Cassette system integrated apparatus

A cassette integrated system. The cassette integrated system includes a mixing cassette, a balancing cassette, a middle cassette fluidly connected to the mixing cassette and the balancing cassette and at least one pod. The mixing cassette is fluidly connected to the middle cassette by at least one fluid line and the middle cassette is fluidly connected to the balancing cassette by at least one fluid line. The at least one pod is connected to at least two of the cassettes wherein the pod is located in an area between the cassettes.

TECHNICAL FIELD

The present invention relates to a cassette system integrated apparatus for pumping fluid.

SUMMARY OF THE INVENTION

In accordance with one aspect of the cassette integrated system, the cassette integrated system includes a mixing cassette, a balancing cassette, a middle cassette fluidly connected to the mixing cassette and the balancing cassette and at least one pod. The mixing cassette is fluidly connected to the middle cassette by at least one fluid line and the middle cassette is fluidly connected to the balancing cassette by at least one fluid line. The at least one pod is connected to at least two of the cassettes wherein the pod is located in an area between the cassettes.

Various embodiments of this aspect of the cassette include one or more of the following. Where the housing includes a top plate, a midplate and a bottom plate. Where the pod includes a curved rigid chamber wall having at least one fluid inlet and at least one fluid outlet. Where the mixing cassette, middle cassette and said balancing cassette further include at least one valve. In some embodiments the value is a membrane valve. Where at least one of the fluid lines connecting the cassettes is a rigid hollow cylindrical structure.

In accordance with one aspect of the cassette integrated system, the cassette integrated system includes a mixing cassette, a middle cassette and a balancing cassette. The mixing cassette includes a mixing cassette housing including at least one fluid inlet line and at least one fluid outlet line. The mixing cassette also includes at least one reciprocating pressure displacement membrane pump fluidly connected to the housing. The pressure pump pumps at least one fluid from the fluid inlet line to at least one of the fluid outlet line. The mixing cassette also includes at least one mixing chamber fluidly connected to the housing. The mixing chamber is fluidly connected to the fluid outlet line. The middle cassette includes a housing having at least one fluid port and at least one air vent port, the air vent port vents a fluid source outside the middle cassette housing. The middle cassette also includes at least one reciprocating pressure displacement membrane pump fluidly connected to the housing. The pump pumps a fluid. The balancing cassette includes a housing including at least two inlet fluid lines and at least two outlet fluid lines. Also, at least one balancing pod fluidly connected to the balancing cassette housing and in fluid connection with the fluid paths. The balancing pod balances the flow of a first fluid and the flow of a second fluid such that the volume of the first fluid equals the volume of the second fluid. The balancing pod includes a membrane wherein the membrane forms two balancing chambers. The balancing cassette also includes at least one reciprocating pressure displacement membrane pump fluidly connected to the balancing cassette housing. The pressure pump pumps a fluid from the fluid inlet line to the fluid outlet line. The mixing cassette is fluidly connected to the middle cassette by at least one fluid line, and the middle cassette is fluidly connected to the balancing pod by at least one fluid line. The reciprocating pressure displacement membrane pumps, mixing chamber and balancing pod are connected to the housings such that the reciprocating pressure displacement membrane pumps, mixing chamber and balancing pod are located in areas between the cassettes.

Various embodiments of this aspect of the cassette include one or more of the following. Where the cassette housings include a top plate, a midplate and a bottom plate. Where the reciprocating pressure displacement pump includes a curved rigid chamber wall and a flexible membrane attached to the rigid chamber wall. The flexible membrane and the rigid chamber wall define a pumping chamber. Also in some embodiments, tie balancing pod includes a curved rigid chamber wall and a flexible membrane attached to the rigid chamber wall. The flexible membrane and the rigid chamber wall define two balancing chambers. Where the mixing chamber includes a curved rigid chamber wall having at least one fluid inlet and at least one fluid outlet. Where the mixing cassette, middle cassette and the balancing cassette further include at least one valve. Some embodiments of the valve include where the valve is a membrane valve. Some embodiments include where the membrane valve is a volcano valve.

Some embodiments include where the at least one of the fluid lines connecting the cassettes is a rigid hollow cylindrical structure. Some embodiments include where at least one of the fluid lines connecting the cassettes contain a check valve within the cylindrical structure. Some embodiments of the system include where the mixing cassette further includes at least one metering membrane pump within the mixing cassette housing. The mixing chamber fluidly connects to the fluid outlet line. Some embodiments of the system include where the balancing cassette further includes at least one metering pump within the housing and fluidly connected to a fluid line. The metering pump pumps a predetermined volume of a fluid such that the fluid bypasses the balancing chambers and wherein the metering pump is a membrane pump.

In accordance with one aspect of the cassette integrated system, the cassette integrated system includes a mixing cassette, a middle cassette and a balancing cassette. The mixing cassette includes a mixing cassette housing including at least one fluid inlet line and at least one fluid outlet line. Also, at least one reciprocating pressure displacement membrane pump fluidly connected to the housing. The pressure pump pumps at least one fluid from the fluid inlet line to at least one of the fluid outlet line. The mixing cassette also includes at least one mixing chamber fluidly connected to the housing. The mixing chamber is fluidly connected to the fluid outlet line. A plurality of membrane valves and a plurality of fluid lines are also included. The valves control the flow of fluid in the fluid lines. The mixing cassette also includes at least one metering membrane pump within the mixing cassette housing. The mixing chamber is fluidly connected to the fluid outlet line.

The middle cassette includes a middle cassette housing having at least one fluid port and at least one air vent port. The air vent port vents a fluid source outside the housing. Also includes are a plurality of fluid lines within the middle cassette housing and a plurality of membrane valves. The valves control the flow of fluid in the fluid. At least one reciprocating pressure displacement membrane pump fluidly connected to the housing is also included. The pump pumps a fluid.

The balancing cassette includes a balancing cassette housing including at least one inlet fluid line and at least one outlet fluid line. A plurality of membrane valves and a plurality of fluid paths are also included. The valves control the flow of fluid in the fluid paths. At least one balancing pod fluidly connected to the balancing cassette housing and in fluid connection with the fluid paths is also included. The balancing pod balances the flow of a first fluid and the flow of a second fluid such that the volume of the first fluid equals the volume of the second fluid. The balancing pod includes a membrane which forms two balancing chambers. The balancing cassette also includes at least one reciprocating pressure displacement membrane pump fluidly connected to the balancing cassette housing. The pressure pump pumps a fluid from the fluid inlet line to the fluid outlet line. Also, at least one metering pump within said housing and fluidly connected to a fluid line, wherein said metering pump is included. The metering pump pumps a predetermined volume of a fluid such that the fluid bypasses the balancing chambers. The metering pump is a membrane pump.

The mixing cassette is fluidly connected to the middle cassette by at least one fluid line. Also, the middle cassette is fluidly connected to the balancing pod by at least one fluid line. The reciprocating pressure displacement membrane pumps, mixing chamber and balancing pod are connected to the housing such that they are located in areas between said cassettes.

Various embodiments of this aspect of the cassette include where at least one of the fluid lines connecting the cassettes is a rigid hollow cylindrical structure.

These aspects of the invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the appended claims and accompanying drawings.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The pumping cassette includes various features, namely, pod pumps, fluid lines and in some embodiment, valves. The cassette embodiments shown and described in this description include exemplary and some alternate embodiments. However, any variety of cassettes having a similar functionality contemplated. As well, although the cassette embodiments described herein are implementations of the fluid schematics as shown inFIGS. 21 and 22, in other embodiments, the cassette may have varying fluid paths and/or valve placements and/or pod pump placements and numbers and thus, is still within the scope of the invention.

In the exemplary embodiment, the cassette includes a top plate, a midplate and a bottom plate. There are a variety of embodiments for each plate. In general, the top plate includes pump chambers and fluid lines, the midplate includes complementary fluid lines, metering pumps and valves and the bottom plate includes actuation chambers (and in some embodiments, the top plate and the bottom plate include complementary portions of a balancing chamber).

In general, the membranes are located between the midplate and the bottom plate, however, with respect to balancing chambers, a portion of a membrane is located between the midplate and the top plate. Some embodiments include where the membrane is attached to the cassette, either overmolded, captured, bonded, press fit, welded in or any other process or method for attachment, however, in the exemplary embodiments, the membranes are separate from the top plate, midplate and bottom plate until the plates are assembled.

The cassettes may be constructed of a variety of materials. Generally, in the various embodiment, the materials used are solid and non flexible. In the preferred embodiment, the plates are constructed of polysulfone, but in other embodiments, the cassettes are constructed of any other solid material and in exemplary embodiment, of any thermoplastic or thermoset.

In the exemplary embodiment, the cassettes are formed by placing the membranes in their correct locations, assembling the plates in order and connecting the plates. In one embodiment, the plates are connected using a laser welding technique. However, in other embodiments, the plates may be glued, mechanically fastened, strapped together, ultrasonically welded or any other mode of attaching the plates together.

In practice, the cassette may be used to pump any type of fluid from any source to any location. The types of fluid include nutritive, non nutritive, inorganic chemicals, organic chemicals, bodily fluids or any other type of fluid. Additionally, fluid in some embodiments include a gas, thus, in some embodiments, the cassette is used to pump a gas.

The cassette serves to pump and direct the fluid from and to the desired locations. In some embodiments, outside pumps pump the fluid into the cassette and the cassette pumps the fluid out. However, in some embodiments, the pod pumps serve to pull the fluid into the cassette and pump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of the fluid paths is imparted. Thus the valves being in different locations or additional valves are alternate embodiments of this cassette. Additionally, the fluid lines and paths shown in the figures described above are more examples of fluid lines and paths. Other embodiments may have more, less and/or different fluid paths. In still other embodiments, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on the embodiment. For example, although the exemplary and alternate embodiments shown and described above include two pod pumps in other embodiments, the cassette includes one. In still other embodiments, the cassette includes more than two pod pumps. The pod pumps can be single pumps or work in tandem to provide a more continuous flow. Either or both may be used in various embodiments of the cassette.

The various fluid inlets and fluid outlets are fluid ports. In practice, depending on the valve arrangement and control, a fluid inlet can be a fluid outlet. Thus, the designation of the fluid port as a fluid inlet or a fluid outlet is only for description purposes. The various embodiments have interchangeable fluid ports. The fluid ports are provided to impart particular fluid paths onto the cassette. These fluid ports are not necessarily all used all of the time; instead, the variety of fluid ports provides flexibility of use of the cassette in practice.

1.2 Exemplary Pressure Pod Pump Embodiments

FIG. 1Ais a sectional view of an exemplary pod pump100that is incorporated into a fluid control or pump cassette (see alsoFIGS. 3 and 4), in accordance with an exemplary embodiment of the cassette. In this embodiment, the pod pump is formed from three rigid pieces, namely a “top” plate106, a midplate108, and a “bottom” plate110(it should be noted that the terms “top” and “bottom” are relative and are used here for convenience with reference to the orientation shown inFIG. 1A). The top and bottom plates106and110include generally hemispheroid portions that when assembled together define a hemispheroid chamber, which is a pod pump100.

A membrane112separates the central cavity of the pod pump into two chambers. In one embodiment, these chambers are: the pumping chamber that receives the fluid to be pumped and an actuation chamber for receiving the control gas that pneumatically actuates the pump. An inlet102allows fluid to enter the pumping chamber, and an outlet104allows fluid to exit the pumping chamber. The inlet102and the outlet104may be formed between midplate108and the top plate106. Pneumatic pressure is provided through a pneumatic port114to either force, with positive gas pressure, the membrane112against one wall of the pod pump cavity to minimize the pumping chamber's volume, or to draw, with negative gas pressure, the membrane112towards the other wall of the pod pump100cavity to maximize the pumping chamber's volume.

The membrane112is provided with a thickened rim116, which is held tightly by a protrusion118in the midplate108. Thus, in manufacturing, the membrane112can be placed in and held by the groove108before the bottom plate110is connected (in the exemplary embodiment) to the midplate108.

Although not shown inFIGS. 1A and 1B, in some embodiments of the pod pump, on the fluid side, a groove is present on the chamber wall. The grove acts to prevent folds in the membrane from trapping fluid in the chamber when emptying.

Referring first toFIG. 1Aa cross sectional view of a reciprocating positive-displacement pump100in a cassette is shown. The pod pump100includes a flexible membrane112(also referred to as the “pump diaphragm” or “membrane”) mounted where the pumping chamber (also referred to as a “liquid chamber” or “liquid pumping chamber”) wall122and the actuation chamber (also referred to as the “pneumatic chamber”) wall120meet. Te membrane112effectively divides that interior cavity into a variable-volume pumping chamber (defined by the rigid interior surface of the pumping chamber wall122and a surface of the membrane112) and a complementary variable-volume actuation chamber (defined by the rigid interior surface of the actuation chamber wall120and a surface of the membrane112). The top portion106includes a fluid inlet102and a fluid outlet104, both of which are in fluid communication with the pumping/liquid chamber. The bottom portion110includes an actuation or pneumatic interface114in fluid communication to with the actuation chamber. As discussed in greater detail below, the membrane112can be urged to move back and forth within the cavity by alternately applying negative or vent to atmosphere and positive pneumatic pressure at the pneumatic interface114. As the membrane112reciprocates back and forth, the sum of the volumes of the pumping and actuation chambers remains constant.

