U.S. patent application number 11/603926 was filed with the patent office on 2007-09-27 for electrokinetic pump designs and drug delivery systems.
Invention is credited to Deon Stafford Anex, David Laurence Black, Michael James Gearhart, Richard Dean Rush, Charles Martin Schwimmer.
Application Number | 20070224055 11/603926 |
Document ID | / |
Family ID | 38067875 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070224055 |
Kind Code |
A1 |
Anex; Deon Stafford ; et
al. |
September 27, 2007 |
Electrokinetic pump designs and drug delivery systems
Abstract
One embodiment of the present invention provides a piston
assembly having a piston housing filled with an electrolyte; a
housing within the piston housing that divides the piston housing
into a first portion and a second portion, the housing having
apertures, a shaft connecting the housing to a piston head outside
of the piston housing; and a porous material inside of the housing
in contact with the electrolyte. Additionally, there are provided a
method for filling the delivery chamber with a delivery fluid by
withdrawing the piston head from within the delivery chamber. Yet
another embodiment provides a method for filling a fluid delivery
assembly by withdrawing a shaft from within the fluid delivery
assembly to simultaneously displace a moving pump element within
the delivery chamber and bypass fluid around a housing in the pump
chamber.
Inventors: |
Anex; Deon Stafford;
(Livermore, CA) ; Schwimmer; Charles Martin; (Los
Gatos, CA) ; Black; David Laurence; (Los Gatos,
CA) ; Rush; Richard Dean; (Belmont, CA) ;
Gearhart; Michael James; (Fremont, CA) |
Correspondence
Address: |
SHAY LAW GROUP LLP
2755 CAMPUS DRIVE
SUITE 210
SAN MATEO
CA
94403
US
|
Family ID: |
38067875 |
Appl. No.: |
11/603926 |
Filed: |
November 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60739390 |
Nov 23, 2005 |
|
|
|
Current U.S.
Class: |
417/404 |
Current CPC
Class: |
F04B 17/00 20130101;
A61M 5/14526 20130101; F04B 19/04 20130101; A61M 2209/045 20130101;
A61M 2005/14513 20130101; Y10T 137/0391 20150401; F04B 19/006
20130101 |
Class at
Publication: |
417/404 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Claims
1. A piston assembly, comprising: A piston housing; A housing
within the piston housing that divides the piston housing into a
first portion and a second portion, the housing having apertures
that provide fluid communication between the first portion and the
second portion; A shaft connecting the housing to a piston head
outside of the piston housing; and A porous material inside of the
housing.
2. The piston assembly of claim 1 where in the piston housing is
filled with an electrolyte.
3. The piston assembly of claim 1 where in the porous material
inside of the housing is in contact with the electrolyte.
4. The piston assembly according to claim 1 wherein the porous
material is a porous dielectric material adapted for operation as
part of an electrokinetic pump.
5. The piston assembly according to claim 1 further comprising: A
sealing element around the piston head or the housing.
6. The piston assembly according to claim 1 further comprising a
second shaft connecting the housing to a handle outside of the
piston housing.
7. The piston assembly according to claim 6 further comprising a
valve within the second shaft wherein actuation of the valve
provides a flow path between the first portion and the second
portion.
8. The piston assembly according to claim 7 wherein the flow path
from one side of the housing to the other side of the housing
includes a bypass through the porous material contained in the
housing.
9. The piston assembly according to claim 7 wherein the valve is
actuatable from a handle attached to the second shaft.
10. The piston assembly according to claim 1 wherein the shaft
extends through a wall in the piston housing.
11. The piston assembly according to claim 5 wherein the sealing
element around the material housing seals the housing to a wall of
the piston housing.
12. The piston assembly according to claim 1 further comprising an
electrode in the first portion and an electrode in the second
portion.
13. The piston assembly according to claim 12 wherein the
electrodes have a double layer capacitance of greater than 10.sup.4
microfarad/cm.sup.2.
14. A pump, comprising: a delivery chamber, a pump chamber and a
wall separating the pump chamber from the delivery chamber; a
piston assembly having a piston head in the delivery chamber, a
housing in the pump chamber and a shaft connecting the piston head
to the housing and passing through the wall separating the pump
chamber from the delivery chamber; and a dielectric material in the
housing.
15. The pump according to claim 14 further comprising: a pair of
electrodes in the pump housing.
16. The pump according to claim 15 wherein one electrode is on each
side of the housing.
17. The pump according to claim 15 wherein the pair of electrodes
are made from a material selected to electrokineticly move a fluid
in the pump chamber.
18. The pump according to claim 14 wherein the delivery chamber and
the pump chamber are in a single housing.
19. The pump according to claim 14 wherein the housing divides the
pump chamber into a first portion and a second portion.
