U.S. patent application number 11/871787 was filed with the patent office on 2008-10-16 for pumping cassette.
This patent application is currently assigned to DEKA Products Limited Partnership. Invention is credited to James D. Dale, Jason A. Demers, Kevin L. Grant, Brian Tracey, Michael J. Wilt.
Application Number | 20080253911 11/871787 |
Document ID | / |
Family ID | 39714513 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080253911 |
Kind Code |
A1 |
Demers; Jason A. ; et
al. |
October 16, 2008 |
Pumping Cassette
Abstract
A pump cassette is disclosed. The pump cassette includes
housing. The housing includes at least one fluid inlet line and at
least one fluid outlet line. Also, the cassette includes at least
one reciprocating pressure displacement membrane pump within the
housing. The pressure pump pumps at least one fluid from the fluid
inlet line to at least one of the fluid outlet line. Also, the
cassette includes at least one mixing chamber within the housing.
The mixing chamber is fluidly connected to the fluid outlet
line.
Inventors: |
Demers; Jason A.;
(Manchester, NH) ; Wilt; Michael J.; (Windham,
NH) ; Grant; Kevin L.; (Litchfield, NH) ;
Dale; James D.; (Nashua, NH) ; Tracey; Brian;
(Litchfield, NH) |
Correspondence
Address: |
DEKA Research and Development Corporation;c/o Wolf, Greenfield & Sacks,
P.C.
600 Atlantic Avenue
Boston
MA
02210-2206
US
|
Assignee: |
DEKA Products Limited
Partnership
Manchester
NH
|
Family ID: |
39714513 |
Appl. No.: |
11/871787 |
Filed: |
October 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60904024 |
Feb 27, 2007 |
|
|
|
60921314 |
Apr 2, 2007 |
|
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|
Current U.S.
Class: |
417/477.2 |
Current CPC
Class: |
A61M 60/40 20210101;
Y10T 137/85978 20150401; F17D 3/00 20130101; A61M 1/1664 20140204;
A61M 60/268 20210101; F04B 43/00 20130101; A61M 1/1639 20140204;
A61M 1/16 20130101; A61M 1/287 20130101; F04B 13/02 20130101; A61M
2205/3368 20130101; F04B 53/06 20130101; F04B 43/0736 20130101;
F04B 41/06 20130101; F04B 53/16 20130101; A61M 60/113 20210101;
F04B 7/02 20130101; F04B 45/0536 20130101; A61M 60/43 20210101;
F04B 9/109 20130101; F04B 49/02 20130101; Y10T 137/0324 20150401;
Y10T 137/0379 20150401; Y02A 90/10 20180101; F04B 45/02 20130101;
A61M 2205/128 20130101; A61M 2205/12 20130101; A61M 60/894
20210101; Y10T 137/86139 20150401; A61M 1/1605 20140204; F04B 23/06
20130101; Y10T 137/2521 20150401; A61M 1/1656 20130101; F04B 49/22
20130101; F04B 53/10 20130101; A61M 2205/3317 20130101; A61M
2205/3324 20130101; A61M 1/1666 20140204; A61M 60/892 20210101 |
Class at
Publication: |
417/477.2 |
International
Class: |
F04B 43/08 20060101
F04B043/08 |
Claims
1. A pump cassette comprising: a housing comprising at least one
fluid inlet line and at least one fluid outlet line; at least one
reciprocating pressure displacement membrane pump within said
housing wherein said pressure pump pumps at least one fluid from
said fluid inlet line to at least one of said fluid outlet line;
and at least one mixing chamber within said housing, said mixing
chamber fluidly connected to said fluid outlet line.
2. The cassette claimed in claim 1 wherein said reciprocating
pressure displacement pump comprising: a curved rigid chamber wall;
and a flexible membrane attached to said rigid chamber wall,
whereby said flexible membrane and said rigid chamber wall define a
pumping chamber.
3. The cassette claimed in claim 1 wherein said cassette housing
comprising: a top plate; a midplate; and a bottom plate.
4. The cassette claimed in claim 1 further comprising at least one
valve.
5. The cassette claimed in claim 4 wherein said at least one valve
comprising a valve housing having a membrane, said membrane
dividing said housing into two chambers.
6. The cassette claimed in claim 1 wherein said mixing chamber
comprising a curved rigid chamber wall having at least one fluid
inlet and at least one fluid outlet.
7. The cassette claimed in claim 1 further comprising at least one
metering membrane pump within said housing, said metering pump
fluidly connected to said mixing chamber on said housing and to a
metering pump fluid line, wherein said metering pump fluid fine is
fluidly connected to said at least one of said at least one fluid
inlet lines.
8. The cassette claimed in claim 7 further comprising wherein said
metering pump fluid line connected to at second fluid inlet
line.
9. A pump cassette comprising: a housing comprising at least two
fluid inlet lines and at least one fluid outlet line; at least one
reciprocating pressure displacement membrane pump within said
housing wherein said pressure pump pumps a fluid from at least one
of said fluid inlet line to at lease one of said fluid outlet line;
at least one mixing chamber within said housing, said mixing
chamber fluidly connected to said fluid outlet line; and at least
one metering membrane pump within said housing, said metering
membrane pump fluidly connected to said mixing chamber on said
housing and to a metering pump fluid line, wherein said metering
pump fluid line is fluidly connected to said at least one of said
at least two fluid inlet lines.
10. The cassette claimed in claim 9 wherein said reciprocating
pressure displacement pump comprising: a curved rigid chamber wall;
and a flexible membrane attached to said rigid chamber wall,
whereby said flexible membrane and said rigid chamber wall define a
pumping chamber.
11. The cassette claimed in claim 9 wherein said cassette housing
comprising: a top plate; a midplate; and a bottom plate.
12. The cassette claimed in claim 9 wherein said mixing chamber
comprising a curved rigid chamber wall having at least one fluid
inlet and at least one fluid outlet.
13. The cassette claimed in claim 9 further comprising at least one
valve.
14. The cassette claimed in claim 13 wherein said at least one
valve comprising a valve housing having a membrane, said membrane
dividing said housing into two chambers.