During typical fluid pumping operations, the application of negative or vent to atmosphere pneumatic pressure to the actuation or pneumatic interface114tends to withdraw the membrane112toward the actuation chamber wall120so as to expand the pumping/liquid chamber and draw fluid into the pumping chamber through the inlet102, while the application of positive pneumatic pressure tends to push the membrane112toward the pumping chamber wall122so as to collapse the pumping chamber and expel fluid in the pumping chamber through the outlet104. During such pumping operations, the interior surfaces of the pumping chamber122and the actuation chamber wall120limit movement of the membrane112as it reciprocates back and forth. In the embodiment shown inFIG. 1A, the interior surfaces of the pumping chamber wall122and the actuation chamber wall120are rigid, smooth, and hemispherical. In lieu of a rigid actuation chamber wall120, an alternative rigid limit structure—for example, a portion of a bezel used for providing pneumatic pressure and/or a set of ribs—may be used to limit the movement of the membrane as the pumping chamber approaches maximum value. Bezels and rib structures are described generally in U.S. patent application Ser. No. 10/697,450 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 30, 2003 and published as Publication No. US 2005/0095154 and related PCT Application No. PCT/US2004/035952 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 29, 2004 and published as Publication No. WO 2005/044435 both of which are hereby incorporated herein by reference in their entireties. Thus, the rigid limit structure—such as the rigid actuation chamber wall120, a bezel, or a set of ribs—defines the shape of the membrane112when the pumping chamber is at its maximum value. In a preferred embodiment, the membrane112(when urged against the rigid limit structure) and the rigid interior surface of the pumping chamber wall122define a spherical pumping chamber volume when the pumping chamber volume is at a minimum.

Thus, in the embodiment shown inFIG. 1A, movement of the membrane112is limited by the pumping chamber wall122and the actuation chamber wall120. As long as the positive and vent to atmosphere or negative pressurizations provided through the pneumatic port114are strong enough, the membrane112will move from a position limited by the actuation chamber wall120to a position limited by the pumping chamber wall122. When the membrane112is forced against the actuation chamber wall120, the membrane and the pumping chamber wall122define the maximum volume of the pumping chamber. When the membrane is forced against the pumping chamber wall122, the pumping chamber is at its minimum volume.

In an exemplary embodiment, the pumping chamber wall122and the actuation chamber wall120both have a hemispheroid shape so that the pumping chamber will have a spheroid shape when it is at its maximum volume. By using a pumping chamber that attains a spheroid shape—and particularly a spherical shape—at maximum volume, circulating flow may be attained throughout the pumping chamber. Such shapes accordingly tend to avoid stagnant pockets of fluid in the pumping chamber. As discussed further below, the orientations of the inlet102and outlet104also tend to have an impact on the flow of fluid through the pumping chamber and in some embodiments, reduce the likelihood of stagnant pockets of fluid forming. Additionally, compared to other volumetric shapes, the spherical shape (and spheroid shapes in general) tends to create less shear and turbulence as the fluid circulates into, through, and out of the pumping chamber.

Referring now toFIGS. 3-4, a raised flow path30is shown in the pumping chamber. This raised flow path30allows for the fluid to continue flowing through the pod pumps after the membrane reaches the end of stroke. Thus, the raised flow path30minimizes the chances of the membrane causing air or fluid to be trapped in the pod pump or the membrane blocking the inlet or outlet of the pod pump which would inhibit continuous flow. The raised flow path30is shown in the exemplary embodiment having particular dimensions, however, in alternate embodiments, as seen inFIGS. 18A-18E, the raised flow path30is narrower, or in still other embodiments, the raised flow path30can be any dimensions as the purpose is to control fluid flow so as to achieve a desired flow rate or behavior of the fluid. Thus, the dimensions shown and described here with respect to the raised flow path, the pod pumps, the valves or any other aspect are mere exemplary and alternate embodiments. Other embodiments are readily apparent.

Referring now toFIG. 1B, an exemplary embodiment of a balancing pod is shown. The balancing pod is constructed similar to the pod pump described above with respect toFIG. 1A. However, a balancing pod includes two fluid balancing chambers, rather than an actuation chamber and a pumping chamber, and does not include an actuation port. Additionally, each balancing chamber includes an inlet102and an outlet104. In the exemplary embodiment, a groove126is included on each of the balancing chamber walls120,122. The groove126is described in further detail below.

The membrane112provides a seal between the two chambers. The balancing chambers work to balance the flow of fluid into and out of the chambers such that both chambers maintain an equal volume rate flow. Although the inlets102and outlets104for each chamber are shown to be on the same side in other embodiments, the inlets102and outlets104for each chamber are on different sides. Also, the inlets102and outlets104can be on either side, depending on the flow path in which the balancing pod is integrated.

In one embodiment of the balancing pod the membrane112includes an embodiment similar to the one described below with respect toFIGS. 6A-6G. However, in alternate embodiments, the membrane112can be over molded or otherwise constructed such that a double-ring seal is not applicable.

1.4 Metering Pumps and Fluid Management System

The metering pump can be any pump that is capable of adding any fluid or removing any fluid. The fluids include but are not limited to pharmaceuticals, inorganic compounds or elements, organic compounds or elements, nutraceuticals, nutritional elements or compounds or solutions, or any other fluid capable of being pumped. In one embodiment, the metering pump is a membrane pump. In the exemplary embodiment, the metering pump is a smaller volume pod pump. In the exemplary embodiment the metering pump includes an inlet and an outlet, similar to a larger pod pump (as shown inFIG. 1Afor example). However, the inlet and outlet are generally much smaller than a pod pump and, in one exemplary embodiment, includes a volcano valve-like raised ring around either the inlet or outlet. Metering pumps include a membrane, and various embodiments of a metering pump membrane are shown inFIGS. 5E-5H. The metering pump, in some embodiments, pumps a volume of fluid out of the fluid line. Once the fluid is in the pod pump, a reference chamber, located outside the cassette, using the FMS, determines the volume that has been removed.

Thus, depending on the embodiment, this volume of fluid that has been removed will not then flow to the fluid outlet, the balance chambers or to a pod pump. Thus, in some embodiments, the metering pump is used to remove a volume of fluid from a fluid line. In other embodiments, the metering pump is used to remove a volume of fluid to produce other results.

FMS may be used to perform certain fluid management system measurements, such as, for example, measuring the volume of subject fluid pumped through the pump chamber during a stroke of the membrane or detecting air in the pumping chamber, e.g., using techniques described in U.S. Pat. Nos. 4,808,161; 4,826,482; 4,976,162; 5,088,515; and 5,350,357, which are hereby incorporated herein by reference in their entireties.

Metering pumps are also used in various embodiments to pump a second fluid into the fluid line. In some embodiments, the metering pump is used to pump a therapeutic or a compound into a fluid line. One embodiment uses the metering pump to pump a volume of compound into a mixing chamber in order to constitute a solution. In some of these embodiments, the metering pumps are configured for FMS volume measurement. In other embodiments, the metering pumps are not.

For FMS measurement, a small fixed reference air chamber is located outside of the cassette, for example, in the pneumatic manifold (not shown). A valve isolates the reference chamber and a second pressure sensor. The stroke volume of the metering pump may be precisely computed by charging the reference chamber with air, measuring the pressure, and then opening the valve to the pumping chamber. The volume of air on the chamber side may be computed based on the fixed volume of the reference chamber and the change in pressure when the reference chamber was connected to the pump chamber.

The exemplary embodiment of the cassette includes one or more valves. Valves are used to regulate flow by opening and closing fluid lines. The valves included in the various embodiments of the cassette include one or more of the following: volcano valves or smooth valves. In some embodiment of the cassette check valves may be included. Embodiments of the volcano valve are shown inFIGS. 2A and 2B, while an embodiment of the smooth valve is shown inFIG. 2C. Additionally,FIGS. 3 and 4show cross sections of one embodiment of a pod pump in a cassette with an inlet and an outlet valve.

Generally speaking, reciprocating positive-displacement pumps of the types just described may include, or may be used in conjunction with various valves to control fluid flow through the pump. Thus, for example, the reciprocating positive-displacement pump or the balancing pods may include, or be used in conjunction with, an inlet valve and/or an outlet valve. The valves may be passive or active. In the exemplary embodiment of the reciprocating positive-displacement pump the membrane is urged back and forth by positive and negative pressurizations, or by positive and vent to atmosphere pressurizations, of a gas provided through the pneumatic port, which connects the actuation chamber to a pressure actuation system. The resulting reciprocating action of the membrane pulls fluid into the pumping chamber from the inlet (the outlet valve prevents liquid from being sucked back into the pumping chamber from the outlet) and then pushes the fluid out of the pumping chamber through the outlet (the inlet valve prevents fluid from being forced back from the inlet).

In the exemplary embodiments, active valves control the fluid flow through the pump(s) and the cassette. The active valves may be actuated by a controller in such a manner as to direct flow in a desired direction. Such an arrangement would generally permit the controller to cause flow in either direction through the pod pump. In a typical system, the flow would normally be in a first direction, e.g., from the inlet to the outlet. At certain other times, the flow may be directed in the opposite direction, e.g., from the outlet to the inlet. Such reversal of flow may be employed, for example, during priming of the pump, to check for an aberrant line condition (e.g., a line occlusion, blockage, disconnect, or leak) or to clear an aberrant line condition (e.g., to try to dislodge a blockage).

Pneumatic actuation of valves provides pressure control and a natural limit to the maximum pressure that may be developed in a system. In the context of a system, pneumatic actuation has the added benefit of providing the opportunity to locate all the solenoid control valves on one side of the system away from the fluid paths.

Referring now toFIGS. 2A and 2B, sectional views of two embodiments of a volcano valve are shown. The volcano valves are pneumatically controlled valves that may be used in embodiments of the cassette. A membrane202, along with the midplate204, defines a valving chamber206. Pneumatic pressure is provided through a pneumatic port208to either force, with positive gas pressure, the membrane202against a valve seat210to close the valve, or to draw, with negative gas pressure, or in some embodiments, with vent to atmospheric pressure, the membrane away from the valve seat210to open the valve. A control gas chamber212is defined by the membrane202, the top plate214, and the midplate204. The midplate204has an indentation formed on it, into which the membrane202is placed so as to form the control gas chamber212on one side of the membrane202and the valving chamber206on the other side.

The pneumatic port208is defined by a channel formed in the top plate244. By providing pneumatic control of several valves in a cassette, valves can be ganged together so that all the valves ganged together can be opened or closed at the same time by a single source of pneumatic pressure. Channels formed on the midplate204, corresponding with fluid paths along with the bottom plate216, define the valve inlet218and the valve outlet220. Holes formed through the midplate204provide communication between the inlet218and the valving chamber206and between the valving chamber206and the outlet220.

The membrane202is provided with a thickened rim222, which fits tightly in a groove224in the midplate204. Thus, the membrane202can be placed in and held by the groove224before the top plate214is connected to the midplate204. Thus, this valve design may impart benefits in manufacturing. As shown inFIGS. 2B and 2C, the top plate214may include additional material extending into control gas chamber212so as to prevent the membrane202from being urged too much in a direction away from the groove224, so as to prevent the membrane's thickened rim222from popping out of the groove224. The location of the pneumatic port208with respect to the control gas chamber212varies in the two embodiments shown inFIGS. 2A and 2B.

FIG. 2Cshows an embodiment in which the valving chamber lacks a valve seat feature. Rather, inFIG. 2C, the valve in this embodiment does not include any volcano features and thus, the valving chamber206, i.e., the fluid side, does not include any raised features and thus is smooth. This embodiment is used in cassettes used to pump fluid sensitive to shearing.FIG. 2Dshows an embodiment in which the valving chamber has a raised area to aid in the sealing of the valving membrane. Referring now toFIGS. 2E-2G, various embodiments of the valve membrane are shown. Although some exemplary embodiments have been shown and described, in other embodiments, variations of the valve and valving membrane may be used.

1.6 Exemplary Embodiments of the Pod Membrane

In some embodiments, the membrane has a variable cross-sectional thickness, as shown inFIG. 4. Thinner, thicker or variable thickness membranes may be used to accommodate tie strength, flexural and other properties of the chosen membranes materials. Thinner, thicker or variable membrane wall thickness may also be used to manage the membrane thereby encouraging it to flex more easily in some areas than in other areas, thereby aiding in the management of pumping action and flow of subject fluid in the pump chamber. In this embodiment the membrane is shown having its thickest cross-sectional area closest to its center. However in other embodiments having a membrane with a varying cross-sectional, the thickest and thinnest areas may be in any location on the membrane. Thus, for example, the thinner cross-section may be located near the center and the thicker cross-sections located closer to the perimeter of the membrane. Still other configurations are possible. Referring toFIGS. 5A-5D, one embodiment of a membrane is shown having various surface embodiments, these include smooth (FIG. 5A), rings (FIG. 5D), ribs (FIG. 5C), dimples or dots (FIG. 5B) of variable thickness and or geometry located at various locations on the actuation and or pumping side of the membrane. In one embodiment of the membrane, the membrane has a tangential slope in at least one section, but in other embodiments, the membrane is completely smooth or substantially smooth.

Referring now toFIGS. 4A,4C and4D, an alternate embodiment of the membrane is shown. In this embodiment, the membrane has a dimpled or dotted surface.

The membrane may be made of any flexible material having a desired durability and compatibility with the subject fluid. The membrane can be made from any material that may flex in response to fluid, liquid or gas pressure or vacuum applied to the actuation chamber. The membrane material may also be chosen for particular bio-compatibility, temperature compatibility or compatibility with various subject fluids that may be pumped by the membrane or introduced to the chambers to facilitate movement of the membrane. In the exemplary embodiment, the membrane is made from high elongation silicone. However, in other embodiments, the membrane is made from any elastomer or rubber, including, but not limited to, silicone urethane, nitrile, EPDM or any other rubber, elastomer or flexible material.