20. The pump according to claim 19 further comprising apertures in
the housing that provide fluid communication between the first
portion and the second portion.
21. The pump according to claim 14 further comprising an
electrolyte in the pump chamber.
22. The pump according to claim 15 wherein each electrode in the
pair of electrodes has a double layer capacitance of more than
10.sup.4 microfarad/cm.sup.2.
23. The pump according to claim 14 further comprising: a bypass
valve in the shaft that provides a fluid pathway from one side of
the housing to the other side of the housing.
24. The pump according to claim 14 further comprising: a bypass
valve in the shaft that provides a fluid pathway from the first
portion to the second portion.
25. The pump according to claim 14 wherein the delivery chamber is
filled with a delivery fluid by relative movement between the pump
chamber and the delivery chamber.
26. The pump according to claim 17 wherein application of an
electric field across the electrodes moves the fluid in the pump
chamber from one side of the housing to the other side of the
housing.
27. The pump according to claim 17 wherein application of an
electric field across the electrodes moves the piston head in the
delivery chamber.
28. The pump according to claim 17 wherein application of an
electric field across the electrodes moves the housing relative to
the pump chamber.
29. A method for operating a fluid delivery system, comprising:
inserting a piston assembly into a delivery chamber, the piston
assembly having a pump housing, a piston head outside of the pump
housing and attached to a shaft extending through a wall in the
pump housing, a housing attached to the shaft and between
electrodes in the pump housing; and filling the delivery chamber
with a delivery fluid by withdrawing the piston head from within
the delivery chamber.
30. A method for operating a fluid this delivery system according
to claim 29, further comprising: fixing the position of the pump
housing relative to the delivery chamber.
31. A method for operating a fluid delivery system according to
claim 29 further comprising: advancing the piston head in the
delivery chamber by moving fluid in the pump chamber.
32. A method according to claim 31 wherein moving fluid within the
pump chamber comprises electrokineticly moving fluid through the
housing.
33. A method according to claim 31 wherein moving fluid within the
pump chamber comprises providing an electric field between the
electrodes.
34. The method according to claim 29 wherein the filling step
comprises withdrawing the pump assembly.
35. A method for operating a fluid delivery assembly having a pump
chamber and a delivery chamber, comprising: withdrawing a shaft
from within the fluid delivery assembly to simultaneously displace
a moving pump element within the delivery chamber and bypass fluid
around a housing in the pump chamber.
36. A method for operating a fluid delivery assembly according to
claim 35 wherein withdrawing a shaft from the pump assembly
introduces a delivery fluid into the delivery chamber and into
contact with the moving pump element.
37. A method of operating fluid delivery assembly according to
claim 35 further comprising: advancing the moving pump element in
the delivery chamber by applying an electrical field across
electrodes in the pump chamber and on either side of the
housing.
38. A method of operating a fluid delivery assembly according to
claim 35, further comprising: electrokineticly moving fluid in the
pump chamber to dispense fluid from the delivery chamber.
39. The method of claim 35 further comprising: Actuating a bypass
in the shaft during the withdrawing step.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/739,390 filed Nov. 23, 2005, titled,
"Electrokinetic Pump Designs and Drug Delivery Systems" which is
incorporated herein by reference in its entirety. This application
is related to the following co-pending patent applications: U.S.
application Ser. No. (not yet assigned) filed herewith titled,
"Electrokinetic Pump Designs and Drug Delivery Systems" (Attorney
Docket number 10076-705.201); U.S. application Ser. No. 10/198,223,
filed Jul. 17, 2002 titled, "Laminated Flow Devices"; U.S.
application Ser. No. 10/273,723 filed Oct. 18, 2002 titled,
"Electrokinetic Device Having Capacitive Electrodes"; U.S.
application Ser. No. 10/322,083 filed Dec. 17, 2002 titled,
"Electrokinetic Device Having Capacitive Electrodes" and U.S.
application Ser. No. 11/112,867 filed Apr. 21, 2005 titled,
"Electrokinetic Delivery Systems, Devices and Methods," each of
which are incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] Pumps and pumping systems exist for the delivery of various
fluids. A variety of pumps are used in a number of various
different configurations and uses. Pumps are used for infusion of
drugs or delivery of drugs into mammals, the sterility of the drugs
is very important. In addition, contamination of the drug or
delivery fluid from the pump system should be reduced or
eliminated. Additionally, it remains an important aspect to
minimize contact between the drug to be delivered and the internal
components of the pump being used to deliver the drug. Filling or
preparing the drug or fluid for delivery should not be time
consuming. These and other difficulties are encountered using
conventional filling and pumping systems.
