell. Blood is fed into an annular space or gap between the internal member and the shell. The blood moves along the longitudinal axis of the shell toward an exit region, with plasma passing through the membrane and out of the shell into a collection container.

The remaining blood components, primarily red blood cells, platelets and white cells, move to the exit region between the internal member and the shell and may be returned to the donor or collected for further processing.

[00031] Spinning membrane separators may provide excellent filtration rates, due primarily to the unique flow patterns ('Taylor vortices") induced in the gap between the spinning membrane and the shell. The Taylor vortices help to keep the blood cells from depositing on and fouling or clogging the membrane. [00032] Other examples of spinning membrane separators are described in U.S. Pat. No. 5,053,121 and U.S. Pat. Pub. No. 2014/0010738, both of which are incorporated by reference herein in their entireties.

[00033] Another spinning membrane separator is described in U.S. Pat. Pub. No. 2017/0182464, incorporated herein by reference. The spinning membrane utilizes circumferential grooves along the surface of the rotor.

[00034] Previous art teaches the use of rotors with circumferential channels or grooves along the length of the rotor. They may include a small number of longitudinal grooves which connect the circumferential grooves. The Attorney Docket No. F-6919 PCT (9362-0714) circumferential grooves include dead end locations at the end of each groove (and possibly adjacent a longitudinal groove) causing air to trap behind the membrane, in between the membrane and the spinning rotor. The trapped air prevents any movement of fluid between the membrane and the rotor. This reduces collection efficiency and can increase procedure times.

[00035] A prime sequence can be utilized to remove some of this trapped air, but it is not completely effective in removing the trapped air. Longitudinal grooves on the rotor can lower or possibly eliminate any trapped air between the membrane and rotor. These longitudinal grooves eliminate or minimize the dead end locations and therefore greatly reduce the potential for trapped air. The fluid flows more easily down the rotor with the longitudinal grooves. Longitudinal grooves, therefore, increase the membrane area utilization, which increases the collection efficiency and can also reduce procedure times.

[00036] Turning to Figs. 1 and 2, a spinning membrane blood separation or filtration device utilizing longitudinal grooves, generally designated 10, is shown. Such a device 10 may be used to extract plasma or filtrate and red blood cells from whole blood obtained from a donor. Only the separation device is shown, but it should be understood that such a separator may be part of a disposable system including collection containers, containers of additives such as saline, SAG, or ACD, return containers, tubing, etc., and that there are also associated control and instrumentation systems for operation of the device.

[00037] The device 10 may include a generally cylindrical outer housing 12, mounted concentrically about a longitudinal vertical central axis. An internal member 14 may be mounted concentric with the central axis. The housing and internal member are relatively rotatable. The outer housing 12 may be stationary and the internal member 14 may be a rotating internal member that is rotatable concentrically within the cylindrical housing 12. The boundaries of the blood flow path may generally be defined by the gap 16 between the interior surface of the housing 12 and the exterior surface of the rotary internal member 14. The spacing between the housing 12 and the internal member 14 can be referred to as the shear or annular gap. A typical shear or annular gap may be approximately 0.025- 0.060 inches (0.067-0.152 cm) and may be of a uniform dimension along the axis, for example, where the axis of the internal member and housing are coincident. Attorney Docket No. F-6919 PCT (9362-0714)

The shear gap may also vary circumferentially for example, where the axes of the housing and internal member are offset.

