Abstract:
A fluid management cassette system comprises a first and second opposed platen with first and second opposed films compressed between the platens. One or more channels formed one or both of the platens form pathways with the films through which fluids can be directed. Valves and other flow control mechanisms can be incorporated.

Description:
BACKGROUND 
       [0001]    The present application relates to fluid manifold and more particularly to a manifold and methods associated therewith in which fluid flow paths are created between a pair of films. 
         [0002]    In the fields of biomedical processing and analysis, fluids are typically manipulated and conducted between various locations via tubing that requires connections and interfaces to control devices. These fluidic systems comprise one or more removable tubing harnesses and the processing machine. The tubing harness or cassette is usually a single use disposable in order to guarantee purity or sterility. The tubing harnesses are loaded onto reusable processing machine by an operator who must connect the control devices such as pumps and valve to the harness. Depending on the complexity of the harness, significant training, time, and potential for errors exist in the use of tubing harnesses. There are multiple connections between tubing sections and components that have the potential for leaking Moreover, the material and assembly cost of a disposable tubing harness or cassette is significant and affects the commercial adoption of products and procedures. 
         [0003]    There have been many systems invented to assist in this loading process to save time, and avoid errors, such as custom cassettes and different types of tubing holders. Manifold systems have been invented where the tubing function is incorporated into channels formed in a rigid member. Typically, manifold, cassette and tubing holder approaches add material costs above the basic tubing harnesses. Additionally cassettes and tubing holders provide a single fluidic configuration that is defined at manufacturing time. Manifolds provide somewhat increased configuration flexibility but are limited to the pathways incorporated into the design. 
       SUMMARY OF THE INVENTION 
       [0004]    A fluid management cassette system according to the present invention comprises a first platen and a second platen opposed to the first platen. A first film and a second film, in opposed relation to each other, are compressed between the first platen and the second platen. One or more channels are formed in at least one of the first platen and second platen whereby fluid can be directed through a pathway formed between the first film and second film at the one or more channels. 
         [0005]    Preferably, the first film has an inward face facing the second film and the second film has an inward face facing the first film and wherein the first film inward face and the second film inward face are sterile. Preferably, they are disposable and replaceable. Also preferably, they are sealed about an extent of their peripheries so as to form a bag. 
         [0006]    Preferably, there is a valve comprising a valve element movable into the channel against one of the first or second films. In one aspect of the invention, the pathway is blocked when the valve element is moved fully into the channel. The valve element can be movable partially into the channel to effect a flow restriction in the pathway without total blockage. 
         [0007]    In one aspect of the invention, at least one of the first platen and second platen comprises a matrix of segments movable from an extended position toward the other of the first platen and second platen to a retracted position away from the other of the first platen and second platen with the channel formed by an arrangement of the segments in their retracted positions. 
         [0008]    A flow control valve can be effected in the channel via one or more of the segments moveable into the channel. 
         [0009]    In one aspect of the invention a fluid pump formed in at least one of the first and second platens. For instance a chamber along one of the one or more channels and having a check valve forming an inlet into the chamber and arranged to allow flow into the chamber can be employed with a pump element at the chamber arranged to apply pressure against one of the first and second films at the chamber. The pressure drives flow out of the chamber and the check valve prevents the flow from going backward. Preferably another check valve is provided at the outlet to prevent backflow into the chamber from the outlet. Alternatively, the pump can comprise a positive displacement element movable along one of the one or more channels to effect a peristaltic pumping action. 
         [0010]    A method according to the present invention provides for managing a fluid flow. The method comprises trapping opposed first and second films between opposed first and second platens; forming a fluid pathway between the first and second films via a channel formed into at least one of the first and second platens; and flowing fluid through the pathway. 
         [0011]    Preferably, the first and second films have surfaces at the pathway and said surfaces are sterile prior to the step of flowing fluid through the pathway. 
         [0012]    Preferably, the step of impeding flow of fluid through the pathway comprises moving a valve element against at least one of the first and second films and into the channel to obstruct flow through the pathway. The movement of the valve element into the channel can completely block flow through the pathway or merely throttle the flow by partially blocking the pathway. 