[0003] Related U.S. application Ser. No. 11/112,867 filed Apr. 21,
2005 titled, "Electrokinetic Delivery Systems, Devices and
Methods," discloses a technique for filling a pump with fluid for
delivery. This technique involves operating the pump system in
reverse to draw the delivery fluid into the pump. Then, after
filling the pump with the delivery fluid, the pump direction is
reversed and the delivery fluid is delivered from the pump.
Reversing pump direction may be a good solution for small amounts
of fluid or for pump configurations that have a very high linear
flow rate. However, the time requirements for loading large volumes
of delivery fluid using this technique may be prohibitive for time
conscious applications and problematic for later pump
operation.
[0004] What are needed are improved techniques for providing the
delivery fluid into the pumping system. The pump filling procedures
should be simple and require small amounts of time.
SUMMARY OF THE INVENTION
[0005] One embodiment of the present invention provides a piston
assembly having a piston housing filled with an electrolyte; a
housing within the piston housing that divides the piston housing
into a first portion and a second portion, the housing having
apertures that provide fluid communication between the first
portion and the second portion; a shaft connecting the housing to a
piston head outside of the piston housing; and a porous material
inside of the housing in contact with the electrolyte.
[0006] In one aspect, the porous material is a porous dielectric
material adapted for operation as part of an electrokinetic pump.
In another aspect, there is a sealing element around the piston
head or the housing. In yet another aspect, there is a second shaft
connecting the housing to a handle outside of the piston housing.
In another aspect there is a valve within the second shaft wherein
actuation of the valve provides a flow path between the first
portion and the second portion. In yet another aspect, the flow
path from one side of the housing to the other side of the housing
includes a bypass through the porous material contained in the
housing. In another aspect, the valve is actuatable from a handle
attached to the second shaft. In another aspect, the shaft extends
through a wall in the piston housing. In another aspect, the
sealing element around the material housing seals the housing to a
wall of the piston housing. In another aspect, there is an
electrode in the first portion and an electrode in the second
portion. In one embodiment, the electrodes have a double layer
capacitance of greater than 10.sup.-4 microfarad/cm.sup.2.
[0007] In another embodiment of the invention, there is provided a
pump having a delivery chamber, a pump chamber and a wall
separating the pump chamber from the delivery chamber; a piston
assembly having a piston head in the delivery chamber, a housing in
the pump chamber and a shaft connecting the piston head to the
housing and passing through the wall separating the pump chamber
from the delivery chamber; and a dielectric material in the
housing.
[0008] In one aspect, there is a pair of electrodes in the pump
housing. In one aspect, there is one electrode is on each side of
the housing. In one embodiment, the pair of electrodes are made
from a material selected to electrokineticly move a fluid in the
pump chamber. In one aspect, the delivery chamber and the pump
chamber are in a single housing. In another aspect, the housing
divides the pump chamber into a first portion and a second portion.
In yet another aspect, there is provided apertures in the housing
that provide fluid communication between the first portion and the
second portion. In another aspect, there is an electrolyte in the
pump chamber. In a further aspect, each electrode in the pair of
electrodes has a double layer capacitance of more than 10.sup.-4
microfarad/cm.sup.2. In yet another aspect, there is a bypass valve
in the shaft that provides a fluid pathway from one side of the
housing to the other side of the housing. In one aspect, the bypass
valve in the shaft that provides a fluid pathway from the first
portion to the second portion. In another aspect, the delivery
chamber is filled with a delivery fluid by relative movement
between the pump chamber and the delivery chamber. In another
aspect, application of an electric field across the electrodes
moves the fluid in the pump chamber from one side of the housing to
the other side of the housing. In one aspect, application of an
electric field across the electrodes moves the piston head in the
delivery chamber. In another aspect, application of an electric
field across the electrodes moves the housing relative to the pump
chamber.
[0009] In another embodiment, there is provided a method for
operating a fluid delivery system by inserting a piston assembly
into a delivery chamber, the piston assembly having a pump housing,
a piston head outside of the pump housing and attached to a shaft
extending through a wall in the pump housing, a housing attached to
the shaft and between electrodes in the pump housing; and filling
the delivery chamber with a delivery fluid by withdrawing the
piston head from within the delivery chamber. In one further
aspect, the method fixes the position of the pump housing relative
to the delivery chamber. In another aspect, there is provided the
step of advancing the piston head in the delivery chamber by moving
fluid in the pump chamber. In one aspect, moving fluid within the
pump chamber comprises electrokineticly moving fluid through the
housing. In another aspect, moving fluid within the pump chamber
comprises providing an electric field between the electrodes. In
yet another aspect, the filling step comprises withdrawing the pump
assembly.
[0010] In another embodiment, there is a method for operating a
fluid delivery assembly having a pump chamber and a delivery
chamber by withdrawing a shaft from within the fluid delivery
assembly to simultaneously displace a moving pump element within
the delivery chamber and bypass fluid around a housing in the pump
chamber.
