U.S. patent application number 15/807940 was filed with the patent office on 2018-03-08 for device and method for dispensing fluid from an infusion pump.
The applicant listed for this patent is Trividia Healthcare Systems, LLC. Invention is credited to Edward D. Arguello, Alexandre A.N. Baptista, Patrick J. Paul.
Application Number | 20180064869 15/807940 |
Document ID | / |
Family ID | 48914410 |
Filed Date | 2018-03-08 |
United States Patent
Application |
20180064869 |
Kind Code |
A1 |
Paul; Patrick J. ; et
al. |
March 8, 2018 |
Device and Method for Dispensing Fluid from an Infusion Pump
Abstract
The present disclosure is directed towards a compact, modular
infusion pump and a delivery mechanism for accurate dispensing of
very small amounts of medication. The infusion pump comprises a
tubular, curved medication reservoir, and a flexible, one-piece
drive train configured to push very small amounts of medication out
of the medication reservoir. A method of measuring a level of
medication inside the medication reservoir or cross-checking the
accuracy of medication delivery is also described.
Inventors: |
Paul; Patrick J.; (Fort
Lauderdale, FL) ; Arguello; Edward D.; (Weston,
FL) ; Baptista; Alexandre A.N.; (Plantation,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Trividia Healthcare Systems, LLC |
Fort Lauderdale |
FL |
US |
|
|
Family ID: |
48914410 |
Appl. No.: |
15/807940 |
Filed: |
November 9, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13934793 |
Jul 3, 2013 |
9839745 |
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15807940 |
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61677624 |
Jul 31, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 5/16831 20130101;
A61M 5/31511 20130101; A61M 2005/31518 20130101; A61M 5/14248
20130101; G01F 23/22 20130101 |
International
Class: |
A61M 5/142 20060101
A61M005/142; G01F 23/22 20060101 G01F023/22; A61M 5/168 20060101
A61M005/168; A61M 5/315 20060101 A61M005/315 |
Claims
1. A modular infusion pump for dispensing a fluid, comprising: a
reservoir module, comprising: a tubular, curved reservoir
containing the fluid, the curved reservoir having a proximal end
and a distal end, and a flexible drive train configured to slidably
fit within the curved reservoir and to expel the fluid through the
proximal end of the reservoir; and a control module comprising an
actuation mechanism for driving the drive train through the
reservoir, and electronic circuitry for measuring the level of
medication inside the reservoir.
2. The modular infusion pump of claim 1, wherein the reservoir
module comprises a medication output port fluidly coupled to the
proximal end of the reservoir.
3. The modular infusion pump of claim 2, further comprising a
cradle configured to mate with the medication output port of the
reservoir module.
4. The modular infusion pump of claim 2, wherein the medication
output port is configured to connect interchangeably with a cradle
configured to adhere direct to a patient's skin, or an infusion set
comprising a medication delivery tubing.
5. The modular infusion pump of claim 1, wherein the reservoir
module comprises a hydrophobic vent configured to equalize pressure
inside and outside the reservoir module.
6. The modular infusion pump of claim 1, wherein the reservoir
module further comprises a feeder track having a continuous, curved
wall structure configured to guide the drive train.
7. The modular infusion pump of claim 1, further comprising a
locking mechanism configured to mate the reservoir module with the
control module.
8. The modular infusion pump of claim 1, wherein the actuation
mechanism includes an electric motor, a drive shaft, and a lead
screw, wherein the lead screw is configured to mechanically engage
the drive train when the reservoir module is connected to the
control module.
9. The modular infusion pump of claim 1, further comprising
parallel resistive traces on an underside of a lid covering the
reservoir module such that the cursor is configured to provide a
moving electrical short between the parallel resistive traces.
10. The modular infusion pump of claim 9, wherein the electronic
circuitry is configured to measure a voltage signal across the
parallel resistive traces.
11. An infusion pump for delivering medication to a user, the pump
comprising: a reservoir module including a tubular medication
reservoir having a curved configuration, the medication reservoir
comprising a medication delivery outlet at a proximal end; a
flexible, and continuous drive train comprising: a plunger at a
proximal end of the drive train, a cursor at a distal end of the
drive train, a flexible filament extending between the cursor and
the plunger, and a plurality of balls positioned along and
connected by the filament between the plunger and the cursor; and a
control module including an actuation device configured to drive
the drive train through the medication reservoir.