The shape of the membrane is dependent on multiple variables. These variables include, but are not limited to: the shape of the chamber, the size of the chamber, the subject fluid characteristics; the volume of subject fluid pumped per stroke; and the means or mode of attachment of the membrane to the housing. The size of the membrane is dependent on multiple variables. These variables include, but are not limited to: the shape of the chamber; the size of the chamber; the subject fluid characteristics; the volume of subject fluid pumped per stroke; and the means or mode of attachment of the membrane to the housing. Thus, depending on these or other variables, the shape and size of the membrane may vary in various embodiments.

The membrane can have any thickness. However, in some embodiments, the range of thickness is between 0.002 inches to 0.125 inches. Depending on the material used for the membrane, the desired thickness may vary. In one embodiment, high elongation silicone is used in a thickness ranging from 0.015 inches to 0.050 inches. However in other embodiments, the thickness may vary.

In the exemplary embodiment, the membrane is pre-formed to include a substantially dome-shape in at least part of the area of the membrane. One embodiment of the dome-shaped membrane is shown inFIGS. 4E and 4F. Again, the dimensions of the dome may vary based on some or more of the variables described above. However, in other embodiments, the membrane may not include a pre-formed dome shape.

In the exemplary embodiment, the membrane dome is formed using liquid injection molding. However, in other embodiments, the dome may be formed by using compression molding. In alternate embodiments, the membrane is substantially flat. In other embodiments, the dome size, width or height may vary.

In various embodiments, the membrane may be held in place by various means and methods. In one embodiment, the membrane is clamped between the portions of the cassette, and in some of these embodiments, the rim of the cassette may include features to grab the membrane. In others of this embodiment, the membrane is clamped to the cassette using at least one bolt or another device. In another embodiment, the membrane is over-molded with a piece of plastic and then the plastic is welded or otherwise attached to the cassette. In another embodiment, the membrane is pinched between the mid plate described with respect toFIGS. 1A and 1Band the bottom plate. Although some embodiments for attachment of the membrane to the cassette are described, any method or means for attaching the membrane to the cassette can be used. The membrane, in one alternate embodiment, is attached directly to one portion of the cassette. In some embodiments, the membrane is thicker at the edge, where the membrane is pinched by the plates, than in other areas of the membrane. In some embodiments, this thicker area is a gasket, in some embodiments an O-ring, ring or any other shaped gasket. Referring again to6A-6D, one embodiment of the membrane is shown with two gaskets62,64. In some of these embodiments, the gasket(s)62,64provides the attachment point of the membrane to the cassette. In other embodiments, the membrane includes more than two gaskets. Membranes with one gasket are also included in some embodiments (seeFIGS. 4A-4D).

In some embodiments of the gasket, the gasket is contiguous with the membrane. However, in other embodiments, the gasket is a separate part of the membrane. In some embodiments, the gasket is made from the same material as the membrane. However, in other embodiments, the gasket is made of a material different from the membrane. In some embodiments, the gasket is formed by over-molding a ring around the membrane. The gasket can be any shape ring or seal desired so as to complement the pod pump housing embodiment. In some embodiments, the gasket is a compression type gasket.

Some embodiments of the cassette include a mixing pod. A mixing pod includes a chamber for mixing. In some embodiments, the mixing pod is a flexible structure, and in some embodiments, at least a section of the mixing pod is a flexible structure. The mixing pod can include a seal, such as an o-ring, or a membrane. The mixing pod can be any shape desired. In the exemplary embodiment, the mixing pod is similar to a pod pump except it does not include a membrane and does not include an actuation port. Some embodiments of this embodiment of the mixing pod include an o-ring seal to seal the mixing pod chamber. Thus, in the exemplary embodiment, the mixing pod is a spherical hollow pod with a fluid inlet and a fluid outlet. As with the pod pumps, the chamber size can be any size desired.

2. Pressure Pump Actuation System

FIG. 7is a schematic showing an embodiment of a pressure actuation system that may be used to actuate a pod pump with both positive and negative pressure, such as the pod pump shown inFIG. 1A. The pressure actuation system is capable of intermittently or alternately providing positive and negative pressurizations to the gas in the actuation chamber of the pod pump. However, in some embodiments,FIG. 7does not apply in these embodiments, actuation of the pod pump is accomplished by applying positive pressure and vent to atmosphere (again, not shown inFIG. 7). The pod pump—including the flexible membrane, the inlet, the outlet, the pneumatic port, the pumping chamber, the actuation chamber, and possibly including an inlet check valve and an outlet check valve or other valves—is part of a larger disposable system. The pneumatic actuation system—including an actuation-chamber pressure transducer, a positive-supply valve, a negative-supply valve, a positive-pressure gas reservoir, a negative-pressure gas reservoir, a positive-pressure-reservoir pressure transducer, a negative-pressure-reservoir pressure transducer, as well as an electronic controller including, in some embodiments, a user interface console (such as a touch-panel screen)—may be part of a base unit.

The positive-pressure reservoir provides to the actuation chamber the positive pressurization of a control gas to urge the membrane towards a position where the pumping chamber is at its minimum volume (i.e., the position where the membrane is against the rigid pumping-chamber wall). The negative-pressure reservoir provides to the actuation chamber the negative pressurization of the control gas to urge the membrane in the opposite direction, towards a position where the pumping chamber is at its maximum volume (i.e., the position where the membrane is against the rigid actuation-chamber wall).

A valving mechanism is used to control fluid communication between each of these reservoirs and the actuation chamber. As shown inFIG. 7, a separate valve is used for each of the reservoirs; a positive-supply valve controls fluid communication between the positive-pressure reservoir arid the actuation chamber, and a negative-supply valve controls fluid communication between the negative-pressure reservoir and the actuation chamber. These two valves are controlled by the controller. Alternatively, a single three-way valve may be used in lieu of the two separate valves. The valves may be binary on-off valves or variable-restriction valves.

The controller also receives pressure information from the three pressure transducers: an actuation-chamber pressure transducer, a positive-pressure-reservoir pressure transducer, and a negative-pressure-reservoir pressure transducer. As their names suggest, these transducers respectively measure the pressure in the actuation chamber, the positive-pressure reservoir, and the negative-pressure reservoir. The actuation-chamber-pressure transducer is located in a base unit but is in fluid communication with the actuation chamber through the pod pump pneumatic port. The controller monitors the pressure in the two reservoirs to ensure they are properly pressurized (either positively or negatively). In one exemplary embodiment, the positive-pressure reservoir may be maintained at around 750 mmHG, while the negative-pressure reservoir may be maintained at around −450 mmHG.

Still referring toFIG. 7, a compressor-type pump or pumps (not shown) may be used to maintain the desired pressures in these reservoirs. For example, two independent compressors may be used to respectively service the reservoirs. Pressure in the reservoirs may be managed using a simple bang-bang control technique in which the compressor servicing the positive-pressure reservoir is turned on if the pressure in the reservoir falls below a predetermined threshold and the compressor servicing the negative-pressure reservoir is turned on if the pressure in the reservoir is above a predetermined threshold. The amount of hysteresis may be the same for both reservoirs or may be different. Tighter control of the pressure in the reservoirs can be achieved by reducing the size of the hysteresis band, although this will generally result in higher cycling frequencies of the compressors. If very tight control of the reservoir pressures is required or otherwise desirable for a particular application, the bang-bang technique could be replaced with a PID control technique and could use PWM signals on the compressors.

The pressure provided by the positive-pressure reservoir is preferably strong enough—under normal conditions—to urge the membrane all the way against the rigid pumping-chamber wall. Similarly, the negative pressure (i.e., the vacuum) provided by the negative-pressure reservoir is preferably strong enough—under normal conditions —to urge the membrane all the way against the actuation-chamber wall. In a further preferred embodiment, however, these positive and negative pressures provided by the reservoirs are within safe enough limits that even with either the positive-supply valve or the negative-supply valve open all the way, the positive or negative pressure applied against the membrane is not so strong as to damage the pod pump or create unsafe fluid pressures (e.g., that may harm a patient receiving pumped blood of other fluid).

It will be appreciated that other types of actuation systems may be used to move the membrane back and forth instead of the two-reservoir pneumatic actuation system shown inFIG. 7, although a two-reservoir pneumatic actuation system is generally preferred. For example, alternative pneumatic actuation systems may include either a single positive-pressure reservoir or a single negative-pressure reservoir along with a single supply valve and a single tank pressure sensor, particularly in combination with a resilient membrane. Such pneumatic actuation systems may intermittently provide either a positive gas pressure or a negative gas pressure to the actuation chamber of the pod pump. In embodiments having a single positive-pressure reservoir, the pump may be operated by intermittently providing positive gas pressure to the actuation chamber, causing the membrane to move toward the pumping chamber wall and expel the contents of the pumping chamber, and releasing the gas pressure, causing the membrane to return to its relaxed position and draw fluid into the pumping chamber. In embodiments having a single negative-pressure reservoir, the pump may be operated by intermittently providing negative gas pressure to the actuation chamber, causing the membrane to move toward the actuation chamber wall and draw fluid into the pumping chamber, and releasing the gas pressure, causing the membrane to return to its relaxed position and expel fluid from the pumping chamber.

3. Fluid Handling

As shown and described with respect toFIGS. 2A-2D, a fluid valve in tie exemplary embodiment consists of a small chamber with a flexible membrane or membrane across the center dividing the chamber into a fluid half and a pneumatic half. The fluid valve, in the exemplary embodiment, has 3 entry/exit ports, two on the fluid half of the chamber and one the pneumatic half of the chamber. The port on the pneumatic half of the chamber can supply either positive pressure or vacuum (or rather than vacuum, in some embodiments, there is a vent to atmosphere) to the chamber. When a vacuum is applied to the pneumatic portion of the chamber, the membrane is pulled towards the pneumatic side of the chamber, clearing the fluid path and allowing fluid to flow into and out of the fluid side of the chamber. When positive pressure is applied to the pneumatic portion of the chamber, the membrane is pushed towards the fluid side of the chamber, blocking the fluid path and preventing fluid flow. In the volcano valve embodiment (as shown inFIGS. 2A-2B) on one of the fluid ports, that port seals off first when closing the valve and the remainder of any fluid in the valve is expelled through the port without the volcano feature. Additionally, in one embodiment of the valves, shown inFIG. 2D, the raised feature between the two ports allows for the membrane to seal the two ports from each other earlier in the actuation stroke (i.e., before the membrane seals the ports directly).

Referring again toFIG. 7, pressure valves are used to operate the pumps located at different points in the flow path. This architecture supports pressure control by using two variable-orifice valves and a pressure sensor at each pump chamber which requires pressure control. In one embodiment one valve is connected to a high-pressure source and the other valve is connected to a low-pressure sink. A high-speed control loop monitors the pressure sensor and controls the valve positions to maintain the necessary pressure in the pump chamber.

Pressure sensors are used to monitor pressure in the pneumatic portion of the chambers themselves. By alternating between positive pressure and vacuum on the pneumatic side of the chamber, the membrane is cycled back and forth across the total chamber volume. With each cycle, fluid is drawn through the upstream valve of the inlet fluid port when the pneumatics pull a vacuum on the pods. The fluid is then subsequently expelled through the outlet port and the downstream valve when the pneumatics deliver positive pressure to the pods.

In many embodiments pressure pumps consist of a pair of chambers. When the two chambers are run 180 degrees out of phase from one another the flow is essentially continuous.

4. Volume Measurement

These flow rates in the cassette are controlled using pressure pod pumps which can detect end-of-stroke. An outer control loop determines the correct pressure values to deliver the required flow. Pressure pumps can run an end of stroke algorithm to detect when each stroke completes. While the membrane is moving, the measured pressure in the chamber tracks a desired sinusoidal pressure. When the membrane contacts a chamber wall, the pressure becomes constant, no longer tracking the sinusoid. This change in the pressure signal is used to detect when the stroke has ended, i.e., the end-of-stroke.

The pressure pumps have a known volume. Thus, an end of stroke indicates a known volume of fluid is in the chamber. Thus, using the end-of-stroke, fluid flow may be controlled using rate equating to volume.

As described above in more detail, FMS may be used to determine the volume of fluid pumped by the metering pumps. In some embodiments, the metering pump may pump fluid without using the FMS volume measurement system, however, in the exemplary embodiments, the FMS volume measurement system is used to calculate the exact volume of fluid pumped.

5. Exemplary Embodiment of the Mixing Cassette

The terms inlet and outlet as well as first fluid, second fluid, third fluid, and the number designations given to valving paths (i.e. “first valving path”) are used for description purposes only. In other embodiments, an inlet can be an outlet, as well, an indication of a first, second, third fluid does not denote that they are different fluids or are in a particular hierarchy. The denotations simply refer to separate entrance areas into the cassette and the first, second, third, etc., fluids may be different fluids or the same fluid types or composition or two or more may be the same. Likewise, the designation of the first, second, third, etc. valving paths do not have any particular meaning, but are used for clearness of description.

The designations given for the fluid inlets (which can also be fluid outlets), for example, first fluid outlet, second fluid outlet, merely indicate that a fluid may travel out of or into the cassette via that inlet/outlet. In some cases, more than one inlet/outlet on the schematic is designated with an identical name. This merely, describes that all of the inlet/outlets having that designation are pumped by the same metering pump or set of pod pumps (which in alternate embodiments, can be a single pod pump).