[0011] In one aspect, withdrawing a shaft from the pump assembly
introduces a delivery fluid into the delivery chamber and into
contact with the moving pump element. In another aspect, advancing
the moving pump element in the delivery chamber by applying an
electrical field across electrodes in the pump chamber and on
either side of the housing. Still another aspect provides
electrokineticly moving fluid in the pump chamber to dispense fluid
from the delivery chamber. In still another aspect includes
actuating a bypass in the shaft during the withdrawing step.
INCORPORATION BY REFERENCE
[0012] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The novel features of the invention are set forth with
particularity in the claims that follow. A better understanding of
the features and advantages of the present invention will be
obtained by reference to the following detailed description that
sets forth illustrative embodiments, in which the principles of the
invention are utilized, and the accompanying drawings of which:
[0014] FIG. 1 is section view of an exemplary pump system.
[0015] FIGS. 2A-2E illustrate details for the loading and delivery
of fluid using the pumping system 900.
[0016] FIGS. 3A-3E illustrate details for the loading and delivery
of fluid using the pumping system 1000.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIG. 1 will be described to provide an understanding of the
basic components and operation of a typical fluid delivery system.
FIG. 1 illustrates a cross section view of a fluid delivery system
1. The fluid delivery system has a first chamber 30, a second
chamber 32 and a third chamber 35. A flow through pump element 20
(such as electrokinetic pump, as shown in FIG. 1) separates the
first chamber 30 from the second chamber 32. A moveable pump
element 40 (such as a floating piston, as shown) separates the
second chamber 32 from the third chamber 35. While in this
illustrative embodiment the moveable element 40 is a floating
piston, any device that provides a moveable barrier may be used as
will be illustrated in the examples that follow. In this
embodiment, the first, the second and the third chambers are within
a single housing 15. Seals 42 are used to seal the moveable pump
element 40 as it moves within the housing 15. An outlet 45 provides
communication between the third chamber 35 and the exterior of
housing 15. An outlet 55 provides communication between the second
chamber 32 and the exterior of housing 15. In this embodiment, a
valve 60 separates the second outlet 55 from the exterior of
housing 15.
[0018] As illustrated, a conduit 71 connects the outlet 55 to the
opening 70. A valve 60 in the conduit 71 controls fluid flow from
the outlet 55 to the opening 70. The valve 60 has a disc 62, stem
64, a spring 66 and a disc or seal 68. Seats 72, 74 in the housing
are shaped to seal with, respectively, discs or seals 62, 68. Valve
60 is shown in the closed position where spring 66 holds discs 68,
62 in place against seats 72, 74. In this embodiment, conduit 71
and valve 60 are disposed in a wall of housing 15. Other
configurations are possible such as a separate valve assembly that
attaches directly to port 55 or a valve/conduit configuration that
ports through the pump element 20 rather than around the pump
element 20 as shown.
[0019] In the illustrated embodiment, the first chamber 30 contains
a moveable pump element 82 (i.e., a diaphragm adjacent the pump
element 20). The first chamber 30 also contains a vent 75, if
needed to ensure free movement of the moveable element 82. The
space between the diaphragm 82 and the pump element 20 contains a
buffer or pump fluid 80 that is selected to operate with the type
of pump element used. If the pump element 20 is an electrokinetic
pump, then the buffer 80 would be an electrolyte selected to
operate with the electrode and porous material materials and
desired operation of the pump. Examples of specific electrolytes
and other details of electrokinetic pumps are described in
co-pending and commonly assigned patent application serial numbers
U.S. application Ser. No. 10/198,223, filed Jul. 17, 2002 titled,
"Laminated Flow Devices"; U.S. application Ser. No. 10/273,723
filed Oct. 18, 2002 titled, "Electrokinetic Device Having
Capacitive Electrodes"; U.S. application Ser. No. 10/322,083 filed
Dec. 17, 2002 titled, "Electrokinetic Device Having Capacitive
Electrodes" and U.S. application Ser. No. 11/112,867 filed Apr. 21,
2005 titled, "Electrokinetic Delivery Systems, Devices and
Methods," each of which are incorporated herein by reference in its
entirety.
[0020] The pump element 20 is connected to supporting electronics 5
by electrical connectors 26. The supporting electronics 5 may be
altered depending upon the type of pump element(s) used but will
generally include a user control interface 6, electronic control
circuitry 8 and a power supply 10. The user control interface 6 may
be a touch screen or other input means to allow a user to operate
the delivery system, select a program or otherwise provide
programming instructions to the system. The electronic control
circuitry contains the programming instructions needed to translate
the user inputs into commands to operate the pump element. The
electronic control circuitry also regulates the power supply to
achieve user desired pumping characteristics such as flow rate and
delivery timing. The power supply 10 may be a battery or the
delivery system may be plugged into an electrical supply. The
supporting electronics are conventional and will be understood by
those of ordinary skill in the art.
