U.S. patent application number 12/190132 was filed with the patent office on 2010-02-18 for volumetric infusion pump and method.
Invention is credited to Anis Rahman.
Application Number | 20100040490 12/190132 |
Document ID | / |
Family ID | 41681382 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100040490 |
Kind Code |
A1 |
Rahman; Anis |
February 18, 2010 |
Volumetric Infusion Pump and Method
Abstract
In a first embodiment, an electromagnetic pump has a housing
including first and second spaced apart electromagnets. A
controller for controlling the magnets and a power source for
powering the electromagnets within the housing. A removable
cassette is in engagement with the housing between the first and
second electromagnets and includes a cavity. The pump also has
inlet and outlet ports in communication with the cavity and a
magnetic piston disposed within the cavity. In preferred
embodiments the electromagnets are capable of operating at
different strengths and different polarities.
Inventors: |
Rahman; Anis; (Kenosha,
WI) |
Correspondence
Address: |
JANSSON SHUPE & MUNGER LTD.
245 MAIN STREET
RACINE
WI
53403
US
|
Family ID: |
41681382 |
Appl. No.: |
12/190132 |
Filed: |
August 12, 2008 |
Current U.S.
Class: |
417/415 |
Current CPC
Class: |
F05C 2251/12 20130101;
F04B 35/045 20130101; F04B 35/06 20130101; F04B 53/14 20130101 |
Class at
Publication: |
417/415 |
International
Class: |
F04B 35/00 20060101
F04B035/00 |
Claims
1. A electromagnetic pump comprising: a housing including first and
second spaced apart electromagnets; a controller for controlling
the magnets within the housing; a power source for powering the
electromagnets within the housing; a cassette in engagement with
the housing between the first and second electromagnets and
including a cavity; an inlet port in communication with the cavity;
an outlet port in communication with the cavity; and a magnetic
piston disposed within the cavity.
2. The electromagnetic pump of claim 1 wherein the cassette is
removable.
3. The electromagnetic pump of claim 1 wherein the piston is
movable between a first open position and a second closed
position.
4. The electromagnetic pump of claim 3 wherein the inlet port is
part of the removable cassette.
5. The electromagnetic pump of claim 4 wherein the outlet port is
part of the removable cassette.
6. The electromagnetic pump of claim 5 wherein the magnetic piston
includes a piston body and a Neodymium magnet.
7. The electromagnetic pump of claim 5 wherein the cavity is on a
first side of the piston and the piston includes an extension
defining a passage on a second side of the piston, the cassette
further including a sterile vent in communication with the
passage.
8. The electromagnetic pump of claim 5 wherein the cassette further
includes a flexible barrier disposed within the cavity.
9. The electromagnetic pump of claim 5 wherein the inlet port
includes a one-way flapper valve.
10. The electromagnetic pump of claim 9 wherein the outlet port
includes a one-way flapper valve.
11. The electromagnetic pump of claim 1 wherein the electromagnets
are capable of operating at different strengths and different
polarities.
12. The electromagnetic pump of claim 3 further comprising a first
sensing device capable of detecting when the piston is in the
closed position.
13. The electromagnetic pump of claim 12 further comprising a
second sensing device capable of detecting when the piston is in
the open position.
14. The electromagnetic pump of claim 13 wherein the first and
second sensing devices are LED sensors and the cassette is capable
of reflecting light from the LED sensors back to the LED
sensors.
15. The electromagnetic pump of claim 3 wherein the default
position of the piston is in the closed position.
16. A method of dispensing a liquid, the method comprising the
steps of: providing an electromagnetic pump including; a housing
including first and second spaced apart electromagnets, a
controller for controlling the magnets within the housing, a power
source for powering the electromagnets within the housing, a
cassette in engagement with the housing between the first and
second electromagnets and including a cavity, an inlet port in
communication with the cavity, an outlet port in communication with
the cavity, a magnetic piston disposed within the cavity; supplying
a liquid to be dispensed to the inlet port; powering the
electromagnets to draw the piston into an open position thereby
drawing the liquid through the inlet port and into the cavity; and
powering the electromagnets to draw the piston into a closed
position thereby pushing the liquid out of the cavity and through
the outlet port.
17. The method of claim 16 further including the step of providing
free-flow protection against liquid flowing back through the inlet
port.
