CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C §120 of U.S.

Provisional Application Serial No. 62/773,838 filed on November 30, 2018, U.S. Provisional Application Serial No. 62/773,635 filed on November 30, 2018, U.S. Provisional Application Serial No. 62/773,625 filed on November 30, 2018, and U.S. Provisional Application Serial No. 62/773,618 filed on November 30, 2018, the contents of which are relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure generally relates to systems for purification and filtration of biochemical mixtures, including purification and filtration devices. In particular, the present disclosure relates to multimodule systems for continuous purification of biochemical mixtures, droplet based microfluidic filtration devices, filtration devices having a plurality of filtration membranes, and filtration devices that suppress filter fouling and methods for suppressing filter fouling.

BACKGROUND

[0003] There has been significant and sustained growth in new drug production featuring, for example, monoclonal antibodies and other proteins. This growth is due to expanding drug pipelines, as well as more efficient cell lines and bioreactor growth optimizations. Downstream purification, often including chromatography, is a part of the drug production process where the most significant investments of time and resources are consumed. Chromatography is a process to separate product from contaminating species and is an important step in drug production and other bioprocessing applications. However, there have been few improvements made to the column chromatography processes. In particular, the processes have not been improved to account for improvements in upstream technology that allow for increased volumes to be processed for longer periods of time. While these results are considered advantageous for several reasons, the improvements are also generally leading to the production of more impurities in the bioprocessing systems which could benefit from downstream chromatography methods and systems that can perform separation of higher volumes in an efficient manner. Additionally, conventional chromatography methods and systems have physical limitations which limit the ability to scale up the methods and systems. The largest chromatography columns currently available on the market would require multiple chromatography cycles to perform separation of only a portion (for example, as lOg/L of product) of the volume of a single bioreactor. Such separation could take as long as 24 hours and cause a significant bottleneck in the overall drug production process.

[0004] A potential solution to the shortcomings of chromatography columns may be found in Tangential Flow Filtration (TFF). TFF is an exemplary separation process that uses membranes to separate components in a liquid solution or suspension on the basis of size or molecular weight differences. Applications include concentration, clarification, and desalting of proteins and other biomolecules such as nucleotides, antigens, and monoclonal antibodies; buffer exchange; process development; membrane selection studies; pre-chromatographic clarification to remove colloidal particles; depyrogenation of small molecules such as dextrose and antibiotics; harvesting, washing or clarification of cell cultures, lysates, colloidal suspensions and viral cultures; and sample preparation.

[0005] One reason for the development of TFF was to provide a solution to the problem of membrane blockage associated with the various conventional fdtration techniques. In TFF, the solution or suspension to be filtered is passed across the surface of the membrane in a cross- flow mode. The driving force for filtration is the transmembrane pressure, usually created with a peristaltic pump. The velocity at which the filtrate is passed through the membrane surface also controls the filtration rate and helps prevent clogging of the membrane. Because TFF recirculates retentate across the membrane surface, membrane fouling is minimized, a high filtration rate is maintained, and product recovery is enhanced. [0006] Conventional TFF devices are formed of a plurality of elements, including a pump, a feed solution reservoir, a filtration assembly and conduits for connecting these elements. Some filtration assembly designs include straight parallel channels positioned on either side of a membrane. Other filtration assembly designs include winding channels positioned on either side of a membrane. In contrast to the straight channels, such winding channels allow filtration to be performed in a smaller footprint. Additionally, such winding channels may expose the solution or suspension to be filtered to a larger membrane surface area for a longer period of time. This in turn facilitates performing efficient filtration at low tangential velocities which may prevent damage to components in the solution or suspension to be filtered, such as cells, cell growth surfaces such as microcarriers, affinity beads, biomolecules, etc. However, in certain

applications, such as in filtration of affinity beads, a high degree of agglomeration of the beads at the surface of the filters has been observed and allows for debris to become trapped leading to clogging of the filter.

SUMMARY

[0007] According to an embodiment of the present disclosure, a multimodule system for continuous purification of biochemical mixtures is provided. The multimodule system includes at least one immobilization module fluidly connected to a feed source and to a resin source, wherein in the at least one immobilization module, chromatography resin from the resin source is contacted with a feed solution from the feed source to bind target compounds from the feed solution with the chromatography resin. The multimodule system also includes at least one wash module fluidly connected to the at least one immobilization module and to a wash solution source, wherein in the at least one wash module, chromatography resin having target compounds bound thereto is contacted with a wash solution from the wash solution source. The multimodule system further includes at least one elution module fluidly connected to the at least one wash module and to an eluent solution source, wherein in the at least one elution module,

chromatography resin having target compounds bound thereto is contacted with an eluent solution from the eluent solution source to release the target compounds from the

chromatography resin. [0008] According to another embodiment of the present disclosure, a droplet-based microfluidic filtration device is provided. The droplet-based microfluidic filtration device includes a flow channel having a liquid inlet, a retentate outlet and a gas injection inlet situated perpendicular to the liquid inlet, a filtration membrane, and a permeate outlet.

[0009] According to an embodiment of the present disclosure, a filtration device is provided. The filtration device includes a flow channel having an inlet and a retentate outlet, an upper chamber having a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes, and a lower chamber having a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes.

[0010] According to an embodiment of the present disclosure, a filtration system is provided. The filtration system includes a plurality of filtration devices each filtration device including a flow channel having an inlet and a retentate outlet, an upper chamber having a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes, and a lower chamber having a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes.

[0011] According to an embodiment of the present disclosure, a method for separating at least one target compound from a fluid stream in a filtration device is provided. The method includes flowing a fluid stream comprising carriers into an inlet of a flow channel of a filtration device, the flow channel comprising a retentate outlet, wherein the filtration device comprises an upper chamber comprising a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes, and a lower chamber comprising a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes The method further includes introducing a liquid solution into the upper chamber of the filtration device.

[0012] According to an embodiment of the present disclosure, a filtration device is provided. The filtration device includes a first module comprising a first flow channel comprising a fluid inlet and a retentate outlet, a second module comprising a second flow channel comprising a fluid inlet and a permeate outlet, at least one filtration membrane separating the first flow channel from the second flow channel, and a vibration element.

[0013] According to an embodiment of the present disclosure, a filtration device is provided. The filtration device includes a vertically oriented flow channel comprising an inlet and a retentate outlet, a first vertically oriented chamber comprising a liquid inlet and a permeate outlet, the first chamber being separated from the flow channel by a first of a plurality of vertically oriented filtration membranes, and a second vertically oriented chamber comprising a liquid inlet and a permeate outlet, the second chamber being separated from the flow channel by a second of the plurality of vertically oriented filtration membranes.

[0014] According to an embodiment of the present disclosure, a method of suppressing filter fouling in a filtration device is provided. The method includes flowing a fluid stream into a first flow channel of a filtration device, flowing a fluid stream into a second flow channel of a filtration device, wherein the second flow channel is separated from the first flow channel by a filtration membrane, applying a transmembrane pressure across the filtration membrane, and vibrating the filtration membrane.

[0015] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0016] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure will be understood more clearly from the following description and from the accompanying figures, given purely by way of non-limiting example, in which:

[0018] Figure 1 illustrates a block diagram of a continuous purification system in accordance with embodiments of the present disclosure;

[0019] Figure 2 illustrates a conventional TFF module;

[0020] Figure 3 illustrates a sectional view of the TFF module of Figure 2;

[0021] Figure 4 illustrates a perspective view of the TFF module of Figure 2;

[0022] Figure 5 illustrates a conventional TFF module;

[0023] Figure 6 schematically illustrates an exemplary droplet-based microfluidic filtration device in accordance with embodiments of the present disclosure;

[0024] Figure 7 schematically illustrates an exemplary droplet-based microfluidic filtration device in accordance with embodiments of the present disclosure;

[0025] Figure 8 schematically illustrates an exemplary separation module including a plurality of droplet-based microfluidic filtration devices in accordance with embodiments of the present disclosure;

[0026] Figure 9 schematically illustrates a filtration device having a plurality of filtration membranes in accordance with embodiments of the present disclosure;

[0027] Figure 10 schematically illustrates a separation module including a plurality of filtration devices having a plurality of filtration membranes in accordance with embodiments of the present disclosure; [0028] Figure 11 schematically illustrates a filtration device having a plurality of filtration membranes in accordance with embodiments of the present disclosure; and

[0029] Figure 12 schematically illustrates a filtration device having a vibration element in accordance with embodiments of the present disclosure;

[0030] Figure 13 schematically illustrates a filtration device which includes a plurality of filtration membranes that are vertically orientated in accordance with embodiments of the present disclosure;

[0031] Figure 14 illustrates a transient model of an exemplary droplet-based microfluidic filtration device in accordance with embodiments of the present disclosure;

[0032] Figure 15 illustrates the formation of a droplet in an exemplary droplet-based microfluidic filtration device in accordance with embodiments of the present disclosure;

[0033] Figure 16 is a flow chart illustrating a method for separating at least one target compound from a fluid stream in accordance with embodiments of the present disclosure; and

[0034] Figure 17 is a flow chart illustrating a method for suppressing filter fouling in filtration devices in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

[0035] Reference will now be made in detail to the present embodiment(s), an example(s) of which is/are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0036] The singular forms“a,”“an” and“the” include plural referents unless the context clearly dictates otherwise. The endpoints of all ranges reciting the same characteristic are independently combinable and inclusive of the recited endpoint. All references are incorporated herein by reference. [0037] As used herein,“have,”“having,”“include,”“including,� �“comprise,”

“comprising” or the like are used in their open-ended sense, and generally mean“including, but not limited to.”

[0038] All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

[0039] The present disclosure is described below, at first generally, then in detail on the basis of several exemplary embodiments. The features shown in combination with one another in the individual exemplary embodiments do not all have to be realized. In particular, individual features may also be omitted or combined in some other way with other features shown of the same exemplary embodiment or else of other exemplary embodiments.

[0040] The terms“top”,“bottom”,“side”,“upper”,“lower� ��,“above”,“below” and the like are used herein for descriptive purposes and not necessarily for describing permanent relative positions. It should be understood that the terms so used are interchangeable under appropriate circumstances such that embodiments of the present disclosure are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0041] One or more embodiments of the present disclosure relate to multimodule systems for continuous purification of biochemical mixtures. The systems described herein include a plurality of modules arranged in series, the modules including, for example, any combination of immobilization modules, wash modules, elution modules, separation modules, and regeneration modules. The system may be operated continuously and eliminates the requirement for storage tanks. Additionally, the systems as described herein may be operated in a loop such that chromatography resin may be recycled and reused. As such, embodiments of the present disclosure reduce the amount of resin required to perform purification of biochemical mixtures. Also described herein are separation devices which facilitate flow of the carriers within the flow channel, which in turn reduces formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membrane of the separation device and prevents fouling of the filtration membrane. Prevention of fouling allows for filtration in the separation devices described herein to be performed more consistently and more efficiently than in conventional tangential filtration assemblies.

[0042] Figure 1 shows a block diagram of a continuous purification system 10 according to embodiments of the present disclosure. As shown, the system 10 includes a plurality of modules arranged in series. As will be described in more detail below, the system 10 may include any combination of at least one immobilization module 12, at least one wash module 14, at least one elution module 16, at least one separation module 18, and at least one regeneration module 20 The system 10 is configured to operate in a continuous mode. Flow rates throughout the system 10 are controlled by pumps at the inlets and outlets in order to counteract any pressure drops in the system 10. While the block diagram of Figure 1 illustrates only one of each of the exemplary modules, it should be appreciated that systems having a plurality of one or more of the exemplary modules are contemplated.

[0043] Embodiments of the present disclosure may include at least one immobilization module 12 In operation, a feed solution is pumped from a feed source 22 into the immobilization module 12 to contact the feed solution with a chromatography resin which is also pumped into the immobilization module 12 from a resin source 24 The feed solution may be any fluid mixture for example a fermentation broth which contains two or more compounds to be separated and the feed source 22 may be, for example, a cell culture vessel such as a bioreactor.