[0021] An exploded view of one type of pump element 20 is shown in
FIG. 1. The pump element 20 shown in FIG. 1 is an electrokinetic
pump element. Electrokinetic pump element contains a porous
material 22 between two capacitive electrodes 24. One example of a
suitable porous material is a nanopore filter. The capacitive
electrodes are connected to the supporting electronics 5 by
electrical connectors 26. The pump element contains a pump fluid or
buffer 80 that is moved through the porous material 22 from one
electrode towards the other electrode depending on how a charge is
applied between the electrodes 24. The electrokinetic flow produced
by the pump element 20 may be in one direction (from one electrode
to the other electrode) or may alternate directions of flow
(towards one electrode and then away from that electrode and
towards the other electrode). Examples of electrokinetic pumps
configurations, electrolytes, electrodes, porous materials (also
referred to as porous dielectric materials) and other details of
are described in co-pending and commonly assigned patent
applications: U.S. application Ser. No. 10/198,223, filed Jul. 17,
2002 titled, "Laminated Flow Devices"; U.S. application Ser. No.
10/273,723 filed Oct. 18, 2002 titled, "Electrokinetic Device
Having Capacitive Electrodes"; U.S. application Ser. No. 10/322,083
filed Dec. 17, 2002 titled, "Electrokinetic Device Having
Capacitive Electrodes" and U.S. application Ser. No. 11/112,867
filed Apr. 21, 2005 titled, "Electrokinetic Delivery Systems,
Devices and Methods," each of which are incorporated herein by
reference in its entirety.
[0022] Optionally, a storage fluid 50 fills the second chamber. The
storage fluid 50 may be a fluid used to maintain the integrity of
the pump element 20 during storage or prior to operation. The
storage fluid 50 may be the same or different than the fluid 80
stored in the first chamber. The storage fluid 50 may also be a
pump fluid (i.e., such as electrolyte suited to operation in an
electrokinetic pump) moved by operation of the pump element 20. A
delivery fluid 36 is stored in the third chamber 35. In some
embodiments, the delivery fluid is a drug, a pharmacological or
therapeutic agent, or other substance to be delivered by operation
of the pump element 20. FIG. 1 also illustrates a conventional
syringe 90 is also illustrated having a body 91 with a tip 92. A
plunger 93 is attached to handle 95 by shaft 94 is disposed within
the body 91.
[0023] Pump system 1 provides one solution to loading the pump
system without the use of the pump element 20 by bypassing the pump
element. Additionally, the pump element 20 remains in a fixed
position within the pump housing during both filling and pumping
operations. The pump systems 900 and 1000 provide an alternative
apparatus and method for filling and delivering fluid. In contrast
to the fixed pump element fluid system 1, the pump element in pump
systems 900, 1000 moves within the pump housing during fluid
delivery operations. The pump element in fluid system 1000 also
moves during pump filling operations. These and other details of
the pump systems 900, 1000 are described below.
[0024] FIGS. 2A-D and FIGS. 3A-E illustrate pumping systems 900,
1000. Novel piston assemblies are at the heart of the systems. The
piston assemblies are designed to move within another pump
component to deliver fluid. Piston assembly 970 (illustrated in
FIG. 2B) and piston assembly 990 (illustrated in FIG. 3B) have
several common components. A piston head 972 is connected to a
housing 980 by a shaft 976. The housing 980 contains a porous
material 984 and a plurality of apertures 982 to allow fluid flow
through the housing 980 and the porous material 984. In one
embodiment, the porous material 984 is a dielectric material
adapted for operation as part of an electrokinetic pump. Examples
of porous dielectric materials described in the co-pending patent
applications described above. A sealing element or elements 974 are
provided around the perimeter of the piston head 972. The piston
head 972 is sealed within a delivery chamber that is separate from
the pump chamber (i.e., delivery chamber 910 in FIG. 2A) or
integrally formed with the pump chamber (i.e., delivery chamber
1010 in FIG. 3A). One or more sealing elements 978 is provided
around the perimeter of the housing 980. The housing 980 is sealed
within the pump chamber using sealing elements 978 as shown in
FIGS. 2A and 3A.
