Patent Document

TECHNICAL FIELD 
       [0001]    This disclosure relates generally to the fluid handling arts and, more particularly, to a driven fluid mixer and related methods. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is often desirable in fluid handling applications to provide a measure of agitation for the fluid, typically using some form of externally driven impeller positioned in a fluid container or vessel. Past approaches have involved the use of direct, shaft-driven impellers, and well as indirect, magnetically coupled impellers, both for positioning in the interior of the fluid container. 
         [0003]    More recently, a proposal has been made for a stirrer for disposable use that may be driven using air, as detailed in U.S. Patent Application Publication No. 2012/0040449, the disclosure of which is incorporated herein by reference. This approach attempts to address the above-mentioned requirement for an external motive device, yet limitations remain. For example, a separate conduit is required for returning the air from the device being driven to the environment outside of the container. Inputting gas to the fluid being processed may also be desirable, and especially in a manner that ensures a substantially even distribution of the gas throughout the fluid, but the proposal in the prior approach is for a tiny fixed aerator along only a portion of one gas delivery line. 
         [0004]    Accordingly, a need is identified for a manner of providing an improved fluid processing arrangement, and bioprocessing in particular. The processing arrangement would be adapted to agitate the fluid, and may provide for the distribution of gas throughout the fluid to maintain desirable processing conditions (e.g., an increased level of dissolved oxygen, in the case of biological applications). In some embodiments, the mixing would be completed without necessitating the use of an external electric motor or the like. Overall, the improved arrangement would thus lead to a simplification of the fluid processing operation with improved results and a concomitant reduction in the expense associated with such use. 
       SUMMARY 
       [0005]    One aspect of this disclosure relates to an apparatus for use in processing a fluid in a vessel and for supplying a gas to the fluid. In one embodiment, the apparatus comprises a mixer adapted for supplying the gas to the fluid in the vessel, and a drive for delivering the gas to the mixer to cause the agitator to rotate. 
         [0006]    The mixer may include an agitator capable of rotating to agitate the fluid, as well as a housing for at least partially housing the agitator. In one embodiment, the agitator comprises an impeller positioned within the housing for being driven by the gas. The agitator may also be external to the housing, and coupled to an impeller positioned within the housing. A magnetic coupling may couple the agitator to the impeller. 
         [0007]    The mixer or, in some embodiments, the agitator, may include a passage for delivering gas to the fluid. The passage may extend within an extension of the agitator. The mixer or agitator may include a plurality of passages for delivering gas from the housing to the fluid. 
         [0008]    The mixer may include at least one first opening serving as a fluid inlet and at least one second opening serving as a fluid outlet. At least one extension may be associated with the at least one second opening, said extension comprising a passage for delivering the gas to the fluid. The extension may comprise a blade associated with the mixer (which blade may connects to the agitator, which agitator is positioned external to a housing forming part of the mixer). The apparatus may further include a sparger connected to the mixer. The drive may also include a conduit for delivering the gas to the mixer. 
         [0009]    In one aspect of the disclosure, an arrangement for processing a fluid using a mixer includes a blade having a passage for delivering a gas to the fluid. The arrangement may further include a drive for causing the mixer to rotate. 
         [0010]    Another aspect of the disclosure pertains to an apparatus for agitating and supplying a fluid to an interior of a vessel. The apparatus comprises a mixer adapted for being rotated within the vessel, said mixer including an interior compartment and an agitator positioned in the interior compartment, and a drive for delivering the fluid to the interior compartment of the mixer. The mixer may be further adapted for releasing the fluid from the interior compartment of the mixer to the vessel interior. In one arrangement according to the foregoing, the drive is adapted to deliver the fluid in a manner that causes the agitator to rotate. 
         [0011]    Yet another aspect of the disclosure relates to an apparatus for use in processing a fluid and supplying a gas to the fluid via a conduit. The apparatus may comprise a vessel for receiving the fluid, and a mixer for mixing the fluid in the vessel. The mixer includes an agitator capable of rotating relative to the vessel to agitate fluid, an inlet for delivering the gas from the conduit for driving the agitator, and an outlet for delivering gas to the fluid. 
         [0012]    In one embodiment, the mixer comprises a housing including the outlet. The housing may include a wall having a plurality of outlets formed therein. The outlet may also be formed in the agitator, or may be connected to a passage in the agitator. The mixer may be located in the interior compartment of the vessel, and may be connected to the vessel. 