12. The infusion pump of claim 11, wherein the medication reservoir
has at least one straight section.
13. The infusion pump of claim 11, wherein the medication reservoir
is curved throughout a length of the reservoir.
14. The infusion pump of claim 11, wherein the cursor is configured
to indicate the position of the drive train within the medication
reservoir.
15. The infusion pump of claim 11, wherein the actuation device
comprises an electric motor that is mechanically coupled to a motor
shaft encoder configured to sense rotation of the electric
motor.
16. The infusion pump of claim 15, wherein an output shaft of the
electric motor is mechanically coupled to at least one gear that is
mechanically coupled to a drive shaft.
17. The infusion pump of claim 16, wherein the drive shaft is
further coupled to a force sensor configured to sense lateral
forces generated by rotation of the drive shaft.
18. The infusion pump of claim 16, wherein the drive shaft is
adapted to mount a lead screw configured to mechanically engage the
drive train, and wherein the drive shaft is configured to enable
the lead screw to slide on the drive shaft axially and to rotate
with the drive shaft.
19. A method of delivering very small amounts of medication from an
infusion pump, comprising: providing tubular medication reservoir
having a medication delivery outlet at a proximal end thereof,
wherein the medication reservoir is adapted to be mounted within
the infusion pump in a curved configuration; providing a flexible,
continuous drive train connected to a plunger at a proximal end
thereof, mounting the medication reservoir in a curved
configuration on the infusion pump; and mounting the drive train in
a curved configuration on the infusion pump.
20. A method of measuring level of medication inside a medication
reservoir of an insulin pump or cross-checking the accuracy of
medication delivery, comprising: providing a modular insulin pump,
comprising: a reservoir module comprising: a tubular, curved
medication reservoir; a flexible, one-piece drive train configured
to slidably fit within the medication reservoir; and a feeder track
to guide the drive train within the reservoir module; and a control
module comprising an actuating mechanism for driving the drive
train through the medication reservoir and electronic circuitry for
measuring the level of medication inside the medication reservoir;
providing parallel resistive traces on the underside of a lid
covering the reservoir module; providing a plunger at a proximal
end and a cursor at a distal end of the drive train, wherein the
cursor is configured to provide a moving electrical short between
the parallel resistive traces; and measuring a voltage signal
across the parallel resistive traces.
Description
RELATED APPLICATIONS
[0001] This application is a continuation patent application of
U.S. patent application Ser. No. 13/934,793, filed on Jul. 3, 2013,
which claims priority to and the benefit of U.S. Provisional
Application No. 61/677,624, filed Jul. 31, 2012, each of which are
incorporated herein by reference in their entireties.
FIELD
[0002] This invention relates to the field of medical infusion
pumps, and in particular, to a system and method for accurate
delivery of very small amounts of fluidic medication from an
infusion pump.
BACKGROUND
[0003] An infusion pump, such as a patch-type infusion pump or a
traditional portable infusion pump, represents an active drug
delivery system, usually having a fluidic reservoir, an onboard
energy source, a pump, a delivery cannula, and a control unit all
integrated into a single device. Patch pumps in particular are
configured to be either entirely disposable or semi-disposable
where parts such as the drug reservoir can be detached and replaced
when empty. More characteristically, patch pumps differ from
earlier portable infusion pumps in that they do not have any
external tubes (infusion sets) and they attach directly to the skin
and deliver drugs transdermally or subcutaneously via a cannula.
Most infusion pumps also have wireless communications capability,
allowing them to communicate wirelessly with a remote controller
used for setting rates, delivering boluses, tracking delivery, etc.