Referring now toFIG. 8, an exemplary embodiment of the fluid schematic of the cassette800is shown. Other schematics are readily discernable. The cassette800includes at least one pod pump828,820and at least one mixing chamber818. The cassette800also includes a first fluid inlet810, where a first fluid enters the cassette. The first fluid includes a flow rate provided by one of the at least one pod pump820,828in the cassette800. The cassette800also includes a first fluid outlet824where fluid exits the cassette800having a flow rate provided by one of the at least one pod pump820,828. The cassette800includes at least one metering fluid line812,814,816that is in fluid connection with the first fluid outlet. The cassette also includes at least one second fluid inlet826where the second fluid enters the cassette800. In some embodiments of the cassette800a third fluid inlet825is also included.

Metering pumps822,830pump the second fluid and the third fluid into the first fluid outlet line. The second fluid and, in some embodiments, the third fluid, connected to the cassette800at the second fluid inlet826and third fluid inlet825respectively, are each fluidly connected to a metering pump822,830and to the first fluid outlet line through a metering fluid line812,814,816. The metering pumps822,830, described in more detail below, in the exemplary embodiment, include a volume measurement capacity such that the volume of fluid pumped by the metering pumps822,830is readily discernable.

The mixing chamber818is connected to the first fluid outlet line824and includes a fluid inlet and a fluid outlet. In some embodiments, sensors are located upstream and downstream from the mixing chamber818. The location of the sensors in the exemplary embodiment are shown and described below with respect toFIGS. 14C,14D andFIGS. 15B and 15C.

The cassette800is capable of internally mixing a solution made up of at least two components. The cassette800also includes the capability of constituting a powder to a fluid prior to pumping the fluid into the mixing chamber. These capabilities will be described in greater detail below.

Various valves832-860impart the various capabilities of the cassette800. The components of the cassette800may be used differently in the different embodiments based on various valving controls.

The fluid schematic of the cassette800shown inFIG. 8may be embodied into various cassette apparatus. Thus, the embodiments of the cassette800including the fluid schematic shown inFIG. 8are not the only cassette embodiments that may incorporate this or an alternate embodiment of this fluid schematic. Additionally, the types of valves, the ganging of the valves, the number of pumps and chambers may vary in various cassette embodiments of this fluid schematic.

Referring now toFIG. 8, a fluid flow-path schematic800is shown with the fluid paths indicated based on different valving flow paths. The fluid flow-path schematic800is described herein corresponding to the valving flow paths in one embodiment of the cassette. The exemplary embodiment of the midplate900of the cassette are shown inFIG. 10with the valves indicated corresponding to the respective fluid flow-path schematic800inFIG. 8. For the purposes of the description, the fluid flow paths will be described based on the valving. The term “valving path” refers to a fluid path that may, in some embodiments, be available based on the control of particular valves. The corresponding fluid side structures ofFIG. 10are shown inFIG. 12A.

Referring now toFIGS. 8 and 10the first valving path includes valves858,860. This valving path858,860includes the metering fluid line812, which connects to the second fluid inlet826. As shown in these FIGS., in some embodiments of the cassette, there are two second fluid inlets826. In practice, these two second fluid inlets826can be connected to the same fluid source or a different fluid source. Either way, the same fluid or a different fluid may be connected to each second fluid inlet826. Each second fluid inlet826is connected to a different metering fluid line812,814.

The first of the two metering fluid lines connected to the second fluid inlet826is as follows. When valve858opens and valve860is closed and metering pump822is actuated, fluid is drawn from the second fluid inlet826and into metering fluid line812. When valve860is open and valve858is closed and the metering pump822is actuated, second fluid continues on metering fluid line812into pod pump820.

Referring now to the second valving path including valve842, when valve842is open and pod pump820is actuated, fluid is pumped from pod pump820to one of the third fluid inlet825. In one embodiment, this valving path is provided to send liquid into a container or source connected to third fluid inlet825.

Referring now to the third valving path including valves832and836this valving path832,835includes the metering fluid line816, which connects to the third fluid inlet825. As shown in these FIGS., in some embodiments of the cassette, there are two third fluid inlets825. In practice, these two third fluid inlets825can be connected to the same fluid source or a different fluid source. Either way, the same fluid or a different fluid may be connected to each third fluid inlet825. Each third fluid inlet825is connected to a different metering fluid line862,868.

When valve832opens and valve836is closed and metering pump830is actuated, fluid is drawn from the third fluid inlet825and into metering fluid line830. When valve836is open and valve832is closed and the metering pump830is actuated, third fluid continues on metering fluid line816into first fluid outlet line824.

Referring now to the fourth valving path, valve846, when valve846is open and pod pump820is actuated, fluid is pumped from pod pump820to one of the third fluid inlet825. In one embodiment, this valving path is provided to send liquid into a container or source connected to third fluid inlet825.

Referring now to the fifth valving path, when valve850opens and pod pump820is actuated, fluid is pumped into the cassette800through the first fluid inlet810, and into pod pump820.

Referring now to the sixth valving path, when valve838is open and pod pump820is actuated, fluid is pumped from pod pump820to the mixing chamber818and to the first fluid outlet824.

The seventh valving path includes valves858,856. This valving path858,856includes the metering fluid line812, which connects to the second fluid inlet826. As shown in these FIGS., in some embodiments of the cassette, there are two second fluid inlets826. In practice, these two second fluid inlets826can be connected the same fluid source or a different fluid source. Either way, the same fluid or a different fluid may be connected to each second fluid inlet826. Each second fluid inlet826is connected to a different metering fluid line812,814.

When valve858opens and valve856is closed and metering pump822is actuated, fluid is drawn from the second fluid inlet826and into metering fluid line812. When valve856is open and valve858is closed, and the metering pump is actuated, second fluid continues on metering fluid line814into pod pump828.

Referring now to the eighth valving path, valve848, when valve848is open and pod pump828is actuated, fluid is pumped from pod pump828to one of the third fluid inlet825. In one embodiment, this valving path is provided to send fluid/liquid into a container or source connected to third fluid inlet825.

Referring now to the ninth valving path including valve844, when valve844is open and pod pump828is actuated, fluid is pumped from pod pump828to one of the third fluid inlet825. In one embodiment, this valving path is provided to send liquid into a container or source connected to third fluid inlet825.

Referring now to the tenth valving path, valve848, when valve848is open and pod pump828is actuated, fluid is pumped from pod pump828to one of the third fluid inlet825. In one embodiment, this valving path is provided to send fluid/liquid into a container or source connected to third fluid inlet825.

The eleventh valving path including valves854and856is shown. This valving path854,856includes the metering fluid line814, which connects to the second fluid inlet826. As shown in these FIGS., in some embodiments of the cassette, there are two second fluid inlets826. In practice, these two second fluid inlets826can be connected the same fluid source or a different fluid source. Either way, the same fluid or a different fluid may be connected to each second fluid inlet826. Each second fluid inlet826is connected to a different metering fluid line812,814.

The second of the two metering fluid lines connected to the second fluid inlet826is shown inFIG. 8. The twelfth valving path is as follows. When valve854opens and valve856is closed and metering pump822is actuated, fluid is drawn from the second fluid inlet826and into metering fluid line814. When valve856is open and valve854is closed arid the metering pump822is actuated, the second fluid continues on metering fluid line814into pod pump828.

Similarly, the thirteenth valving path is seen when valve854opens and valve860is closed and metering pump822is actuated, fluid is drawn from the second fluid inlet826and into metering fluid line814. When valve860is open and valve854is closed, and the metering pump822is actuated, the second fluid continues on metering fluid line814into pod pump820.

Referring now to the fourteenth valving path including valve852. When valve852opens and pod pump828is actuated, fluid is pumped into the cassette800through the first fluid inlet810, and into pod pump828.

Referring now to the fifteenth valving path, when valve840is open and pod pump828is actuated, fluid is pumped from pod pump828to the mixing chamber818and to the first fluid outlet824. The sixteenth valving path including valve834, when valve834is open and valve836opens, and the metering pump830is actuated, fluid from the third fluid inlet825flows on metering fluid line862and to metering fluid line816.

In the exemplary fluid flow-path embodiment shown inFIG. 8, and corresponding structure of the cassette shown inFIG. 10, valves are open individually. In the exemplary embodiment, the valves are pneumatically open. Also, in the exemplary embodiment, the fluid valves are volcano valves, as described in more detail in this specification.

Referring now toFIGS. 11A-11D, the top plate1100of exemplary embodiment of the cassette is shown. In the exemplary embodiment, the pod pumps820,828and the mixing chambers818on the top plate1100, are formed in a similar fashion. In the exemplary embodiment, the pod pumps820,828and mixing chamber818, when assembled with the bottom plate, have a total volume of capacity of 38 ml. However, in other embodiments, the mixing chamber can have any size volume desired.

Referring now toFIGS. 11C and 11D, the bottom view of the top plate1100is shown. The fluid paths are shown in this view. These fluid paths correspond to the fluid paths shown inFIGS. 12A-12Din the midplate1200. The top plate1100and the top of the midplate1200form the liquid or fluid side of the cassette for the pod pumps820,828and for one side of the mixing chamber818. Thus, most of the liquid flow paths are on the top1100and midplates1200. Referring toFIGS. 12C and 12D, the first fluid inlet810and the first fluid outlet824are shown.

Still referring toFIGS. 11A-11D, the pod pumps820,828include a groove1002(in alternate embodiments, this is a groove). The groove1002is shown having a particular size and shape, however, in other embodiments, the size and shape of the groove1002can be any size or shape desirable. The size and shape shown inFIGS. 11A-11Dis the exemplary embodiment. In all embodiments of the groove1002, the groove1002forms a path between the fluid inlet side and the fluid outlet side of the pod pumps820,828. In alternate embodiments, the groove1002is a groove in the inner pumping chamber wall of the pod pump.

The groove1002provides a fluid path whereby when the membrane is at the end-of-stroke there is still a fluid path between the inlet and outlet such that the pockets of fluid or air do not get trapped in the pod pump. The groove1002is included in both the liquid/fluid and air/actuation sides of the pod pumps820,828. In some embodiments, the groove1002may also be included in the mixing chamber818(seeFIGS. 13A-13Dwith respect to the actuation/air side of the pod pumps820,828and the opposite side of the mixing chamber818. In alternate embodiments, the groove1002is either not included or on only one side of the pod pumps820,828.

In an alternate embodiment of the cassette, the liquid/fluid side of the pod pumps820,828may include a feature (not shown) whereby the inlet and outlet flow paths are continuous and a rigid outer ring (not shown) is molded about the circumference of the pumping chamber is also continuous. This feature allows for the seal, formed with the membrane (not shown) to be maintained. Referring toFIG. 11E, the side view of the exemplary embodiment of the top plate1100is shown.

Referring now toFIGS. 12A-12D, the exemplary embodiment of the midplate1200is shown. The midplate1200is also shown inFIGS. 9A-9Fand10A-10F, where these figures correspond withFIGS. 12A-12D. Thus,FIGS. 9A-9Fand10A-10F indicate the locations of the various valves and valving paths. The locations of the membranes (not shown) for the respective pod pumps820,828as well as the location of the mixing chamber818are shown.

Referring now toFIG. 12C, in the exemplary embodiment of the cassette, sensor elements are incorporated into the cassette so as to discern various properties of the fluid being pumped. In one embodiment, three sensor elements are included. However, in the exemplary embodiment, six sensor elements (two sets of three) are included. The sensor elements are located in the sensor cell1314,1316. In this embodiment, a sensor cell1314,1316is included as an area on the cassette for sensor(s) elements. In the exemplary embodiment, the three sensor elements of the two sensor cells1314,1316are housed in respective sensor elements housings1308,1310,1312and1318,1320,1322. In the exemplary embodiment, two of the sensor elements housings1308,1312and1318,1320accommodate a conductivity sensor elements and the third sensor elements housing1310,1322accommodates a temperature sensor elements. The conductivity sensor elements and temperature sensor elements can be any conductivity or temperature sensor elements in the art. In one embodiment, the conductivity sensors are graphite posts. In other embodiments, the conductivity sensor elements are posts made from stainless steel, titanium, platinum or any other metal coated to be corrosion resistant and still be electrically conductive. The conductivity sensor elements will include an electrical lead that transmits the probe information to a controller or other device. In one embodiment, the temperature sensor is a thermister potted in a stainless steel probe. However, in alternate embodiments, a combination temperature and conductivity sensor elements is used similar to the one described in co-pending U.S. Patent Application entitled Sensor Apparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S. application Ser. No. 11/871,821).

In alternate embodiments, there are either no sensors in the cassette or only a temperature sensor, only one or more conductivity sensors or one or more of another type of sensor.

Referring now toFIG. 12E, the side view of the exemplary embodiment of the midplate1200is shown.

Referring now toFIGS. 13A-13D, the bottom plate1300is shown. Referring first toFIGS. 13A and 13B, the inner or inside surface of the bottom plate1300is shown. The inner or inside surface is the side that contacts the bottom surface of the midplate (not shown, seeFIG. 9B). The bottom plate1300attaches to the air or actuation lines (not shown). The corresponding entrance holes for the air that actuates the pod pumps820,828and valves (not shown, seeFIGS. 10A-10F) in the midplate1300can be seen. Holes810,824correspond to the first fluid inlet and first fluid outlet shown in FIGS.12BC and12D,810,824respectively. The corresponding halves of the pod pumps820,828and mixing chamber818are also shown, as are the grooves1002for the fluid paths. The actuation holes in the pumps are also shown. Unlike the top plate, the bottom plate1300corresponding halves of the pod pumps820,828and mixing chamber818make apparent the difference between the pod pumps820,828and mixing chamber818. The pod pumps820,828include an air/actuation path on the bottom plate1300, while the mixing chamber818has identical construction to the half in the top plate. The mixing chamber818mixes liquid and therefore, does not include a membrane (not shown) nor an air/actuation path. The sensor cell1314,1316with the three sensor element housings1308,1310,1312and1318,1320,1322are also shown.