         [0013]    Still a further aspect of the disclosure is an apparatus for use in fluid processing and for supplying at least one gas to the fluid during the processing via a conduit. The apparatus comprises a flexible vessel for receiving the fluid, and a mixer including an agitator adapted for being rotated relative to the vessel by way of the gas from the conduit. The mixer is further adapted for delivering the at least one gas to the fluid. In one embodiment, the flexible vessel comprises a bag including an opening for receiving the mixer such that the agitator is positioned in an interior compartment of the bag. 
         [0014]    A further aspect of the disclosure relates to a gas driven mixer including a sparger for creating bubbles in a fluid being mixed. Furthermore, according to the disclosure, an apparatus may comprise a fluid container having an interior compartment in which the gas driven mixer including the sparger is located. 
         [0015]    Yet another aspect of the disclosure relates to a fluid mixer adapted for providing gas to the fluid during the mixing, comprising: a first sparger for supplying gas to the fluid in a first direction and a second sparger for supplying gas to the fluid in a second direction. The mixer may further include a first source of a first gas connected to the first sparger and a second source of a second gas connected to the second sparger. 
         [0016]    The disclosure may also provide a disposable bioreactor including a flexible pouch having an interior compartment for receiving a fluid, wherein it also includes a single-use stirring system placed entirely within said pouch; said stirring system comprising a drive adapted for delivering a gas to the interior of the flexible pouch and at least one stirrer driven in rotation by said drive. The stirrer may comprise an agitator adapted for rotating relative to the vessel. The agitator may deliver gas from the drive to the fluid. 
         [0017]    This disclosure also relates to a method for processing a fluid, comprising: driving a mixer in contact with the fluid using a gas; and delivering the gas from the mixer to the fluid. In one possible approach, the delivering step comprises delivering the gas from the mixer to the fluid at a location remote from the mixer. 
         [0018]    Another aspect of the disclosure relates to an apparatus for mixing a fluid. The apparatus may comprise a vessel for receiving the fluid, a mixer for agitating the fluid in the vessel, and at least two conduits, each conduit connected to the vessel at one end and to the mixer at the other end and adapted for supplying a fluid to the mixer. 
         [0019]    The conduits may each be adapted to supply a different fluid to the mixer, such as a different gas or a gas and liquid. The mixer may include an inlet associated with each of the conduits, as well as an outlet for releasing the fluid to the vessel. Each conduit may connect to the vessel at one end of a double-ended connector adapted for connecting to an external fluid source. 
         [0020]    Each conduit may connect to the vessel at substantially the same height. Alternatively, each conduit may connect to the vessel at a different height. Consequently, the mixer may comprise an impeller having an axis of rotation aligned with a vertical axis or not aligned therewith (such as by forming an acute angle). 
         [0021]    This disclosure also pertains to an apparatus for mixing a fluid, comprising: a vessel including at least one sidewall forming an interior compartment for receiving the fluid; a mixer for agitating the fluid in the vessel; and a plurality of connectors for connecting the mixer to at least one sidewall of the vessel such that an axis of rotation of the mixer is not aligned with a vertical axis. The mixer may be fluid-driven, and at least one of the connectors may comprise a conduit for supplying a fluid for driving the mixer. The mixer may further include an outlet for releasing the fluid to the vessel. Each connector connects to the vessel at a substantially different height. 
         [0022]    An apparatus comprising a flexible mixing bag, and a liquid substance circulation device associated with said flexible mixing bag, said liquid substance circulation device in turn comprising: an upper wall; a side wall, said upper wall and said side wall cooperatively defining a compartment; and a rotary magnetic element located in said compartment; wherein: at least one inlet is formed in said liquid substance circulation device for delivering a gas to the compartment. The outlet release gas from said device in the form of bubbles, and the apparatus may further include a source of gas for supplying gas to the inlet. 
         [0023]    A further aspect of the disclosure relates to a method of supplying gas to a fluid in an interior of a mixing vessel, comprising shearing the gas bubbles in a compartment prior to introducing the gas from the compartment to the fluid in the interior of the mixing vessel external to the compartment. The method may further include the step of delivering the gas to a fluid in the compartment prior to the shearing step. 