Some infusion pumps are completely self-contained and have a
control capability built into the device. Infusion pumps are
designed for basal and bolus drug doses set at fixed and variable
rates. Infusion pumps, and in particular the patch-type infusion
pumps, can be used as wearable drug delivery devices for continuous
delivery of medication at various rates or volumes. For example,
infusion pumps can be used for round-the-clock insulin delivery for
diabetes management. There are profound performance and design
challenges involved in developing a successful infusion pump
configuration for continuous drug delivery regimens. For pediatric
use in particular, infusion pump systems for continuous drug
administration must have precise control over the amount of drug
delivered and the rate of delivery at any time, in addition to
their miniature size. Further, an infusion pump must be as
unobtrusive to the wearer as possible, and preferably also be
inconspicuous to others. Compact, ergonomic form factors, while
desirable from a wearer lifestyle perspective, cannot compromise
delivery control. Precise control is all the more challenging to
achieve in a compact form factor when delivery rates are very
small, as is typical in the case of basal insulin delivery.
SUMMARY
[0004] The present disclosure is directed towards a compact,
modular infusion pump and a delivery mechanism for accurate
dispensing of very small amounts of medication. The devices and
methods of the present disclosure can be employed with all types of
infusion pumps, including, but not limited to, patch-type infusion
pumps.
[0005] An exemplary embodiment of the present disclosure is a
modular infusion pump for dispensing a fluid, the pump comprising a
reservoir module and a control module. The reservoir module
comprises a curved reservoir containing the fluid, the curved
reservoir having a proximal end and a distal end, and a flexible
drive train configured to slidably fit within the curved reservoir
and to expel the fluid through the proximal end of the reservoir.
The control module comprises an electric motor, a drive shaft, and
a lead screw, wherein the lead screw is configured to mechanically
engage the drive train when the reservoir module is coupled to the
control module.
[0006] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0007] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description, serve to explain
the principles of the various aspects of the invention.
[0008] FIG. 1 illustrates a prior art syringe-type reservoir having
a rigid, rectilinear plunger rod;
[0009] FIG. 2 illustrates a long, curved medication reservoir for
use in a patch pump, in accordance with exemplary embodiments of
the present disclosure;
[0010] FIG. 3A illustrates a flexible plunger rod comprising a
drive train having an assembly of interconnected ball segments, in
accordance with exemplary embodiments of the present
disclosure:
[0011] FIG. 3B illustrates a close-up view of a plunger at the
proximal end of the drive train embodiment depicted in FIG. 3A:
[0012] FIGS. 4A-4C illustrate a sequential method of filling a
reservoir with medication, in accordance with exemplary embodiments
of the present disclosure:
[0013] FIG. 5 illustrates a cross-sectional top view of the drive
train embodiment depicted in FIG. 3A;
[0014] FIG. 6A illustrates an alternative drive train having an
assembly of interconnected ball segments, in accordance with
exemplary embodiments of the present disclosure;
[0015] FIG. 6B illustrates a close-up view of a ball segment of the
drive train embodiment depicted in FIG. 6A;
[0016] FIG. 7A illustrates another alternative drive train having
an assembly of interconnected ball segments, in accordance with
exemplary embodiments of the present disclosure;
[0017] FIG. 7B illustrates a top view of a ball segment of the
drive train embodiment depicted in FIG. 7A;
[0018] FIG. 8A illustrates a single-piece drive train, in
accordance with exemplary embodiments of the present
disclosure:
[0019] FIG. 8B illustrates a close-up view of the single-piece
drive train embodiment depicted in FIG. 8A along with the lead
screw component driving the drive train;
[0020] FIG. 9A illustrates a different configuration of centering
elements for the single-piece drive train embodiment depicted in
FIG. 8A;
[0021] FIG. 9B illustrates the single-piece drive train embodiment
depicted in FIG. 9A as positioned within an exemplary curved
reservoir;
[0022] FIG. 10A illustrates a modular infusion pump, in accordance
with exemplary embodiments of the present disclosure;
[0023] FIG. 10B illustrates an exploded view of the infusion pump
embodiment depicted in FIG. 10A;
[0024] FIG. 11 illustrates the underside of the control module of
the infusion pump embodiment depicted in FIGS. 10A and 10B;
[0025] FIG. 12 illustrates a top-view of the reservoir module of
the infusion pump embodiment depicted in FIGS. 10A and 10B;
[0026] FIGS. 13A-13E illustrate the underside of the reservoir
module of an exemplary infusion pump embodiment having separate
medication output port and fill port;
[0027] FIGS. 14A and 14B illustrate the interior components of the
reservoir module of the infusion pump embodiment depicted in FIGS.