In this context, the term“compound” is used in a broad sense for any entity such as a molecule, chemical compound, cell, etc. The feed solution may not be passed directly from the source 22 Instead the feed solution may be subjected to one or more steps of pre- treatment, such as filtration, prior to entering the immobilization module 12. In the immobilization module 12, contact with the chromatography resin results in binding of target compounds in the feed solution with the chromatography resin. As used herein, the term“target compound” refers to any compound which is to be separated from the feed solution. A target compound can be biological entities of natural biological or biochemical origin or produced by biological or biochemical processes. It should be appreciated that a target compound may be a desired product such as, for example, a drug, diagnostic or vaccine, or in the alternative, a target compound may be a contaminant or a compound generally considered as an undesirable product which is to be removed from one or more desired products. The chromatography resin is chosen such that functional groups of the ligands are capable of binding target compounds, for example, via a “lock/key” mechanism, such as antibody/antigen; enzyme/receptor; biotin/avidin, etc. The target compounds may be, but are not limited to, proteins, such as membrane proteins or antibodies, e.g. monoclonal antibodies, fusion proteins comprising antibody or antibody fragments, such as Fab-fragments, and recombinant proteins; peptides; nucleic acids, such as DNA or RNA, e.g. oligonucleotides, plasmids, or genomic DNA; cells, such as prokaryotic or eukaryotic cells or cell fragments; virus; prions; carbohydrates; lipids etc. After a sufficient amount of time, the solution including chromatography resin having target compounds bound thereto may be removed from the immobilization module 12 through an outlet fluidly connected to the next module in the purification system 10.

[0044] Embodiments of the present disclosure may include at least one wash module 14.

In operation, a solution containing the chromatography resin flows to the wash module 14 where the chromatography resin having target compounds bound thereto is brought into contact with a wash solution which may be supplied to the wash module 14 from a wash solution source 26.

The wash solution may include, for example, a buffer. Washing the chromatography resin is performed in conditions which provide for substantially all of the target compounds to remain bound to the chromatography resin while compounds not bound to the chromatography resin enter the wash solution. After a sufficient amount of time, the solution containing the chromatography resin may be removed from the wash module 14 through an outlet fluidly connected to the next module in the purification system 10 and the wash solution (including compounds not bound to the chromatography resin) may be removed through a separate outlet connected to a vessel 32 where the wash solution is collected or discarded as waste.

[0045] Embodiments of the present disclosure may include at least one elution module

16. In operation, the solution containing the chromatography resin flows to the elution module 16 where the chromatography resin is brought into contact with an eluent solution which may be supplied to the elution module 16 from an eluent solution source 28. The eluent solution may include, for example, a solvent, and is capable of releasing the target compounds from the chromatography resin. Eluting the chromatography resin is performed in conditions which provide for substantially all of the target compounds to be released from the chromatography resin and enter the eluent solution. After a sufficient amount of time, the eluent solution containing the chromatography resin may be removed from the elution module 16 through an outlet fluidly connected to the next module in the purification system 10 and the eluent solution ((including the target compounds) may be removed through a separate outlet connected to a vessel 34 where the eluent solution is collected or discarded as waste.

[0046] Embodiments of the present disclosure may include at least one regeneration module 20. In operation, after the target compounds have been removed from the

chromatography resin, the solution containing the chromatography resin flows to the regeneration module 20 where the chromatography resin is brought into contact with a regeneration solution which may be supplied to the regeneration module 20 from a regeneration solution source 30. The regeneration solution may include, for example, a buffer, and is capable of refreshing the chromatography resin to prepare the chromatography resin to be returned to the resin source 24 and ultimately to the at least one immobilization module 12 to repeat the purification process. Alternatively, the chromatography resin may be removed along with the regeneration solution through a separate outlet connected to a vessel 36 where the

chromatography resin and/or the regeneration solution may be disposed of at the end of the purification process.

[0047] Embodiments of the present disclosure may include at least one separation module 18. The exemplary system illustrated in Figure 1 shows separation modules 18 positioned downstream of the at least one wash module 14 and the at least one elution module 16, but it should be appreciated that separation modules 18 may be positioned downstream of outlets of any of the at least one immobilization module 12, the at least one wash module 14, the at least one elution module 16 and the at least one regeneration module 20. For example, a solution containing the chromatography resin may flow from an outlet of the immobilization module 12 to a separation module 18 where the chromatography resin is separated from other components of the solution. Similarly, the wash solution containing the chromatography resin may flow from an outlet of the wash module 14 to a separation module 18 where the

chromatography resin is separated from other compounds that enter the wash solution, the eluent solution containing the chromatography resin may flow from an outlet of the elution module 16 to a separation module 18 where the chromatography resin is separated from the target compounds that enter the eluent solution, or the regeneration solution containing

chromatography resin may flow from an outlet of the regeneration module 20 to a separation module 18 where the chromatography resin is separated from other components of the regeneration solution.

[0048] It should be appreciated that, according to embodiments of the present disclosure, the module at which the desired product is removed from the purification system 10 will depend on the conditions selected for the purification method. For example, the desired product may be the target compound and may be removed from the system in the eluent solution. Alternatively, the desired product may not be the target compound and may be removed from the system in the wash solution. As yet another alternative, two or more products may be desired products. For example, the user may collect a compound that is not a target compound in the wash solution as a first desired product and may also collect the target compound as a second desired product. According to embodiments of the present disclosure, any of the compounds in the feed solution may be considered the desired product and it is ultimately within the user’s discretion which compounds to collect for later use or processing and which compounds to discard.

[0049] According to embodiments of the present disclosure, in lieu of distinct separation modules 18, the at least one immobilization module 12, the at least one wash module 14, the at least one elution module 16 and/or the at least one regeneration module 20 may include at least one separation device as will be described in more detail below. Referencing the wash module 14 merely as an example, the wash module 14 may include a vessel fluidly connected to at least one separation device. Within the vessel, the solution containing the chromatography resin having target compounds bound thereto is brought into contact with a wash solution. The combination of the wash solution with the chromatography resin having target compounds bound thereto may then be transferred to the at least one separation device within the wash module 14 where the chromatography resin is separated from other compounds that enter the wash solution.

Alternatively, the at least one immobilization module 12, the at least one wash module 14, the at least one elution module 16 and/or the at least one regeneration module 20 may be at least one separation device. Again, referencing the wash module 14 merely as an example, the wash module 14 may be at least one separation device in which occurs contact of the solution containing the chromatography resin with a wash solution as well as separation of the solution containing the chromatography resin from other compounds that enter the wash solution.

[0050] Separation modules according to embodiments of the present disclosure may include filtration devices as described herein. Figure 2 illustrates an example of a conventional tangential filtration assembly and Figure 3 shows a sectional view of the tangential filtration assembly of Figure 2. As shown the filtration assembly 15 includes a pressure resistant housing having two filtration modules 8, 9 fixed to each other. Each of the modules 8, 9 includes a tangential flow channel 4. When the modules 8, 9 are fixed to each other, the filtration assembly 15 includes two tangential flow channels 4 arranged on either side of a filtration element 10. The filtration element 10 includes two filtration membranes 1 arranged on either side of a sheet of porous material in sandwich construction. The membranes mounted on the porous material define a feed side which contacts a sample solution and a permeate side positioned in contact with the porous support material. An inlet 5 and an outlet 6 for communicating a sample solution are arranged in the housing and are fluidly connected to the tangential flow channels 4.

[0051] The tangential flow channels 4 are winding channels which, as shown in Figure 2, include a number of straight channel sections 4a, 4b, 4c etc. separated by bent transitional zones 7ab, 7bc, 7cd, etc., where the bent transitional zones 7ab, 7bc, 7cd, etc. fluidly connect a straight channel section 4a, 4b, 4c, etc. with a subsequent straight channel section 4a, 4b, 4c, etc. The channel sections 4a, 4b, 4c, etc. and the bent transitional zones 7ab, 7bc, 7cd, etc. are arranged such that a sample solution flowing from the inlet 5 to the outlet 6 changes direction by 180° when the sample solution flows through a bent transitional zone 7ab, 7bc, 7cd, etc. from a first straight channel section 4a, 4b, 4c, etc. to a subsequent straight channel section 4a, 4b, 4c, etc.

[0052] Figure 4 illustrates a perspective view of the tangential filtration assembly of

Figure 2 and shows the arrangement of the two filter membranes of the filtration element in a sandwich construction. Figure 4 shows one of the tangential flow channels 4 of one of the filtration modules 8, 9 in contact with a side of one of the filtration membranes 1. As also shown, the outlet 6 is fluidly connected to the tangential flow channel 4 at an endpoint of the tangential flow channel 4 through an outlet channel 16. Similarly, the inlet 5 is also fluidly connected to the one of the tangential flow channel 4 at the opposite endpoint of the tangential flow channel 5 through an inlet channel (not shown).

[0053] The conventional tangential filtration assembly is illustrated in Figures 2-4 for purposes of illustration only. As will be understood from the discussion provided herein, embodiments of the present disclosure relate to microfluidic filtration devices which may be utilized to perform tangential filtration.

[0054] Figure 5 further illustrates a conventional tangential filtration assembly. The assembly 100 includes a first filtration module 106 having a tangential flow channel 116 and a second filtration module 108 having a tangential flow channel 118. The first filtration module 106 includes an inlet 126 and an outlet 136 each fluidly connected to the tangential flow channel 116 at opposite endpoints of the tangential flow channel 116. Similarly, the second filtration module 108 includes an inlet 128 and an outlet 138 each fluidly connected to the tangential flow channel 118 at opposite endpoints of the tangential flow channel 118.

[0055] As shown in Figure 5, the assembly 100 includes a filtration membrane 110 positioned between, and separating, tangential flow channel 116 and tangential flow channel 118. The filtration membrane 110 is formed of a porous material and has a first surface 120 and a second surface 130. In operation of the filtration assembly 100, fluid within the tangential flow channels 116, 118 flows tangentially over opposite surfaces 120, 130 of the filtration membrane 110. The specific material and the specific pore size of the filtration membrane 110 may be selected based on the size of a target compound that will be separated by the filtration assembly 100. Optionally, the pore size of the filtration membrane 1 10 may be larger than the target compound to allow the target compound to pass through the filtration membrane 110.

Alternatively, the pore size of the filtration membrane 110 may be smaller than the target compound to prevent the target compound from passing through the filtration membrane 110. Thus, depending on the pore size of the filtration membrane, the target compound is either (i) separated from the fluid stream and, in most instances, from other particles or molecules in the fluid stream, or (ii) maintained in the fluid stream and, in most instances, other particles or molecules are separated from the fluid stream. As described herein, the target compound may be attached to a carrier such as a microcarrier or to a chromatography resin, for example in the form of a chromatography affinity bead and the specific material and the specific pore size of the filtration membrane 110 may be selected based on the size of the chromatography resin or carrier. In such instances, the pore size of the filtration membrane 110 may be smaller than the chromatography resin or carrier to prevent the chromatography resin or carrier from passing through the filtration membrane 110.

[0056] Like the tangential filtration assembly shown in Figure 4, the filtration membrane

110 may alternatively include two filtration sheets arranged on either side of a porous material in sandwich construction. The filtration sheets may be arranged in contact with, or mounted on, the porous material such that a first outer surface 120 of one of the filtration sheets contacts a fluid stream in one of the tangential flow channels 116, 118 and a first outer surface 130 of the other of the filtration sheets contacts a fluid stream in the other of the tangential flow channels 116, 118. Such filtration sheets also include second surfaces opposing the first surfaces positioned in contact with the porous material.

[0057] In operation, a first fluid stream flows into tangential flow channel 116 through inlet 126 and a second fluid stream flows into tangential flow channel 118 through inlet 128.

The first fluid stream passes tangentially over the first surface 120 of the filtration membrane 110 at the same time that the second fluid stream passes tangentially over the second surface 130 of the filtration membrane 110. The first fluid stream then passes out of tangential flow channel 116 through outlet 136 and the second fluid stream passes out of tangential flow channel 118 through outlet 138 where any of the streams may be collected in a collection vessel, recirculated back to the respective inlet 126, 128 of the respective tangential flow channel 116, 118, or fed to a second filtration assembly connected in series with the first filtration assembly.