18. The method of claim 17 wherein the free-flow protection is
provided by the controller controlling the piston to default to the
closed position.
19. The method of claim 16 further including the step of sensing
the position of the piston within the cavity.
20. The method of claim 19 where the housing includes a sensor for
reading the location of the piston.
21. The method of claim 20 wherein the sensor is an LED.
22. The method of claim 18 further including the step of
calculating the volume of liquid delivered via movement of the
piston.
23. The method of claim 22 wherein after the step of powering the
second electromagnet to draw the piston into a second position
thereby pushing the liquid out of the cavity and through the outlet
port, the second electromagnet is depowered, thereby allowing a
cycle of powering the first electromagnet, depowering the first
electromagnet, and powering the second electromagnet is capable of
being repeated plurality of times, the method further including the
step of: calculating the total volume of liquid delivered via the
plurality of cycles.
24. The method of claim 23 wherein the steps of calculating are
performed by the controller.
25. The method of claim 16 wherein the cassette is removeable.
26. The method of claim 25 further including the step of sensing
for the presence of the removable cassette in the pump.
27. The method of claim 23 wherein the movement of the piston
between the open and closed positions is at a velocity, the method
further comprising the step of varying the velocity of the piston
to control a rate of delivery.
28. The method of claim 27 wherein the velocity is varied by
comparing a required delivery rate to an actual delivery rate where
the actual delivery rate is determined by sensing the position of
the piston within the cavity.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to the field of medial
devices and more particularly to a portable self-contained medical
pump capable of delivering precise doses.
BACKGROUND
[0002] The field of medical pumps has seen many improvements over
the years, with numerous designs for specific types of uses.
Examples includes pumps for the delivery of insulin, artificial
heart pumps and many non-specific pump designs. Some of these
designs incorporate electromagnets to produce the pump effect or
utilize a removable medicine camber.
[0003] For example, U.S. Pat. No. 4,786,240 to Koroly et al.
discloses a two chamber pump that utilizes an electromagnet within
the chamber. Permanent magnets are placed at either ends of a
chamber and an electromagnet is embedded within a flexible septum
in the chamber. The polarity of the electromagnet is flipped thus
alternately moving the electromagnet between the two permanent
magnets, thus pumping fluid into and out of either side of the two
pumping chambers created by the septum.
[0004] Another prior pump design is disclosed in U.S. Pat. No.
4,915,017 to Perlov. In this design diaphragms of various
flexibility are utilized to create multi-chamber pumps. In some
versions of the disclosed pump magnetic coils are utilized, along
with a magnet in the diaphragm to count the number of time the pump
has cycled and thus track the total flow of fluid through the
pump.
[0005] In a third design, an electromagnetic pump is disclosed in
U.S. Pat. No. 5,607,292 to Rao. In this design a single
electromagnet is used in conjunction with elastromeric spring seals
to pump fluid in and out of a chamber.
[0006] A final prior art pump design is disclosed in U.S. Pat. No.
7,377,907 to Shekalim. In this design a complex labyrinth is
utilized to regulate flow from the pump and includes a removable
cartridge to house the labyrinth and a fluid reservoir for the
fluid to be delivered by the pump.
SUMMARY
[0007] In a first embodiment, an electromagnetic pump has a housing
including first and second spaced apart electromagnets. A
controller for controlling the magnets and a power source for
powering the electromagnets within the housing. A removable
cassette is in engagement with the housing between the first and
second electromagnets and includes a cavity. The pump also has
inlet and outlet ports in communication with the cavity and a
magnetic piston disposed within the cavity. In preferred
embodiments the electromagnets are capable of operating at
different strengths and different polarities.
[0008] In some other embodiments, the piston is movable between a
first open position and a second closed position. Also, the inlet
and outlet ports may be part of the removable cassette. The inlet
and outlet ports can take any form known in the art but it is
preferred that the ports are one-way flapper valves.
[0009] In another embodiment the magnetic piston includes a piston
body and a Neodymium magnet. Furthermore, the cavity may be on a
first side of the piston and the piston includes an extension
defining a passage on a second side of the piston. In such an
embodiment the cassette would further include a sterile vent in
communication with the passage. In further embodiments the cassette
further includes a flexible barrier disposed within the cavity.