[00038] The annular gap 16 may vary along the axial direction. For example, an increasing gap width in the direction of flow may be implemented to limit hemolysis. Such a gap width may range from about 0.025 to about 0.075 inches (0.06-0.19 cm). For example, the axes of the housing 12 and the internal member 14 could be coincident and the diameter of the internal member 14 decrease in the axial direction (direction of flow) while the diameter of inner surface of the housing 12 remains constant or the diameter of the housing 12 increases while the internal member 14 diameter remains constant, or both surfaces vary in diameter. The gap width may be varied by varying the outer diameter of the internal member 14 and/or the inner diameter of the facing housing surface. The width dimension of the gap 16 may be selected so that at the desired relative rotational speed, Taylor vortices are created in the gap and hemolysis is limited. [00039] Referring to Figs. 1 and 2, whole blood may be fed from an inlet conduit 20 through an inlet orifice 22, which directs the blood into the blood flow entrance region in a path tangential to the circumference about the upper end of the internal member 14. At the bottom end of the cylindrical outer housing 12, the housing inner wall includes an exit orifice 34. The cylindrical outer housing 12 may be completed by an upper end cap 40 and a bottom end housing 44 terminating in a plasma outlet orifice 46 concentric with the central axis.

[00040] The internal member 14 may be rotatably mounted between the upper end cap 40 and the bottom end housing 44. The internal member 14 may comprise a shaped central mandrel or rotor 50 defining a circumference and a hollow interior, the outer surface of which may be shaped to define a series of spaced-apart longitudinal grooves or ribs 52 separated by annular lands 54 (shown more clearly in other figures). At one or more ends of the rotor 50, these grooves 52 may be in communication with a central orifice or manifold 58 via an opening 58a and bridge 58b. Located near or at the bridge, there may be at least one circumferential groove 56. In some instances, there may be a single circumferential groove.

[00041] The surface of the rotary internal member 14 may be at least partially or entirely covered by a cylindrical porous membrane 62. The membrane

62 may have a nominal pore size of 0.6 microns, although other pore sizes may Attorney Docket No. F-6919 PCT (9362-0714) alternatively be used. In one embodiment, pore sizes in the range of 0.2 microns to 5 microns may be used. "Pore size" generally refers to the cross-sectional dimension of the pores, and not the depth of the pores through the filter layer. For both pores of circular and non-circular shapes, "pore size" generally refers to the smallest cross-sectional dimension of the pores, unless otherwise stated. The membrane 62 may be a fibrous mesh membrane, cast membrane, track-etched membrane, etc. For example, the membrane 62 may have a polyester mesh (substrate) with nylon particles solidified thereon, thereby creating a tortuous path through which only certain sized components will pass. In another embodiment, the membrane may be made of a thin (e.g., approximately 15 micron thick) sheet of, for example, polycarbonate, nylon, and/or both, and pores may be, e.g., approximately 3-5 microns. The pores may be sized to allow small, formed components (e.g., platelets, microparticles, etc.) to pass, while the desired cells (e.g., red and/or white blood cells) are collected. In another embodiment, the membrane thickness may be in the range of 10 to 190 microns and have any suitable pore size from 0.2 microns to 5 microns.

[00042] The membrane 62 may comprise one or more layers. The membrane may be comprised of a single nylon layer. In one embodiment, the membrane 62 comprises two layers. The two layers may include a polyester layer and a nylon layer. In one embodiment, the polyester layer may be disposed underneath the nylon layer and act as a scaffold/support for the nylon layer to prevent collapse of the membrane into the grooves. The nylon layer should have a thickness value and an air permeability value that minimizes obstruction or hindrance of fluid flow. In one embodiment, the nylon layer may have a thickness of 100-200 microns, preferably 150 microns and an air permeability of 50-130 cc/cm ² /sec.

[00043] The scaffold/support layer may comprise polyester in one embodiment, but in an alternate embodiment, the scaffold/support layer may comprise another suitable material or combination of materials. In one embodiment, the polyester may be a woven polyester material. The woven polyester may be a woven polyester mesh. In another embodiment, the scaffold/support layer may comprise a polyester blend. The outer layer may comprise a polycarbonate layer in one embodiment, but in an alternate embodiment, the outer layer may comprise another suitable material or Attorney Docket No. F-6919 PCT (9362-0714) combination of materials. For example, polyethersulfone (PES) and/or a PES blend may be used as an outer layer in one embodiment.

[00044] In another embodiment, the membrane may be comprised of a single layer with multiple materials. The polyester, such as a woven polyester mesh, and the nylon may be entangled in a single layer. The nylon may be present in the interstices of the woven polyester mesh.