[0058] One of the fluid streams includes a mixture containing a target compound, or chromatography resin or carrier having a target compound attached thereto. For purposes of ease and clarity, the first fluid stream will be described herein as including a mixture containing a target compound, or chromatography resin or carrier having a target compound attached thereto, and will be described as flowing into and through tangential flow channel 116, while the second fluid stream will be described herein as flowing into and through tangential flow channel 118. However, it should be understood that either of the first and second streams may include a mixture containing a target compound, or chromatography resin or carrier having a target compound attached thereto, and either of the first and second streams may flow through either of the tangential flow channels 116, 118.

[0059] According to embodiments of the present disclosure, the pressure at which the first stream is introduced into tangential flow channel 116 at the inlet 126 and the pressure at which the first stream is removed from tangential flow channel 116 at the outlet 136 may be controlled to provide substantially constant operational pressure in tangential flow channel 116 along the length of the filtration membrane 110. Similarly, the pressure at which the second stream is introduced into tangential flow channel 118 at the inlet 128 and the pressure at which the second stream is removed from tangential flow channel 118 at the outlet 138 may be controlled to provide substantially constant operational pressure in tangential flow channel 118 along the length of the filtration membrane 110. The operational pressures in the tangential flow channels 116, 118 may be maintained such that a pressure differential between the operational pressure in tangential flow channel 116 and the operational pressure in tangential flow channel 118, or in other words, a transmembrane pressure, is applied across the filtration membrane 110.

[0060] As a result of the transmembrane pressure, as the first fluid stream and the second fluid stream flow on opposite sides of the filtration membrane 110, species small enough to pass through the pores of the filtration membrane 110 traverse the filtration membrane 110.

Depending on the pore size of the material of the filtration membrane 110, species small enough to pass through pores of the filtration membrane 110 move from the first fluid stream to the second fluid stream. If larger than the pores of the material of the filtration membrane 110, the target compound may remain in the first fluid stream in tangential flow channel 116.

Alternatively, if smaller than the pores of the material of the filtration membrane 110, the target compound may pass through the filtration membrane 110 and into the second fluid stream in tangential flow channels 118. Where the fluid stream includes chromatography resin having a target compound attached thereto, the chromatography resin does not pass through the filtration membrane 110 and instead remains in tangential flow channel 116. The rate at which the species traverse the filtration membrane 110 is dependent on a number of factors including: the particular species; the constituents of the first and second fluid streams; the flow rate of the first and second fluid streams; the physical characteristics of the filtration membrane 110; the pressures in the first tangential flow channel 116 and the second tangential flow channel 118; and the temperature of the first and second fluid streams.

[0061] As used herein, the term“transmembrane flux” refers to the rate that species pass through pores of the filtration membrane 110. In certain filtration processes, a high

transmembrane flux may be advantageous. However, a high transmembrane flux may lead to the formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membrane 110. In some circumstances, this concentration of molecules, particles, and/or carriers may form a compact gel-like layer on the surface of the filtration membrane 110 which reduces the transmembrane flux and diminishes the performance of the filtration assembly.

[0062] According to embodiments of the present disclosure, the separation module 18 or the separation devices described herein may include droplet-based microfluidic filtration devices such as are illustrated in Figures 6 and 7. Figure 6 schematically illustrates an exemplary droplet- based microfluidic filtration device 200. As shown, the device 200 may have a similar configuration as the tangential filtration assembly 100 shown in Figure 5 with a filtration membrane 210 as described above positioned between, and separating, flow channel 216 and flow channel 218. The first flow channel includes a liquid inlet 226 and a retentate outlet 236, and the second flow channel 218 includes a liquid inlet 228 and a permeate outlet 238. The device 200 further includes a T-junction where a gas injection inlet 250 is fluidly connected to, for example, flow channel 216, and situated perpendicular to the inlet liquid 226. In operation, a fluid stream flows into flow channel 216 through liquid inlet 226 and a gas stream flows into the flow channel 216 through the gas injection inlet 250. Droplets are formed as a result of the interaction between the fluid stream and the gas stream. Where the fluid stream includes chromatography resin or a carrier that is suspended in the droplets due to a secondary

recirculating flow inside of the droplets. Species small enough to pass through the pores of the filtration membrane 210 traverse the filtration membrane 210 and other species too large to pass through the pores of the filtration membrane 210, including the chromatography resin suspended in the droplets, do not traverse the filtration membrane 210 and flow from the liquid inlet 226 to the retentate outlet 236. Advantageously, the droplets provide separation between the chromatography resin suspended in the droplets and the walls of the flow channel as well as the surface of the filtration membrane 220. Such separation facilitates flow of the chromatography resin or carriers within the droplets to the retentate outlet 236, which in turn reduces formation of a concentration of molecules, particles, and/or chromatography resin or carriers on the surface of the filtration membrane 210.

[0063] Figure 7 schematically illustrates an exemplary droplet-based microfluidic filtration device 300. As shown, the device 300 includes a flow channel 316 having a T-junction where a gas injection inlet 350 is fluidly connected to the flow channel 316 and situated perpendicular to a liquid inlet 326. The droplet-based microfluidic filtration device 300 further includes a retentate outlet 336 and at least one permeate outlet 338. The at least one permeate outlet 338 is fluidly connected to the flow channel 316 by a permeate channel 340. The permeate channel 340 is separated from the flow channel 316 by a filtration membrane 310. The droplet- based microfluidic filtration devices shown in Figure 7 includes three permeate outlets 338 and three corresponding permeate channels 340. However, it should be understood that the droplet- based microfluidic filtration device 300 maybe include any number of permeate outlets 338 and corresponding permeate channels 340. In operation, a fluid stream flows into flow channel 316 through liquid inlet 326 and a gas stream flows into the flow channel 316 through the gas injection inlet 350. Droplets are formed as a result of the interaction between the fluid stream and the gas stream. Where the fluid stream includes chromatography resin or carriers, the

chromatography resin is suspended in the droplets due to a secondary recirculating flow inside of the droplets. Species small enough to pass through the pores of the filtration membrane 310 traverse the filtration membrane 310 and pass through permeate channel 340 to the at least one permeate outlet 338, and other species too large to pass through the pores of the filtration membrane 310, including the chromatography resin suspended in the droplets, do not traverse the filtration membrane 310 and flow to the retentate outlet 336. Advantageously, the droplets provide separation between the chromatography resin or carriers in the droplets and the walls of the flow channel 316 as well as the surface of the filtration membrane 310. Such separation facilitates flow of the chromatography resin or carriers in the droplets to the retentate outlet 336, which in turn reduces formation of a concentration of molecules, particles, and/or

chromatography resin or carriers on the surface of the filtration membrane 310.

[0064] Figure 8 schematically illustrates an exemplary separation module 400 including a plurality of droplet-based microfluidic filtration devices. The droplet-based microfluidic filtration devices shown in Figure 8 are similar to the device illustrated in Figure 6, but it should be appreciated that the system may include devices similar to the device illustrated in Figure 7 or may include at least one device similar to device shown in Figure 6 and at least one device similar to the device shown in Figure 7. The separation module 400 as shown includes an input line 410 having a plurality of branches 410a, 410b, 410c fluidly connected to the liquid inlets 226a, 226b, 226c of the plurality of droplet-based microfluidic filtration devices 200a, 200b, 200c. In operation, a fluid stream to be filtered is delivered from a source 420 (which may be another module in the purification system 10) through the plurality of branches 410a, 410b, 410c and into the flow channels 216a, 216b, 216c of the respective devices 200a, 200b, 200c. As the fluid stream flows into the flow channels 216a, 216b, 216c, a gas stream flows into the flow channels 216a, 216b, 216c through the gas injection inlet 250a, 250b, 250c and droplets are formed as a result of the interaction between the fluid stream and the gas stream. Where the fluid stream includes chromatography resin or carriers, the chromatography resin or carriers are suspended in the droplets due to a secondary recirculating flow inside of the droplets. Species small enough to pass through the pores of the filtration membranes 210a, 210b, 210c traverse the filtration membrane 210a, 210b, 210c and other species too large to pass through the pores of the filtration membrane 210a, 210b, 210c, including the chromatography resin suspended in the droplets, do not traverse the filtration membrane 210a, 210b, 210c and flow to the retentate outlets 236a, 236b, 236c. Figure 8 illustrates a separation module 400 having three separate droplet-based microfluidic filtration devices 200a, 200b, 200c, but it should be appreciated that the separation module 400 may include any number of droplet-based microfluidic filtration devices. Additionally, the droplet-based microfluidic filtration devices 200a, 200b, 200c of the separation module 400 shown in Figure 8 are configured in parallel. It is also contemplated, though not shown in the figures, that the plurality of droplet-based microfluidic filtration devices may alternatively, or in addition, include droplet-based microfluidic filtration devices in series such that the liquid inlet 226 of a subsequent device is fluidly connected to either of the retentate outlet 236 or the permeate outlet 238 of a first of the plurality of droplet-based microfluidic filtration devices 200a, 200b, 200c.

[0065] According to embodiments of the present disclosure, the separation module 400 or separation devices as described herein may include filtration devices having a plurality of filtration membranes such as are illustrated in Figure 9. Figure 9 schematically illustrates an exemplary filtration device 1200 in accordance with embodiments of the present disclosure. As shown, the device 1200 includes a flow channel 1216, an upper chamber 1246 and a lower chamber 1248. An upper filtration membrane 1210 separates the upper chamber 1246 from the flow channel 1216 and a lower filtration membrane 1240 separates the lower chamber 1248 from the flow channel 1216. The upper filtration membrane 1210 and the lower filtration membrane 1240 may have substantially equal pore size. Alternatively, the upper filtration membrane 1210 may have a pore size that is less than the pore size of the lower filtration membrane 1240. The flow channel 1216 includes an inlet 1226 and a retentate outlet 1236. The upper chamber 1246 includes a liquid inlet 1256 and the lower chamber 1248 includes a permeate outlet 1258. [0066] In operation, a fluid stream flows into flow channel 1216 through inlet 1226, along the length of the filtration membranes 1210, 1240 and out of the retentate outlet 1236. Liquid is also introduced into the upper chamber 1246 through liquid inlet 1256. As will be described in further detail below, the liquid introduced into the upper chamber 1246 through liquid inlet 1256 may be chosen based on the desired treatment of the fluid stream in the flow channel 1216. For example, where the fluid stream includes chromatography resin, the liquid may be, for example, but without limitation, a wash solution, an eluent solution, a regeneration solution, or any other liquid solution or mixture. As with dead end filtration where the flow of liquid is substantially perpendicular to a membrane surface, liquid in the upper chamber 1246 flows to the upper filtration membrane 1210, traverses the membrane 1210, and contacts the fluid stream in the flow channel 1216. As the fluid stream flows tangentially through the flow channel 1216, flow of the liquid through the flow channel 1216 substantially perpendicular to the filtration membranes 1210, 1240 creates a pressure which allows some of the compounds to flow toward lower filtration membrane 1240. Species small enough to pass through the pores of the lower filtration membrane 1240 traverse the membrane 1240 and other species too large to pass through the pores of the lower filtration membrane 1240, including chromatography resin in the fluid stream, do not traverse the membrane 1240 and flow tangentially to the retentate outlet 1236.

[0067] The portion of the fluid stream that flows out of the retentate outlet 1236, referred to herein as the retentate, may be collected for use in later processes. For example, where the retentate includes carriers such as chromatography affinity beads, the carriers may be collected and transferred to a batch chromatography process or a column chromatography process.

Optionally, the retentate may be recycled back to the inlet 1226 of flow channel 1216 for a subsequent pass through the filtration device 1200. Optionally, when recycled in the same filtration device 1200, the liquid introduced into the upper chamber 1246 through liquid inlet 1256 may be the same as, or may be different than, the liquid introduced into the upper chamber 1246 through liquid inlet 1256 during the previous pass. For example, the liquid introduced into the upper chamber 1246 through liquid inlet 1256 during a first pass may be a wash solution, while the liquid introduced into the upper chamber 1246 through liquid inlet 1256 during subsequent passes may be a wash solution, or alternatively, another solution, such as an eluent solution or a regeneration solution.