         [0024]    Still another aspect of the disclosure pertains to an apparatus for use in processing a fluid in a vessel and for supplying a gas to the fluid from a source external to the vessel. The apparatus comprises a mixer including an agitator capable of rotating relative to the vessel to agitate the fluid, said mixer including a housing having an inlet for receiving the gas, and a drive for causing the agitator to rotate. The agitator may comprise a magnetic impeller and the drive is adapted to form a non-contact coupling with the magnetic impeller. The housing may comprise a plurality of inlets for receiving the gas, as well as one or more outlets for forming gas bubbles. 
         [0025]    A related aspect of the disclosure pertains to a method of forming a mixing vessel, comprising the step of providing a mixer for associating with the vessel, said mixer including a compartment adapted for receiving a gas from a source external to the mixing vessel; and providing a drive external to the vessel for forming a non-contact coupling for driving the mixer. 
         [0026]    A method of mixing a fluid in a vessel also forming an aspect of this disclosure comprises supplying a gas to a mixer; and driving the mixer by way of a non-contact coupling formed with an external motive device. The method may further include the step of supplying a plurality of different gases to the mixer, as well as the step of supplying the gas to the mixer through a plurality of inlets. The method may further include the step of supplying a liquid to the mixer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0027]      FIG. 1  is a partially schematic perspective view of one embodiment of a mixer; 
           [0028]      FIG. 2  is a partially cross-sectional top plan view of another embodiment of a mixer; 
           [0029]      FIGS. 2   a ,  2   b , and  2   c  are differing schematic views of alternate embodiments of the mixer; 
           [0030]      FIGS. 3 and 4  are partially cross-sectional and perspective views of an embodiment of the mixer; 
           [0031]      FIG. 5  is a schematic view of a container including a mixer according to the disclosure; 
           [0032]      FIG. 6  is a partially cutaway, cross-sectional side view of the mixer of  FIG. 6 ; 
           [0033]      FIG. 7  is a perspective view of another embodiment of a mixer; 
           [0034]      FIG. 8  is a partially cross-sectional, schematic view of a container including a mixer; 
           [0035]      FIGS. 9 and 10  are schematic views of alternative arrangements of mixers in containers; 
           [0036]      FIG. 11  is a partially schematic perspective view of another embodiment of a mixer; and 
           [0037]      FIG. 12  is a schematic view illustrating a possible mode of operation of the mixer of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Reference is now made to  FIGS. 1 and 2 , which illustrate implementations of a fluid processing apparatus according to the disclosure. In the  FIG. 1  embodiment, the apparatus for processing fluid is in the form of a mixer  10  adapted for being associated with a vessel or container (not shown) capable of at least temporarily containing the fluid. The association may be, for example, by positioning the mixer  10  in the interior compartment, surrounded by the fluid when present. The vessel or container may be, for example, a disposable or single use bioreactor, fermenter, or the like, and may be in the form of an at least partially flexible container, which may be referred to as a bag or pouch, but as noted below can take different forms. 
         [0039]    The mixer  10  may comprise a housing  12 , for at least partially containing an agitator for agitating the fluid. The agitator may take the form of an impeller  14  adapted for rotating within the housing  12 , such as by being mounted to a bearing (not shown) that is fixed in place (which may include a slide bearing, a roller bearing, a thrust bearing, or like structure) or one that is not fixed in place (such as a fluid bearing) that facilitates low friction, controlled rotation. The impeller  14  may also be associated with an axle (not shown) journaled in the housing  12  and defining the axis of rotation. The agitator, such as impeller  14 , may include blades, vanes, or like elements, as illustrated, but may comprise any structure capable of agitating the fluid. 
         [0040]    A drive may also be provided for driving the mixer  10  and causing it to agitate the fluid in the associated vessel or container. In one embodiment, the drive may include a conduit  16  for introducing a fluid in the form of a gas, such as air, used to actuate the impeller  14 , such as by causing it to bodily rotate or spin relative to the housing  12  and any vessel or container with which the mixer  10  is associated (such as by being positioned at least partly within an interior compartment thereof). The gas may be delivered to the interior of the housing  12  under pressure from an external supply, such as a compressor, fan, blower, pressurized container, or the like. 
         [0041]    The housing  12  also includes one or more openings that serve to facilitate the mixing of the fluid. In the particular embodiment of  FIG. 1 , the housing  12  includes a sidewall  12   a  with one or more circumferentially spaced openings that are elongated in a vertical direction V, as shown. A further wall of the housing  12 , such as the upper or top wall  12   b,  may also be provided with one or more openings. The housing  12  may also include a planar bottom wall (not shown), which may be the wall associated with the mixer  10 . 