15. A pump cassette comprising: a housing comprising at least three
fluid inlet lines and at least one fluid outlet line; at least two
reciprocating pressure displacement membrane pumps within said
housing wherein said pressure pump pumps a fluid from at least one
of said fluid inlet lines to at lease one of said fluid outlet
line; at least one mixing chamber within said housing, said mixing
chamber fluidly connected to said fluid outlet line; and at least
two metering membrane pumps within said housing, said metering
pumps fluidly connected to respective fluid inlet lines and to said
mixing chamber on said housing wherein said metering pumps pump a
volume of a respective fluid from said fluid inlet lines to a fluid
line fluidly connected to said mixing chamber.
16. The cassette claimed in claim 9 wherein said reciprocating
pressure displacement pump comprising: a curved rigid chamber wall;
and a flexible membrane attached to said rigid chamber wall,
whereby said flexible membrane and said rigid chamber wall define a
pumping chamber.
17. The cassette claimed in claim 15 wherein said cassette housing
comprising; a top plate; a midplate; and a bottom plate.
18. The cassette claimed in claim 15 wherein said mixing chamber
comprising a curved rigid chamber wall having at least one fluid
inlet and at least one fluid outlet.
19. The cassette claimed in claim 15 further comprising at least
one valve.
20. The cassette claimed in claim 19 wherein said at least one
valve comprising a valve housing having a membrane, said membrane
dividing said housing into two chambers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from the following U.S.
Provisional Patent Applications, both of which are hereby
incorporated herein by reference in their entireties:
[0002] U.S. Provisional Patent Application No. 60/904,024 entitled
Hemodialysis System and Methods filed on Feb. 27, 2007; and
[0003] U.S. Provisional Patent Application No. 60/921,314 entitled
Sensor Apparatus filed on Apr. 2, 2007 both of which are hereby
incorporated by reference in their entireties.
TECHNICAL FIELD
[0004] The present invention relates to a pumping cassette for
pumping fluid.
SUMMARY OF THE INVENTION
[0005] In accordance with one aspect of the pump cassette the
cassette includes housing. The housing includes at least one fluid
inlet line and at least one fluid outlet line. Also, the cassette
includes at least one reciprocating pressure displacement membrane
pump within the housing. The pressure pump pumps at least one fluid
from the fluid inlet line to at least one of the fluid outlet line.
Also, the cassette includes at least one mixing chamber within the
housing. The mixing chamber is fluidly connected to the fluid
outlet line.
[0006] Various embodiments of this aspect of the cassette include
one or more of the following. 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. Where
the cassette housing includes a top plate, a midplate and a bottom
plate. Where the cassette also includes at least one valve. In some
embodiments, the at least one valve includes a valve housing having
a membrane. The membrane divides the housing into two 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 cassette also includes at least one metering membrane
pump within the housing. The metering pump fluidly connects to the
mixing chamber on the housing and to a metering pump fluid line.
The metering pump fluid line is fluidly connected to the at least
one of the at least one fluid inlet lines. Some embodiments of the
metering pump include where the fluid line is connected to at
second fluid inlet line.
[0007] In accordance with another aspect of the pump cassette the
cassette includes a housing including at least two fluid inlet
lines and at least one fluid outlet line. Also included is at least
one reciprocating pressure displacement membrane pump within the
housing. The pressure pump pumps a fluid from at least one of the
fluid inlet line to at lease one of the fluid outlet line. The
cassette also includes at least one mixing chamber within the
housing, the mixing chamber fluidly connected to the fluid outlet
line. Also included is at least one metering membrane pump within
the housing. The metering membrane pump fluidly connects to the
mixing chamber on the housing and to a metering pump fluid line.
The metering pump fluid line is fluidly connected to the at least
one of the at least two fluid inlet lines.
[0008] Various embodiments of this aspect, of the cassette include
one or more of the following. 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. Where
the cassette housing includes a top plate, a midplate and a bottom
plate. Where the mixing chamber includes a curved rigid chamber
wall having at least one fluid inlet and at least one fluid outlet.
Where the cassette further includes at least one valve. In some
embodiments, the valve includes a valve housing having a membrane
dividing the housing into two chambers.
[0009] In accordance with another aspect of the pump cassette
includes a housing. The housing includes at least three fluid inlet
lines and at least one fluid outlet line. The cassette also
includes at least two reciprocating pressure displacement membrane
pumps within the housing that pump a fluid from at least one of the
fluid inlet lines to at lease one of the fluid outlet line. Also,
the cassette includes at least one mixing chamber within the
housing that is fluidly connected to the fluid outlet line. The
cassette also includes at least two metering membrane pumps within
the housing. The metering pumps are fluidly connected to respective
fluid inlet lines and to the mixing chamber on the housing. The
metering pumps pump a volume of a respective fluid from the fluid
inlet lines to a fluid line fluidly connected to the mixing
chamber.
[0010] Various embodiments of this aspect of the cassette include
one or more of the following. 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. Where
the cassette housing includes a top plate, a midplate and a bottom
plate. Where the cassette includes at least one valve. Some
embodiments include where the valve includes a valve housing having
a membrane, the membrane dividing the housing into two
chambers.