[00045] The rotary internal member 14 may be mounted in the upper end cap 40 to rotate about a pin 64, which may be press fit into the end cap 40 on one side and seated within a cylindrical bearing surface in an end cylinder 66 forming part of the rotary internal member 14. The internal member 14 or outer housing 12 may be rotated by any suitable rotary drive device or system. A drive motor exterior to the housing 12 may be coupled to a drive member. As the annular drive member is rotated, the internal member 14 may rotate.

[00046] At the lower end of the rotary internal member 14, the central outlet orifice 58 may communicate with a central bore 76 in an end bearing 78 that is concentric with the central axis which communicates with the plasma outlet orifice 46.

[00047] Fig. 3 is a perspective view of the rotor component 50 of the blood filtration device in Figs. 1 and 2. Fig. 4 is an enlarged fragmentary perspective view of the area within circle 4 on the rotor of Fig. 3. Fig. 4 shows in detail the longitudinal grooves 52 and annular lands 54 along with the circumferential groove 56. The opening 58a to the plasma bridge is shown in closer detail. [00048] Fig. 5 is an exploded view of the spinning blood filtration device 10. As described above, the cylindrical housing 12 of the system 10 may house the internal member 14 which includes rotor surface 50 with grooves concentrically and relatively rotatably about a common central axis. A membrane 62 may cover the internal member 14, and the annular gap 16 may be formed by the spacing between the housing 12 and the internal member 14, with the membrane 62 separating the different blood components.

[00049] Figs. 6, 8, and 10 show various cross sections taken perpendicular to the longitudinal axis of the rotor 50, while the associated Figs. 7, 9, and 11 respectively show perspective views starting from the respective cross section . Figs. 6 and 7 illustrate views taken above the plasma bridge 58b of the filtration device. Fig. 6 is cross-sectional view taken along line 6-6 of Fig. 5, while Fig. 7 is Attorney Docket No. F-6919 PCT (9362-0714) a perspective view from above the plasma bridge 58b. Longitudinal grooves 52 and associated annular lands 54 are shown on the outer surface of the rotor 50. Circumferential groove 56 is also shown toward the end of rotor 50, at the plasma bridge 58b. Fig. 6 also includes the membrane 62. The plasma bridge extends across the diameter of the rotor 50 with at least one opening 58a, with two openings shown, at the circumferential groove 56. Plasma that filters through the membrane 62 travels down longitudinal grooves 52 to circumferential groove 56 and directed to the plasma bridge 58b through opening 58a on the rotor.

[00050] Turning now to Figs. 8 and 9, Fig. 8 is a cross-sectional view taken along line 8-8 of Fig. 5 at the plasma bridge 58b and circumferential groove 56, while Fig. 9 is a perspective view taken from the same vantage point. The plasma bridge extends across the diameter of the rotor 50 with at least one opening 58a at the circumferential groove 56. The plasma bridge 58b has a central orifice 58, which leads to the central bore 76. The plasma is directed through the bridge to the central bore and through the outlet 46.

[00051] Turning now to Figs. 10 and 11 , Fig. 10 is a cross-sectional view taken along line 10-10 of Fig. 5 looking up toward the top of the rotor 50, while Fig. 11 is a perspective view taken from the same vantage point. Pin 64 is visible from the cross section, through the hollow interior 70 of the rotor 50.

[00052] Figs. 12 and 13 are longitudinal cross-sectional views to better illustrate the features of the filtration device 10 and the rotor. Specifically, a clearer view of the plasma bridge 58b of the rotor 50 is shown along with the relationship between the rotor 50 of the internal member with the outer housing 12 and the annular gap 16.

[00053] The placement of the grooves may be varied within the disclosed embodiments of the current disclosure. The spacing of the grooves may vary.

The longitudinal grooves may be spaced evenly along the surface of the rotor 50. The grooves may also be varying in distance between one another. The grooves may be parallel to each other along the length of the rotor 50.