10A and 10B;
[0028] FIG. 15A illustrates a medication level sensing system, in
accordance with exemplary embodiments of the present
disclosure;
[0029] FIGS. 15B and 15C illustrate how electrical terminals of the
medication level sensing system depicted in FIG. 15A make contact
with the electronics in an exemplary control module;
[0030] FIG. 16 illustrates a top close-up view of the medication
level sensing system depicted in FIG. 15A, and
[0031] FIGS. 17A-17C illustrate the output mechanism of the control
module, in accordance with exemplary embodiments of the present
disclosure.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0032] Reference will now be made in detail to certain embodiments
consistent with the present disclosure, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts. It is to be understood that the
devices and methods of the present disclosure can be employed with
all types of infusion pumps for fluidic medication delivery.
[0033] A first aspect of the present disclosure is a method of
implementing an infusion pump capable of delivering very small
amounts of medication. In exemplary embodiments of the present
disclosure, precise delivery of very small amounts of fluidic
medication is achieved by using a medication reservoir that is
sized as a long syringe having a small cross-section. In
illustrative embodiments, the medication reservoir is in the form
of a long, narrow tube. The tube houses a plunger that is sized to
fit snugly, but slidably within the tube. In exemplary embodiments,
the tube has a circular cross-section, although any other
cross-section (e.g., oval, etc.) that allows the plunger to fit
securely within the tube and provide a seal can be used. The
plunger is configured to slide along the inner walls of the tube
allowing the reservoir to be filled with fluidic medication and to
expel the medication through an opening at a proximal end (i.e.,
the end of the tube that is proximate a medication delivery port)
of the reservoir.
[0034] Delivery of small volumes of fluid is mechanically more
precise when a long, narrow reservoir is employed, because a
smaller cross-section translates to a smaller volume of fluid
expelled for each unit of forward movement ("step size") of a
plunger. For very small basal deliveries, e.g. pediatric insulin
basal rate of 250 nL/hour, very precise movements of the plunger
are required. Additionally, at such low infusion rates, friction
between the plunger and the reservoir causes a jerking effect,
known as stiction, and the fluid is delivered as a series of small
boluses instead of a steady, continuous flow. The larger the
cross-section of the plunger, the larger its circumference, which
concomitantly increases stiction, requiring higher motor forces to
overcome, and therefore increasing battery drain. A long, narrow
medication reservoir having a small cross-section plunger
encounters lesser stiction in translation, as well as other
mechanical noises, and therefore requires lower plunger force for
fluid displacement. A smaller cross section, and therefore a long
aspect ratio, subsequently facilitates more accurate delivery of a
low basal dosage at a lower power demand. A small cross-section
plunger also experiences less force due to differential pressure
between the inside and outside of the tube.
[0035] A long aspect ratio reservoir, however, poses a design
challenge in compact infusion pumps FIG. 1 demonstrates a
conventional syringe-type pump 10. Pump 10 comprises a reservoir
body 12 having a length x, a plunger 14 for receiving/expelling a
fluid within reservoir body 12, a lead screw 16, and a plunger rod
18 for driving plunger 14 through the length x of the reservoir
body 12. As illustrated in FIG. 1, a rigid, rectilinear plunger rod
18 would have to be at least as long as reservoir body 12 in order
to displace plunger 14 along the entire length of the reservoir
body; that is, the total length of the syringe-type pump 10 would
be approximately 2 when reservoir body 12 is completely filled with
medication. Consequently, a long, rectilinear plunger rod can
potentially dominate the size of a small, compact infusion pump and
make implementation of such a pump very difficult.
