Tangential viral filtration
Viral filters include a filter member featuring a first surface and a second surface and having a thickness extending between the first and second surfaces in a first direction, and a plurality of channels formed in the filter member, each of the channels having a channel axis, where during use, a solution carrying a viral load flows in a direction parallel to the first surface, and at least a portion of the viral load enters the membrane through the first surface and propagates in the first direction, and where for at least 50% of the channels in the filter member, the channel axis is oriented at an angle of between 5 degrees and 85 degrees relative to the first direction.
1. A method for removing viral particles from a solution, the method comprising:
(a) transporting a solution comprising viral particles through a filter unit comprising a filter member;
(b) capturing a portion of the solution that passes through a filter member in a direction orthogonal to a flow direction of the transported solution through the filter unit;
(c) transporting a remaining portion of the solution that does not pass through the filter member into a reservoir;
(d) recirculating a portion of the solution from the reservoir through the filter unit; and
(e) repeating steps (b)-(d) to capture multiple portions of the solution, where each captured solution passes through the filter member,
wherein the filter member has a thickness and comprises a plurality of channels, and wherein for each of at least 50% of the channels in the filter member, a channel axis is oriented at an angle of between 5 degrees and 85 degrees relative to a thickness direction of the filter member.
2. The method of claim 1 , wherein transporting the remaining portion of the solution that does not pass through the filter member into the reservoir comprises pumping the remaining portion of the solution into the reservoir.
3. The method of claim 1 , wherein recirculating the portion of the solution from the reservoir through the filter unit comprises applying a fluid pressure to the reservoir to drive transport of the portion of the solution from the reservoir to the filter unit.
4. The method of claim 3 , further comprising maintaining a constant applied fluid pressure to the reservoir during transport of the portion of the solution from the reservoir to the filter unit.
5. The method of claim 4 , further comprising maintaining the constant applied fluid pressure to the reservoir to recirculate each portion of the solution from the reservoir through the filter unit.
6. The method of claim 1 , wherein the filter unit has a cylindrical shape and wherein the filter member has a tubular shape.
7. The method of claim 6 , wherein the captured portion of the solution passes through the filter member in one or more radial directions of the filter unit.
8. The method of claim 1 , wherein each of the plurality of channels comprises an opening at a first surface of the filter member, and wherein a ratio of a total area of the openings to a total area of the first surface is 0.10 or more.
9. The method of claim 8 , wherein the filter member is tubular, and wherein the first surface of the filter member is an inner surface of the tubular filter member.
10. The method of claim 1 , wherein each of the plurality of channels has a volume, and wherein a ratio of a total volume of the channels to a total volume of the filter member is 0.05 or more.
11. The method of claim 1 , wherein each of at least some channels of the plurality of channels comprises an opening at a first surface of the filter member having a first cross-sectional area in the first surface, and the first cross-sectional area is smaller than a second cross-sectional area of the channel at a location between the first surface and a second surface of the filter member.
12. The method of claim 11 , wherein the filter member is tubular, and wherein the first surface of the filter member is an inner surface of the tubular filter member.
13. The method of claim 11 , wherein a ratio of the first cross-sectional area to the second cross-sectional area is 0.95 or less.
14. The method of claim 11 , wherein the at least some channels comprise at least 40% of the plurality of channels.
15. The method of claim 1 , wherein the channel axes of the plurality of channels comprise a distribution of orientations relative to the thickness direction of the filter member, and wherein an average orientation of the distribution is a member selected from the group consisting of: between 10 degrees and 30 degrees relative to the thickness direction; between 30 degrees and 50 degrees relative to the thickness direction; and between 50 degrees and 80 degrees relative to the thickness direction.
16. The method of claim 1 , wherein each of at least some channels of the plurality of channels comprises one or more secondary channels extending from the channel axis.
17. The method of claim 1 , wherein the filter member is formed from a first material, and wherein each of at least some channels of the plurality of channels comprises a second material positioned on an interior surface of the channel.
18. The method of claim 17 , wherein a ratio of an average thickness of the second material on the interior surface of the at least some channels to a maximum cross-sectional dimension of the at least some channels is 0.2 or less.
19. The method of claim 1 , wherein the plurality of channels is a first plurality of channels, and wherein the filter member comprises:
a first layer comprising the first plurality of channels; and
a second layer comprising a second plurality of channels.
20. The method of claim 19 , wherein an average orientation of axes of the first plurality of channels relative to the thickness direction of the filter member is different from an average orientation of axes of the second plurality of channels relative to the thickness direction of the filter member.