[0010] In yet other embodiments the electromagnetic pump further
includes a first sensing device capable of detecting when the
piston is in the closed position. It is preferred that the pump
also include a second sensing device capable of detecting when the
piston is in the open position. It is highly preferred that the
first and second sensing devices are LED sensors and the cassette
is capable of reflecting light from the LED sensors back to the LED
sensors.
[0011] In highly preferred embodiments the default position of the
piston is in the closed position.
[0012] In other embodiments a method of dispensing a liquid is
disclosed. The method includes the step of providing an
electromagnetic pump. The pump includes a housing including first
and second spaced apart electromagnets, a controller for
controlling the magnets within the housing, a power source for
powering the electromagnets within the housing, a cassette in
engagement with the housing between the first and second
electromagnets and including a cavity, inlet and outlet ports in
communication with the cavity and a magnetic piston disposed within
the cavity. Next a liquid to be dispensed is supplied to the inlet
port and the first electromagnet is powered to draw the piston into
an open position thereby drawing the liquid through the inlet port
and into the cavity. The first electromagnet is depowered and the
second electromagnet is powered to draw the piston into a closed
position thereby pushing the liquid out of the cavity and through
the outlet port. In the current invention the concept of depowering
the magnet includes, but is not limited to, two different
operations. The first operation of depowering is removing the
charge from the electromagnet in question thus allowing the pull
from the opposite electromagnet to work on piston independently.
Alternatively, the operation described as depowering is to reverse
the polarity of the electromagnet thus pushing the piston if the
electromagnet had been pulling it.
[0013] In another embodiment of the method, the method further
includes the step of providing free-flow protection against liquid
flowing back through the inlet port. It is preferred that the
free-flow protection is provided via a one-way flapper valve. In
addition, or separately free-flow protection can also be provided
by the controller controlling the piston to default to the closed
position.
[0014] In still further embodiments, the method also includes the
step of sensing the position of the piston within the cavity. It is
preferred that this step is accomplished by the housing including a
sensor for reading the location of the piston. It is highly
preferred that the sensor is an LED.
[0015] In other embodiments, the method further includes the step
of calculating the volume of liquid delivered via movement of the
piston. Preferably, after the step of powering the second
electromagnet to draw the piston into a second position thereby
pushing the liquid out of the cavity and through the outlet port,
the second electromagnet is depowered, thereby allowing a cycle of
powering the first electromagnet, depowering the first
electromagnet, and powering the second electromagnet is capable of
being repeated plurality of times. In such an embodiment the method
further includes the step of calculating the total volume of liquid
delivered via the plurality of cycles. It is highly preferred that
the steps of calculating are performed by the controller.
[0016] In other preferred embodiments the cassette is removable. In
such an embodiment, it is highly preferred that the method further
include the step of sensing for the presence of the removable
cassette in the pump.
[0017] Also, wherein the movement of the piston between the open
and closed positions is at a velocity, it is preferred that the
method further include the step of varying the velocity of the
piston to control a rate of deliver. The method further includes
varying the dwell time between depowering the first electromagnet
and powering the second electromagnet to control the rate of
delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a front view of a preferred embodiment of an
electromagnetic pump;
[0019] FIG. 2 is a perspective view of the pump housing of FIG. 1
in the open position;
[0020] FIG. 3 is an exploded view of the cassette of FIG. 1;
[0021] FIG. 4 is a perspective view of the cylinder of FIG. 3;
[0022] FIG. 5 is a perspective view of the bottom of the cassette
cap of FIG. 1;
[0023] FIG. 6 is a side view of the barrier of FIG. 3;
[0024] FIG. 7 is a perspective view of the piston of FIG. 3;
[0025] FIG. 8 is a perspective view of the valve assembly of FIG.
3;
[0026] FIG. 9 is a perspective view of the main body of the valve
assembly of FIG. 3;
[0027] FIG. 10 is a cutaway view of the cassette of FIG. 1 in the
open position; and
[0028] FIG. 11 is a cutaway view of the cassette of FIG. 1 in the
closed position.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Referring now to FIGS. 1 and 2, a preferred embodiment of an
electromagnetic pump 10 is shown. The pump 10 includes a housing 12
and a removable cassette 14. The housing 12 includes an upper
portion 16 and a lower portion 18 and has a top 20, a bottom 22,
and a front 24. At the top 20 of the housing 12 two magnet sections
26 are formed with a cassette space 28 formed between. The housing
12 is preferably made of plastic to keep weight at a minimum since
this preferred embodiment is designed to be worn by the user. The
cassette space 28 is bounded by the magnet sections 26 on the sides
and a cassette receiving surface 30 on the bottom. The cassette 14
fits into the cassette space 28 and is held in place via a detent
mechanism. However, any means of holding the cassette 14 in place
could be utilized.