[0011] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features and advantages of the present
invention will be better understood by reading the following
detailed description, taken together with the drawings wherein:
[0013] FIG. 1A is a sectional view of one embodiment of a pod-pump
that is incorporated into embodiments of cassette;
[0014] FIG. 1B is a sectional view of an exemplary embodiment of a
pod pump that is incorporated into embodiments of the cassette;
[0015] FIG. 2A is an illustrative sectional view of one embodiment
of one type of pneumatically controlled valve that is incorporated
into some embodiments of the cassette;
[0016] FIG. 2B is a sectional view of another embodiment of one
type of pneumatically controlled valve that is incorporated into
some embodiments of the cassette;
[0017] FIG. 2C is a sectional view of another embodiment of one
type of pneumatically controlled valve that is incorporated into
some embodiments of the cassette;
[0018] FIG. 2D is a sectional view of another embodiment of one
type of pneumatically controlled valve that is incorporated into
some embodiments of the cassette;
[0019] FIGS. 2E-2F are top and bottom views of embodiments of the
valving membrane;
[0020] FIG. 2G shows pictorial, top and cross sectional views of
one embodiment of the valving membrane;
[0021] FIG. 3 is a sectional view of a pod pump within a
cassette;
[0022] FIG. 4 is a sectional view of a pod pump within a cassette
having a variable membrane;
[0023] FIGS. 4A and 4B are top and section views respectively of a
pod pump within a cassette having a dimpled/variable membrane;
[0024] FIGS. 4C and 4D are pictorial views of a single ring
membrane with a variable surface;
[0025] FIGS. 5A-5D are side views of various embodiments of
variable membranes;
[0026] FIGS. 5E-5H are pictorial views of various embodiments of
the metering pump membrane;
[0027] FIGS. 6A and 6B are pictorial views of a double ring
membrane with a smooth surface;
[0028] FIGS. 6C and 6D are pictorial views of a double ring
membrane with a dimple surface;
[0029] FIGS. 6E and 6F are pictorial views of double ring membranes
with variable surfaces;
[0030] FIG. 6G is a cross sectional view of a double ring membrane
with a variable surface;
[0031] FIG. 7 is a schematic showing a pressure actuation system
that may be used to actuate a pod pump;
[0032] FIG. 8 is one embodiment of the fluid flow-path schematic of
the cassette;
[0033] FIG. 9 is an alternate embodiment fluid flow-path schematic
for an alternate embodiment of the cassette;
[0034] FIG. 10 is an isometric front view of the exemplary
embodiment of the actuation side of the midplate of the cassette
with the valves indicated corresponding to FIG. 8;
[0035] FIG. 11A are front and isometric views of the exemplary
embodiment of the outer top plate of the cassette;
[0036] FIG. 11B are front and isometric views of the exemplary
embodiment of the inner top plate of the cassette;
[0037] FIG. 11C is a side view of the exemplary embodiment of the
top plate of the cassette;
[0038] FIG. 12A are front and isometric views of the exemplary
embodiment of the fluid side of the midplate of the cassette;
[0039] FIG. 12B are front and isometric views of the exemplary
embodiment of the air side of the midplate of the cassette;
[0040] FIG. 12C is a side view of the exemplary embodiment of the
midplate of the cassette;
[0041] FIG. 13A are front and isometric views of the exemplary
embodiment of the inner side of the bottom plate of the
cassette;
[0042] FIG. 13B are front and isometric views of the exemplary
embodiment of the outer side of the bottom plate of the
cassette;
[0043] FIG. 13C is a side view of the exemplary embodiment of the
midplate of the cassette;
[0044] FIG. 14A is a top view of the assembled exemplary embodiment
of the cassette;
[0045] FIG. 14B is a bottom view of the assembled exemplary
embodiment of the cassette;
[0046] FIG. 14C is an exploded view of the assembled exemplary
embodiment of the cassette;
[0047] FIG. 14D is an exploded view of the assembled exemplary
embodiment of the cassette;
[0048] FIGS. 15A-15C show cross sectional views of the exemplary
embodiment of the assembled cassette;
[0049] FIG. 16A show isometric and top views of an alternate
embodiment of the top plate according to an alternate embodiment of
the cassette;
[0050] FIG. 16B show bottom views of an alternate embodiment of the
top plate according to an alternate embodiment of the cassette;
[0051] FIG. 16C shows a side view of the alternate embodiment of
the top plate;
[0052] FIG. 17A show isometric and top views of an alternate
embodiment of the midplate according to an alternate embodiment of
the cassette;
[0053] FIG. 17B show isometric and bottom views of an alternate
embodiment of the midplate according to an alternate embodiment of
the cassette;
[0054] FIG. 17C shows a side view of the alternate embodiment of
the midplate;
[0055] FIG. 18A show isometric and top views of an alternate
embodiment of the bottom plate according to an alternate embodiment
of the cassette;
[0056] FIG. 18B show isometric and bottom views of an alternate
embodiment of the bottom according to an alternate embodiment of
the cassette;
[0057] FIG. 18C shows a side view of the alternate embodiment of
the bottom plate;
[0058] FIG. 19A is a top view of an assembled alternate embodiment
of the cassette;
[0059] FIG. 19B is an exploded view of the assembled alternate
embodiment of the cassette;
[0060] FIG. 19C is an exploded view of the assembled alternate
embodiment of the cassette; and
[0061] FIGS. 20A-20B shows a cross sectional view of the exemplary
embodiment of the assembled cassette.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0062] 1. Pumping Cassette
[0063] 1.1 Cassette
[0064] 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 is contemplated. As well,
although the cassette embodiments described herein are
implementations of the fluid schematics as shown in FIGS. 8A and
8B, in other embodiments, the cassette may have varying fluid paths
and/or valve placement and/or pod pump placements and numbers and
thus, is still within the scope of the invention.
[0065] 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).
[0066] 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.
[0067] The cassettes may be constructed of a variety of materials.
Generally, in the various embodiment, the materials used are solid
and nan 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 1.2 Exemplary Pressure Pod Pump Embodiments
[0075] FIG. 1A is a sectional view of an exemplary pod pump 100
that is incorporated into a fluid control or pump cassette (see
also FIGS. 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" plate 106, a midplate 108, and a
"bottom" plate 110 (it should be noted that the terms "top" and
"bottom" are relative and are used here for convenience with
reference to the orientation shown in FIG. 1A). The top and bottom
plates 106 and 110 include generally hemispheroid portions that
when assembled together define a hemispheroid chamber, which is a
pod pump 100.
[0076] A membrane 112 separates 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 inlet 102 allows fluid to enter the pumping
chamber, and an outlet 104 allows fluid to exit the pumping
chamber. The inlet 102 and the outlet 104 may be formed between
midplate 108 and the top plate 106. Pneumatic pressure is provided
through a pneumatic port 114 to either force, with positive gas
pressure, the membrane 112 against one wall of the pod pump cavity
to minimize the pumping chamber's volume, or to draw, with negative
gas pressure, the membrane 112 towards the other wail of the pod
pump 100 cavity to maximize the pumping chamber's volume.