         [0013]    In one aspect of the invention, at least one of the first and second platens comprises a matrix of segments movable from an extended position toward the other of the first platen and second platen to a retracted position away from the other of the first platen and second platen and the channel is formed by an arrangement of the segments in their retracted positions. 
         [0014]    Pumping fluid along the channel can be effected by engaging segments along the channel in a wave pattern to induce flow along the channel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is an exploded perspective view of a fluid manifold according to the present invention; 
           [0016]      FIG. 2  is a perspective view of the fluid manifold of  FIG. 1 ; 
           [0017]      FIG. 3  is a sectional view along lines  3 - 3  of  FIG. 1 , with its platens shown in a spaced apart configuration with the bag in between; 
           [0018]      FIG. 4  is a sectional as in  FIG. 3  but with the platens pressed together and with fluid pathways carrying fluid; 
           [0019]      FIG. 5  is a sectional view along lines  5 - 5  of  FIG. 1  showing the pumping chamber; 
           [0020]      FIG. 6  is a sectional view taken along lines  6 - 6  of  FIG. 1  showing the check valve; 
           [0021]      FIG. 7  is a perspective view of a bottom block of an alternative fluid manifold according to the present invention and which has reconfigurable fluid channels; and 
           [0022]      FIGS. 8A  to D are side elevation views in time sequence of a flow path of the manifold of  FIG. 7  showing peristaltic pumping action. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIGS. 1 and 2  depict a fluidic manifold system  10  according to the present invention comprising in gross a shaped bottom block  12 , a compliant fluid bag  14  and an unshaped top block  16 . The bag  14  is a fluid or gas containing compartment preferably formed by folding or sealing films of a biocompatible material such as, and without limitation, PVC, PolyUrethanes, Polyethelynes, Silicones and Polypropylenes and installing one or more inlet connections  18  and one or more outlet connections  20 . Other arrangements are possible; for instance fluid carrying tubes (not shown in  FIGS. 1 and 2 ) can be provided already connected to the bag  14  and carrying their own connectors for connection to fluid sources or dispensing apparatus. Either or both of the connectors and tubing can be formed integral with the bag  14 . The top block  16  has a flat lower surface  22  which contacts a top film  24  forming the bag  14 . The bottom block  12  has an upper surface  26  having channels  28  formed thereon and which contacts a lower film  30  forming the bag  14 . Rather than being flat, the top block lower surface  22  could have mating channels (not shown) in registry with the channels  28  of the bottom block  12  or which are independently positioned with respect to those channels  28 . 
         [0024]    Turning also now to  FIGS. 3 to 6  the interaction between the bag  14 , top and bottom blocks  16  and  12  and the channels  28  form fluid pathways  32  through the bag  14 . The bag is trapped between the blocks  12  and  16  which act as platens compressing the bag in some areas and not where the channels  28  are present. The bag is flexible to act as a gasket sealing the pathways  32 . Preferably the material of the bag  14  itself has some resiliency to enhance its action in sealing as a gasket. While the blocks  12  and  16  are preferably rigid for durability one or both could be formed of or have attached thereto a resilient material to assist in sealing. This could be conveniently be applied to the flat surface  22  and be replaceable when worn or when different resiliency characteristics are desired. 
         [0025]    The arrangement (best seen in  FIGS. 1 and 2 ) of the channels  28  determines the fluid pathways  32 . The fluid manifold system  10  shown has an inlet  34  and the channel  28  leads therefrom to a check valve  36 . From the check valve the channel  28  leads to a variable flow valve  38  and then to a pumping chamber  40 . From the pumping chamber  40  two channels  28  lead to a first outlet valve  42  and outlet  44  and to a second outlet valve  46  and second outlet  48 . The inlet  34  corresponds with the bag inlet connection  18  and the outlets  44  and  48  with the bag outlet connections  20 , preferably in such an arrangement that the bag  14  only fits in one orientation to prevent incorrect placement thereof. 