[0025] FIG. 2A illustrates a pump 900 that includes a delivery
chamber 910, a pump chamber or piston housing 950 and a wall 931
separating the pump chamber 950 from the delivery chamber 910. The
piston housing 950 is filled with a suitable electrolyte 80. A
piston assembly 970 has a piston head 972 in the delivery chamber
910 (i.e., outside of the pump housing 950), a housing 980 in the
piston housing or pump chamber 950 and a shaft 976 connecting the
piston head 972 to the housing 980. The shaft 976 passes through
the wall 931 separating the pump chamber 950 from the delivery
chamber 910. As shown in FIG. 2B, the housing 980 divides the
piston housing 950 into a first portion 950A and a second portion
950B. A pair of electrodes 924 are in the pump housing 950 where
there is one electrode 924 is on each side of the housing 980.
There is an electrode 924 in the first portion 950A and an
electrode 924 in the second portion 950B. In one embodiment, each
electrode in the pair of electrodes has a double layer capacitance
of more than 10.sup.-4 microfarad/cm.sup.2. A porous material 984
is contained inside of the housing 980 and in contact with the
electrolyte 80. The housing 980 has apertures 982 that provide
fluid communication between the first portion 950A and a second
portion 950B. The housing 980 is sealed within the piston housing
950 using sealing element 978.
[0026] The housing 910 includes an outlet 945 and an interior space
915. The interior space 915 is sized and shaped to sealingly
receive the piston head 972. The piston housing 950 is adapted for
pumping operations using the piston assembly 970. The housing 950
includes electrodes 924 positioned on either end of housing
interior. The piston assembly 970 is disposed within the housing
950 with shaft 976 extending through a sealed opening 943. The
housing 950 is inserted into the interior space 915 and the piston
972 is advanced against the interior 915 adjacent the outlet 945.
The pump system 900 is now ready for filling.
[0027] The pump system 900 is filled by attaching a vial 105 or
other suitable container to the outlet 1045 and then withdrawing
the piston housing 950 from the delivery interior 915 as indicated
by the arrow in FIG. 2C. The relative movement of the pump chamber
950 to the delivery chamber 910 draws the delivery fluid 36 from
vial 105 through the outlet 945 and into the interior 915 as shown
in FIG. 2C. Next, the vial 105 is removed and a delivery device,
such as an infusion set 96, is attached to outlet 945. An optional
purge or prime procedure is illustrated in FIG. 2D. Before
attachment of the delivery device, after attachment of the delivery
device or both before and after attachment of the delivery device
the system may be primed or purged of air by advancing the piston
housing 950 relative to the delivery chamber 910 as indicated by
the arrows in FIG. 2D.
[0028] Prior to commencement of pumping, the position of the piston
housing 950 is fixed relative to the delivery chamber 910. In one
embodiment, the housings 910, 950 are fixed when feature 912 on
delivery chamber 910 and feature 934 on chamber 950 are locked in
place using bars 492 and spaces 494 within the frame 490 as
illustrated in FIG. 2E.
[0029] Pumping begins when an electric field is applied across
electrodes 924. Application of an electric field across the
electrodes 924 moves electrolyte 80 in the pump chamber 950 from
one side of the housing 980 (i.e., the portion 950B) to the other
side of the housing (i.e. the portion 950A). In one embodiment, the
electrolyte 80 is moved electrokineticly through the apertures 982
and the porous material 984 from one electrode 924 towards the
other as indicated by the arrows in FIG. 2E. This movement of the
electrolyte decreases the volume of the portion 950B and increases
the volume of the portion 950A. Increasing volume of portion 950A
moves the housing 980 and the piston head 972 towards the outlet
945 which in turn expels delivery fluid 36 out through outlet
945.
[0030] Turning now to FIGS. 3A and 3B that illustrate the pumping
system 1000. The pumping system 1000 includes a delivery chamber
1010 and a pump chamber 1020 within a single housing (i.e., the
pump housing 1005). The delivery chamber 1010 has an outlet 1045
and a vent 1012. A vial 105 filled with a delivery fluid 36 is
attached to outlet 1045 and the pump system 1000 is ready for
filling. The piston assembly 990, illustrated in FIG. 3B, is
disposed within the pump housing 1005. The piston assembly 990 is
arranged within a piston housing or pump chamber 1020 filled with
an electrolyte 80. A housing 980 within the piston housing divides
the piston housing into a first portion 980A and a second portion
980B and maintained by seals 978. The housing 980 has apertures 982
that provide fluid communication between the first portion 980A and
the second portion 980B. The housing 980 contains a porous material
984 in communication with the electrolyte 80. The porous material
984 may be a porous dielectric material adapted for operation as
part of an electrokinetic pump. A pair of electrodes 1024 are
provided in the pump chamber 1020. One electrode 1024 is provided
on each side of the housing 980 (i.e., one electrode in the first
portion 980A and one electrode in the second portion 980B). In the
illustrated embodiment, the electrodes, dielectric material and
electrolyte are selected to provide electrokinetic movement of the
electrolyte within the pump chamber and through the housing 980. In
one embodiment, the electrodes are made of a material having a
double layer capacitance greater than 10.sup.-4
microfarads/cm.sup.2.