[0077] The membrane 112 is provided with a thickened rim 116, which
is held tightly by a protrusion 118 in the midplate 108. Thus, in
manufacturing, the membrane 112 can be placed in and held by the
groove 108 before the bottom plate 110 is connected (in the
exemplary embodiment) to the midplate 108.
[0078] Although not shown in FIGS. 1A and 1B, in some embodiments
of the pod pump, on the fluid side, a groove is present on the
chamber wall. The groove acts to prevent folds in the membrane from
trapping fluid in the chamber when emptying.
[0079] Referring first to FIG. 1A a cross sectional view of a
reciprocating positive-displacement pump 100 in a cassette is
shown. The pod pump 100 includes a flexible membrane 112 (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") wall 122 and the actuation chamber (also
referred to as the "pneumatic chamber") wall 120 meet. The membrane
112 effectively divides that interior cavity into a variable-volume
pumping chamber (defined by the rigid interior surface of the
pumping chamber wall 122 and a surface of the membrane 112) and a
complementary variable-volume actuation chamber (defined by the
rigid interior surface of the actuation chamber wall 120 and a
surface of the membrane 112). The top portion 106 includes a fluid
inlet 102 and a fluid outlet 104, both of which are in fluid
communication with the pumping/liquid chamber. The bottom portion
110 includes an actuation or pneumatic interface 114 in fluid
communication with the actuation chamber. As discussed in greater
detail below, the membrane 112 can 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
interface 114. As the membrane 112 reciprocates back and forth, the
sum of the volumes of the pumping and actuation chambers remains
constant.
[0080] During typical fluid pumping operations, the application of
negative or vent to atmosphere pneumatic pressure to the actuation
or pneumatic interface 114 tends to withdraw the membrane 112
toward the actuation chamber wall 120 so as to expand the
pumping/liquid chamber and draw fluid into the pumping chamber
through the inlet 102, while the application of positive pneumatic
pressure tends to push the membrane 112 toward the pumping chamber
wall 122 so as to collapse the pumping chamber and expel fluid in
the pumping chamber through the outlet 104. During such pumping
operations, the interior surfaces of the pumping chamber wall 122
and the actuation chamber wall 120 limit movement of the membrane
112 as it reciprocates back and forth. In the embodiment shown in
FIG. 1A, the interior surfaces of the pumping chamber wall 122 and
the actuation chamber wall 120 are rigid, smooth, and
hemispherical. In lieu of a rigid actuation chamber wall 120, 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. U.S. 2005/0095154
(Attorney Docket No. 1062/D75) 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 (Attorney Docket No. 1062/D71WO), both of which are
hereby incorporated herein by reference in their entireties. Thus,
the rigid limit structure--such as the rigid actuation chamber wall
120, a bezel, or a set of ribs--defines the shape of the membrane
112 when the pumping chamber is at its maximum value. In a
preferred embodiment, the membrane 112 (when urged against the
rigid limit structure) and the rigid interior surface of the
pumping chamber wall 122 define a spherical pumping chamber volume
when the pumping chamber volume is at a minimum.
[0081] Thus, in the embodiment shown in FIG. 1A, movement of the
membrane 112 is limited by the pumping chamber wall 122 and the
actuation chamber wall 120. As long as the positive and vent to
atmosphere or negative pressurizations provided through the
pneumatic port 114 are strong enough, the membrane 112 will move
from a position limited by the actuation chamber wall 120 to a
position limited by the pumping chamber wall 122. When the membrane
112 is forced against the actuation chamber wall 120, the membrane
and the pumping chamber wall 122 define the maximum volume of the
pumping chamber. When the membrane is forced against the pumping
chamber wall 122, the pumping chamber is at its minimum volume.
[0082] In an exemplary embodiment, the pumping chamber wall 122 and
the actuation chamber wall 120 both 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 inlet 102 and outlet 104 also 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.
[0083] Referring now to FIGS. 3-4, a raised flow path 30 is shown
in the pumping chamber. This raised flow path 30 allows for the
fluid to continue flowing through the pod pumps after the membrane
reaches the end of stroke. Thus, the raised flow path 30 minimizes
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 path
30 is shown in the exemplary embodiment having particular
dimensions, however, in alternate embodiments, as seen in FIGS.
18A-18E, the raised flow path 30 is narrower, or in still other
embodiments, the raised flow path 30 can 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.
[0084] 1.3 Exemplary Balancing Pods Embodiment
[0085] Referring now to FIG. 1B, an exemplary embodiment of a
balancing pod is shown. The balancing pod is constructed similar to
the pod pump described above with respect to FIG. 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
inlet 102 and an outlet 104. In the exemplary embodiment, a groove
126 is included on each of the balancing chamber walls 120, 122.
The groove 126 is described in further detail below.
[0086] The membrane 112 provides 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 inlets 102 and outlets 104 for each
chamber are shown to be on the same side, in other embodiments, the
inlets 102 and outlets 104 for each chamber are on different sides.
Also, the inlets 102 and outlets 104 can be on either side,
depending on the flow path in which the balancing chamber is
integrated.
[0087] In one embodiment of the balancing chambers the membrane 112
includes an embodiment similar to the one described below with
respect to FIG. 6A-6G. However, in alternate embodiments, the
membrane 112 can be over molded or otherwise constructed such that
a double-ring seal is not applicable.
[0088] 1.4 Metering Pumps and Fluid Management System
[0089] The metering pump can he 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 in FIG.
1A for 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 in FIGS. 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.
[0090] 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.
[0091] 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.
[0092] Metering pumps are also used in various embodiments to pump
a second fluid info 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.
[0093] 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.
[0094] 1.5 Valves
[0095] 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
in FIGS. 2A and 2B, while an embodiment of the smooth valve is
shown in FIG. 2C. Additionally, FIGS. 3 and 4 show cross sections
of one embodiment of a pod pump in a cassette with an inlet and an
outlet valve.