Referring now toFIG. 13C and 13D, the actuation ports1306are shown on the outside or outer bottom plate1300. An actuation source is connected to these actuation ports1306. Again, the mixing chamber818does not have an actuation port as it is not actuated by air. Referring toFIG. 13E, a side view of the exemplary embodiment of the bottom plate1300is shown.

In the exemplary embodiment, the membrane is a gasket o-ring membrane as shown inFIG. 5A. However, in some embodiments, a gasket o-ring membranes having texture, including, but not limited to, the various embodiments inFIGS. 4D, or5B-5D may be used. In still other embodiments, the membranes shown inFIGS. 6A-6Gmay also be used.

Referring next toFIGS. 14A and 14B, the assembled exemplary embodiment of the cassette1400is shown.FIGS. 14C and 14Eare an exploded view of the exemplary embodiment of the cassette1400. The membranes1600are shown. As can be seen fromFIGS. 14C and 14E, there is one membrane1602for each of the pods pumps. In the exemplary embodiment, the membrane for the pod pumps is identical. In alternate embodiments, any membrane may be used, and one pod pump could use one embodiment of the membrane while the second pod pump can use a different embodiment of the membrane (or each pod pump can use the same membrane).

The various embodiments of the membrane used in the metering pumps1604, in the preferred embodiment, are shown in more detail inFIGS. 5E-5H. The various embodiments of the membrane used in the valves1222is shown in more detail inFIGS. 2E-2G. However, in alternate embodiments, the metering pump membrane as well as the valve membranes may contain textures for example, but not limited to, the textures shown on the pod pump membranes shown inFIGS. 5A-5D.

One embodiment of the conductivity sensor elements1314,1316and the temperature sensor element1310, which make up the sensor cell1322, are also shown inFIGS. 14C and 14E. Still referring toFIGS. 14C and 14E, the sensor elements are housed in sensor blocks (shown as1314,1316inFIGS. 12C and 13Aand B) which include areas on the bottom plate1300and the midplate1200. O-rings seal the sensor housings from the fluid lines located on the upper side of the midplate1200and the inner side of the top plate1100. However, in other embodiments, an o-ring is molded into the sensor block or any other method of sealing can be used.

5.2 Cross Sectional Views

Referring now toFIGS. 15A-15C, various cross sectional views of the assembled cassette are shown. Referring first toFIG. 15A, the membranes1602are shown in a pod pumps820,828. As can be seen from the cross section, the o-ring of the membrane1602is sandwiched by the midplate1200and the bottom plate1300. A valve membrane1606can also be seen. As discussed above, each valve includes a membrane.

Referring now toFIG. 15B, the two conductivity sensors1308,1312and the temperature sensor1310are shown. As can be seen from the cross section, the sensors1308,1310,1312are in the fluid line824. Thus, the sensors1308,1310,1312are in fluid connection with the fluid line and can determine sensor data of the fluid exiting fluid outlet one824. Still referring toFIG. 15B, a valve836cross section is shown. As shown in this FIG., in the exemplary embodiment, the valves are volcano valves similar to the embodiment shown and described above with respect toFIG. 2B. However, as discussed above, in alternate embodiment, other valves are used including, but not limited, to those described and shown above with respect toFIGS. 2A,2C and2D.

Referring now toFIG. 15C, the two conductivity sensor elements1318,1320and the temperature sensor element1322are shown. As can be seen from the cross section, the sensor elements1318,1320,1322are in the fluid line824. Thus, the sensor elements1318,1320,1322are in fluid connection with the fluid line and can be used to determine sensor data of the fluid entering the mixing chamber (not shown in this figure). Thus, in the exemplary embodiment, the sensor elements1318,1320,1322are used to collect data regarding fluid being pumped into the mixing chamber. Referring back toFIG. 12C, sensor elements1308,1310,1312are used to collect data regarding fluid being pumped from the mixing chamber and to the fluid outlet. However, in alternate embodiments, no sensors are or only one set, or only one type of sensor element (i.e., either temperature conductivity sensor element) is used. Any type of sensor may be used and additionally, any embodiment of a temperature, a conductivity sensor element or a combined temperature/conductivity, sensor element.

As described above, the exemplary embodiment is one cassette embodiment that incorporates the exemplary fluid flow-path schematic shown inFIG. 8. However, there are alternate embodiments of the cassette that incorporate many of the same features of the exemplary embodiment, but in a different structural design and with slightly different flow paths. One of these alternate embodiments is the embodiment shown inFIGS. 16A-20B.

Referring now toFIGS. 16A-16E, views of an alternate embodiment of the top plate1600are shown. The features of the top plate1600are alternate embodiments of corresponding features in the exemplary embodiment. This alternate embodiment includes two mixing chambers1622,1624and three metering pumps. Thus, this embodiment represents the flexibility in the cassette design. In various embodiments, the cassette can mix any number of fluids, as well, can meter them separately or together.FIG. 9shows a fluid flow-path schematic of the cassette shown inFIGS. 16A-20B.

Referring now toFIGS. 17A-17E, views of an alternate embodiment of the midplate1700are shown.FIGS. 18A-18Eshow views of an alternate embodiment of the bottom plate1800.

Referring now toFIG. 19A, an assembled alternate embodiment of the cassette1900is shown.FIGS. 19C-19Dshow exploded views of the cassette1900where the pod pump membrane1910, valve membranes1914and metering pump membranes1912are shown. The three metering pumps1616,1618,1620can be seen as well as the respective membranes1912. In this embodiment, three fluids can be metered and controlled volumes of each can be mixed together in the mixing chambers1622,1624.FIGS. 20A and 20Bshow a cross sectional view of the assembled cassette1900.

As this alternate embodiment shows, there are many variations of the pumping cassette and the general fluid schematic shown inFIG. 8. Thus, additional mixing chambers and metering pumps can add additional capability to the pumping cassette to mix more than two fluids together.

5.3 Exemplary Embodiments of the Mixing Cassette

In practice, the cassette may be used to pump any type of fluid from any source to any location. The types of fluid include nutritive, nonnutritive, inorganic chemicals, organic chemicals, bodily fluids or any other type of fluid. Additionally, fluid in some embodiments includes a gas, thus, in some embodiments; the cassette is used to pump a gas.

The cassette serves to pump and direct the fluid and to the desired locations. In some embodiments, outside pumps pump the fluid into the cassette and the cassette pumps the fluid out. However, in some embodiments, the pod pumps serve to pull the fluid into the cassette and pump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of the fluid paths is imparted. Thus, the valves being in different locations or additional valves are alternate embodiments of this cassette. Additionally, the fluid lines and paths shown in the figures described above are mere examples of fluid lines and paths. Other embodiments may have more, less and/or different fluid paths. In still other embodiments, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on the embodiment. For example, although the exemplary and alternate embodiments shown and described above include two pod pumps, in other embodiments, the cassette includes one. In still other embodiments, the cassette includes more than two pod pumps. The pod pumps can be single pumps or work in tandem to provide a more continuous flow. Either or both may be used in various embodiments of the cassette.

The various ports are provided to impart particular fluid paths onto the cassette. These ports are not necessarily all used all of the time, instead, the variety of ports provide flexibility of use of the cassette in practice.

The pumping cassette can be used in a myriad of applications. However, in one exemplary embodiment, the pumping cassette is used to mix a solution that includes at least two ingredients/compounds. In the exemplary embodiment, three ingredients are mixed. However, in other embodiments, less than three or more than three can be mixed by adding metering pumps mixing chambers, inlets/outlets, valves and fluid lines. These variations to the cassette design are readily discernable.

As used herein, the terms “source ingredient” or “sources of ingredients” refers to ingredients other than the fluid pumped into the cassette from the first fluid inlet. These source ingredients are contained in a container, or provided by a source, connected to the cassette.

In the exemplary embodiment, the pumping cassette includes the ability to connect four sources of ingredients to the cassette in addition to the fluid inlet line. In the exemplary embodiment, the fluid inlet is connected to a water source. However, in other embodiments, the fluid inlet line is connected to a container of a liquid/fluid solution or to another source of fluid/liquid.

In the exemplary embodiment, the four additional sources of ingredients can be four of the same source ingredients, or two of one source ingredient and two of another. Using two of each source ingredient, or four of one source ingredient, pumping and mixing can be done in a continuous manner without having to replace the sources. However, depending on the source, the number of redundant sources of each ingredient will vary. For example, the source could be a connection to a very large container, a smaller container or a seemingly “endless” source. Thus, depending on the volume being pumped and the size of the source, the number of containers of a source ingredient may vary.

One of the fluid paths described above with respect toFIG. 8includes a path where the pod pumps pump liquid into the cassette and to two of the source ingredients sources or containers. This available functionality of the cassette allows two of the source ingredients to be, at least initially, powder that is constituted with the fluid/liquid from the fluid inlet line. As well, there is a valving path for both pod pumps that can accomplish pumping fluid to the ingredient sources. Thus, in one embodiment, the valves are controlled for a period of time such that continuous pumping of fluid into the fluid inlet and to two source ingredient containers is accomplished. This same valving path can be instituted to the other two source ingredient containers or to one of the other two source ingredient containers in addition to or in lieu of the valving path shown inFIG. 8. In other embodiments, fluid inlet liquid is pumped to only one source ingredient container.

Additionally, in some embodiments, fluid is pumped into the fluid inlet and to the source ingredients where the source ingredients are fluid. This embodiment may be used in situations where the fluid inlet fluid is a source ingredient that needs to be mixed with one of the source ingredients prior to pumping. This functionality can be designed into any embodiment of the pumping cassette. However, in some embodiments, this valving path is not included.

In the exemplary embodiment, the metering pumps allow for the pumping of the source ingredients in known volumes. Thus, careful pumping allows for mixing a solution requiring exact concentrations of the various ingredients. A single metering pump could pump multiple source ingredients. However, as an ingredient is pumped, small amounts of that ingredient may be present in the metering fluid line and thus, could contaminate the ingredient and thus, provide for an incorrect assessment of the volume of that second ingredient being pumped. Therefore, in the exemplary embodiment, at least one metering pump is provided for each source ingredient, and thus, a single metering pump is provided for two sources of source ingredients where those two sources contain identical source ingredients.

In the exemplary embodiment, for each source ingredient, a metering pump is provided. Thus, in embodiments where more than two source ingredients are present, additional metering pumps may be included for each additional source ingredient in the pumping cassette. In the exemplary embodiment, a single metering pump is connected to two source ingredients because in the exemplary embodiment, these two source ingredients are the same. However, in alternate embodiments, one metering pump can pimp more than one source ingredient and be connected to more than one source ingredient even if they are not the same.

Sensors or sensor elements may be included in the fluid lines to determine the concentration, temperature or other characteristic of the fluid being pumped. Thus, in embodiments where the source ingredient container included a powder, water having been pumped by the cassette to the source ingredient container to constitute the powder into solution, a sensor could be used to ensure the correct concentration of the source ingredient. Further, sensor elements may be included in the fluid outlet line downstream from the mixing chamber to determine characteristics of the mixed solution prior to the mixed solution exiting the cassette through the fluid outlet. Additionally, a downstream valve can be provided to ensure badly mixed solution is not pumped outside the cassette through the fluid outlet. Discussion of the exemplary embodiment of the sensor elements is included above.

One example of the pumping cassette in use is as a mixing cassette as part of a hemodialysis system. The mixing cassette would be used to mix dialysate to feed a dialysate reservoir outside the cassette. Thus, the cassette would be connected to two containers of each citric acid and NaCl/bicarbonate. Two metering pumps are present in the cassette, one dedicated to the citric acid and the other to the NaCl/Bicarbonate. Thus, one metering pump works with two source ingredient containers.

In the exemplary embodiment, the NaCl/Bicarbonate is a powder and requires the addition of water to create the fluid source ingredient solution. Thus, water is pumped into the first fluid inlet and into the source containers of NaCl/Bicarbonate. Both pod pumps can pump out of phase to rapidly and continuously provide the necessary water to the source containers of NaCl/Bicarbonate.

To mix the dialysate, the citric acid is pumped by a metering pump into a pod pump and then towards the mixing chamber. Water is pumped into the pod pumps as well, resulting in a desired concentration of citric acid. Sensor elements are located upstream from the mixing chamber to determine if the citric acid is in the proper concentration and also, the pod pumps can pump additional water towards the mixing chamber if necessary to achieve the proper concentration.

The NaCl/Bicarbonate is pumped by the second metering pump and into the fluid outlet line upstream from the mixing chamber. The citric acid and fluid NaCl/Bicarbonate will enter the mixing chamber. The two source ingredients will then mix and be pumped out the fluid outlets.

In some embodiments, sensor elements are located downstream from the mixing chamber. These sensor elements can ensure the concentration of the finished solution proper, Also, in some embodiments, a valve may be located downstream from the fluid outlet. In situations where the sensor data shows the mixing has not been successful or as desired, this valve can block the dialysate from flowing into the reservoir located outside the cassette.

In alternate embodiments of the cassette, addition metering pumps can be includes to remove fluid from the fluid lines. Also, additional pod pumps may be included for additional pumping features. In alternate embodiments of this dialysate mixing process, three metering pumps and two mixing chambers are used (as shown inFIG. 9). The citric acid, salt, and bicarbonate are each pumped separately in this embodiment. One mixing chamber is similar to the one described above, and the second mixing chamber is used to mix the salt and bicarbonate prior to flowing to the other mixing chamber, where the mixing between the citric acid NaCl/Bicarbonate will be accomplished.