[0068] Figure 10 schematically illustrates an exemplary separation module including a plurality of filtration devices as described herein. The separation module 1300 is shown in Figure 10 as including three filtration devices 1200a, 1200b, 1200c. However, it should be understood that the separation module 1300 is not so limited and may include any number of filtration devices. The separation module 1300 shown in Figure 10 includes three filtration devices 1200a, 1200b, 1200c fluidly connected in series. Each filtration device 1200a, 1200b, 1200c includes a flow channel 1216a, 1216b, 1216c, an upper chamber 1246a, 1246b, 1246c and a lower chamber 1248a, 1248b, 1248c. An upper filtration membrane 1210a, 1210b, 1210c separates the upper chamber 1246a, 1246b, 1246c from the flow channel 1216a, 1216b, 1216c and a lower filtration membrane 1240a, 1240b, 1240c separates the lower chamber 1248a, 1248b, 1248c from the flow channel 1216a, 1216b, 1216c. The flow channel 1216a, 1216b, 1216c includes an inlet 1226a, 1226b, 1226c and a retentate outlet 1236a, 1236b, 1236c. The upper chamber 1246a, 1246b, 1246c includes a liquid inlet 1256a, 1256b, 1256c and the lower chamber 1248a, 1248b, 1248c includes a permeate outlet 1258a, 1258b, 1258c. The filtration devices 1200a, 1200b, 1200c operate as described above with reference to filtration device 1200.

[0069] In operation of separation module 1300, a fluid stream flows out of the retentate outlet 1236a, through fluid connection 1310 which fluidly connects filtration device 1200a to the inlet 1226a of filtration device 1200b. Similarly, the fluid stream flows through flow channel 1216b, out of retentate outlet 1236b and through fluid connection 1320 which fluidly connects filtration device 1200b to the inlet 1226c of filtration device 1200c. Liquid is also introduced into the upper chamber 1246a, 1246b, 1246c through respective liquid inlet 1256a, 1256b, 1256c. As with dead end filtration where the flow of liquid is substantially perpendicular to a membrane surface, liquid in the upper chamber 1246a, 1246b, 1246c flows to the upper filtration membrane 1210a, 1210b, 1210c, traverses the membrane 1210a, 1210b, 1210c, and contacts the fluid stream in the flow channel 1216a, 1216b, 1216c. As the fluid stream flows tangentially through the flow channel 1216a, 1216b, 1216c, flow of the liquid through the flow channel 1216a, 1216b, 1216c substantially perpendicular to the filtration membranes 1210a, 1210b, 1210c, 1240a, 1240b, 1240c generates a pressure which allows some of the compounds to flow toward lower filtration membrane 1240a, 1240b, 1240c. Species small enough to pass through the pores of the lower filtration membrane 1240a, 1240b, 1240c traverse the membrane 1240a, 1240b, 1240c and other species too large to pass through the pores of the lower filtration membrane 1240a, 1240b, 1240c, including carriers in the fluid stream, do not traverse the membrane 1240a, 1240b, 1240c and flow tangentially to the retentate outlet 1236a, 1236b, 1236c.

[0070] In separation module 1300, the liquid introduced into the upper chambers 1246a,

1246b, 1246c through the respective liquid inlets 1256a, 1256b, 1256c may be the same or may be different. For example, according to embodiments of the present disclosure, the liquid introduced into each of the upper chambers 1246a, 1246b, 1246c may be a wash solution, an eluent solution, or a regeneration solution. Alternatively, according to another example, the liquid introduced into upper chamber 1246a may be a wash solution, while the liquid introduced into upper chamber 1246b may be an eluent solution, and the liquid introduced into upper chamber 1246c may be a regeneration solution. When the fluid stream includes carriers such as chromatography affinity beads, the separation module 1300 facilitates performing each of the steps of washing, eluting and regenerating the chromatography affinity beads in a single, closed system. After flowing out of the retentate outlet 1236c, the retentate may be collected for use in later processes. For example, where the retentate includes carriers such as chromatography affinity beads, the carriers may be collected and transferred to a batch chromatography process or a column chromatography process. Optionally, the retentate may be recycled back to inlet 1226a of flow channel 1216a for a subsequent pass through the separation module 1300.

[0071] Figure 11 schematically illustrates an exemplary filtration device in accordance with embodiments described herein. As shown, the filtration device 1400 includes a flow channel 1416, an upper chamber 1446 and a lower chamber 1448. An upper filtration membrane 1410 separates the upper chamber 1446 from the flow channel 1416 and a lower filtration membrane 1440 separates the lower chamber 1448 from the flow channel 1416. The flow channel 1416 includes an inlet 1426 and a retentate outlet 1436. [0072] The upper chamber 1446 includes a plurality of upper chamber portions 1446a,

1446b, 1446c separated by walls 1486a, 1486b. For example, in the exemplary filtration device 1400 shown in Figure 11, upper chamber portion 1446a is separated from upper chamber portion 1446b by wall 1486a and upper chamber portion 1446b is separated from upper chamber portion 1446c by wall 1486b. Each of the upper chamber portions 1446a, 1446b, 1446c include a liquid inlet 1256a, 1256b, 1256c. The walls 1486a, 1486b separate the upper chamber portions 1446a, 1446b, 1446c such that liquid introduced into one of the upper chamber portions 1446a, 1446b, 1446c through liquid inlet 1256a, 1256b, 1256c does not flow into any other of the upper chamber portions 1446a, 1446b, 1446c. The device 1400 is shown in Figure 11 as including three upper chamber portions 1446a, 1446b, 1446c and two walls 1486a, 1486b. However, it should be understood that the device 1400 is not so limited and may include“n” number of upper chamber portions, and“n-1” number of walls in the upper chamber 1446, where n is any integer greater than 1.

[0073] The lower chamber 1448 includes a plurality of upper chambers 1448a, 1448b,

1448c separated by walls 1488a, 1488b. For example, in the exemplary tangential filtration device 1400 shown in Figure 11, lower chamber 1448a is separated from lower chamber 1448b by wall 1488a and lower chamber 1448b is separated from lower chamber 1448c by wall 1488b. Each of the upper lower 1446a, 1446b, 1446c include a permeate 1258a, 1258b, 1258c. The walls 1488a, 1488b separate the lower chambers 1448a, 1448b, 1448c such that fluid which traverses the lower filtration membrane 440 flows into one of the lower chambers 1448a, 1448b, 1448c, but does not flow into any other of the lower chambers 1448a, 1448b, 1448c. The device 400 is shown in Figure 11 as including three lower chambers 1448a, 1448b, 1448c and two walls 1488a, 1488b. However, it should be understood that the device 1400 is not so limited and may include“n” number of lower chamber portions, and“n-1” number of walls in the lower chamber 1448, where n is any integer greater than 1.

[0074] In operation of filtration device 1400, a fluid stream flows into flow channel 1416 through inlet 1426, along the length of the filtration membranes 1410, 1440 and out of the retentate outlet 1436. Liquid is also introduced into the upper chamber portions 1446a, 1446b, 1446c through liquid inlets 1456a, 1456b, 1456c and is maintained within the individual upper chambers 1446a, 1446b, 1446c by walls 1486a, 1486b. The liquid introduced into the each of the upper chambers 1446a, 1446b, 1446c through liquid inlets 1456a, 1456b, 1456c may be chosen based on the desired treatment of the fluid stream in the flow channel 1416. The fluid may be, for example, but without limitation, a wash solution such as a washing buffer, an eluent solution such as a solvent, a regeneration solution such as a regeneration buffer, or any other liquid solution or mixture. As with dead end filtration where the flow of liquid is substantially perpendicular to a membrane surface, liquid from the upper chamber portions 1446a, 1446b, 1446c flows to the upper filtration membrane 1410, traverses the membrane 1410, and contacts the fluid stream in flow channel 1416. As the fluid stream flows tangentially through the flow channel 1416, flow of the liquid through the flow channel 1416 substantially perpendicular to the filtration membranes 1410, 1440 generates a pressure which allows some of the compounds to flow toward lower filtration membrane 1440. Species small enough to pass through the pores of the lower filtration membrane 1440 traverse the membrane 1440 and other species too large to pass through the pores of the lower filtration membrane 1440, including carriers in the fluid stream, do not traverse the membrane 1440 and flow tangentially to the retentate outlet 1436.

[0075] In filtration device 1400, the liquid introduced into the upper chamber portions

1446a, 1446b, 1446c through the respective liquid inlets 1456a, 1456b, 1456c may be the same or may be different. For example, according to embodiments of the present disclosure, the liquid introduced into each of the upper chamber portions 1446a, 1446b, 1446c may be a wash solution, an eluent solution, or a regeneration solution. Alternatively, according to another example, the fluid introduced into upper chamber 1446a may be a wash solution, while the fluid introduced into upper chamber 1446b may be an eluent solution, and the fluid introduced into upper chamber 1446c may be a regeneration solution. When the fluid stream includes carriers such as chromatography affinity beads, the filtration device 1400 facilitates performing each of the steps of washing, eluting and regenerating the chromatography affinity beads in a single, closed device. After flowing out of the retentate outlet 1436, the retentate may be collected for use in later processes. For example, where the retentate includes carriers such as chromatography affinity beads, the carriers may be collected and transferred to a batch chromatography process or a column chromatography process. Optionally, the retentate may be recycled back to the inlet 1426 of flow channel 1416 for a subsequent pass through the device 1400.

[0076] According to embodiments of the present disclosure, the separation module 18 or separation devices as described herein may include filtration devices such as are illustrated in Figures 12-13. Figure 12 schematically illustrates an exemplary filtration device 700. As shown, the device 700 may have a similar configuration as the tangential filtration assembly 100 shown in Figure 5 with a filtration membrane 710 as described above positioned between, and separating, flow channel 716 and flow channel 718. The first flow channel includes a liquid inlet 726 and a retentate outlet 736, and the second flow channel 718 includes a liquid inlet 728 and a permeate outlet 738. Species small enough to pass through the pores of the filtration membrane 710 traverse the filtration membrane 710 and other species too large to pass through the pores of the filtration membrane 710, including the carriers suspended in the droplets, do not traverse the filtration membrane 710 and flow from the liquid inlet 726 to the retentate outlet 736.

[0077] The device 700 may further include a vibration element 780. As used herein, the terms“vibrate” or "vibration" are used to refer to the oscillating, reciprocating, or other periodic motion of a rigid or elastic body or surface forced from a position or state of equilibrium. As shown in Figure 12, the vibration element 780 may be fastened to the filtration membrane 710 and may be configured to provide localized vibration to the filtration membrane 210. It should be appreciated that according to embodiments of the present disclosure, the vibration element 780 may be positioned in contact with the filtration membrane 710 without being fastened thereto. Alternatively, the vibration element 780 may be fastened to, or positioned in contact with, the filtration device 700 and may be configured to provide global vibration to the entire device 700, which in turn vibrates the filtration membrane 710. As used herein, the term“localized vibration” is used to refer to the controlled vibration of specific areas of a device, and the term “global vibration” is used to refer to vibration of an entire device. The vibration element 780 may be, for example but without limitation, various pneumatic or electric vibrators which create a reciprocating motion of the filtration membrane 710. Such vibration produces a turbulent flow of fluid in proximity to the filtration membrane 710 and causes the molecules, particles, and/or carriers to move away from the filtration membrane 710, which in turn reduces formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membrane 710. Advantageously, the vibration element 780 provides a non-destructive, energy efficient element which is relatively easy to install in the filtration device 700, requires little maintenance, is easily adjustable, and is easily scalable as the size of the filtration device 700 increases for specific bioprocessing applications.

[0078] Figure 13 schematically illustrates an exemplary filtration device according to embodiments of the present disclosure which includes a plurality of filtration membranes that are vertically orientated. As shown, the device 800 includes a vertically oriented flow channel 816 separated from a first chamber 846 by a first vertically oriented filtration membrane 810 and separated from a second chamber 848 by a second vertically oriented filtration membrane 840. The filtration membranes 810, 840 may have substantially equal pore size. The flow channel 816 includes an inlet 826 and a retentate outlet 836. The first chamber 846 includes a liquid inlet 842 and a permeate outlet 856 and the second chamber 848 also includes a liquid inlet 844 and a permeate outlet 858.