[0096] 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).
[0097] 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).
[0098] 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.
[0099] Referring now to FIGS. 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 membrane 202, along with the midplate 204, defines
a valving chamber 206. Pneumatic pressure is provided through a
pneumatic port 208 to either force, with positive gas pressure, the
membrane 202 against a valve seat 210 to 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 seat 210
to open the valve. A control gas chamber 212 is defined by the
membrane 202, the top plate 214, and the midplate 204. The midplate
204 has an indentation formed on it, into which the membrane 202 is
placed so as to form the control gas chamber 212 on one side of the
membrane 202 and the valving chamber 206 on the other side.
[0100] The pneumatic port 208 is defined by a channel formed in the
top plate 214. 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
midplate 204, corresponding with fluid paths along with the bottom
plate 216, define the valve inlet 218 and the valve outlet 220.
Holes formed through the midplate 204 provide communication between
the inlet 218 and the valving chamber 206 and between the valving
chamber 206 and the outlet 220.
[0101] The membrane 202 is provided with a thickened rim 222, which
fits tightly in a groove 224 in the midplate 204. Thus, the
membrane 202 can be placed in and held by the groove 224 before the
top plate 214 is connected to the midplate 204. Thus, this valve
design may impart benefits in manufacturing. As shown in FIGS. 2B
and 2C, the top plate 214 may include additional material extending
into control gas chamber 212 so as to prevent the membrane 202 from
being urged too much in a direction away from the groove 224, so as
to prevent the membrane's thickened rim 222 from popping out of the
groove 224. The location of the pneumatic port 208 with respect to
the control gas chamber 212 varies in the two embodiments shown in
FIGS. 2A and 2B.
[0102] FIG. 2C shows an embodiment in which the valving chamber
lacks a valve seat feature. Rather, in FIG. 2C, the valve in this
embodiment does not include any volcano features and thus, the
valving chamber 206, 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. 2D shows
an embodiment in which the valving chamber has a raised area to aid
in the sealing of the valving membrane. Referring now to FIGS.
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.
[0103] 1.6 Exemplary Embodiments of the Pod Membrane
[0104] In some embodiments, the membrane has a variable
cross-sectional thickness, as shown in FIG. 4. Thinner, thicker or
variable thickness membranes may be used to accommodate the
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 to FIGS. 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.
[0105] Referring now to FIGS. 4A, 4C and 4D, an alternate
embodiment of the membrane is shown. In this embodiment, the
membrane has a dimpled or dotted surface.
[0106] 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 ilex 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.
[0107] 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.
[0108] 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.
[0109] 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
in FIGS. 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.
[0110] 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.
[0111] 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 to FIGS. 1A and 1B and 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 to 6A-6D, one embodiment of the membrane is
shown with two gaskets 62, 64. In some of these embodiments, the
gasket(s) 62, 64 provides 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 (see FIGS. 4A-4D).
[0112] 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.
[0113] 1.7 Mixing Pods
[0114] 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. [0115] 2. Pressure Pump Actuation
System
[0116] FIG. 7 is 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 in FIG.
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. 7 does not apply in these embodiments, actuation
of the pod pump is accomplished by applying positive pressure and
vent to atmosphere (again, not shown in FIG. 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.
[0117] 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).
[0118] A valving mechanism is used to control fluid communication
between each of these reservoirs and the actuation chamber. As
shown in FIG. 7, a separate valve is used for each of the
reservoirs; a positive-supply valve controls fluid communication
between the positive-pressure reservoir and 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.
[0119] 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.
[0120] Still referring to FIG. 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.
[0121] 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 or
other fluid).
[0122] 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 in FIG. 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. [0123]
3. Fluid Handling
[0124] As shown and described with respect to FIGS. 2A-2D, a fluid
valve in the 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 in
FIGS. 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 in FIG. 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).
[0125] Referring again to FIG. 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.
[0126] 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.
[0127] 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. [0128] 4.
Volume Measurement
[0129] These flow rates in the cassette are controlled using
pressure pod pumps which can defect 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.
[0130] 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.
[0131] 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. [0132] 5. Exemplary Embodiment of the
Pumping Cassette
[0133] 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.
[0134] 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).
[0135] Referring now to FIG. 8, an exemplary embodiment of the
fluid schematic of the cassette 800 is shown. Other schematics are
readily discernable. The cassette 800 includes at least one pod
pump 828, 820 and at least one mixing chamber 818. The cassette 800
also includes a first fluid inlet 810, where a first fluid enters
the cassette. The first fluid includes a flow rate provided by one
of the at least one pod pump 820, 828 in the cassette 800. The
cassette 800 also includes a first fluid outlet 824 where fluid
exits the cassette 800 having a flow rate provided by one of the at
least one pod pump 820, 828. The cassette 800 includes at least one
metering fluid line 812, 814, 816 that is in fluid connection with
the first fluid outlet. The cassette also includes at least one
second fluid inlet 826 where the second fluid enters the cassette
800. In some embodiments of the cassette 800 a third fluid inlet
825 is also included.
[0136] Metering pumps 822, 830 pump 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 cassette 800 at
the second fluid inlet 826 and third fluid inlet 825 respectively,
are each fluidly connected to a metering pump 822, 830 and to the
first fluid outlet line through a metering fluid line 812, 814,
816. The metering pumps 822, 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 pumps 822, 830
is readily discernible.
[0137] The mixing chamber 818 is connected to the first fluid
outlet line 824 and includes a fluid inlet and a fluid outlet. In
some embodiments, sensors are located upstream and downstream from
the mixing chamber 818. The location of the sensors in the
exemplary embodiment are shown and described below with respect to
FIGS. 14C, 14D and FIGS. 15B and 15C.
[0138] The cassette 800 is capable of internally mixing a solution
made up of at least two components. The cassette 800 also 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.
[0139] Various valves 832-860 impart the various capabilities of
the cassette 800. The components of the cassette 800 may be used
differently in the different embodiments based on various valving
controls.