[0030] The front 24 of the housing 12 includes an LCD display 32
for display of information related to dosage to the user. The
housing 12 shown varies between open and closed positions by the
upper housing 16 and lower housing 18 being pivotally joined at the
magnet sections 26. However, in other embodiments the upper and
lower housings 16, 18 could be joined at the side or any other
known manner. In yet other embodiments the housings could be
separate but lock together to from a housing.
[0031] Referring now to FIG. 2, internally, the housing 12 includes
a controller 34 mounted to the upper housing 16 and connected to
the LCD display 32. The housing 12 further includes two variable
power electromagnets 36 housed in the magnet sections 26 of the
lower housing 18 which are controlled by the controller 34. For
example a dipole custom electromagnet made by BOMAG company may be
utilized. These electromagnets 36 thus have the ability to project
stronger or weaker electromagnet fields based on power supplied to
them. Two LED emitters/sensors 38a and 38b are also disposed within
the housing 12 and controlled by the controller 36. The LED
emitters/sensors 38a and 38b are positioned to be in alignment with
the upper and lower positions of the piston of the cassette 14
respectively, which will be discussed in greater detail below. The
LED emitters/sensors 38 are capable of emitting a light and
detecting if the light is being reflected back or not. Because the
LEDs 38 emit light into the cassette 14 the cassette receiving
surface 30 of the housing 12 maybe clear to allow passage of the
light or may incorporate holes for positioning of the LEDs 38.
However in other embodiments infrared emitters could be utilized
thus eliminating the need for transparency. LEDs 38, controller 34,
electromagnets 36 and LCD display 32 all draw power from
rechargeable battery pack 39 held within the lower housing 18.
However other power supply setups could be utilized, for example,
in some embodiments, the controller 34 could include a button cell
lithium battery to power the LCD without draining the main battery.
In yet other embodiments the device could be AC powered and/or DC
powered primarily but AC powered during the recharging process.
[0032] Referring now to FIGS. 3-9 the cassette 14 of the pump 10 is
shown in detail. The cassette 14 includes a cylinder 40, a top cap
42 and a bottom cap 44. The cylinder 40 is preferably of a clear
plastic and has open top and bottom portions and defines an
interior cavity 46. The cylinder 40 may also include an upper
reflector 41 and a lower reflector 43. These reflectors are aligned
opposite the LEDs 38a and 38b. The bottom cap 44 encloses the
bottom of the cylinder 40 and is a sterile vent, made of a material
such as expanded polytetrafluoroethylene (ePTFE) supported by an
outer plastic ring.
[0033] Referring specifically to FIGS. 3, 5, 10 and 11 the top cap
42 is shown. The top cap 42 encloses the top of the cylinder 40 and
is preferably made of plastic. The top cap 42 is circular and
includes a top portion 48 and a lower portion 50. The top potion 48
includes an inlet connection 52 and an outlet connection 54. These
connections 52, 54 define passages to corresponding inlet port 56
and outlet port 58 on the lower portion 50 of the top cap 42. The
lower portion 50 also defines a valve recess 59. The top cap 42
also includes a cutout 60 along a ridge 62 around the lower portion
50. The cutout 60 allows light from the LED to pass into the cavity
46.
[0034] Referring again to FIGS. 3-9 the cassette 14 further
includes a valve assembly 62, a barrier 64, a magnet 66, and a
piston 68. The valve assembly includes a main body 70 which is
sized to fit within the valve recess 59 of the top cap 42 and acts
as a seal to separate the inlet port 56 and outlet port 58 from the
cavity 46. The main body 70 defines two port openings 72 and two
valve openings 74. A port opening 72 is aligned with each of the
inlet port 56 and outlet port 58 when the valve assembly 62 is in
place in the top cap 42. A one-way valve 76 covers each port
opening 72. The valve 76 over the inlet port 56 opens into the
cavity 46 and the valve 76 over the outlet port 58 opens into the
top cap 42. Each valve 76 includes a base 80 connected to via a
living hinge 82 to a flap 84. The valve 76 is attached to the main
body 70 by a t-shaped extension 86 through the valve opening 74.