[0079] In operation, a fluid stream flows into flow channel 816 through inlet 826, along the length of the filtration membranes 810, 840 and out of the retentate outlet 836. Liquid is also introduced into the first chamber 846 through liquid inlet 842 and into the second chamber 848 through liquid inlet 844. The flow rates of liquid through the first chamber 846 and the second chamber 848 are controlled to create a transmembrane pressure across the first filtration membrane 810 that is substantially equal to the transmembrane pressure across the second filtration membrane 840. As the fluid stream flows vertically through the flow channel 816 and substantially perpendicular to the filtration membranes 810, 840, the transmembrane pressure species small enough to pass through the pores of the filtration membranes 810, 840 to traverse the membranes 810, 840 and other species too large to pass through the pores of the filtration membranes 810, 840, including carriers in the fluid stream, to remain in the flow channel 816 and to flow tangentially to the retentate outlet 836. [0080] The portion of the fluid stream that flows out of the retentate outlet 836, referred to herein as the retentate, may be collected for use in later processes. For example, where the retentate includes carriers such as chromatography affinity beads, the carriers may be collected and transferred to a batch chromatography process or a column chromatography process.

Optionally, the retentate may be recycled back to the inlet 826 of flow channel 816 for a subsequent pass through the filtration device 800.

[0081] The vertical orientation of the filtration device 800 results in a flow of a fluid stream through the flow channel 816 in a direction substantially similar to the direction of the gravitational force, which is perpendicular to the surface of the first and second filtration membranes 810, 840. As such, the vertical orientation of the filtration device 800 takes advantage of the gravitational force to prevent concentration of molecules, particles, and/or carriers on the surface of the filtration membrane, which in turn results in suppression of filter fouling during operation of the filtration device 800. Additionally, by maintaining a substantially equal transmembrane pressure across the first filtration membrane 810 and the second filtration membrane 840, molecules, particles, and/or carriers in the fluid stream do not favor movement in the direction of either of the filtration membranes 810, 840 and thus do not concentrate on the surface of the filtration membranes 810, 840 during operation of the filtration device 800.

[0082] As will be described in further detail below, backwashing of the filtration membrane(s) may be performed in any of the devices described herein to further suppress filter fouling. Additionally, though not illustrated, the filtration device 800 shown in Figure 13 may also include a vibration element as described with reference to the filtration device 700 shown in Figure 12.

[0083] Separation modules according to embodiments of the present disclosure may include filtration devices as described herein. One or more embodiments of the present disclosure relate to droplet-based microfluidic filtration devices having a flow channel including a liquid inlet and a gas injection inlet situated perpendicular to the liquid inlet. The filtration devices further include a filtration membrane and a permeate outlet. When a fluid stream flows into the flow channel through the liquid inlet and a gas stream enters the flow channel through the gas injection inlet, droplets are formed as a result of the interaction between the fluid stream and the gas stream. Where the fluid stream includes carriers, the carriers are suspended in the droplets due to a secondary recirculating flow inside of the droplets. Advantageously, the droplets provide separation between the carriers suspended in the droplets and the walls of the flow channel as well as the surface of the filtration membrane. Such separation facilitates flow of the carriers within the flow channel, which in turn reduces formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membrane and prevents clogging of the filtration membrane. Prevention of clogging allows for filtration in the droplet- based microfluidic filtration devices described herein can be performed more consistently and more efficiently than in conventional tangential filtration assemblies.

[0084] To study the formation and transport of droplets, a 3D transient model was designed using CFD modeling software. In particular, the CFD modeling software used was FLUENT (commercially available from Fluent Inc., New York, NY). The 3D transient model is illustrated in Figure 8 and includes a gas injection inlet and a liquid inlet forming a T-junction in a flow channel. The model further includes a permeate outlet channel separated from the flow channel by a filtration membrane and a bead outlet at an end of the flow channel opposite the liquid inlet. For the simulations described herein, water was chosen as the liquid while air properties were chosen for the gas phase. A first simulation was performed for a droplet-based microfluidic device that did not have a permeate outlet channel separated from the flow channel by a filtration membrane. A second simulation was performed for a droplet-based microfluidic device having a permeate outlet channel separated from the flow channel by a filtration membrane.

[0085] The volume of fluid method (VOF) was used to model the interaction between the liquid and the gas. VOF models each fluid phase by formulating local conservation equations for mass, momentum and energy and replacing the jump conditions at the interface by smoothly varying volumetric forces. This allows tracking of the complicated movement and folding of the interface indirectly by tracking the motion of each of the fluid phases and then determining the interface position as a function of time from the volumetric fluid fractions resulting from the movement of all fluid phases. The VOF approach is thus able to handle flows where the interface folds, breaks or merges.

[0086] Based on Reynold’s Number Calculation, the fluid flow of the present model is considered to be laminar. Because filtration modules are commonly operated at relatively low flow rates, such as between about 0.5 ml/min and about 1.0 ml/min, it was determined that the Reynolds number for such flow rates was less than 2100. Additionally, the present model was designed to account for surface tension effects. Because calculations for the Weber Number yielded values much less than 1 , it was determined that surface tension effects could not be neglected. Based on the calculation of a Peclet number of less than 1, it was determined that flow in the model is dominated by convection. As such, second order upwind differencing was used for the discretization of momentum equations. The pressure field was calculated via the PISO algorithm. A first order implicit scheme was chosen for the time discretization with variable time stepping. Proper time step controls were applied to ensure that the global Courant number during simulations were below 0.25. The flow under consideration is subjected to gravitational body force, and therefore the implicit body force treatment scheme was employed in the present model.

[0087] At the junction of the gas injection inlet and the liquid inlet, gas and liquid velocities were specified which were based on conventional operating flow rates for filtration devices. Pressure conditions were also specified at each of the permeate outlet channel and the bead outlet. No slip boundary conditions were specified at the walls of the channel and inlets and outlets associated with a constant contact angle. The filtration membrane was modeled as a porous zone having a thickness of 55 microns, a porosity of 2% and permeability to air and water in the range of 10 ¹³ m ² to 10 ¹⁴ m ² . In the model, a contact angle for the walls was assumed to be 150°

[0088] It is believed that the length of a formed droplet can be important to the performance of a droplet-based microfluidic device. Generally, longer droplets would be less favorable as more filtration would be required to concentrate carriers at the carrier outlet. One factor affecting droplet size is the liquid-to-gas flow rate ratio. Relatively short slugs can be formed by maintaining a liquid-to-gas flow rate ratio of less than, or about, 1, with the proviso that gas flow greater than liquid flow can limit the formation of droplets or cause formed droplets to burst. As such, the present model was designed to have liquid-to-gas flow rate of 1 : 1.

[0089] The first simulation, as described above, was performed to primarily understand droplet formation dynamics. Due to the low Reynolds number in such droplet based microfluidic devices, inertial forces were neglected, and the droplet formation/breakup characteristics were attributed to interfacial tension, viscous shear stresses and pressure gradient across the gas/liquid interface. Figure 9 illustrates the formation of a droplet at the T-junction of the channel of the modeled droplet-based microfluidic device. Under the modeled conditions, the droplets broke up upon contacting the wall of the channel. Without wishing to be bound by any particular theory, it is believed that the interfacial forces and shear stresses on the droplet contribute to the breakup of the droplet.

[0090] In modeling the formation of the droplets, a secondary recirculating flow was observed within the droplets. This secondary recirculating flow suspends carriers within the droplets and prevents settling of the carriers in the channel and/or on the filtration membrane. Generally, as droplets flow along the channel, the fluid elements of the droplets closest to the channel walls move at a slower pace than the fluid elements closest to the center of the droplets. Owing to the immiscibility of the gas and liquid phases, the faster moving fluid elements of the droplets cannot penetrate the gas/liquid interface and results in vortices in the droplets as they are forced to move towards the channel walls. The vortices of the droplets of the present model were observed to be at the back, the front, the upper, and the lower sections of the droplets.

[0091] The minimum recirculation velocity which is required to keep the carriers suspended in the droplets can be calculated. The free settling velocity of the carriers, Vs, can be calculated by balancing the forces acting on the carrier, for example, gravity, buoyancy and drag, and can be expressed as in Formula 1 : where p _P is the density of carrier, p is the density of the fluid, CD is the drag coefficient, V _P is the volume of the carrier and Ap are the surface area of the carrier. For the present model, the carriers have sizes varying from about 40 microns to about 100 microns a density of about 1.05 g/cc. Assuming Stoke’s drag, where CD can be expressed as in Formula 2, the settling velocity of the carrier is estimated to be 0.005 m/s.

24/Reynold’s Number (2)

In contrast, the minimum recirculation velocity in the droplets is estimated to be about 0.1 m/s. The first simulation demonstrates that, because the recirculation velocity is about two orders of magnitude greater than the settling velocity of the carriers, the recirculation velocity is large enough to suspend the carriers in the droplets. Suspension of the carriers in the droplets prevents direct contact between the carriers and the walls of the channel, facilitates consistent flow of the carriers through the channel and prevents a concentration of settled carriers at the bottom of the channel.

[0092] The second simulation, as described above, was performed to primarily understand filtration capabilities of the model. Figure 9 illustrates the filtration process at different stages in the modeled droplet-based microfluidic device. A back pressure of about 1.5 psi was applied to the permeate outlet channel to form a transmembrane pressure across the filtration membrane. A calculation based on drag and lift forces can be performed to determine the minimum velocity to prevent deposition of carriers on the filtration membrane. Utilizing a lift force expression and balancing lift and drag forces on the carrier, the critical velocity for preventing settling of the carriers on the filtration membrane, Vc, can be computed as shown in Formula 3: where Dp is the carrier diameter, r _w is the tangential shear stress, p is the density of the liquid and m is the viscosity of the liquid. Using appropriate values, the critical velocity is estimated to be 0.0183 m/s. As described above, the minimum recirculation velocity in the droplets is estimated to be about 0.1 m/s. Because the recirculation velocity is an order of magnitude greater than the critical velocity, the recirculation velocity is large enough to prevent settling of the carriers on the filtration membrane.

[0093] The second simulation demonstrates that formed droplets are capable of flowing through the channel of the droplet-based microfluidic device and that at least some of the liquid will pass through the filtration membrane and into the permeate outlet channel, while the carriers flow to the carrier outlet.

[0094] One or more embodiments of this disclosure relate to filtration devices having a plurality of filtration membranes, as well as to filtration methods. The filtration devices described herein combine aspects of dead-end filtration with aspects of cross flow filtration to generate necessary pressure in the device to perform filtration treatments while minimizing the formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membranes, thus preventing clogging of the filtration membrane. Prevention of clogging.

[0095] Provided herein are also methods for separating at least one target compound from a fluid stream in filtration devices as described herein. Figure 16 is a flow chart illustrating a method 900 as described herein. It should be appreciated that Figure 16 is merely illustrative of embodiments of the methods described herein, that not all of the steps shown need be performed, and that steps of embodiments of the methods described herein need not be performed in any particular order except where an order is specified. As described above, the steps of method 900 may be performed in filtration devices and systems as described herein. One or more of the steps of the method 900 may be performed in a single filtration device, such as described with reference to filtration device 1400 above, or one or more of the steps may be performed in a plurality of filtration devices in series, such as is described with reference to filtration system 1300 above. Additionally, one or more of the steps of the method 900 may be performed in a single filtration device by recycling the retentate from the retentate outlet to the inlet of the flow channel, such as described with reference to fdtration device 1200 and filtration device 1400, or one or more of the steps may be performed in a plurality of filtration devices in series by recycling the retentate from the retentate outlet of one of the plurality of filtration devices to the inlet of the flow channel of another of the plurality of filtration devices, such as is described with reference to filtration system 1300 above.