[0140] The fluid schematic of the cassette 800 shown in FIG. 8 may
be embodied into various cassette apparatus. Thus, the embodiments
of the cassette 800 including the fluid schematic shown in FIG. 8
are 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.
[0141] Referring now to FIG. 8, a fluid flow-path schematic 800 is
shown with the fluid paths indicated based on different valving
flow paths. The fluid flow-path schematic 800 is described herein
corresponding to the valving flow paths in one embodiment of the
cassette. The exemplary embodiment of the midplate 900 of the
cassette are shown in FIG. 10 with the valves indicated
corresponding to the respective fluid flow-path schematic 800 in
FIG. 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 of FIG. 10 are shown in FIG. 12A.
[0142] Referring now to FIGS. 8 and 10 the first valving path
includes valves 858, 860. This valving path 858, 860 includes the
metering fluid line 812, which connects to the second fluid inlet
826. As shown in these FIGS., in some embodiments of the cassette,
there are two second fluid inlets 826. In practice, these two
second fluid inlets 826 can 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 inlet 826.
Each second fluid inlet 826 is connected to a different metering
fluid line 812, 814.
[0143] The first of the two metering fluid lines connected to the
second fluid inlet 826 is as follows. When valve 858 opens and
valve 860 is closed and metering pump 822 is actuated, fluid is
drawn from the second fluid inlet 826 and into metering fluid line
812. When valve 860 is open and valve 858 is closed and the
metering pump 822 is actuated, second fluid continues on metering
fluid line 812 into pod pump 820.
[0144] Referring now to the second valving path including valve
842, when valve 842 is open and pod pump 820 is actuated, fluid is
pumped from pod pump 820 to one of the third fluid inlet 825. In
one embodiment, this valving path is provided to send liquid into a
container or source connected to third fluid inlet 825.
[0145] Referring now to the third valving path including valves 832
and 836 this valving path 832, 835 includes the metering fluid line
816, which connects to the third fluid inlet 825. As shown in these
FIGS., in some embodiments of the cassette, there are two third
fluid inlets 825. In practice, these two third fluid inlets 825 can
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 inlet 825. Each third fluid inlet 825 is connected
to a different metering fluid line 862, 868.
[0146] When valve 832 opens and valve 836 is closed and metering
pump 830 is actuated, fluid is drawn from the third fluid inlet 825
and into metering fluid line 830. When valve 836 is open and valve
832 is closed and the metering pump 830 is actuated, third fluid
continues on metering fluid line 816 into first fluid outlet line
824.
[0147] Referring now to the fourth valving path, valve 846, when
valve 846 is open and pod pump 820 is actuated, fluid is pumped
from pod pump 820 to one of the third fluid inlet 825. In one
embodiment, this valving path is provided to send liquid into a
container or source connected to third fluid inlet 825.
[0148] Referring now to the fifth valving path, when valve 850
opens and pod pump 820 is actuated, fluid is pumped into the
cassette 800 through the first fluid inlet 810, and into pod pump
820.
[0149] Referring now to the sixth valving path, when valve 838 is
open and pod pump 820 is actuated, fluid is pumped from pod pump
820 to the mixing chamber 818 and to the first fluid outlet
824.
[0150] The seventh valving path includes valves 858, 856. This
valving path 858, 856 includes the metering fluid line 812, which
connects to the second fluid inlet 826. As shown in these FIGS., in
some embodiments of the cassette, there are two second fluid inlets
826. In practice, these two second fluid inlets 826 can 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 inlet 826. Each second fluid inlet 826 is connected to
a different metering fluid line 812, 814.
[0151] When valve 858 opens and valve 856 is closed and metering
pump 822 is actuated, fluid is drawn from the second fluid inlet
826 and info metering fluid line 812. When valve 856 is open and
valve 858 is closed, and the metering pump is actuated, second
fluid continues on metering fluid line 814 into pod pump 828.
[0152] Referring now to the eighth valving path, valve 848, when
valve 848 is open and pod pump 828 is actuated, fluid is pumped
from pod pump 828 to one of the third fluid inlet 825. In one
embodiment, this valving path is provided to send fluid/liquid into
a container or source connected to third fluid inlet 825.
[0153] Referring now to the ninth valving path including valve 844,
when valve 844 is open and pod pump 828 is actuated, fluid is
pumped from pod pump 828 to one of the third fluid inlet 825. In
one embodiment, this valving path is provided to send liquid into a
container or source connected to third fluid inlet 825.
[0154] Referring now to the tenth valving path, valve 848, when
valve 848 is open and pod pump 828 is actuated, fluid is pumped
from pod pump 828 to one of the third fluid inlet 825. In one
embodiment, this valving path is provided to send fluid/liquid into
a container or source connected to third fluid inlet 825.
[0155] The eleventh valving path including valves 854 and 856 is
shown. This valving path 854, 856 includes the metering fluid line
814, which connects to the second fluid inlet 826. As shown in
these FIGS., in some embodiments of the cassette, there are two
second fluid inlets 826. In practice, these two second fluid inlets
826 can 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 inlet 826. Each second fluid inlet
826 is connected to a different metering fluid line 812, 814.
[0156] The second of the two metering fluid lines connected to the
second fluid inlet 826 is shown in FIG. 8. The twelfth valving path
is as follows. When valve 854 opens and valve 856 is closed and
metering pump 822 is actuated, fluid is drawn from the second fluid
inlet 826 and into metering fluid line 814. When valve 856 is open
and valve 854 is closed and the metering pump 822 is actuated, the
second fluid continues on metering fluid line 814 into pod pump
828.
[0157] Similarly, the thirteenth valving path is seen when valve
854 opens and valve 860 is closed and metering pump 822 is
actuated, fluid is drawn from the second fluid inlet 826 and into
metering fluid line 814. When valve 860 is open and valve 854 is
closed, and the metering pump 822 is actuated, the second fluid
continues on metering fluid line 814 into pod pump 820.
[0158] Referring now to the fourteenth valving path including valve
852. When valve 852 opens and pod pump 828 is actuated, fluid is
pumped into the cassette 800 through the first fluid inlet 810, and
into pod pump 828.