[0031] A shaft 976 connects the housing 980 to a moveable pump
element (here, a piston head 972) and a handle 994 outside of the
piston housing 1020. The shaft 976 may be a single piece as
illustrated or be formed of multiple pieces. An example of a
multiple piece shaft would be a first shaft connecting the housing
980 to the piston head 972 and a second shaft connecting the
housing 980 to the handle 994. Sealing elements 1018, 1028 maintain
the fluid integrity where the shaft passes through the pump chamber
walls via openings 1014, 1026. The piston assembly 990 also
includes a bypass feature not found in piston assembly 970. The
piston assembly 990 includes a valve 988 within the shaft 976 that
provides a fluid pathway from one side of the housing 980 (i.e.,
the first portion 980A) to the other side of the housing 980 (i.e.,
the second portion 980B) without passing the fluid through the
porous material 984. The valve 988 or fluid path through the shaft
976 provides a bypass through the porous material contained in the
housing without requiring operation of the electrodes or inducing
flow though the material 984. The valve 988 is actuatable from a
handle 994 attached to the housing 980. In the illustrated
embodiment, a button 996 located on the handle 994 is used to
depress the spring in 986, open valve 988 and to allow fluid flow
through the shaft 976 around the housing 980.
[0032] FIG. 3C illustrates a method of operating a fluid delivery
system 1000 having a pump chamber 1020 and a delivery chamber 1010.
Filling is performed by withdrawing the shaft 976 within the fluid
delivery assembly to simultaneously displace a moving pump element
within the pump chamber (i.e., the piston head 972) and bypass
fluid around the housing 980 in the pump chamber 1020 (as shown by
the arrows in pump chamber 1020). FIG. 3C also illustrates that the
button 996 in handle 994 is depressed (thereby opening the bypass
with valve 988) while the handle 994 is withdrawn. Once a vial 105
or other suitable container is attached to the outlet 1045,
withdrawing the shaft 976 from the pump assembly also introduces
the delivery fluid 36 into the delivery chamber 1010 and into
contact with the moveable pump element (i.e., the piston head 972).
When the button 996 is depressed the bypass valve 988 allows fluid
allows buffer 80 to pass from one side of the housing 980 to the
other side as illustrated by the arrows. Now that buffer 80 may
move freely within the pumping chamber 1020, the handle 994 is
withdrawn thereby withdrawing piston head 972 within the delivery
chamber 1010. This action draws delivery fluid 36 into the delivery
chamber the outlet 1045.
[0033] As shown in FIG. 3D, when the filling operation is complete,
the button 996 is released. When button 996 is released, action by
spring 986 forces the valve 988 closed thereby preventing further
passage of buffer 80 through the bypass valve as illustrated in
FIG. 3D. A delivery device is attached to the outlet 1045. In the
illustrated embodiment, the delivery device is an infusion set 96
having an outlet 1080.
[0034] Pumping begins with the application of an electric field
across the electrodes 1024 that moves the electrolyte 80 in the
pump chamber from one side of the housing 980 to the other as
indicated by the arrows inside chamber 1020. The movement of
electrolyte from portion 980B into 980A moves the housing 980 and
the piston head 972 towards the outlet 1045 by increasing the
volume of portion 980A while decreasing the volume of the portion
980B. In the illustrated configuration, when an electric field is
applied across electrodes 1024, electrolyte 80 is moved
electrokineticly through the apertures 982 and the porous material
984 from one electrode 924 towards the other electrode 1024 as
indicated by the arrows inside chamber 1020. As such, movement of
the buffer 80 through the apertures 982 moves the housing 980.
Movement of the housing 980 in turn advances the piston head 972 to
expel delivery fluid 36 out through outlet 1045 and delivery device
96.
[0035] The foregoing illustrative embodiments have used certain
terms to provide an explanation of the principal involved or
operation of the illustrated systems. It is to be appreciated that
numerous alternatives for components and elements are possible. For
example, the pump element and components in the pump chamber may
form an electrokinetic pump as described but may be reconfigured to
accommodate the use of diaphragm pumps, piston pumps, and
piezoelectric pumps. The supporting electronics 5 and electrical
connectors 26 would be modified as needed according to the type of
pump element and other components used. Additionally, many of the
illustrative configurations described the use of a movable pump
element such as piston head 972. It is to be appreciated that the
movable pump element may be a piston or a diaphragm and that both
may be used in a single system (i.e., as illustrated in FIG. 1).
The diaphragm may be a `rolling` type diaphragm. Rolling diaphragms
have a convolute that allows predictable travel of the diaphragm.