[0096] The method may include a step 910 of flowing a fluid stream into a flow channel of a filtration device. The fluid stream, which may include carriers, flows tangentially along the length of the filtration membranes of the filtration device and out of a retentate outlet. The fluid stream may be any fluid mixture, for example the output from a batch chromatography process or a column chromatography process in which contact with carriers in the chromatography process results in binding of target compounds with the carrier.

[0097] The method may further include a step 920 of introducing a liquid solution into the upper chamber of the filtration device. The liquid solution traverses the upper filtration membrane and enters the flow channel where the liquid solution contacts the carriers in the fluid stream. Flow of the liquid solution through the flow channel substantially perpendicular to the filtration membranes generates a pressure which allows some of the compounds to flow toward lower filtration membrane. Portions of the liquid solution and species of the fluid stream small enough to pass through the pores of the filtration membrane traverse the lower filtration membrane and enter the lower chamber.

[0098] The liquid solution may be a wash solution, in which case step 920 includes step

920a of washing the carriers of the fluid stream. The wash solution may include, for example, a buffer. Washing the carrier is performed in conditions which provide for substantially all of the target compounds to remain bound to the carriers while compounds not bound to the carriers enter the wash solution. The wash solution, including the compounds not bound to the carriers, then traverses the lower filtration membrane and enters a lower chamber where it may flow out of the filtration device through a permeate outlet. [0099] The liquid solution may be an eluent solution, in which case step 920 includes step 920b of eluting the carriers in the fluid stream. Eluting the carriers is performed in conditions which provide for substantially all of the compounds bound to the carriers to be released from the carriers and to enter the eluent solution. The eluent solution, including the compounds released from the carriers, then traverses the lower filtration membrane and enters the lower chamber where it may flow out of the filtration device through the permeate outlet.

[00100] The liquid solution may be a regeneration solution in which case step 920 includes step 920c of refreshing the carriers. Refreshing the carriers may include adding a regeneration solution, such as a regeneration buffer, to the filtration device to prepare the carrier to be returned to a chromatography process. A regeneration solution is a solution that substantially restores a chromatography matrix, such as a chromatography affinity bead, to its original strength or properties.

[00101] According to embodiments of the present disclosure, step 920 of introducing a liquid solution into the upper chamber of the filtration device may include introducing a plurality of liquid solutions into a plurality of upper chamber portions of the filtration device. The plurality of liquid solutions may be the same or may be different. For example, each of the plurality of liquid solutions may be wash solutions, eluent solutions or regeneration solutions. Alternatively, at least one of the plurality of liquid solutions may be a wash solution, an eluent solution or a regeneration solution and another of the plurality of liquid solutions may be another of a wash solution, an eluent solution or a regeneration solution. According to one non-limiting embodiment, the filtration device includes three upper chamber portions and introducing a plurality of liquid solutions into a plurality of upper chamber portions of the filtration device includes introducing a wash solution into a first of the three upper chamber portions, introducing an eluent solution into a second of the three upper chamber portions and introducing a regeneration solution into the third of the three upper chamber portions.

[00102] The method may further include a step 930 of collecting the retentate from the retentate outlet. According to embodiments of the present disclosure, the retentate includes the carriers. Optionally, step 930 of collecting the retentate from the retentate outlet may include collecting the desired product. The method may further include a step 940 of collecting the permeate from the permeate outlet. Optionally, step 940 of collecting the permeate from the permeate outlet may include collecting the desired product. It should be appreciated that, according to embodiments of the present disclosure, the step of the method at which the desired product is removed from the filtration device will depend on the conditions selected for the separation method. For example, the desired product may be the target compound, or the compound bound to the carriers, and may be removed from the filtration device in an eluent solution by performing step 920b of eluting the carriers in the fluid stream. Alternatively, the desired product may not be the target compound and may be removed from the filtration device in a wash solution by performing step 920a of washing the carriers of the fluid stream. As yet another alternative, two or more products may be desired products. For example, the user may collect compounds not bound to the carriers in the wash solution as a first desired product and may also collect the target compound as a second desired product. According to embodiments of the present disclosure, any of the compounds in the fluid stream may be considered the desired product and it is ultimately within the user’s discretion which compounds to collect for later use or processing and which compounds to discard.

[00103] Following collecting the retentate, the method may further include a step 950 of flowing the retentate into a flow channel of a filtration device. Flowing the retentate into a flow channel of a filtration device may include a step 950a of flowing the retentate from a first filtration device into a flow channel of a second filtration device. The step 950a of flowing the retentate from a first filtration device into a flow channel of a second filtration device may follow performing in the first filtration device any one of step 920a of washing the carriers of the fluid stream, step 920b of eluting the carriers in the fluid stream, or step 920c of refreshing the carriers. Following the step 950a of flowing the retentate from a first filtration device into a flow channel of a second filtration device, any one of step 920a of washing the carriers of the fluid stream, step 920b of eluting the carriers in the fluid stream, or step 920c of refreshing the carriers may be performed in the second filtration device. [00104] Alternatively, flowing the retentate into a flow channel of a filtration device may include a step 950b of flowing the retentate from a first filtration device into the flow channel of the same first filtration device. The step 950b of flowing the retentate from a first filtration device into the flow channel of the same first filtration device may follow performing in the first filtration device any one of step 920a of washing the carriers of the fluid stream, step 920b of eluting the carriers in the fluid stream, or step 920c of refreshing the carriers. Following the step 950b of flowing the retentate from a first filtration device into the flow channel of the same first filtration device, any one of step 920a of washing the carriers of the fluid stream, step 920b of eluting the carriers in the fluid stream, or step 920c of refreshing the carriers may be performed in the same first filtration device.

[00105] One or more embodiments of the present disclosure relate to filtration devices that suppress filter fouling and methods for suppressing filter fouling. The filtration devices control fouling by preventing concentration of molecules, particles, and/or carriers on the surface of the filtration membrane. Controlling fouling allows for filtration in the filtration devices described herein to be performed more consistently and more efficiently than in conventional tangential filtration assemblies. Furthermore, controlling fouling in accordance with embodiments of the present disclosure promotes maintenance of transmembrane flux, reduces the frequency that the filtration membranes must be cleaned, reduces the down time of operation of the device, and enhances membrane lifetime.

[00106] Figure 17 is a flow chart illustrating a method 1700 for suppressing filter fouling in filtration devices as described herein. It should be appreciated that Figure 17 is merely illustrative of embodiments of the methods described herein, that not all of the steps shown need be performed, and that steps of embodiments of the methods described herein need not be performed in any particular order except where an order is specified.

[00107] The method may include a step 1710 of flowing a fluid stream into a first flow channel of a filtration device. The fluid stream, which may include carriers, flows tangentially along the length of the filtration membranes of the filtration device and out of a retentate outlet.

The fluid stream may be any fluid mixture, for example the output from a batch chromatography process or a column chromatography process in which contact with carriers in the chromatography process results in binding of target compounds with the carrier.

[00108] The method may further include a step 1720 of flowing a fluid stream into a second flow channel of a filtration device, where the second flow channel is arranged on the opposite side of a filtration element from the first flow channel. The method may further include a step 1730 of applying a transmembrane pressure across the filtration membrane. The transmembrane pressure allows species in the first flow channel that are small enough to pass through the pores of the filtration membrane to traverse the filtration membrane and enter the second flow channel. Optionally, the step 1720 of flowing a fluid stream into a second flow channel of a filtration device may include flowing a fluid stream into a plurality of second flow channels of the filtration device where each of the plurality of second flow channels are arranged on opposite sides of a plurality of filtration elements from the first flow channel. Additionally, the step 1730 of applying a transmembrane pressure across the filtration membrane may include applying a transmembrane pressure across the plurality of filtration membranes. The

transmembrane pressure allows species in the first flow channel that are small enough to pass through the pores of the plurality of filtration membranes to traverse the plurality of filtration membrane and enter the plurality of second flow channels.

[00109] The method may further include a step 1740 of vibrating the filtration membrane. Step 1740 may include applying localized vibration to the filtration membrane. Alternatively, step 1740 may include applying global vibration to the filtration device. Vibrating the filtration membrane may be performed continuously during operation of the filtration device, or may be performed during predetermined periods of time. As one non-limiting example, vibrating the filtration membrane may be performed for a predetermined period of time during operation of the filtration device. As an alternative non-limiting example, vibrating the filtration membrane may be performed when no fluid stream is flowing through the first or second flow channel of the filtration device, but is not performed when a fluid stream is flowing through the first or second flow channel of the filtration device. Where the device includes a plurality of filtration membranes, the step 1740 of vibrating the filtration membrane may include vibrating at least one of the plurality of filtration membranes. For example, the step 1740 may include vibrating a first of the plurality of the filtration membranes while not vibrating a second of the plurality of filtration membranes. As an alternative, the step 1740 may include vibrating all of the plurality of filtration membranes, or at least two of the plurality of filtration membranes, at the same time.

[00110] The method may further include a step 1750 of backwashing the filtration membrane. The step 1750 of backwashing the filtration membrane may generally include reversing the transmembrane pressure such that fluid in the second flow channel traverses the filtration membrane and enters the first flow channel. Where the device includes a plurality of filtration membranes, the step 1750 of backwashing the filtration membrane may include backwashing at least one of the plurality of filtration membranes. For example, the step 1750 may include backwashing a first of the plurality of the filtration membranes while not backwashing a second of the plurality of filtration membranes. As an alternative, the step 1750 may include backwashing all of the plurality of filtration membranes, or at least two of the plurality of filtration membranes, at the same time. The backwashing cleans accumulated molecules, particles, and/or carriers from within the pores of the filtration membrane and also reduces formation of a concentration of molecules, particles, and/or carriers on the surface of the filtration membrane. Backwashing the filtration membrane may include flowing a fluid stream into the second flow channel through one of the liquid inlet or the permeate outlet of the second flow channel and closing the other of the liquid inlet and the permeate outlet. Where the device includes a plurality of second flow channels, backwashing the filtration membrane may include flowing a fluid stream into at least one of the plurality of second flow channels. The fluid may include a gas, a liquid or combination thereof and, optionally, the fluid may be a pressurized fluid.

[00111] Examples

[00112] To study the effect of filter fouling suppression as described herein, 10% by volume of DOWEX™ 50WX2 Resin Beads (commercially available from The Dow Chemical Company, Midland, Michigan) were suspended in water and flowed into a plurality of tangential flow filtration device at a flow rate of 10 ml/min. The flow rates at the retentate and permeate outlets were 5.0 ml/min and were controlled by a pump. A first configuration (Device A) was a conventional tangential flow filtration device which served as a reference. In a second configuration (Device B), a tangential flow filtration device was impacted with a mechanical force external to the device. In a third configuration (Device C), a vibration element was connected to the device which provided a frequency of 800Hz to the filtration membrane of the tangential flow filtration device. In the reference Device A, the pressure in the device was monitored and fouling was observed to occur after about 300 seconds when the pressure in the device exceed about 0.3 bar. In contrast, the Devices B and C were observed to delay fouling by about 33% as compared to the reference Device A.

[00113] In configurations similar to the configuration of Device A described above, the effect of backwashing the filtration membrane was studied. Under similar operating parameters as described above, the flow direction of the pumps was reversed at regular intervals to perform a backwash of the filtration membrane. In a first device (Device D), the flow direction was reversed about every 14 seconds for about 1 second. In a second device (Device E), the flow direction was reversed about every 28 seconds for about 2 seconds. Both of Device D and Device E fluctuated from a high pressure immediately prior to backwashing to a low pressure immediately following backwashing. Because of the longer period between backwashes, higher pressures were observed in Device E than in Device D. After about 600 seconds of operation, the highest pressure in Device E was observed to be about 0.25 bar at a time immediately prior to backwashing. In contrast, after about 600 seconds of operation, the highest pressure in Device D was observed to be about 0.18 bar immediately prior to backwashing and the Device D was observed to delay fouling for a longer period than Device E.