[0159] Referring now to the fifteenth valving path, when valve 840
is open and pod pump 828 is actuated, fluid is pumped from pod pump
828 to the mixing chamber 818 and to the first fluid outlet 824.
The sixteenth valving path including valve 834, when valve 834 is
open and valve 836 opens, and the metering pump 830 is actuated,
fluid from the third fluid inlet 825 flows on metering fluid line
862 and to metering fluid line 816.
[0160] In the exemplary fluid flow-path embodiment shown in FIG. 8,
and corresponding structure of the cassette shown in FIG. 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.
[0161] Referring now to FIGS. 11A-11B, the top plate 1100 of
exemplary embodiment of the cassette is shown. In the exemplary
embodiment, the pod pumps 820, 828 and the mixing chambers 818 on
the top plate 1100, are formed in a similar fashion. In the
exemplary embodiment, the pod pumps 820, 828 and mixing chamber
818, 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.
[0162] Referring now to FIG. 11B, the bottom view of the top plate
1100 is shown. The fluid paths are shown in this view. These fluid
paths correspond to the fluid paths shown in FIGS. 12A-12B in the
midplate 1200. The top plate 1100 and the top of the midplate 1200
form the liquid or fluid side of the cassette for the pod pumps
820, 828 and for one side of the mixing chamber 818. Thus, most of
the liquid flow paths are on the top 1100 and midplates 1200.
Referring to FIG. 12B, the first fluid inlet 810 and the first
fluid outlet 824 are shown.
[0163] Still referring to FIGS. 11A and 11B, the pod pumps 820, 828
include a groove 1002 (in alternate embodiments, this is a groove).
The groove 1002 is shown having a particular size and shape,
however, in other embodiments, the size and shape of the groove
1002 can be any size or shape desirable. The size and shape shown
in FIGS. 11A and 11B is the exemplary embodiment. In all
embodiments of the groove 1002, the groove 1002 forms a path
between the fluid inlet side and the fluid outlet side of the pod
pumps 820, 828. In alternate embodiments, the groove 1002 is a
groove in the inner pumping chamber wall of the pod pump.
[0164] The groove 1002 provides 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 groove 1002 is included in
both the liquid/fluid and air/actuation sides of the pod pumps 820,
828. In some embodiments, the groove 1002 may also be included in
the mixing chamber 818 (see FIGS. 13A-13B with respect to the
actuation/air side of the pod pumps 820, 828 and the opposite side
of the mixing chamber 818. In alternate embodiments, the groove
1002 is either not included or on only one side of the pod pumps
820, 828.
[0165] In an alternate embodiment of the cassette, the liquid/fluid
side of the pod pumps 820, 828 may 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 to FIG. 11E, the side view of the exemplary embodiment of
the top plate 1100 is shown.
[0166] Referring now to FIGS. 12A-12B, the exemplary embodiment of
the midplate 1200 is shown. The midplate 1200 is also shown in
FIGS. 9A-9F and 10A-10F, where these FIGS. correspond with FIGS.
12A-12B. Thus, FIGS. 9A-9F and 10A-10F indicate the locations of
the various valves and valving paths. The locations of the
membranes (not shown) for the respective pod pumps 820, 828 as well
as the location of the mixing chamber 818 are shown.
[0167] Referring now to FIG. 12A, 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 cell 1314,
1316. In this embodiment, a sensor cell 1314, 1316 is included as
an area on the cassette for sensor(s) elements. In the exemplary
embodiment, the three sensor elements of the two sensor cells 1314,
1316 are housed in respective sensor elements housings 1308, 1310,
1312 and 1318, 1320, 1322. In the exemplary embodiment, two of the
sensor elements housings 1308, 1312 and 1318, 1320 accommodate a
conductivity sensor elements and the third sensor elements housing
1310,1322 accommodates 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 U.S. Patent Application entitled
Sensor Apparatus Systems, Devices and Methods filed Oct. 12, 2007
(DEKA-024XX).
[0168] 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.
[0169] Referring now to FIG. 12C, the side view of the exemplary
embodiment of the midplate 1200 is shown.
[0170] Referring now to FIGS. 13A-13B, the bottom plate 1300 is
shown. Referring first to FIG. 13A, the inner or inside surface of
the bottom plate 1300 is shown. The inner or inside surface is the
side that contacts the bottom surface of the midplate (not shown,
see FIG. 9B). The bottom plate 1300 attaches to the air or
actuation lines (not shown). The corresponding entrance holes for
the air that actuates the pod pumps 820, 828 and valves (not shown,
see FIGS. 10A-10F) in the midplate 1300 can be seen. Holes 810, 824
correspond to the first fluid inlet and first fluid outlet shown in
FIG. 12B, 810, 824 respectively. The corresponding halves of the
pod pumps 820, 828 and mixing chamber 818 are also shown, as are
the grooves 1002 for the fluid paths. The actuation holes in the
pumps are also shown. Unlike the top plate, the bottom plate 1300
corresponding halves of the pod pumps 820, 828 and mixing chamber
818 make apparent the difference between the pod pumps 820, 828 and
mixing chamber 818. The pod pumps 820, 828 include an air/actuation
path on the bottom plate 1300, while the mixing chamber 818 has
identical construction to the half in the top plate. The mixing
chamber 818 mixes liquid and therefore, does not include a membrane
(not shown) nor an air/actuation path. The sensor cell 1314, 1316
with the three sensor element housings 1308, 1310, 1312 and 1318,
1320, 1322 are also shown.
[0171] Referring now to FIG. 13B, the actuation ports 1306 are
shown on the outside or outer bottom plate 1300. An actuation
source is connected to these actuation ports 1306. Again, the
mixing chamber 818 does not have an actuation port as it is not
actuated by air. Referring to FIG. 13C, a side view of the
exemplary embodiment of the bottom plate 1300 is shown.