         [0026]    The outlet valves  42  and  46  are simple plungers  50  which block the pathway  32  to prevent flow therethrough. The variable flow valve  38  also comprises a plunger which can be adjusted to partially block the pathway  32 . The check valve  36  comprises a valve body  41  having a curved inlet surface  43  and a flat outlet surface  45  and which is biased closed by a spring  47 . Flow against the inlet surface  43  provides pressure to overcome the bias of the spring  47  an move the valve body  41  open to allow flow. Flow against the outlet surface  45  will not generate enough pressure to overcome the bias. 
         [0027]    By alternately applying suction and pressure to the pumping chamber  40  through an air line  52  a pumping effect can be achieved and the check valve  36  will cause the flow to be toward the outlets  44  and  48 . An additional check valve (not shown) may be desirable on the outlet from the pumping chamber  40  to prevent back flow into it and to enhance the pumping efficiency. A mechanical solution may also be employed such as a piston (not shown) which moves against the film  30  at the pumping chamber  40 . Alternatively, rollers (not shown) or other positive displacement type drivers could be applied to a section of the pathway  32  to effect a peristaltic pumping action. 
         [0028]    Pressure sensors (not shown) can be effected by placing a force measuring sensor, such as a strain gauge, into one of the blocks  12  or  16  at the pathways  32 . The force applied thereto by the fluid within the pathway  32  can be calibrated to indicate pressure. Flow volume can be determined with multiple pressure sensors and calculating pressure drop through a section of the pathway  32  between them having known dimensions, perhaps assisted with a metering constriction of the pathway  32 . Flow measurements can also be calibrated with an external flowmeter. 
         [0029]    Flexibility in fluid management can be achieved in a second embodiment of a block  54  (see  FIG. 7 ) which replaces the block  12 . The block  54  comprises a matrix of sections  56  each of which is capable of independent actuation, preferably variable, such that channels  58  can be created by retracting certain sections  56  and valves  57  by extending sections  56  within the channels  58 . The valves  57  can be flow control valves by only partially extending a section  56 . Only a simplified version is shown for illustrating the principle with a channel  58  formed by retracted sections  56  and extending from an inlet  51  and branching to two outlets  53  and  55 , with the outlet  55  blocked by the valve  57  which comprises one of the sections  56  being extended into the channel  58 . The entire operational portion of the block  54  can comprise the sections  56  or in can have some channels and features permanently formed therein with only some portions of the block  54  comprised of the sections  56 . The sections  56  can be used to effect valves and pumps and other flow control items. 
         [0030]    For instance, peristaltic pumping action could be effected by actuating sections  56  within a channel  58  in waves as illustrated in  FIGS. 8A  to D, where each of the sections  56  are coded with a letter for illustration, and they operate between a first rigid surface  60  and a second surface  62  formed of the individual sections  56  (the bag  14  is omitted for clarity but would be positioned between the surfaces  60  and  62 ). At time T 1  ( FIG. 8A ) section  56  coded “a” is fully actuated and that coded “b” is on its way up. At a slightly later time T 2  ( FIG. 8B ) the section  56  coded “a” is on its way down, “b” is fully actuated and “c” is on its way up. By time T 3  ( FIG. 8C ) “a” is fully retracted, “b” is on the way down, “c” is fully actuated” and “d” is on the way up. By time T 4  ( FIG. 8D ) both “a” and “c” are fully retracted etc. In this fashion a wave of flow is created through the channel  58 . 
         [0031]    Preferably each section is independently controlled and actuated via a control system and independent linear actuators or solenoids  60 . Other suitable mechanisms for independently controlling movement of the sections  56  are contemplated, such as pneumatic or hydraulic cylinders, mechanical lever actuators, electric motors, etc. In some applications the desired sections may be smaller than reasonable cost actuators, in which instance the actuators  60  can be arranged into a matrix  62  (only a small portion of such matrix being illustrated in  FIG. 7 ), preferably matching the matrix of sections  56 , and a series of movement actuation lines  64 , such as Bowden cables, can transmit the movement of the actuator to the individual sections  56 . Thus, the actuators would not need to be miniaturized to meet the dimensions of the sections  56 . 
         [0032]    The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.