Various embodiments of the cassette for mixing various solutions are readily discernable. The fluid lines, valving, metering pumps, mixing chambers, pod pumps and inlet/outlets are modular elements that can be mixed and matched to impart the desired mixing functionality onto the cassette.

In various embodiments of the cassette, the valve architecture varies in order to alter the fluid flow-path. Additionally, the sizes of the pod pumps, metering pump and mixing chambers may also vary, as well as the number of valves, pod pumps, metering pumps, sensors, mixing chambers and source ingredient containers connected to the cassette. Although in this embodiment, the valves are volcano valves, in other embodiments, the valves are not volcano valves anti in some embodiments are smooth surface valves.

6. Exemplary Embodiment of the Middle Cassette

Referring now toFIG. 21, an exemplary embodiment of the fluid schematic of the pumping cassette3800is shown. Other schematics are readily discernable and one alternate embodiment of the schematic is shown inFIG. 21. Still referring toFIG. 21, the cassette3800includes at least one pod pump3820,3828and at least one vent3830. The cassette3800also includes at least one fluid port. In the schematic, a plurality of ports3804,3810,3824,3826,3830,3832,3846,3848,3850,3852,3854are shown. However, in alternate embodiments, the number of ports and/or locations can be different. The plurality of port options presents a number of possible pumping schematics for any type of fluid for any function.

The cassette additionally includes at least one pod pump3820,3828to pump fluid through at least one port and into and/or out of the cassette. The exemplary embodiment includes two pod pumps3820,3828. However, in alternate embodiments, one or more pod pumps are included in the cassette. In the exemplary embodiment, two pod pumps3820,3828may provide for continuous or steady flow. The vent3830provides a vent to atmosphere for a fluid reservoir fluidly connected to, but outside of, the cassette.

The fluid schematic of the cassette3800shown inFIG. 21may be embodied into various cassette apparatus. Thus, the various embodiments of the cassette3800that include a fluid flow path represented by the fluid schematic shown inFIG. 21are not the only cassette embodiments that may incorporate this or an alternate embodiment of this fluid schematic. Additionally, the types of valves, the order of actuation of the valves, and the number of pumps may vary in various cassette embodiments of this fluid schematic. Also, additional features may be present in embodiments of the pumping cassette that are not represented in the schematic or on the cassette embodiments shown and described herein.

Still referring toFIG. 21, in one scenario, fluid enters the cassette through a port3810and is pumped to either a first pump fluid path3812or a second pump fluid path3818. In one embodiment, pump inlet valves3808,3814alternately open and close, and the valve3808,3814that is open at any given time allows the fluid to flow into its respective fluid path3812,3818and into the respective pod pump3820,3828. The respective pump inlet valve3808,3814then closes, and the corresponding pump outlet valve3816,3822opens. The fluid is pumped out of the pod pump3820,3828and through first fluid outlet3824. However, in other embodiments, both valves3808,3814open and close at the same time. In some embodiments, no valves are in the cassette.

A vent3830provides a location for a reservoir or other container or fluid source to vent to atmosphere. In some embodiments, the source of the first fluid is connected to the vent3830. A valve3802controls the venting pathway.

Although in one scenario, fluid is pumped into port3810, in other embodiments fluid is pumped into the cassette through any of the ports3804,3824,3826,3830,3832,3846,3848,3850,3852,3854and then out of the cassette through any of the ports3804,3810,3824,3826,3830,3832,3846,3848,3850,3852,3854. Additionally, the pod pumps3820,3828in various embodiments pump fluid in the opposite direction than described above.

In general, the cassette3800provides pumping power to pump fluid as well as fluid flow paths between ports and around the cassette.

In one embodiment, the one or more ports3804,3810,3824,3826,3830,3832,3846,3848,3850,3852,3854are attached to a filter or other treatment area for the fluid being pumped out of the cassette. In some embodiments, pod pumps3820,3828provide enough pumping force to push the fluid through a filter or other treatment area.

In some embodiments, the pumping cassette includes additional fluid paths and one or more additional pod pumps. Additionally, the cassette in some embodiments includes additional venting paths.

The various flow paths possible in the cassette, represented by one embodiment inFIG. 21, are controlled by the valves3802,3808,3814,3816,3822,3836,38338,3840,3842,3844,3856. Opening and closing the valves3802,3808,3814,3816,3822,3836,3838,3840,3842,3844,3856in different orders leads to very different fluid pumping paths and options for pumping. Referring now toFIGS. 23C,24A,24B and24C, the various valves and ports are shown on a n exemplary embodiment of the cassette.

In some embodiments of the pumping cassette, more valves are included or additional flow paths and/or ports are included. In other embodiments, there are a smaller number of valves, flow path and/or ports. In some embodiments of the cassette, the cassette may include one or more air traps, one or more filters, and/or one or more check valves.

The embodiments of the fluid flow-path schematic shown inFIG. 21, or alternate embodiments thereof, can be embodied into a structure. In the exemplary embodiment, the structure is a three plate cassette with actuating membranes. Alternate embodiments of the cassette are also described below.

Referring now toFIGS. 23A and 23B, the outer side of the top plate3900of the exemplary embodiment of the cassette is shown. The top plate3900includes one half of the pod pumps3820,3828. This half is the fluid/liquid half where the source fluid will flow through. The inlet and outlet pod pump fluid paths are shown. These fluid paths lead to their respective pod pumps3820,3828.

The pod pumps3820,3828include a raised flow path3908,3910. The raised flow path3908,3910allows for the fluid to continue to flow through the pod pumps3820,3828after the membrane (not shown) reaches the end of stroke. Thus, the raised flow path3908,3910minimizes the membrane causing air or fluid to be trapped in the pod pump3820,3828or the membrane blocking the inlet or outlet of the pod pump3820,3828, which would inhibit flow. The raised flow path3908,3910is shown in the exemplary embodiment having particular dimensions. In alternate embodiments, the raised flow path3908,3910is larger or narrower, or in still other embodiments, the raised flow path3908,3910can be any dimension as the purpose is to control fluid flow so as to achieve a desired flow rate or behavior of the fluid. Thus, the dimensions shown and described here with respect to the raised flow path, the pod pumps, the valves, or any other aspect are mere exemplary and alternate embodiments. Other embodiments are readily apparent.

FIGS. 23C and 23Dshow the inner side of the top plate3900of the exemplary embodiment of the cassette.FIG. 23Eshows a side view of the top plate3900.

Referring now toFIGS. 24A and 24B, the fluid/liquid side of the midplate31000is shown. The areas complementary to the fluid paths on the inner top plate shown inFIGS. 23C and 23Dare shown. These areas are slightly raised tracks that present a surface finish that is conducive to laser welding, which is one mode of manufacturing in the exemplary embodiment. Other modes of manufacturing the cassette are discussed above. Referring toFIGS. 24A and 24B, the ports of the exemplary embodiment of the cassette are labeled corresponding to the schematic shown and described above with respect toFIG. 21. One port is not labeled, port3852. This port is best seen inFIG. 23C.

Referring next toFIGS. 24C and 24D, the air side, or side facing the bottom plate (not shown, shown inFIGS. 25A-25E) of the midplate31000is shown according to the exemplary embodiment. The air side of the valve holes3802,3808,3814,3816,3822,3836,3838,3840,3842,3844,3856correspond to the holes in the fluid side of the midplate31000(shown inFIGS. 24A and 24B). As seen inFIGS. 26C and 26D, membranes31220complete pod pumps3820,3828while membranes31222complete valves3802,3808,3814,3816,3822,3836,38338,3840,3842,3844,3856. The valves38023808,3814,3816,3822,3836,3838,3840,3842,3844,3856are actuated pneumatically, and as the membrane is pulled away from the holes, liquid/fluid is allowed to flow. As the membrane is pushed toward the holes, fluid flow is inhibited. The fluid flow is directed by the opening and closing of the valves3802,3808,3814,3816,3822,3836,3838,3840,3842,3844,3856. The exemplary embodiment of the valve is a volcano valve, shown in described above with respect toFIGS. 2A and 2B. One embodiment of the valve membrane31222is shown inFIG. 2E, alternate embodiments are shown inFIGS. 2F-2G.

Referring next toFIGS. 25A and 25B, the inner view of the bottom plate31100is shown. The inside view of the pod pumps3820,3828, and the valves3802,3808,3814,3816,3822,3836,3838,3840,3842,3844,3856actuation/air chamber is shown. The pod pumps3820,3828, and the valves3802,3808,3814,3816,3822,3836,3838,3840,3842,3844,3856are actuated by a pneumatic air source. Referring now toFIGS. 25C and 25D, the outer side of the bottom plate31100is shown. The source of air is attached to this side of the cassette. In one embodiment, tubes connect to the tubes on the valves and pumps1102. In some embodiments, the valves are ganged, and more than one valve is actuated by the same air line.

Referring now toFIGS. 26A and 26B, an assembled cassette31200is shown. An exploded view of the assembled cassette31200shown inFIGS. 26A and 26Bis shown inFIGS. 26C and 26D. In these views, the exemplary embodiment of the pod pump membranes31220is shown. The exemplary embodiment includes membranes shown inFIGS. 5A-5D. The gasket of the membrane provides a seal between the liquid chamber (in the top plate3900) and the air/actuation chamber (in the bottom plate31100). In some embodiment, including those shown inFIGS. 5B-5D, texture on the dome of the membranes31220provide, amongst other features, additional space for air and liquid to escape the chamber at the end of stroke. In alternate embodiments of the cassette, the membranes shown inFIGS. 6A-6Gmay be used. Referring toFIGS. 6A-6G, as discussed in greater detail above, these membranes include a double gasket62,64. The double gasket62,64feature would be preferred in embodiments where both sides of the pod pump include liquid or in applications where sealing both chambers sides is desired. In these embodiments, a rim complementary to the gasket or other feature (not shown) would be added to the inner bottom plate31100for the gasket62to seal the pod pump chamber in the bottom plate31100.

Referring now toFIG. 27, a cross sectional view of the pod pumps3828in the cassette is shown. The details of the attachment of the membrane31220can be seen in this view. Again, in the exemplary embodiment, the membrane31220gasket is pinched by the midplate31000and the bottom plate31100.A rim on the midplate31000provides a feature for the gasket to seal the pod pump3828chamber located in the top plate3900.

Referring next toFIG. 27, this cross sectional view shows the valves3834,3836in the assembled cassette. The membranes31220are shown assembled and are held in place, in the exemplary embodiment, by being sandwiched between the midplate31000and the bottom plate31100.

Still referring toFIG. 27, this cross sectional view also shows a valve3822in the assembled cassette. The membrane31222is shown held in place by being sandwiched between the midplate31000and the bottom plate31100.

As described above, the exemplary embodiment described above represents one cassette embodiment that incorporates the exemplary fluid flow-path schematic shown inFIG. 21. However, there are alternate embodiments of the cassette that incorporate many of the same features of the exemplary embodiment, but in a different structural design. One of these alternate embodiments is the embodiment shown inFIGS. 28A-34B. An alternate schematic is shown inFIG. 22. This schematic, although similar to the schematic shown inFIG. 21, can be viewed to show the fluid paths of the alternate embodiment shownFIGS. 28A-34B.

Referring now toFIGS. 28A-28E, views of an alternate embodiment of the top plate31400are shown. The features of the top plate31400are alternate embodiments of corresponding features in the exemplary embodiment. Referring toFIGS. 28C and 28D, the pod pumps3820,3828are cut into the inside of the top plate1400. And, as can be seen inFIGS. 28A and 28B, the pod pumps3820,3828do not protrude on the outside top plate31400.

In this embodiment, w hen the cassette is assembled, as shown inFIGS. 33A-33B, the plates31400,31600,31800are sealed from each other using gaskets shown inFIGS. 29 and 31as31500and31700respectively. Referring now to the exploded view of the cassette inFIGS. 33C and 33D, the pod pump membranes31220and valving membranes31222are shown. Additionally, in some embodiments, a check valve housing cell31114is additionally included.

Still referring toFIGS. 33C-33D, in this alternate embodiment, the cassette1900is assembled with connection hardware31910. Thus, the cassette31900is mechanically assembled and held together by connection hardware31910. In this embodiment, the connection hardware is screws but in other embodiments, the connection hardware31910is metal posts. Any connection hardware may be used in alternate embodiments including, but not limited, to rivets, shoulder bolts, and bolts. In additional alternate embodiments, the plates are held together by an adhesive.

Still referring toFIGS. 33C and 33D, check valves31920are shown. In this embodiment, the check valves31920are duck-bill check valves, but in other embodiments, the check valves can be any type of check valve. In this embodiment, the check valves are held by a check valve cell31922. Additionally, in some embodiments, more check valves are used in the cassette. For example, in this embodiment, and in some embodiments of the exemplary embodiment described above that includes check valves, additional check valve holders31926,31928are shown. These provide holders for additional check valves. In still other embodiments, an air trap31924may be included as shown in this embodiment. Referring now toFIGS. 35A-35D, one embodiment of the duck-bill check valve is shown. However, in other embodiments, any check valve or alternate embodiments of a duck-bill check valve may be used.

Referring now toFIGS. 34A and 34B, cross sectional views of the assembled cassette and the gaskets'31500,31700relation to the assembled cassette assembly is shown.

In the alternate embodiment, the gaskets31500,31700are made from silicone, but in other embodiments, the gaskets31500,31700may be made from other materials. Still referring toFIGS. 34A and 34B, the connection hardware31910is shown. Referring toFIG. 34B, the cross sectional view shows the duck-bill check valves31920in the assembled cassette.