[00054] The grooves along the rotor may also vary in depth, size and/or width. Groove depth D is the distance between the top edge of the annular land 54 and the bottom of groove 52. In one embodiment, depth D may be greater than 0.03 inches and preferably approximately 0.06 inches up to 0.10 inches. In addition to deeper grooves being able to accommodate higher volume of fluid Attorney Docket No. F-6919 PCT (9362-0714) collection by the rotor 50, a greater depth D may allow for minimal hindrance of the collection process in the event that some collapse of the membrane 62 against a portion of groove 52 occurs.

[00055] Figs. 14 includes a perspective view of one embodiment of a rotor of a filtration device of the current disclosure. The depth of the grooves may be different on the rotor proximal to the inlet of the filtration device versus the depth on the rotor proximal to the outlets of the filtration device. In one embodiment, the depth of the grooves toward the inlet of the rotor are less than the depth of the grooves on the rotor toward the outlets of the rotor. Fig. 14 shows two different cross-section portions of the rotor 50, a first section 80 and a second section 90, 80 can be more proximal to the inlet of the filtration device and 90 more proximal to the outlets of the filtration device. The grooves 52a and annular lands 54a have a first depth D1 and the grooves 52b and annular lands 54b have a second depth D2. Alternatively, the grooves may be a consistent depth throughout the length of the rotor 50. D1 and D2 can be the same or similar. D1 can be less than D2 and vice versa.

[00056] In one embodiment, grooves 52 may gradually increase longitudinally in depth D along the length of rotor 50 from the end proximal to inlet conduit 20 to the end proximal to orifices 34 and 46. In one embodiment, depth D1 may be as low as 0.033 inches at the end proximal to inlet conduit 20, incrementally increase to approximately 0.066 inches at any point between the end proximal to inlet conduit 20 and the end proximal to orifices 34 and 46, and incrementally increase up to 0.099 inches at D2 at the end proximal to outlet orifices 34 and 46. The grooves may also abruptly increase at specific points along each longitudinal groove 52.

[00057] Fig. 15 illustrates an alternate groove arrangement of a rotor of a filtration device of the current disclosure. Fig. 15 shows a possible helical groove arrangement on a rotor 150. The helical grooves may be separate discrete grooves. The grooves in this arrangement can vary similarly to the longitudinal groves, as previously discussed. The grooves 152 and annular lands 154 in this arrangement can be evenly or unevenly spaced apart. The grooves may also vary along the length of the rotor with regards to depth, size, and/or width and as mentioned in regard to the longitudinal grooves, particularly increasing in depth toward the plasma bridge and/or outlets of the rotor. The individual helical Attorney Docket No. F-6919 PCT (9362-0714) grooves may vary in depth along the length of the rotor or may be a consistent depth. In the case of a consistent depth for each helical groove, the grooves may increase in depth as their proximity to the outlets increases. There may also be a single continuous helical groove that wraps around the length of the rotor from the inlet to the plasma bridge and/or outlets. The single continuous groove may increase in depth as it progresses down the length of the rotor from the inlet to the outlets and/or bridge. The single continuous groove may also be a consistent depth.

[00058] The embodiments disclosed herein are for the purpose of providing a description of the present subject matter, and it is understood that the subject matter may be embodied in various other forms and combinations not shown in detail.

[00059] Therefore, specific embodiments and features disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims.

[00060] Thus, filtration devices with improved rotor groove arrangements have been disclosed. It will be understood that the embodiments and examples described above are illustrative of some of the applications of the principles of the present subject matter. Numerous modifications may be made by those skilled in the art without departing from the spirit and scope of the claimed subject matter, including those combinations of features that are individually disclosed or claimed herein. For these reasons, the scope hereof is not limited to the above description but is as set forth in the following claims, and it is understood that claims may be directed to the features hereof, including as combinations of features that are individually disclosed or claimed herein.