[00114] The effect of filter fouling suppression in a vertically oriented device as described herein was also studied. In a first vertical configuration (Device F) a device having a straight flow channel separated by a filtration membrane from a first chamber was constructed such that fluid in the device flows in a substantially similar to the direction of the gravitational force. In a second vertical configuration (Device G) a device having a straight flow channel separated by a first filtration membrane from a first chamber and separated by a second filtration membrane from a second chamber was constructed such that fluid in the device flows in a substantially similar to the direction of the gravitational force. 10% by volume of DOWEX™ 50WX2 Resin Beads were suspended in water and flowed into the flow channels of Devices F and G at a flow rate of 10 ml/min. The flow rate at the outlet of the first chamber in Device F was 5.0 ml/min and was controlled by a pump. The flow rates at the outlets of the first and second chambers in Device G were 2.5 ml/min and were controlled by a pump. The pressure in the devices was monitored and a constant increase in pressure was observed for both of Devices F and G over a period of about 2 hours. However, after the period of about 2 hours, the increase of pressure in Device G was observed to be 1 Ox smaller than the increase of pressure in Device F over the same period of time.

[00115] Illustrative Implementations

[00116] The following is a description of various aspects of implementations of the disclosed subject matter. Each aspect may include one or more of the various features, characteristics, or advantages of the disclosed subject matter. The implementations are intended to illustrate a few aspects of the disclosed subject matter and should not be considered a comprehensive or exhaustive description of all possible implementations.

[00117] Aspect 1 is directed to a multimodule system for continuous purification of biochemical mixtures comprising:_at least one immobilization module fluidly connected to a feed source and to a resin source, wherein in the at least one immobilization module, chromatography resin from the resin source is contacted with a feed solution from the feed source to bind target compounds from the feed solution with the chromatography resin;_at least one wash module fluidly connected to the at least one immobilization module and to a wash solution source, wherein in the at least one wash module, chromatography resin having target compounds bound thereto is contacted with a wash solution from the wash solution source; and at least one elution module fluidly connected to the at least one wash module and to an eluent solution source, wherein in the at least one elution module, chromatography resin having target compounds bound thereto is contacted with an eluent solution from the eluent solution source to release the target compounds from the chromatography resin. [00118] Aspect 2 is directed to the system of Aspect 1, further comprising at least one regeneration module fluidly connected to a regeneration solution source, wherein in the at least one regeneration module, chromatography resin is contacted with a regeneration solution from the regeneration solution source to refresh the chromatography resin.

[00119] Aspect 3 is directed to the system of Aspect 2, wherein the at least one regeneration module is fluidly connected to the resin source.

[00120] Aspect 4 is directed to the system of any of the preceding Aspects, further comprising at least one separation module disposed downstream of, and fluidly connected to, at least one of the at least one immobilization module, the at least one wash module, and the at least one elution module, wherein the at least one separation module comprises a separation device.

[00121] Aspect 5 is directed to the system of any of the preceding Aspects, wherein at least one of the at least one immobilization module, the at least one wash module, and the at least one elution module comprises a separation device.

[00122] Aspect 6 is directed to the system of any of Aspects 4-5 wherein the separation device comprises a droplet-based microfluidic filtration device comprising: a flow channel comprising a liquid inlet, a retentate outlet and a gas injection inlet situated perpendicular to the liquid inlet; at least one filtration membrane; and at least one permeate outlet.

[00123] Aspect 7 is directed to the system of Aspect 6, comprising a first module and a second module, wherein the first module comprises the flow channel and the second module comprises a second flow channel, wherein the second flow channel comprises a fluid inlet and the permeate outlet, and wherein the filtration membrane separates the flow channel from the second flow channel.

[00124] Aspect 8 is directed to the system of any of Aspect 6-7, wherein the filtration membrane comprises a first surface and a second surface, and wherein a fluid stream in the flow channel flows tangentially over the first surface of the filtration membrane and a fluid stream in the second flow channel flows tangentially over the second surface of the filtration membrane. [00125] Aspect 9 is directed to the system of Aspect 6, wherein the at least one permeate outlet is fluidly connected to the flow channel by a permeate channel.

[00126] Aspect 10 is directed to the system of Aspect 8, wherein the at least one filtration membrane separates the flow channel from the permeate channel.

[00127] Aspect 11 is directed to the system of any of Aspects 9-10 comprising a plurality of permeate outlets and a plurality of filtration membranes, wherein each of the plurality of permeate outlets is fluidly connected to the flow channel by one of a plurality of permeate channels, and wherein each of the plurality of filtration membranes separates the flow channel from one of a plurality of permeate channels.

[00128] Aspect 12 is directed to the system of any of Aspects 6-11, wherein a fluid stream flows into the flow channel and a gas stream flows into the gas injection inlet and wherein droplets are formed by the interaction between the fluid stream and the gas stream.

[00129] Aspect 13 is directed to the system of Aspect 12, wherein contents of the fluid stream are suspended in the droplets due to a secondary recirculating flow inside of the droplets.

[00130] Aspect 14 is directed to the system of any of Aspects 12-13, wherein the fluid stream comprises carriers.

[00131] Aspect 15 is directed to the system of Aspect 14, wherein the carriers comprise chromatography affinity beads.

[00132] Aspect 16 is directed to the system of any of Aspects 4-5 wherein the separation device comprises a filtration device comprising: a flow channel comprising an inlet and a retentate outlet; an upper chamber comprising a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes; and a lower chamber comprising a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes. [00133] Aspect 17 is directed to the system of Aspect 16, wherein a fluid stream flows into the inlet of the flow channel, tangentially along the plurality of membranes, and out of the retentate outlet.

[00134] Aspect 18 is directed to the system of Aspect 17, wherein the fluid stream comprises chromatography affinity beads.

[00135] Aspect 19 is directed to the system of any of Aspects 16-18, wherein a fluid is introduced into the upper chamber through the liquid inlet, traverses the first of a plurality of filtration membranes and flows into the flow channel substantially perpendicular to a surface of the plurality of filtration membranes.

[00136] Aspect 20 is directed to the system of Aspect 19, wherein the fluid introduced into the upper chamber is one of a wash solution, an eluent solution, and a regeneration solution.

[00137] Aspect 21 is directed to the system of any of Aspects 16-20, wherein the upper chamber comprises a plurality of upper chamber portions, wherein each of the upper chamber portions comprises a liquid inlet, and wherein each of the plurality of upper chamber portions is separated from adjacent upper chamber portions by a wall.

[00138] Aspect 22 is directed to the system of any of Aspects 16-21, wherein the lower chamber comprises a plurality of lower chamber portions, wherein each of the lower chamber portions comprises a permeate outlet, and wherein each of the plurality of lower chamber portions is separated from adjacent lower chamber portions by a wall.

[00139] Aspect 23 is directed to the system of any of Aspects 16-22, wherein the first of the plurality of filtration membranes and the second of the plurality of filtration membranes comprise substantially equal pore size.

[00140] Aspect 24 is directed to the system of any of Aspects 16-22, wherein the first of the plurality of filtration membranes comprise a pore size that is smaller than the pore size of the second of the plurality of filtration membranes. [00141] Aspect 25 is directed to the system of any of Aspects 4-5 wherein the separation device comprises a filtration device comprising: a first module comprising a first flow channel comprising a fluid inlet and a retentate outlet; a second module comprising a second flow channel comprising a fluid inlet and a permeate outlet; at least one filtration membrane separating the first flow channel from the second flow channel; and a vibration element.

[00142] Aspect 26 is directed to the system of Aspect 25, wherein the vibration element is positioned in contact with the at least one filtration membrane and is configured to provide localized vibration to the at least one filtration membrane.

[00143] Aspect 27 is directed to the system of Aspect 25, wherein the vibration element is positioned in contact with, the filtration device and is configured to provide global vibration to the filtration device.

[00144] Aspect 28 is directed to the system of Aspect 25, wherein the vibration element is a pneumatic vibrator.

[00145] Aspect 29 is directed to the system of Aspect 25, wherein the vibration element is an electric vibrator.

[00146] Aspect 30 is directed to the system of any of Aspects 25-29, wherein the at least one filtration membrane comprises a first surface and a second surface, and wherein a fluid stream in the first flow channel flows tangentially over the first surface of the filtration membrane and a fluid stream in the second flow channel flows tangentially over the second surface of the filtration membrane.

[00147] Aspect 31 is directed to the system of any of Aspects 25-30, wherein when a transmembrane pressure is applied across the filtration membrane, a species passes from a fluid stream in the first flow channel through the filtration membrane.

[00148] Aspect 32 is directed to the system of any of Aspects 25-31, wherein a fluid stream in the first flow channel comprises carriers. [00149] Aspect 33 is directed to the system of Aspect 32, wherein the carriers comprise chromatography affinity beads.

[00150] Aspect 34 is directed to the system of any of Aspects 4-5 wherein the separation device comprises a filtration device comprising: a vertically oriented flow channel comprising an inlet and a retentate outlet; a first vertically oriented chamber comprising a liquid inlet and a permeate outlet, the first chamber being separated from the flow channel by a first of a plurality of vertically oriented filtration membranes; and a second vertically oriented chamber comprising a liquid inlet and a permeate outlet, the second chamber being separated from the flow channel by a second of the plurality of vertically oriented filtration membranes.

[00151] Aspect 35 is directed to the system of Aspect 34, wherein when a transmembrane pressure is applied across each of the plurality of vertically oriented filtration membranes, a species passes from a fluid stream in the flow channel through the filtration membranes.

[00152] Aspect 36 is directed to the system of any of Aspects 34-35, wherein a fluid stream in the flow channel comprises carriers.

[00153] Aspect 37 is directed to the system of Aspect 36, wherein the carriers comprise chromatography affinity beads.

[00154] Aspect 38 is directed to the system of any of Aspects 6-37, wherein the filtration membrane comprises a porous material.

[00155] Aspect 39 is directed to the system of any of Aspects 6-38, wherein the filtration membrane comprises two filtration sheets arranged on either side of a porous material.

[00156] Aspect 40 is directed to a droplet-based microfluidic filtration device comprising: a flow channel comprising a liquid inlet, a retentate outlet and a gas injection inlet situated perpendicular to the liquid inlet; at least one filtration membrane; and at least one permeate outlet. [00157] Aspect 41 is directed to the device of Aspect 40, comprising a first module and a second module, wherein the first module comprises the flow channel and the second module comprises a second flow channel, wherein the second flow channel comprises a fluid inlet and the permeate outlet, and wherein the filtration membrane separates the flow channel from the second flow channel.

[00158] Aspect 42 is directed to the device of any of Aspects 40-41, wherein the filtration membrane comprises a first surface and a second surface, and wherein a fluid stream in the flow channel flows tangentially over the first surface of the filtration membrane and a fluid stream in the second flow channel flows tangentially over the second surface of the filtration membrane.

[00159] Aspect 43 is directed to the device of Aspect 40, wherein the at least one permeate outlet is fluidly connected to the flow channel by a permeate channel.

[00160] Aspect 44 is directed to the device of Aspect 43, wherein the at least one fdtration membrane separates the flow channel from the permeate channel.

[00161] Aspect 45 is directed to the device of any of Aspects 43-44 comprising a plurality of permeate outlets and a plurality of filtration membranes, wherein each of the plurality of permeate outlets is fluidly connected to the flow channel by one of a plurality of permeate channels, and wherein each of the plurality of filtration membranes separates the flow channel from one of a plurality of permeate channels.

[00162] Aspect 46 is directed to the device of any of Aspects 40-45, wherein the filtration membrane comprises a porous material.

[00163] Aspect 47 is directed to the device of any of Aspects 40-46, wherein the filtration membrane comprises two filtration sheets arranged on either side of a porous material.

[00164] Aspect 48 is directed to the device of any of Aspects 40-47, wherein when a transmembrane pressure is applied across the filtration membrane, a species passes from a fluid stream in the flow channel through the filtration membrane. [00165] Aspect 49 is directed to the device of any of Aspects 40-48, wherein a fluid stream flows into the flow channel and a gas stream flows into the gas injection inlet and wherein droplets are formed by the interaction between the fluid stream and the gas stream.

[00166] Aspect 50 is directed to the device of Aspect 49 wherein contents of the fluid stream are suspended in the droplets due to a secondary recirculating flow inside of the droplets.

[00167] Aspect 51 is directed to the device of any of Aspects 49-50-, wherein the fluid stream comprises carriers.