[0036] A second aspect of the present disclosure is a method and
system for employing a long aspect ratio medication reservoir
within an infusion pump of small footprint. In exemplary
embodiments, a long syringe-type reservoir is implemented in the
form of a long, curved reservoir. In one such embodiment, the long,
curved reservoir comprises alternating curved and straight
sections. In another embodiment, the reservoir has at least one
straight section. In yet another embodiment, the reservoir is
curved throughout its length. FIG. 2 illustrates a long, curved
reservoir 20 for use in an infusion pump. Curved reservoir 20
comprises a tube 22 having a reservoir terminal 26. Tube 22 is
connected to the reservoir terminal 26 using, for example, an
O-ring, an adhesive sealant, etc. In exemplary embodiments, the
dimensions of tube 22 are determined by the volume of medication
intended for the reservoir. In some exemplary embodiments designed
for the delivery of 2.20 cc of medication, the possible ratios of
lengths (mm) and inner diameters (mm) of the reservoir tube 22
(having a circular cross-section) can be as follows: 28.0/10.0,
57.2/7.0; 129.5/4.7; or 311.2/3.0.
[0037] Tube 22 is constructed of a material that is compatible with
the medication that the reservoir is intended to store and
dispense. In illustrative embodiments, tube 22 is made of a metal,
for example, stainless steel. In other embodiments, tube 22 is made
of a polymeric material. In exemplary embodiments, tube 22 is made
of high density polyethylene (HDPE). In some embodiments, flexible
HDPE tubing is extruded as a single piece and then formed into the
desired configuration by bending, and other techniques. An
exemplary HDPE extruded tube 22 has a circular cross-section. The
wall thickness of one such HDPE extruded tube 22 is about 1 mm or
less. In another embodiment, square cross-section extrusion is used
to form reservoir tube 22. In exemplary embodiments, the inner
diameter of tube 22 is consistent throughout its length to maintain
a hermetic seal between the plunger and the inner wall of the tube.
Further, in certain embodiments, care is taken to minimize surface
defects on the inner wall of tube 22, since surface defects can
potentially result in excessive friction between the plunger and
the inner wall of tube 22, as well as leakage of medication from
the reservoir. In some embodiments, the inner surface of tube 22 is
provided with a surface coating to lower friction with the plunger.
Care is taken to choose a surface finish that is compatible with
the medication. Certain low friction materials, such as PTFE
(polytetrafluoroethylene) and FEP (fluorinated ethylene propylene)
can also be used to form reservoir 20 and do not require low
friction coating of their inner wall.
[0038] Another aspect of the present disclosure is a delivery
mechanism for dispensing fluid from curved reservoir 20. In
exemplary embodiments, fluid is dispensed by driving a plunger
through curved reservoir 20 using a flexible plunger rod that can
conform to a given shape of curved reservoir 20 and by accurately
controlling the forward displacement of the plunger or piston. In
exemplary embodiments, the flexible plunger rod comprises a drive
train 34 having an assembly of interconnected ball segments 36, as
illustrated in FIG. 3A. Drive train 34 is configured to travel
through any given geometry of curved reservoir 20. In some
embodiments, drive train 34 is driven by a lead screw 38. In one
such embodiment, lead screw 38 has a profile which allows lead
screw rotation to transmit force to drive train 34, but does not
allow drive train 34 to drive lead screw 38 in reverse when the
drive train is subjected to a strong longitudinal force.
[0039] Drive train 34 comprises a plunger 32 attached at a proximal
end (the end that is proximate a medication delivery port when
curved reservoir 20 is empty) and a cursor 33 attached at a distal
end (the end that is farthest away from the medication delivery
port) of the assembly of ball segments. Throughout the rest of this
disclosure, the end of the drive train (or the end of the
reservoir) that is proximate to the medication delivery port is
referred to as the proximal end.
[0040] In exemplary embodiments, cursor 33 functions as a sensor
that can indicate the position of the drive train within the
reservoir, and thereby denote the level of medication within the
reservoir (described in detail later in this disclosure). FIG. 3B
shows a close-up view of plunger 32 at the proximal end of drive
train 34. In exemplary embodiments, as illustrated in FIG. 3B,
plunger 32 comprises a supporting core with two elastomeric O-rings
37 extending radially outwards. The O-rings are configured to
provide hermetic seal between plunger 32 and the inner wall of
curved reservoir 20. In some embodiments, plunger 32 is configured
to be compressible. In one such embodiment, plunger 32 is an
elastomeric ball plunger configured to facilitate travel through
the changing curvature of reservoir 20. In an alternative
embodiment, plunger 32 is a ball plunger comprising a rigid sphere
with an elastomeric outer shell. Additional plunger configurations
can include x-rings, flanged elastomeric cap, etc., designed to
achieve hermetic seal and low-friction movement between plunger 32
and inner wall of curved reservoir 20.