Other Aspects

[00061] Aspect 1. A blood filtration device comprising: an outer housing having an interior wall; an internal member mounted interior of the outer housing comprising a rotor having an outer surface defining a circumference with a porous membrane disposed thereon with a hollow interior to separate blood into a filtrate that passes through the membrane onto the outer surface of the rotor and a retentate that does not pass through the membrane; the outer housing and Attorney Docket No. F-6919 PCT (9362-0714) internal member being relatively rotatable and defining an annular gap between the outer housing and outer surface of the internal member; an inlet for directing fluid into the annular gap; a first outlet for exiting filtrate passing through the porous membrane onto the outer surface of the rotor and into the interior of the rotor; and a second outlet for directing from the annular gap retentate remaining in the annular gap; wherein the rotor has a first end adjacent the inlet and a second end adjacent the first outlet, the outer surface of the rotor further comprising a plurality of longitudinal grooves extending underneath the membrane and at least one circumferential groove adjacent the second end, with a bridge extending radially through the interior of the rotor and defining a flow path for the filtrate between the outer surface and the interior of the rotor.

[00062] Aspect 2. The blood filtration device of Aspect 1 , wherein the filtrate primarily comprises plasma and/or platelets, and the retentate primarily comprises blood cells.

[00063] Aspect 3. The blood filtration device of Aspect 1 , wherein the longitudinal discrete grooves are evenly spaced.

[00064] Aspect 4. The blood filtration device of Aspect 1 , wherein the longitudinal grooves are parallel to each other.

[00065] Aspect 5. The blood filtration device of Aspect 1 , further comprising an opening on the rotor connecting the exterior of the rotor to the bridge.

[00066] Aspect 6. The blood filtration device of Aspect 1 , further comprising a single circumferential groove.

[00067] Aspect 7. The blood filtration device of Aspect 6, wherein the single circumferential groove is located on that point on the rotor where the bridge is.

[00068] Aspect 8. The blood filtration device of Aspect 1 , wherein each longitudinal groove varies between a first depth adjacent the inlet and a second depth adjacent the outlets.

[00069] Aspect 9. The blood filtration device of Aspect 8, wherein the first depth is less than the second depth. Attorney Docket No. F-6919 PCT (9362-0714)

[00070] Aspect 10. The blood filtration device of Aspect 1 , wherein the depth of the longitudinal groove is uniform from the inlet to the outlets.

[00071] Aspect 11. The blood filtration device of Aspect 1 , wherein the outer surface of the rotor alternatively comprises at least one groove extending helically between the first and second ends of the rotor underneath the membrane instead of a plurality of longitudinal grooves.

[00072] Aspect 12. The blood filtration device of Aspect 11 , wherein the at least one helical groove is a single continuous groove. [00073] Aspect 13. The blood filtration device of Aspect 11 , comprising a plurality of grooves extending helically.

[00074] Aspect 14. The blood filtration device of Aspect 13, wherein the helical discrete grooves are evenly spaced.

[00075] Aspect 15. The blood filtration device of Aspect 13, wherein the helical grooves are parallel to each other.

[00076] Aspect 16. The blood filtration device of Aspect 13, wherein each helical groove varies between a first depth adjacent the inlet and a second depth adjacent the outlets.

[00077] Aspect 17. The blood filtration device of Aspect 16, wherein the first depth is less than the second depth.

[00078] Aspect 18. The blood filtration device of Aspect 13, wherein the depth of each helical groove is uniform from the inlet to the outlets of the rotor.

[00079] Aspect 19. The blood filtration device of Aspect 13, wherein the plurality of helical grooves have at least two different depths.

[00080] Aspect 20. The blood filtration device of Aspect 19, wherein the first depth is for at least one helical groove adjacent the inlet and the second depth is for at least one helical groove adjacent the outlets.

[00081] Aspect 21 . The blood filtration device of Aspect 20, wherein the first depth is less than the second depth. Attorney Docket No. F-6919 PCT (9362-0714)

[00082] Aspect 22. The blood filtration device of Aspect 21 , wherein the depth of the groove increases as proximity of the groove to the outlets increases.