         [0042]    In use, a gas, such as air, or other fluid delivered to inlet  16  may propel the impeller  14  about an axis of rotation and relative to the housing  12 , which may remain stationary. In the case of gas, it mixes with any liquid present in the interior compartment E when the mixer  10  is at least partially submerged. In one particular embodiment, as illustrated, fluid may be drawn through the opening(s) in the upper wall  12   b,  which thus creates an inlet I, mix with the gas or air in the interior of the housing  12  to drive the impeller  14 , and then a composite fluid (e.g., air-liquid mixture) ejects from the opening(s) in the sidewall  12   a,  which thus serve as outlet(s) O. 
         [0043]    As should be appreciated, this may result not only in fluid agitation, but also mixing of the injected gas (e.g., air) with the fluid, and may thus improve the concentration of dissolved gas (e.g., oxygen). The temporary residence of a gas in the interior compartment E of the housing  12  combined with the rotation of the impeller  14  may also help to create shear in the gas bubbles. This may create finer bubbles as compared to the case in which the gas is simply introduced into the fluid in the vessel without encountering mixer  10 . 
         [0044]    The openings in the sidewall  12   a  may be unobstructed, as shown in  FIG. 1 . Alternatively, as indicated in the cross-sectional view of  FIG. 2 , these sidewall openings may be adapted for delivering the gas-fluid mixture from the interior compartment E in a controlled manner. For instance, one or more of the openings may be provided with a porous substrate  18  that regulates the rate of delivery of the mixture from the housing  12  (and concomitantly controls the resident time of the gas in the interior compartment E once delivered thereto from conduit  16 ). The substrate  18  may comprise a membrane having micro- or macroscopic openings (e.g., holes, pores, slits, etc.) in order to provide the desired level of regulation. A substrate (not shown) may also be provided in association with the opening in the upper wall  12   b  in order to regulate fluid flow into the interior compartment E of the housing  12 , and could possibly include the option of blocking fluid flow such that only gas exits the housing as a result in the supply through conduit  16 . The openings may also be provided with removable covers, such as doors (not shown), to allow for selective use (e.g., one or more may be opened, while others are closed), depending on the particular application. 
         [0045]    Additionally, or alternatively, the housing  12  may include optional extensions  20  for communicating with one or more of the openings in the sidewall  12   a.  The extensions  20  may be tubular, and project from periphery of the housing  12 , such as in the radial direction R. Consequently, the extensions  20  may serve to eject the gas-fluid mixture at a remote location from the housing. This may improve the gas distribution thoughout the fluid, especially in the case of multiple extensions  20  that project in different directions (radial, vertical, or any combination thereof). The extensions  20  may also comprise or be associated with spargers. 
         [0046]    The mixer  10  may also be used in various alternative embodiments. For example, multiple inputs may be provided for introducing the same or different fluids (liquid or gas) to the housing  12 . Thus, in the embodiment shown, four conduits  16   a,    16   b,    16   c,  and  16   d  are illustrated by way of example only, each being connected to the sidewall  12   a  of the housing  12  (which may still include openings as discussed previously). 
         [0047]    This arrangement may allow for different gases (e.g., oxygen, nitrogen, carbon dioxide, etc.), liquids (nutrients, fresh media, etc.), or combinations of both to be simultaneously introduced into the compartment E of the mixer  10 . Likewise, the arrangement could allow for multiple sources of the same fluid to be used in connection with the mixer  10 , with the delivery being either sequential or simultaneous. 
         [0048]      FIG. 2   b  shows that the openings in the sidewall  12   a  may be arranged to create bubbles from any gas introduced into the interior compartment of the housing  12 , such as via the inlet  16  or inlets. For example, groups of relatively small (e.g.,  1 - 2  mm) openings may be provided in and along the sidewall  12   a , such as in spaced columns L, but any desired pattern may be used. Likewise, as mentioned above and shown in  FIG. 2   c , the openings may be covered with a substrate  18  that is porous (such as, but not limited to, one having openings of about 50 μ or less) to form bubbles from any gas introduced into the housing  12  via inlet(s)  16 . Combinations of the two approaches could also be used. These approaches to supplying gas to the fluid surrounding the mixer  10  may also be applied to extensions  20  from the housing  12 . 