6.1 Exemplary Embodiments of the Middle Cassette

In practice, the cassette may be used to pump any type of fluid from any source to any location. The types of fluid include nutritive, nonnutritive, inorganic chemicals, organic chemicals, bodily fluids, or any other type of fluid. Additionally, fluid in some embodiments include a gas, thus, in some embodiments, the cassette is used to pump a gas.

The cassette serves to pump and direct tie fluid from and to the desired locations. In some embodiments, outside pumps pump the fluid into the cassette and the cassette pumps the fluid out. However, in some embodiments, the pod pumps serve to pull the fluid into the cassette and pump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of the fluid paths is imparted. Thus, the valves being in different locations or additional valves are alternate embodiments of this cassette. Additionally, the fluid lines and paths shown in the figures described above are mere examples of fluid lines and paths. Other embodiments may have more, less, and/or different fluid paths. In still other embodiment, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on the embodiment. For example, although the exemplary and alternate embodiments shown and described above include two pod pumps, in other embodiments, the cassette includes one. In still other embodiments, the cassette includes more than two pod pumps. The pop pumps can be single pumps or work in tandem to provide a more continuous flow. Either or both may be used in various embodiments of the cassette.

The terms inlet and outlet as well as fluid paths are used for description purposes only. In other embodiments, an inlet can be an outlet. The denotations simply refer to separate entrance areas into the cassette.

The designations given for the fluid inlets (which can also be fluid outlets) for example, first fluid outlet, second fluid outlet, merely indicate that a fluid may travel out of or into the cassette via that inlet/outlet. In some cases, more than one inlet/outlet on the schematic is designated with an identical name. This merely describes that all of the inlet/outlets having that designation are pumped by the same metering pump or set of pod pumps (which in alternate embodiments, can be a single pod pump).

The various ports are provided to impart particular fluid paths onto the cassette. These ports are not necessarily all used all of the time, instead, the variety of ports provide flexibility of use of the cassette in practice.

Referring again toFIG. 21, one embodiment provides for a fluid reservoir to be fluidly attached to the vent port3830allowing for the reservoir to vent to atmosphere. Additionally, in some embodiments, an FMS reference chamber is fluidly attached to the reservoir and thus, as fluid is added or removed from the reservoir, the volume may be determined using the FMS. Some embodiments include additional vent ports in the cassette and thus, some embodiments of the cassette may be attached to more than one fluid reservoir.

One embodiments includes a fluid line extending from port3850to port3848and controlled by valves3838,3836. In one embodiment, port3848may be fluidly attached to a reservoir. As such, port3810may also be attached to the same reservoir. Thus, in one embodiment, port3850provides a fluid line to the reservoir, and port3810provides a fluid line suck that the pod pumps pump fluid from the reservoir into the cassette. In some embodiments, valve3858controls a bypass line from the reservoir to another fluid line controlled by valve3842.

Some embodiments may include an air trap within the fluid lines and/or at least one sensor. The sensor can be any sensor having a capability to determine any fluid or non-fluid sensor data. In one embodiment, three sensor elements are included in a single fluid line. In some embodiments, more than one fluid line includes the three sensor elements. In the three sensor element embodiment, two of the sensor elements are conductivity sensor elements and the third sensor element is a temperature sensor element. The conductivity sensor elements and temperature sensor element can be any conductivity or temperature sensor in the art. In one embodiment, the conductivity sensors are graphite posts. In other embodiments, the conductivity sensor elements are posts made from stainless steel, titanium, platinum, or any other metal coated to be corrosion resistant and still be electrically conductive. The conductivity sensor elements will include an electrical lead that transmits the probe information to a controller or other device. In one embodiment, the temperature sensor is a thermister potted in a stainless steel probe. However, in alternate embodiments, a combination temperature and conductivity sensor elements is used similar to the one described in co-pending U.S. Patent Application entitled Sensor Apparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S. application Ser. No. 11/871,821).

In alternate embodiments, there are either no sensors in the cassette or only a temperature sensor, only one or more conductivity sensors or one or more of another type of sensor.

7. Exemplary Embodiment of the Balancing Cassette

Referring now to FIG36, an exemplary embodiment of the fluid schematic of the balancing pumping and metering cassette4800is shown. Other schematics are readily discernable. The cassette4800includes at least one pod pump4828,4820and at least one balancing pod4822,4812. The cassette4800also includes a first fluid inlet4810, where a first fluid enters the cassette. The first fluid includes a flow rate provided outside the cassette4800. The cassette4800also includes a first fluid outlet4824where the first fluid exits the cassette4800having a flow rate provided by one of the at least one pod pumps4828. The cassette4800includes a second fluid inlet4826where the second fluid enters the cassette4800, and a second fluid outlet4816where the second fluid exits the cassette.

Balancing pods4822,4812in the cassette4800provide for a desired balance of volume of fluid pumped into and out of the cassette4800, i.e., between the first fluid and the second fluid. The balancing pods4822,4812, however, may be bypassed by way of the metering pump4830. The metering pump4830pumps a volume of second fluid (or first fluid in other embodiments) out of the fluid line, bypassing the balancing pod4822,4812. Thus, a smaller or reduced volume (i.e., a “new” volume) of the fluid that has been removed by the metering pump4830will actually enter the balancing pod4822,4812and thus, the metering pump4830functions to provide a “new” volume of second fluid by removing the desired volume from the fluid path before the second fluid reaches the balancing pod4822,4812(or in other embodiments, removing first fluid the desired volume from the fluid path before the second fluid reaches the balancing pod4822,4812) resulting in less first fluid (or in other embodiments second fluid) being pumped for that pump cycle.

The fluid schematic of the cassette4800show inFIG. 36may be embodied into various cassette apparatus. Thus, the embodiments of the cassette4800including the fluid schematic shown inFIG. 36are not the only cassette embodiments that may incorporate this or an alternate embodiment of this fluid schematic. Additionally, the types of valves, the ganging of the valves, the number of pumps and chambers may vary in various cassette embodiments of this fluid schematic.

Referring still toFIG. 36, a fluid flow-path schematic4800is shown. The fluid flow-path schematic4800is described herein corresponding to the flow paths in one embodiment of the cassette. The exemplary embodiment of the midplate4900of the cassette is shown inFIG. 49Awith the valves corresponding to the fluid flow-path schematic inFIG. 36indicated. The valving side of the midplate4900shown inFIG. 38Acorresponds to the fluid side shown inFIG. 38B.

Referring first toFIG. 48AwithFIG. 49A, a first fluid enters the cassette at the first fluid inlet4810. The first fluid flows to balancing pod A4812. Balancing pod A412is a balancing pod as described above. Balancing pod A4812initially contained a first volume of second fluid. When the first fluid flows into the balancing pod A4812, the membrane forces the second fluid out of balancing pod A4812. The second fluid flows through the drain path4814and out the first fluid outlet4816.

At the same time, pod pump4820includes a volume of second fluid. The volume of second fluid is pumped to balancing pod B4822. Balancing pod B4822contains a volume of first fluid, and this volume of first fluid is displaced by the volume of second fluid. The volume of first fluid from balancing pod B4822flows to the second fluid outlet4824and exits the cassette. A volume of a second fluid enters the cassette at fluid inlet two4826and flows to pod pump A4828.

Referring still toFIG. 36withFIG. 38A, the second fluid is pumped from pod pump A4828to balancing pod A4812. The second fluid displaces the first fluid in balancing pod A4812. The first fluid from balancing pod A4812flows to the second fluid outlet4824.

First fluid flows into the cassette through the first fluid inlet4810and flows to balancing pod B4822. The first fluid displaces the second fluid in balancing pod B4822, forcing the second fluid to flow out of the cassette through the first fluid outlet4816. Second fluid flows into the cassette through the second fluid inlet4826and to pod pump B4820.

The metering pump can be actuated at a time and its function is to remove fluid from the fluid path in order to bypass the balancing pod. Thus, any volume of fluid removed would act to decrease the volume of the other fluid flowing out of the second fluid outlet4824. The metering pump is independent of the balancing pods4812,4822and the pod pumps4820,4828. The fluid enters through fluid inlet two4826and is pulled by the metering pump4830. The metering pump then pumps the volume of fluid through the second fluid outlet4816.

Although in the embodiment of the fluid schematic shown inFIG. 36, the metering pump is described only with respect to second fluid entering the cassette through fluid inlet two4826, the metering pump can easily bypass first fluid entering the cassette through fluid inlet one4810. Thus, depending on whether the desired end result is to have less of the first fluid or less of the second fluid, the metering pump and valves that control the fluid lines in the cassette can perform accordingly to accomplish the result.

In the exemplary fluid flow-path embodiment shown inFIG. 36, and corresponding structure of the cassette shown inFIG. 38A, valves are ganged such that they are actuated at the same time. In the preferred embodiment, there are four gangs of valves4832,4834,4836,4838. In the preferred embodiment, the ganged valves are actuated by the same air line. However, in other embodiments, each valve has its own air line. Ganging the valves as shown in the exemplary embodiment creates the fluid-flow described above. In some embodiments, ganging the valves also ensures the appropriate valves are opened and closed to dictate the fluid pathways as desired.

In the exemplary embodiment, the fluid valves are volcano valves, as described in more detail in this specification. Although the fluid flow-path schematic has been described with respect to a particular flow path, in various embodiments, the flow paths can change based on the actuation of the valves and the pumps. Additionally, the terms inlet and outlet as well as first fluid and second fluid are used for description purposes only. In other embodiments, an inlet can be an outlet, as well as, a first and second fluid may be different fluids or the same fluid types or composition.

Referring now toFIGS. 39A-39E, the top plate41000of the exemplary embodiment of the cassette is shown. Referring first toFIGS. 39A and 39B, the top view of the top plate41000is shown. In the exemplary embodiment, the pod pumps4820,4828and the balancing pods4812,4822on the top plate, are formed in a similar fashion. In the exemplary embodiment, the pod pumps4820,4828and balancing pods4812,4822, when assembled with the bottom plate, have a total volume of capacity of 38 ml. However, in various embodiments, the total volume capacity can be greater or less than in the exemplary embodiment. The first fluid inlet4810and the second fluid outlet4816are shown.

Referring now toFIGS. 39C and 39D, the bottom view of the top plate41000is shown. The fluid paths are shown in this view. These fluid paths correspond to the fluid paths shown inFIG. 38Bin the midplate4900. The top plate41000and take top of the midplate form the liquid or fluid side of the cassette for the pod pumps4820,4828and for one side o the balancing pods4812,4822. Thus, most of the liquid flow paths are on the top and midplates. The other side of the balancing pods'4812,4822flow paths is located on the inner side of the bottom plate, not shown here, shown inFIGS. 40A and 41B.

Still referring toFIGS. 39C and 39D, the pod pulps4820,4828and balancing pods4812,4822include a groove41002. The groove41002is shown having a particular shape, however, in other embodiments, the shape of the groove41002can be any shape desirable. The shape shown inFIGS. 39C and 39Dis the exemplary embodiment. In all embodiments of the groove41002, the groove forms a path between the fluid inlet side and the fluid outlet side of the pod pumps4820,4828and balancing pods4812,4822.

The groove41002provides a fluid path whereby when the membrane is at the end of stroke, there is still a fluid path between the inlet and outlet such that the pockets of fluid or air do not get trapped in the pod pump or balancing pod. The groove41002is included in both the liquid and air sides of the pod pumps4820,4828and balancing pods4812,4822(seeFIGS. 40A and 41Bwith respect to the air side of the pod pumps4820,4828and the opposite side of the balancing pods4812,4822).

The liquid side of the pod pumps4820,4828and balancing pods4812,4822, in the exemplary embodiment, include a feature whereby the inlet and outlet flow paths are continuous while the outer ring41004is also continuous. This feature allows for the seal, formed with the membrane (not shown) to be maintained.

Referring toFIG. 39E, the side view of the exemplary embodiment of the top plate41000is shown. The continuous outer ring41004of the pod pumps4820,4828and balancing pods4812,4822can be seen.

Referring now toFIGS. 40A-41E, the bottom plate41100is shown. Referring first toFIGS. 40A and 41B, the inside surface of the bottom plate41100is shown. The inside surface is the side that contacts the bottom surface of the midplate (not shown, seeFIGS. 41B). The bottom plate41100attaches to the air lines (not shown). The corresponding entrance holes for the air that actuates the pod pumps4820,4928and valves (not shown, seeFIG. 41B) in the midplate can be seen41106. Holes41108,41110correspond to the second fluid inlet and second fluid outlet shown inFIGS. 41C,4824,4826respectively,. The corresponding halves of the pod pumps4820,4828and balancing pods4812,4822are also shown, as are the grooves41112for the fluid paths. Unlike the top plate, the bottom plate corresponding halves of the pod pumps4820,4828and balancing pods4812,4822make apparent the difference between the pod pumps4820,4828and balancing pods4812,4822. The pod pumps4820,4828include only a air path on the second half in the bottom plate, while the balancing pod4812,4822have identical construction to the half in the top plate. Again, the balancing pods4812,4822balance liquid, thus, both sides of the membrane, not shown, will include a liquid fluid path, while the pod pumps4820,4828are pressure pumps that pump liquid, thus, one side includes a liquid fluid path and the other side, shown in the bottom plate41100, includes an air actuation chamber or air fluid path.