The valves 76 are preferably made of a molded silicone
material.
[0035] The barrier 64, magnet 66 and piston 68 are positioned
within the cavity 46. Referring now to FIGS. 6, 10 and 11, the
barrier 64 defines the inner cavity 88 or fluid area of the pump 10
which is in communication with the inlet port 56 and outlet port 58
via the valve assembly 62. The barrier 64 is preferably of a molded
silicone material and includes an upper seal 90 and a cylinder
portion 92 and a connecting ridge 94. The upper seal 90 includes an
L-shaped extension 91 from the top of the barrier 64 that wraps
around the top of the cylinder 40 and is held in place via any
known methods. For example, if the cylinder 40 is made of plastic
the barrier 64 may be held in place via ultrasonic welding.
Alternatively, if the cylinder 40 is made of glass the barrier 64
may be adhesively attached to the top cap 42 and cylinder 40. The
connecting ridge 94 is in contact with the magnet 66. The magnet 66
is circular and is a strong permanent magnet such as a D81-N50
Neodymium magnet from K&J Magnetics. Finally, the piston 68
includes an upper surface 96 which includes a circular seal 98
around a recess 100. The magnet 66 fits within the recess 100 and
the connecting ridge 94 is in sealing contact with the seal 98. The
piston 68 also defines an open interior opposite upper surface
96.
[0036] Referring now to FIGS. 10 and 11, the magnet 66 is primarily
in one of two positions: an open position (FIG. 10) where the
piston 68 is in contact with the bottom cap 44 and a closed
position (FIG. 11) where the piston 68 (along with the magnet 66)
compresses the barrier 64 toward the top of the cassette 14. This
closed position is the default position for the magnet 66 whereby
the inner cavity 88 is compressed closed and fluid cannot flow
(even in the event of a valve failure) from the inlet port 56 to
the outlet port 58.
[0037] In operation, a cassette 14 is inserted into the pump 10.
The LEDs 38 then detect the presence of the cassette 14 because of
the reflection of light from the reflectors 41, 43 back to the LEDs
38. The inlet connection 52 is connected to a source of
fluid/medicine to be delivered and the outlet connection 54 is
connected to the patient for delivery. The controller 34 sends a
first control signal to the electromagnets 36 which in turn are
powered to move the magnet 66 from the default closed position to
the open position. When the magnet 66 is moved fluid is drawn from
the inlet port 56 through the valve 76 and into the inner cavity
88. The magnets 36 are powered until the LED 38b recognizes that
the magnet has moved as far to the bottom of the cavity 46 as it
can by the reflection from the reflector 43 being cut off. When the
magnet 66 has moved as far as possible (into the open position),
the inner cavity 88 then contains a known amount of fluid since the
volume of the inner cavity 88 is known.
[0038] The controller then sends a second control signal to the
electromagnets 36, which powers the electromagnets 36 to reverse
the polarity thus pushing the magnet 66 toward the closed position.
As the magnet 66 moves toward the closed position fluid is pushed
out of the inner cavity 88 and through the outlet port 58 and its
corresponding valve 76. Once the magnet reaches the closed position
and activates (i.e. cut off the reflection from the reflector 41)
the corresponding LED 38a the controller 34 can calculate the
amount of time it took to move the magnet 66 from the open position
to the closed position. This amount of time can then be compared to
an expected amount of time for such movement. The amount of time
could vary based upon the viscosity of the fluid being delivered.
If the time is longer than expected, the controller 34 can utilize
more power in the next cycle (a cycle being from closed position to
open position to closed position) to speed up delivery to reach a
desired or preset delivery rate. This allows a high level of
delivery accuracy. This pumps' delivery accuracy is also increased
in that the pump can track the number of cycles and calculate the
total delivery of fluid along with tracking the rate, this
information can then be utilized to increase or decrease the pump
rate accordingly.
[0039] While the principles of the invention have been shown and
described in connection with specific embodiments, it is to be
understood that such embodiments are by way of example and are not
limiting.
* * * * *