         [0049]    Reference is now made to  FIGS. 3 and 4 , which illustrate a further embodiment in which an impeller  14  may be driven by a fluid, such as for example a gas supplied by a conduit  16  from an external supply. The impeller  14  within the housing  12  is adapted for forming a non-contact coupling with an external agitator  22  for positioning within a container or vessel (not shown) to create the desired fluid agitation. The non-contact coupling may be achieved using magnets G. 
         [0050]    In the illustrated embodiment of  FIGS. 3 and 4 , a portion of the agitator  22 , such as an axle  24  extending into the housing  10 , is adapted for delivering the gas or air that drives the agitator (such as by engaging the impeller  14 ), to the fluid external to the housing  12 . This may be achieved by providing the axle  24  with an internal passage  26 . At one end  26   a,  this passage  26  may communicate with the interior compartment E, and at the other end  26   b  with the fluid external to the housing  12 . This other end  26   b  may be adapted to permit the delivery of the gas to the fluid, as well as to prevent the fluid from entering the passage  26  and thus the housing  12 . This may be achieved using a suitable control device, such as a one-way valve in the form of a porous membrane  28  having pores of sufficient size to allow the gas to pass but not the fluid (and depending on the pore size may also serve to create bubbles in the fluid and thus serve as a sparger and perform a sparging function). However, the end  26   b  of the passage  26  may also simply be open to the fluid. 
         [0051]      FIG. 5  shows another embodiment in which the gas from the housing  12  is released into a surrounding fluid through an opening in the mixer  10 . As further indicated by  FIG. 6 , the opening may be formed in the housing sidewall  12   a,  and also may be associated with an extension  20  for delivering the gas to the fluid in a controlled manner (e.g., direction, flow rate, etc.) and at a location remote from the agitator  22 . While only one opening is depicted, it may be appreciated that multiple openings may be provided, as shown in the embodiment of  FIGS. 1 and 2 . Also, as with that embodiment, the extension(s)  20  are optionally provided and may project in different directions (radially, vertically, tangentially, or combinations thereof). In any case, it can be appreciated that only a single conduit  16  may be used to deliver the fluid to the mixer  10 , which allows for a simply arrangement to be created. 
         [0052]    A container C is also shown in  FIG. 5  for receiving the mixer  10 . The container C may comprise a partially or completely rigid tank, or a partially or fully flexible vessel (bag, pouch, or the like). The mixer  10  may be indirectly connected to a wall W of the container C, such as by a tether formed using the conduit  16 , to create a spaced or indirect connection. The mixer  10  may be arranged such that the wall  12   a  of the housing  12  is connected directly to the wall W of the container C, including possibly in suspension. 
         [0053]    Turning now to  FIG. 7 , a further embodiment of a mixer  10  is shown. In this embodiment, a portion of the agitator  22  is adapted to receive the gas from the housing  12 , which gas is introduced to cause the relative movement between the two structures. For example, the agitator  22  may be associated with an axle (not shown) having a passage  26  similar to that shown in  FIG. 3 . Rather than releasing the gas directly to the fluid at a single location, the passage  26  at one end  26   b  forms a distributor that distributes the fluid through one or more internal channels  22   a  in the agitator  22 . The channels  22   a  may, in turn, communicate with openings in the agitator  22  for delivering the gas to the surrounding fluid. For example, the openings in the agitator  22  may be associated with extensions, such as blades  22   b,  which may be tubular or otherwise adapted to deliver the gas from the channels  22   a  to the surrounding fluid (which extensions may thus be considered to form spargers for creating gas bubbles in the fluid). 
         [0054]    As should be appreciated, the rotation of the agitator  22  as the result of the gas delivery through conduit  16  to housing  12  combined with the delivery of the gas to the fluid advantageously performs the dual function of agitating the fluid while delivering gas to it (and especially when the passage  26  is arranged to supply the gas to multiple sides of the agitator  22  simultaneously, as shown). Thus, the gas delivery in this particular embodiment is provided in two different directions, which as shown may be opposite each other (yet both aligned with the axis of rotation of the mixer  10 ). Furthermore, as discussed elsewhere herein, it is possible to use multiple inlets or conduits  16  for supplying different fluids from different sources (not shown) if desired, supplying fluids at different rates, or alternating the supply. 