In the exemplary embodiment of the cassette, sensor elements are incorporated into the cassette so as to discern various properties of the fluid being pumped. In one embodiment, the three sensor elements are included. In the exemplary embodiment, the sensor elements are located in the sensor cell41114. The cell41114accommodates three sensor elements in the sensor element housings41116,41118,41120. In the exemplary embodiment, two of the sensor housings41116,41118accommodate a conductivity sensor element and the third sensor element housing41120accommodates a temperature sensor element. The conductivity sensor elements and temperature sensor elements can be any conductivity or temperature sensor elements in the art. In one embodiment, the conductivity sensor elements are graphite posts. In other embodiments, the conductivity sensor elements are posts made from stainless steel, titanium, platinum or any other metal coated to be corrosion resistant and still be electrically conductive. The conductivity sensor element will include an electrical lead that transmits the probe information to a controller or other device. In one embodiment, the temperature sensor is a thermister potted in a stainless steel probe. However, in alternate embodiments, a combination temperature and conductivity sensor elements is used similar to the one described in co-pending U.S. Patent Application entitled Sensor Apparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S. application Ser. No. 11/871,821).

In this embodiment, the sensor cell41114is a single opening to the fluid line connection to the fluid line.

In alternate embodiments, there are either no sensors in the cassette or only a temperature sensor, only one or more conductivity sensors or one or more of another type of sensor.

Still referring toFIGS. 40A and 41B, the actuation side oft the metering pup4830is also shown as well as the corresponding air entrance hole41106for the air that actuates the pump.

Referring now toFIGS. 41C and 41D, the outer side of the bottom plate41100is shown. The valve, pod pumps4820,4828and metering pump4830air line connection points41122are shown. Again, the balancing pods4812,4822do not have air line connect points as the are not actuated by air. As well, the corresponding openings in the bottom plate41100for the second fluid outlet4824and second fluid inlet4826are shown.

Referring now toFIG. 41E, a side view of the bottom plate41100is shown. In the side view, the rim41124that surrounds the inner bottom plate41100can be seen. The rim41124is raised and continuous, providing for a connect point for the membrane (not shown). The membrane rests on this continuous and raised rim41124providing for a seal between the half of the pod pumps,4820,4828and balancing pods4812,4822in the bottom plate41100and the half of the pod pumps4820,4828and balancing pods4812,4822in the top plate (not shown, seeFIGS. 39A-39D).

In the exemplary embodiment, the membrane is a double o-ring membrane as shown inFIG. 6A. However, in some embodiments, a double o-ring membrane having texture, including, but not limited to, the various embodiments inFIGS. 6B-6Fmay be used.

Referring now toFIGS. 42A and 42B, the assembled exemplary embodiment of the cassette41200is shown.FIGS. 42C and 42Dare exploded views of the exemplary embodiment of the cassette41200. The membranes41210are shown. As can be seen fromFIGS. 42C and 42D, there is one membrane41220for each of the pods pumps and balancing pods. In the exemplary embodiment, the membrane for the pod pumps and the balancing pods are identical. The membrane in the exemplary embodiment is a double o-ring membrane as shown inFIGS. 6A-6B. However, in alternate embodiments, any double o-ring membrane may be used, including, but not limited to, the various embodiments shown inFIGS. 6C-6F. However, in other embodiments, the double o-ring membrane is used in the balancing pods, but a single o-ring membrane, as shown inFIGS. 4A-4Dis used in the pod pumps.

The membrane used in the metering pump41224, in the preferred embodiment, is shown in more detail inFIG. 5G, with alternate embodiments shown inFIGS. 5E,5F and5H. The membrane used in the valves41222is shown in more detail inFIG. 2E, with alternate embodiments shown inFIGS. 2F-2G. However, in alternate embodiments, the metering pump membrane as well as the valve membranes may contain textures, for example, but not limited to, the textures shown on the pod pump/balancing pod membranes shown inFIGS. 5A-5D.

One embodiment of the conductivity sensor elements41214,41216and the temperature sensor41218, which make up the sensor cell41212, are also shown inFIGS. 42C and 42D. Still referring toFIGS. 42C and 42D, the sensor cell housing41414includes areas on the bottom plate41100and the midplate4900. O-rings seal the sensor housing41414from the fluid lines located on the upper side of the midplate4900shown inFIG. 42Cand the inner side of the top plate41000shown inFIG. 42D. However, in other embodiments, an o-ring is molded into the sensor cell, or any other method of sealing can be used.

7.2 Cross Sectional Views

Referring now toFIGS. 43A-43C, various cross sectional views of the assembled cassette are shown. Referring first toFIG. 43A, the membrane41220is shown in a balancing pod4812and a pod pump4828. As can be seen from the cross section, the double o-ring of the membrane41220is sandwiched by the midplate4900, the bottom plate41100and the top plate41000.

Referring now toFIG. 43B, the two conductivity sensor elements41214,41216and the temperature sensor element41218are shown. As can be seen from the cross section, the sensor elements41214,41216,41218are in the fluid line41302. Thus, the sensor elements41214,41216,41218are in fluid connection with the fluid line and can determine sensor data of the first fluid entering the first fluid inlet4810. Referring now toFIG. 43C, this cross sectional view shows the metering pump4830as well as the structure of the valves.

As described above, the exemplary embodiment is one cassette embodiment that incorporates the exemplary fluid flow-path schematic shown inFIG. 36. However, there are alternate embodiments of the cassette that incorporate many of the same features of the exemplary embodiment, but in a different structural design. Additionally, there are alternate embodiment fluid flow paths, for example, the fluid flow path schematic shown inFIG. 37. The alternate embodiment cassette structure corresponding to this schematic is shown inFIGS. 44A-48.

Referring now toFIGS. 44A-44E, views of an alternate embodiment of the top plate41400are shown. The features of the top plate41400are alternate embodiments of corresponding features in the exemplary embodiment.

Referring now toFIGS. 45A-45E, views of an alternate embodiment of the midplate41500are shown.FIGS. 46A-46Eshow views of an alternate embodiment of the bottom plate41600.

Referring now toFIGS. 47A-47B, an assembled alternate embodiment of the cassette41700is shown.FIGS. 47C-47Dshow exploded views of the cassette41700.FIG. 47Eis a cross sectional view of the assembled cassette41700.

Referring now toFIGS. 48A-52Banother alternate embodiment of the cassette is shown. In this embodiment, when the cassette is assembled, as shown inFIGS. 51A-51B, the plates41800,41900,42000are sealed from each other using gaskets. Referring toFIGS. 51C-51D, the gaskets42110,42112are shown. This embodiment additionally includes membranes (not shown).FIG. 52Ais a cross sectional view of the assembled cassette, the gaskets42110,42112relation to the assembled cassette assembly is shown.

7.3 Exemplary Embodiments of the Balancing Cassette

The pumping cassette can be used in a myriad of applications. However, in one exemplary embodiment, the pumping cassette is used to balance fluid going into the first fluid inlet and out the first fluid outlet with fluid coming into the cassette through the second fluid inlet and exiting the cassette through the second fluid outlet (or vice versa). The pumping cassette additionally provides a metering pump to remove a volume of fluid prior to that volume affecting the balancing chambers or adds a volume of fluid prior to the fluid affecting the balancing chambers.

The pumping cassette may be used in applications where it is critical that two fluid volumes are balanced. Also, the pumping cassette imparts the extra functionality of metering or bypassing a fluid out of the fluid path, or adding a volume of the same fluid or a different fluid into the fluid path. The flow paths shown in the schematic are bi-directional, and various flow paths may be created by changing the valve locations and or controls, or adding or removing valves. Additionally, more metering pumps, pod pumps and/or balancing pods may be added, as well as, more or less fluid paths and valves. Additionally, inlets and outlets may be added as well, or the number of inlets or outlets may be reduced.

One example is using the pumping cassette as an inner dialysate cassette as part of a hemodialysis system. Clean dialysate would enter the cassette through the first fluid inlet and pass through the sensor elements, checking if the dialysate is at the correct concentration and/or temperature. This dialysate would pass through the balancing chambers and be pumped through the first fluid outlet and into a dialyzer. The second fluid in this case is used or impure dialysate from the dialyzer. This second fluid would enter through the second fluid inlet and balance with the clean dialysate, such that the amount of dialysate that goes into the dialyzer is equal to the amount that comes out.

The metering pump may be used to remove additional used dialysate prior to that volume being accounted for in a balancing chamber, thus, creating a “false” balancing chamber through an ultra filtration (“UF”) bypass. The situation is created where less clean dialysate by a volume equaled to the bypassed volume will enter the dialyzer.

In this embodiment, the valves controlling fluid connections to the balancing pods shall be oriented such that the volcano feature of the valve is on the fluid port connected to the balancing pod. This orientation directs most of the fluid displaced by the valve as it is thrown away from the balancing pod.

The valves controlling fluid connections to the UF pump shall be oriented such that the volcano feature of the valve is on the fluid port connected to the pumping chamber. In the exemplary embodiment, the nominal stroke volume of each inside dialysate pump chamber shall be 38 ml. The nominal volume of each balancing pod shall be 38 ml. The stroke volume of the UF pump shall be 1.2 ml +/−0.05 ml. The inner dialysate pump low-pressure pneumatic variable values shall vent to ambient atmospheric pressure. This architecture feature minimizes the chance that dissolved gas will leave the dialysate while inside of the balancing chambers. Other volumes of pod pumps, balancing pods and metering pumps are easily discernable and would vary depending on the application. Additionally, although the embodiment described discusses venting to ambient, in other applications, negative pressure can be administered.

In various embodiments of the cassette, the valve architecture varies in order to alter the fluid flow path. Additionally, the sizes of the pod pumps, metering pump and balancing pods may also vary, as well as the number of valves, pod pumps, metering pumps and balancing pods . Although in this embodiment, the valves are volcano valves, in other embodiments, the valves are not volcano valves and in some embodiments are smooth surface valves.

8. Exemplary Embodiment of the Cassette System Integrated

As described above, a mixing cassette may be used to mix dialysate, and then send the dialysate to a storing vessel or reservoir. The middle cassette provides a vent for a container and a variety of fluid lines and ports, and the balancing cassette provides a system for balancing the volume of fluid that enters a cassette in one direction with the volume that enters the cassette in another direction. Additionally, the balancing cassette provides a metering function, where a volume of fluid from one direction may be pumped such that it bypasses the balancing chambers and does not affect the balancing volumes. In some embodiments, these three cassettes may be combined into a system. Fluid lines can connect the cassettes such that a cassette system integrated is formed. However, various hoses can be difficult to manage and also, get tangled, removed from the ports or the connection may be disrupted in one of a variety of ways.

One embodiment of this would be to simply connect the fluid lines. However, in the exemplary embodiment, the three cassette exemplary fluid flow-path schematics are combined into a cassette device which makes the system more compact and also, there are benefits with respect to manufacture.

In an exemplary embodiment of this the cassette system integrated, the three cassettes are combined in an efficient, stand alone, cassette system. The fluid flow-path schematics shown and described above with respect to the various individual cassettes are combined. Thus, in some cases, fluid lines bay be in two different cassettes to save space or efficiency, but in fact, the fluid lines follow many of the same paths as shown in the schematics.

Referring now toFIGS. 53A-53B, the mixing cassette of the cassette system is shown. Referring toFIGS. 54A-54B, the middle cassette for the cassette system is shown. Finally, referring toFIGS. 55A-55B, the balancing cassette for the cassette system is shown.

Referring now toFIG. 56A, the assembled cassette system integrated is shown. The mixing cassette500, middle cassette600and balancing cassette700are linked by fluid lines. The pods are between the cassettes. Referring now toFIGS. 56B and 56C, the various views show the efficiency the cassette system integrated. The fluid lines1200,1300,1400are shown inFIG. 60,FIG. 61andFIG. 62respectively . The fluid flows between the cassette through these lines. Referring now toFIGS. 60 and 61, these fluid lines represent larger1300, and smaller1200check valve fluid lines. In the exemplary embodiment, the check valves are duck hill valves, however, in other embodiments, any check valve may be used. Referring toFIG. 62, fluid line1400is a fluid line that does not contain a check valve.

Referring now toFIGS. 56D and 56E, the various pods502,504,506,602,604,702,704,706,708are shown. Each of the pod housing are constricted identically, however, the inside of the pod housing is different depending on whether the pod is a pod pump502,504602,604,702,704a balancing chamber pods706,708or a mixing chamber pod504.

Referring now toFIGS. 57A-57C, the exemplary embodiment of the pod is shown. The pod includes two fluid ports902,904(an inlet and an outlet) and the pod may be constructed differently in the various embodiments. A variety of embodiments of construction are described in pending U.S. patent application Ser. No. 11/787,212, filed Apr. 13, 2007 and entitled Fluid Pumping Systems, Devices and Methods (E78), which is hereby incorporated herein by reference in its entirety.

Referring now toFIGS. 57A,57D, and57E the groove906in the chamber is shown. A groove9306is included on each half of the pod housing. In other embodiments, a groove is not included and in some embodiments, a groove is only included in one half of the pod.

Referring now toFIGS. 58A and 58B, the exemplary embodiment of the membrane used in the pod pumps502,504602,604,702,704is shown. This membrane is shown and described above with respect toFIG. 5A. In other embodiments, any of the membranes shown inFIGS. 5B-5Dmay be used. An exploded view of a pod pump according to the exemplary embodiment is shownFIG. 59.

The membrane used in the balancing chamber pods706,708in the preferred embodiments is shown and described above with respect toFIGS. 6A-6G. The mixing chamber pod504does not include a membrane in the exemplary embodiment. However, in the exemplary embodiment, the mixing chamber pod504includes a o-ring to seal the mixing chamber.

In the exemplary embodiment, the membrane valve membrane is shown inFIG. 2E, however, alternate embodiments as shown inFIGS. 2F and 2Gmay also be used. The metering pumps, in the exemplary embodiment, may use any of the membranes shown inFIGS. 5E-5H.