[0172] 5.1 Membranes
[0173] In the exemplary embodiment, the membrane is a gasket o-ring
membrane as shown in FIG. 5A. However, in some embodiments, a
gasket o-ring membranes having texture, including, but not limited
to, the various embodiments in FIG. 4D, or 5B-5D may be used. In
still other embodiments, the membranes shown in FIGS. 6A-6G may
also be used.
[0174] Referring next to FIGS. 14A and 14B, the assembled exemplary
embodiment of the cassette 1400 is shown. FIGS. 14C and 14D are an
exploded view of the exemplary embodiment of the cassette 1400. The
membranes 1600 are shown. As can be seen from FIGS. 14C and 14D,
there is one membrane 1602 for 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).
[0175] The various embodiments of the membrane used in the metering
pumps 1604, in the preferred embodiment, are shown in more detail
in FIGS. 5E-5H. The various embodiments of the membrane used in the
valves 1222 is shown in more detail in FIGS. 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 in FIGS.
5A-5D.
[0176] One embodiment of the conductivity sensor elements 1314,
1316 and the temperature sensor element 1310, which make up the
sensor cell 1322, are also shown in FIGS. 14C and 14D. Still
referring to FIGS. 14C and 14D, the sensor elements are housed in
sensor blocks (shown as 1314, 1316 in FIGS. 12B and 13A) which
include areas on the bottom plate 1300 and the midplate 1200.
O-rings seal the sensor housings from the fluid lines located on
the upper side of the midplate 1200 and the inner side of the top
plate 1100. However, in other embodiments, an o-ring is molded into
the sensor block or any other method of sealing can be used.
[0177] 5.2 Cross Sectional Views
[0178] Referring now to FIGS. 15A-15C, various cross sectional
views of the assembled cassette are shown. Referring first to FIG.
15A, the membranes 1602 are shown in a pod pumps 820, 828. As can
be seen from the cross section, the o-ring of the membrane 1602 is
sandwiched by the midplate 1200 and the bottom plate 1300. A valve
membrane 1606 can also be seen. As discussed above, each valve
includes a membrane.
[0179] Referring now to FIG. 15B, the two conductivity sensors
1308, 1312 and the temperature sensor 1310 are shown. As can be
seen from the cross section, the sensors 1308, 1310, 1312 are in
the fluid line 824. Thus, the sensors 1308, 1310, 1312 are in fluid
connection with the fluid line and can determine sensor data of the
fluid exiting fluid outlet one 824. Still referring to FIG. 15B, a
valve 836 cross 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 to FIG. 2B.
However, as discussed above, in alternate embodiment, other valves
are used including, but not limited, to those described and shown
above with respect to FIGS. 2A, 2C and 2D.
[0180] Referring now to FIG. 15C, the two conductivity sensor
elements 1318, 1320 and the temperature sensor element 1322 are
shown. As can be seen from the cross section, the sensor elements
1318, 1320, 1322 are in the fluid line 824. Thus, the sensor
elements 1318, 1320, 1322 are 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 elements 1318, 1320, 1322 are used
to collect data regarding fluid being pumped into the mixing
chamber. Referring back to FIG. 12B, sensor elements 1308, 1310,
1312 are 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 or 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.
[0181] As described above, the exemplary embodiment is one cassette
embodiment that incorporates the exemplary fluid flow-path
schematic shown in FIG. 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 in FIGS. 16A-20B.
[0182] Referring now to FIGS. 16A-16C, views of an alternate
embodiment of the top plate 1600 are shown. The features of the top
plate 1600 are alternate embodiments of corresponding features in
the exemplary embodiment. This alternate embodiment includes two
mixing chambers 1622, 1624 and 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. 9 shows a fluid
flow-path schematic of the cassette shown in FIGS. 16A-20B.
[0183] Referring now to FIGS. 17A-17C, views of an alternate
embodiment of the midplate 1700 are shown. FIGS. 18A-18C show views
of an alternate embodiment of the bottom plate 1800.
[0184] Referring now to FIG. 19A, an assembled alternate embodiment
of the cassette 1900 is shown. FIGS. 19C-19D show exploded views of
the cassette 1900 where the pod pump membranes 1910, valve
membranes 1914 and metering pump membranes 1912 are shown. The
three metering pumps 1616, 1618, 1620 can be seen as well as the
respective membranes 1912. In this embodiment, three fluids can be
metered and controlled volumes of each can be mixed together in the
mixing chambers 1622, 1624. FIGS. 20A and 20B show a cross
sectional view of the assembled cassette 1900.
[0185] As this alternate embodiment shows, there are many
variations of the pumping cassette and the general fluid schematic
shown in FIG. 8. Thus, additional mixing chambers and metering
pumps can add additional capability to the pumping cassette to mix
more than two fluids together.
[0186] 5.3 Exemplary Embodiments of the Pumping Cassette
[0187] 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.
[0188] 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.
[0189] 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.
[0190] 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.
[0191] 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.
[0192] 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.
[0193] 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.
[0194] 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.
[0195] 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.
[0196] One of the fluid paths described above with respect to FIG.
8 includes 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 in FIG. 8. In other embodiments, fluid inlet
liquid is pumped to only one source ingredient container.
[0197] 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.
[0198] 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.
[0199] 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 pump more than one
source ingredient and be connected to more than one source
ingredient even if they are not the same.
[0200] 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.
[0201] 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.
[0202] In the exemplary embodiment, the NaCl/Bicarbonate is a
powder and requires the addition of water to create the fluid
source ingredient solution. Thus, wafer 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.
[0203] 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.
[0204] 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 outlet.
[0205] In some embodiments, sensor elements are located downstream
from the mixing chamber. These sensor elements can ensure the
concentration of the finished solution is 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.
[0206] 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 in FIG. 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.
[0207] 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.
[0208] 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 and in some embodiments are smooth surface
valves.
[0209] While the principles of the invention have been described
herein, it is to be understood by those skilled in the art that
this description is made only by way of example and not as a
limitation as to the scope of the invention. Other embodiments are
contemplated within the scope of the present invention in addition
to the exemplary embodiments shown and described herein.
Modifications and substitutions by one of ordinary skill in the art
are considered to be within the scope of the present invention.
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