While a rolling diaphragm does have advantages, the invention is
not so limited and other types of diaphragms and moveable pump
elements may be used.
[0036] The process of drug aspirating and air purging has been
shortened in many of the illustrative descriptions. For
configurations describing filling the pump with delivery fluid, the
description simply indicates to pull back on a handle or pump
housing to drawn drug or delivery fluid in. Those of ordinary skill
will appreciate that this is an abbreviated instruction. Like any
drug aspiration process, trapped air is vented before the drug is
delivered. As such, the full process includes drawing drug in by
pulling back on the handle or housing, then while holding the unit
with the drug exit port at the top, flick the unit to release
bubbles, and then press the syringe handle in to purge air out of
the unit. The process is repeated if necessary until all visible
air is removed and the unit is filled with the desired amount of
drug. This process is identical to the typical method used by
medical practitioners to aspirate drug into syringes and purge
air.
[0037] A generic infusion set 96 is described and many of the pump
system embodiments are represented as connected to an infusion set.
While not illustrated in every embodiment, a similar configuration
of an infusion set connection or other suitable delivery device can
be inferred for all pump system embodiments. Alternatively, the
delivery fluid 36 or drug may be dispensed without an infusion set
such as, for example, when it is delivered directly into a canula
or elsewhere.
[0038] The use of liquid and/or air seals have been illustrated in
some embodiments. In some embodiments, those components requiring
seals (piston head 972, housing 980, etc.) have two o-ring seals
while in other embodiments only one o-ring seal shown. Two seals
are typically used in medical syringes and have thus been shown in
pairs on most of the pistons described herein. It is to be
appreciated that one or more o-rings may be used, however, or
alternate types of seals may be employed.
[0039] Any of the configurations may be partially filled with drug
or delivery fluid to any desired amount. Additionally, in some
embodiments, the portion of pump housing (i.e. delivery chambers
910, 1010) that stores the delivery fluid would be transparent and
graduated to allow visibility and amount of the delivery fluid 36
present. In addition, a transparent housing generally would also
allow visibility of any air that needs to be purged during the
filling process. Volumetric increment markings may also be
appropriately provided on the pump housing by printing, stamping,
embossing, painting or otherwise indicating the contents of the
delivery fluid 36 within a drug or delivery chamber.
[0040] One benefit of the pumping systems described herein is that
these systems provide indirect pumping of delivered liquids
regardless of the type of pump used for pump element 20 or pumping
configuration. The pump components are contained within piston
housing 950 or pump chamber 1020 and as the descriptions above make
clear, the delivery fluid 36 does not pass through any pump
mechanism and is actually separated from the pump components. As
such, the pump systems described herein can be reused without
concern of contamination of a deliverable fluid via contact with
previously contacted surfaces of the pump mechanism (e.g. interior
of pump, piston pump, etc.) by previously used delivery fluids.
Another advantage is the decreased likelihood of damage to fluids
that are susceptible to mechanical and/or chemical degradation such
as long chain protein molecules and peptides. Mechanical actions
including compression, shearing, and extrusion, as well as exposure
to electrical currents can cause molecular level damage to some
fluids. By obviating the need for the fluids to pass through the
pump mechanism, concern over pumping damage to these compounds is
diminished.
[0041] The term buffer has been used throughout the description.
Buffer refers to any suitable working fluid that may be used by a
particular pumping system. In many pumping system embodiments, the
buffer or working fluid is any fluid having a viscosity low enough
to be pumped through the pump element. In those embodiments where
the pump element is an electrokinetic pump, working fluid is an
electrolyte suited to the specific electrodes and dielectric
material used by the electrokinetic pump. In one specific
embodiment, the electrolyte is a buffered electrolyte. One buffered
electrolyte is Tris Sorbate (sp?). [DEON: Please confirm. Are there
other specific electrolytes or pump fluids or suitable working
fluids or storage fluids for pumps generally and EK pumps
specifically?]
[0042] The term delivery fluid has been used throughout the
description. In many pumping system embodiments, the delivery fluid
is any fluid having a viscosity low enough to be pumped through
action of the pump element. In some embodiments, the delivery fluid
is a pharmacological agent. In other embodiments, the delivery
fluid is a therapeutic agent. In still other embodiments, the
delivery fluid is a saline solution or Ringers solution.
[0043] While numerous embodiments of the present invention have
been shown and described herein, one of ordinary skill in the art
will appreciate that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
invention. In addition, the intended uses of the present invention
include a variety of medical applications as well as other
applications where highly precise, compact devices for fluid
transport are needed. It should be understood that various
alternatives to these embodiments of the invention described herein
may be employed in practicing the invention. It is intended at the
following claims defined the scope of the invention and it methods
and structures within the scope of these claims and their
equivalents be covered thereby.
* * * * *