         [0055]    A further embodiment of a mixer  10  is shown in  FIG. 8 , which is illustrated as part of a container C having a flexible wall W and thus forming a bag or pouch. The mixer  10  comprises a housing  12  for receiving an impeller  14 , which may be driven by a gas supplied through an external conduit  16 . The impeller  14  is directly attached to an agitator  22  external to the housing  12  by an axle  24 , and thus the two structures rotate together. Optionally, a passage  26  may be formed along the axle  24  to deliver the gas to the fluid, such as by extending through the passages in the agitator  22  and forming an outlet along extensions thereof, such as blades  22   a.  Alternatively or additionally, the housing  12  may be adapted for releasing the gas into the surrounding fluid, such as by using openings (not shown in  FIG. 8 , but see  FIGS. 1 and 2 ). 
         [0056]      FIGS. 9 and 10  illustrate different approaches to mounting the mixer  10  relative to an external container C, which may comprise a rigid vessel or a flexible vessel, such as a bag or pouch.  FIG. 9  shows that a plurality of external conduits  16 , such as flexible tubes, may be connected between the housing  12  and the sidewall(s) W of the container C (which may be considered a single sidewall when the container is generally cylindrical, as shown, but could also be multiple sidewalls when the container has a polygonal configuration, such as cubic or rectangular). The tubes serving as conduits  16  may be connected to the wall W or walls (e.g, a first conduit may connect with a first wall and a second one with a second wall) in a manner that allows for the transmission of fluid, such as by using connectors  30  in the form of double-ended fittings (which may be similar in construction, for example, to the extension  20  shown in  FIGS. 5  and  FIG. 6 ). The connectors  30  may be specially adapted for coupling with a source of fluid (gas or liquid) external to the container C, such as by using a locking engagement (bayonet, screw fitting, or the like), which may be delivered under sterile conditions if desired. 
         [0057]    As should be appreciated, the connectors  30  may be positioned along the container C at any height. Moreover, the connectors  30  may each be positioned at the same height, or one or more may be positioned at different heights (see, e.g., h 1  and h 2  in  FIG. 10 ) to alter the position of the mixer  10  (note, for example, acute angle a between the rotational axis of impeller  14 , which is not aligned with an axis extending in the vertical direction V). The connectors  30  may be one or more tubes as discussed above, or may include one or more non-tubular tethers for tethering the mixer to the container C. 
         [0058]    Actuation of the mixer  10  may be achieved without using the fluid to do so. Thus, as shown in  FIGS. 11 and 12 , an external drive  32  may be used for driving the impeller  14  to rotate within housing  12 , while a fluid, such as air, is introduced via the conduit  16  associated therewith. The drive  32  may form a non-contact coupling with the impeller  14  through an external wall W associated with the mixer  10  (and possibly fanning part of a larger vessel or container, not shown). For example, as shown in  FIG. 12 , driven magnets  34  of the impeller  14  may associated with drive magnets  36  driven by the drive  32  (which arrangement could also be applied to the  FIG. 8  embodiment). The housing  12  may include the fluid inlet I and may provide the output  0  in the manner described herein. Further details of possible non-contact drive arrangements may be found in U.S. Pat. No. 7,481,572 and International Application PCT/EP07/53998, both of which are incorporated herein by reference. As another example, one or more of the connectors  30  in the  FIGS. 9 and 10  embodiments may also be used to supply electricity for powering the mixer  10 . 
         [0059]    The foregoing descriptions of several embodiments made according to the disclosure of certain inventive principles herein are presented for purposes of illustration and description. The embodiments described are not intended to be exhaustive or to limit the invention to the precise form disclosed and, in fact, any combination of the components of the disclosed embodiments is contemplated. The term “flexible” as used herein in the context of the vessel refers to a structure of the vessel that, in the absence of auxiliary support, may conform to the shape of the fluid contained in the vessel, as contrasted with a “rigid” structure, which retains a pre-determined shape when the fluid is in the vessel. A liquid, such as water, may also be used to drive the mixer  10  in certain embodiments (e.g.,  FIGS. 1 and 2 ), and which arrangement may be used to pump the liquid. A vent may also be provided for venting the interior compartment of any vessel including the mixer  10 , and may be associated with a sterile filter in order to maintain an aseptic condition in the vessel (which may be otherwise hermetically sealed). Modifications or variations are possible in light of the above teachings. For example, any shape or style of agitator may be used, including one with vanes or fins similar to the blades shown in the figures. The embodiments described were chosen to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention when interpreted in accordance with the breadth to which it is fairly, legally, and equitably entitled.

Technology Category: 7