[00168] Aspect 52 is directed to the device of Aspect 51, wherein the carriers comprise chromatography affinity beads.

[00169] Aspect 53 is directed to the device of Aspect 51, wherein the carriers comprise microcarriers.

[00170] Aspect 54 is directed to a system comprising a plurality of the droplet-based microfluidic filtration devices of any of Aspects 40-53, wherein a fluid stream source is fluidly connected to the liquid inlets of each of the plurality of the droplet-based microfluidic filtration devices.

[00171] Aspect 55 is directed to a filtration device comprising: a flow channel comprising an inlet and a retentate outlet, an upper chamber comprising a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes; and a lower chamber comprising a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes.

[00172] Aspect 56 is directed to the filtration device of Aspect 55, wherein a fluid stream flows into the inlet of the flow channel, tangentially along the plurality of membranes, and out of the retentate outlet.

[00173] Aspect 57 is directed to the filtration device of Aspect 56, wherein the fluid stream comprises chromatography affinity beads. [00174] Aspect 58 is directed to the filtration device of any of Aspects 55-57, wherein a fluid is introduced into the upper chamber through the liquid inlet, traverses the first of a plurality of filtration membranes and flows into the flow channel substantially perpendicular to a surface of the plurality of filtration membranes.

[00175] Aspect 59 is directed to the filtration device of Aspect 58, wherein the fluid introduced into the upper chamber is a wash solution.

[00176] Aspect 60 is directed to the filtration device of Aspect 58, wherein the fluid introduced into the upper chamber is an eluent solution.

[00177] Aspect 61 is directed to the filtration device of Aspect 58, wherein the fluid introduced into the upper chamber is a regeneration solution.

[00178] Aspect 62 is directed to the filtration device of any of Aspects 55-61, wherein the upper chamber comprises a plurality of upper chamber portions, wherein each of the upper chamber portions comprises a liquid inlet, and wherein each of the plurality of upper chamber portions is separated from adjacent upper chamber portions by a wall.

[00179] Aspect 63 is directed to the filtration device of any of Aspects 55-62, wherein the lower chamber comprises a plurality of lower chamber portions, wherein each of the lower chamber portions comprises a permeate outlet, and wherein each of the plurality of lower chamber portions is separated from adjacent lower chamber portions by a wall.

[00180] Aspect 64 is directed to the filtration device of any of Aspects 55-62, wherein the first of the plurality of filtration membranes and the second of the plurality of filtration membranes comprise substantially equal pore size.

[00181] Aspect 65 is directed to the filtration device of any of Aspects 55-63, wherein the first of the plurality of filtration membranes comprise a pore size that is smaller than the pore size of the second of the plurality of filtration membranes. [00182] Aspect 66 is directed to a filtration system comprising a plurality of filtration devices each filtration device comprising: a flow channel comprising an inlet and a retentate outlet, an upper chamber comprising a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes; and a lower chamber comprising a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes.

[00183] Aspect 67 is directed to the filtration system of Aspect 66, wherein a fluid stream flows into the inlet of the flow channel of a first of the plurality of filtration devices, tangentially along the plurality of membranes, out of the retentate outlet and into a fluid connection between the retentate outlet and the inlet of the flow channel of a subsequent filtration device.

[00184] Aspect 68 is directed to the filtration system of Aspect 66, wherein the fluid stream comprises chromatography affinity beads.

[00185] Aspect 69 is directed to the filtration system of any of Aspects 66-68, wherein a fluid is introduced into the upper chamber of at least one of the plurality of filtration devices through the liquid inlet, traverses the first of a plurality of filtration membranes and flows into the flow channel perpendicular to a surface of the plurality of filtration membranes.

[00186] Aspect 70 is directed to the filtration system of Aspect 69, wherein the fluid introduced into the upper chamber of at least one of the plurality of filtration devices is a wash solution.

[00187] Aspect 71 is directed to the filtration system of Aspect 69, wherein the fluid introduced into the upper chamber of at least one of the plurality of filtration devices is an eluent solution.

[00188] Aspect 72 is directed to the filtration system of Aspect 69, wherein the fluid introduced into the upper chamber of at least one of the plurality of filtration devices is a regeneration solution. [00189] Aspect 73 is directed to the filtration system of any of Aspects 66-72, wherein the first of the plurality of filtration membranes and the second of the plurality of filtration membranes comprise substantially equal pore size.

[00190] Aspect 74 is directed to the filtration system of any of Aspects 66-72, wherein the first of the plurality of filtration membranes comprise a pore size that is smaller than the pore size of the second of the plurality of filtration membranes.

[00191] Aspect 75 is directed to a method for separating at least one target compound from a fluid stream in a filtration device, the method comprising: flowing a fluid stream comprising carriers into an inlet of a flow channel of a filtration device, the flow channel comprising a retentate outlet, wherein the filtration device comprises an upper chamber comprising a liquid inlet, the upper chamber being separated from the flow channel by a first of a plurality of filtration membranes, and a lower chamber comprising a permeate outlet, the lower chamber being separated from the flow channel by a second of the plurality of filtration membranes; introducing a liquid solution into the upper chamber of the filtration device.

[00192] Aspect 76 is directed to the method of Aspect 75, wherein introducing a liquid solution into the upper chamber of the filtration device generates a pressure which drives the liquid solution through the upper filtration membrane, into the flow channel and toward the lower filtration membrane.

[00193] Aspect 77 is directed to the method of any of Aspects 75-76, wherein the liquid solution comprises a wash solution and wherein introducing a liquid solution into the upper chamber of the filtration device comprises washing the carriers of the fluid stream.

[00194] Aspect 78 is directed to the method of any of Aspects 75-77, wherein the liquid solution comprises an eluent solution and wherein introducing a liquid solution into the upper chamber of the filtration device comprises eluting the carriers in the fluid stream. [00195] Aspect 79 is directed to the method of any of Aspects 75-78, wherein the liquid solution comprises a regeneration solution and wherein introducing a liquid solution into the upper chamber of the filtration device comprises refreshing the carriers.

[00196] Aspect 80 is directed to the method of Aspect 75, wherein the upper chamber of the filtration device comprises a plurality of upper chamber portions, and wherein introducing a liquid solution into the upper chamber of the fdtration device comprises introducing a plurality of liquid solutions into the plurality of upper chamber portions.

[00197] Aspect 81 is directed to the method of Aspect 80, wherein each of the plurality of liquid solutions comprises a wash solution, an eluent solution, or a regeneration solution.

[00198] Aspect 82 is directed to the method of Aspect 80, wherein one of the plurality of liquid solutions comprises a wash solution, an eluent solution, or a regeneration solution, and another of the plurality of liquid solutions comprises another of a wash solution, an eluent solution, or a regeneration solution.

[00199] Aspect 83 is directed to the method of any of Aspects 75-82, further comprising collecting retentate from the retentate outlet.

[00200] Aspect 84 is directed to the method of Aspect 83, wherein collecting retentate from the retentate outlet comprises collecting the desired product.

[00201] Aspect 85 is directed to the method of any of Aspects 75-84, further comprising collecting permeate from the permeate outlet.

[00202] Aspect 86 is directed to the method of Aspect 85, wherein collecting permeate from the permeate outlet comprises collecting the desired product.

[00203] Aspect 87 is directed to the method of any of Aspects 83-86, further comprising flowing the retentate into a flow channel of a filtration device. [00204] Aspect 88 is directed to the method of Aspect 87, wherein flowing the retentate into a flow channel of a filtration device comprises flowing the retentate from a first filtration device into a flow channel of a second filtration device.

[00205] Aspect 89 is directed to the method of Aspect 87, wherein flowing retentate into a flow channel of a filtration device comprises flowing the retentate from a first filtration device into the flow channel of the same first filtration device.

[00206] Aspect 90 is directed to a filtration device comprising: a first module comprising a first flow channel comprising a fluid inlet and a retentate outlet; a second module comprising a second flow channel comprising a fluid inlet and a permeate outlet; at least one filtration membrane separating the first flow channel from the second flow channel; and a vibration element.

[00207] Aspect 91 is directed to the filtration device of Aspect 90, wherein the vibration element is positioned in contact with the at least one filtration membrane and is configured to provide localized vibration to the at least one filtration membrane.

[00208] Aspect 92 is directed to the filtration device of Aspect 90, wherein the vibration element is positioned in contact with, the filtration device and is configured to provide global vibration to the filtration device.

[00209] Aspect 93 is directed to the filtration device of Aspect 90, wherein the vibration element is a pneumatic vibrator.

[00210] Aspect 94 is directed to the filtration device of Aspect 90, wherein the vibration element is an electric vibrator.

[00211] Aspect 95 is directed to the filtration device of any of Aspects 90-94, wherein the at least one filtration membrane comprises a first surface and a second surface, and wherein a fluid stream in the first flow channel flows tangentially over the first surface of the filtration membrane and a fluid stream in the second flow channel flows tangentially over the second surface of the filtration membrane.

[00212] Aspect 96 is directed to the filtration device of any of Aspects 90-95, wherein the filtration membrane comprises a porous material.

[00213] Aspect 97 is directed to the filtration device of any of Aspects 90-96, wherein the filtration membrane comprises two filtration sheets arranged on either side of a porous material.

[00214] Aspect 98 is directed to the filtration device of any of Aspects 90-97, wherein when a transmembrane pressure is applied across the filtration membrane, a species passes from a fluid stream in the first flow channel through the filtration membrane.

[00215] Aspect 99 is directed to the filtration device of any of Aspects 90-98, wherein a fluid stream in the first flow channel comprises carriers.

[00216] Aspect 100 is directed to the device of Aspect 99, wherein the carriers comprise chromatography affinity beads.

[00217] Aspect 101 is directed to a filtration device comprising: a vertically oriented flow channel comprising an inlet and a retentate outlet; a first vertically oriented chamber comprising a liquid inlet and a permeate outlet, the first chamber being separated from the flow channel by a first of a plurality of vertically oriented filtration membranes; and a second vertically oriented chamber comprising a liquid inlet and a permeate outlet, the second chamber being separated from the flow channel by a second of the plurality of vertically oriented filtration membranes.

[00218] Aspect 102 is directed to the filtration device of Aspect 101, wherein the filtration membrane comprises a porous material.

[00219] Aspect 103 is directed to the filtration device of any of Aspects 101-102, wherein the filtration membrane comprises two filtration sheets arranged on either side of a porous material. [00220] Aspect 104 is directed to the filtration device of any of Aspects 101-103, wherein when a transmembrane pressure is applied across each of the plurality of vertically oriented filtration membranes, a species passes from a fluid stream in the flow channel through the filtration membranes.

[00221] Aspect 105 is directed to the filtration device of any of Aspects 101-104, wherein a fluid stream in the flow channel comprises carriers.

[00222] Aspect 106 is directed to the filtration device of Aspect 105, wherein the carriers comprise chromatography affinity beads.

[00223] Aspect 107 is directed to a method of suppressing filter fouling in a filtration device, the method comprising: flowing a fluid stream into a first flow channel of a filtration device; flowing a fluid stream into a second flow channel of a filtration device, wherein the second flow channel is separated from the first flow channel by a filtration membrane; applying a transmembrane pressure across the filtration membrane; and vibrating the filtration membrane.

[00224] Aspect 108 is directed to the method of Aspect 107, wherein vibrating the filtration membrane comprises applying localized vibration to the filtration membrane.

[00225] Aspect 109 is directed to the method of Aspect 107, wherein vibrating the filtration membrane comprises applying global vibration to the filtration device.

[00226] Aspect 110 is directed to the method of any of Aspect 107-109, further comprising backwashing the filtration membrane.

[00227] Aspect 111 is directed to the method of any of Aspect 107-110, wherein the filtration device comprises a plurality of second flow channels and a plurality of filtration membranes, and wherein each of the plurality of second flow channels is separated from the first flow channel by one of a plurality of filtration membranes.

[00228] Aspect 112 is directed to the method of Aspect 110, wherein vibrating the filtration membrane comprises vibrating at least one of the plurality of filtration membranes. [00229] While the present disclosure includes a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the present disclosure.