[0041] FIGS. 4A-4C illustrate a method of filling curved reservoir
20 with medication. For ease of illustration, curved reservoir 20
is depicted as a straight reservoir in FIGS. 4A-4C. As would be
understood by a person of ordinary skill in the art, the following
method of filling a syringe-type reservoir can be used with both a
curved and a straight reservoir. During the fill stage, drive train
34 is not connected to lead screw 38. Reservoir 20 is delivered to
a user with plunger 32 bottomed out at a proximal end 42 of
reservoir 20, as shown in FIG. 4A. As the user fills the reservoir
with medication using a fill syringe, plunger 32 and drive train 34
are driven back towards a distal end 44 of reservoir 20, as shown
in FIG. 4B. In one exemplary embodiment, reservoir 20 is filled
with medication via a fill port that is separate and distinct from
a medication dispensing port through which medication is supplied
to a user. In another exemplary embodiment, the fill port and the
medication dispensing port are the same. Further details about the
fill port and the medication dispensing port are provided later in
this application in reference to an exemplary infusion pump.
[0042] Referring again to FIG. 4B, drive train 34 is located either
within the reservoir 20, or in a feeder track 31, depending on the
position of plunger 32 within reservoir 20. When reservoir 20 is
completely filled with the medication, drive train 34 is located
completely within feeder track 31. Lead screw 38 then engages drive
train 34 at a proximal section of feeder track 31, as depicted in
FIG. 4C. As a result of the lead screw rotation, drive train 34
travels in the forward direction towards proximal end 42 of the
reservoir to supply medication to the user. In some exemplary
embodiments, the delivery mechanism is specifically designed to
prevent back-driving, i.e., to prevent drive train 34 from
traveling in the reverse direction towards the distal end of
reservoir 20. This mechanism prevents curved reservoir 20 from
being refilled with medication more than once, and thus, requires
reservoir module 120 to be disposed of after a single use.
[0043] In exemplary embodiments, the assembly of ball segments 36
is configured to be incompressible and flexible. FIG. 5 is a
cross-sectional view of an exemplary embodiment of drive train 34.
As illustrated in FIG. 5, drive train 34 comprises a series of ball
segments 36 each having a through hole to receive a filament 54
that connects all the components together starting at plunger 32 at
the proximal end and cursor 33 at the distal end. In one such
embodiment, ball segments 36 comprise 4.5 mm round rigid balls each
having a 1 mm through hole. The rigidity of ball segments 36 ensure
that drive train 34 is not compressed or deformed during operation.
In exemplary embodiments, filament 54 is flexible and elastic,
which allows bending of drive train 34 to facilitate travel through
the curvature of reservoir 20 and feeder track 31. In certain
embodiments, the length of filament 54 is selected to maintain
drive train 34 under slight axial compression. The flexibility and
elasticity of filament 54, along with the slight compressive force
keeping all the ball segments 36 in direct contact, ensure that
successive ball segments 36 are pulled up to lead screw 38 without
a gap between them.
[0044] FIG. 6A illustrates an alternative embodiment of drive train
34 designed to facilitate the assembly process. In one such
embodiment, ball segments 36 comprise a keyhole feature 62 having a
center hole 63 and a tapered slot 65. FIG. 6B is a close-up view of
a ball segment 36 comprising keyhole 62. Keyhole 62 is configured
such that the diameter of center hole 63 is smaller than the width
of slot 65 at the outermost portion of the keyhole, but bigger than
the width of the slot at its innermost portion. To assemble drive
train 34, ball segments 36 are positioned with their slots aligned.
Filament 54, which has a diameter bigger that the smallest width of
the tapered slot 65, is stretched to decrease its diameter. This
allows filament 54 to be lowered into center holes 63 of the ball
segments all at once. Once the stretched filament is lowered into
center holes 63, the filament is released and allowed to regain its
original diameter. Since the original diameter of filament 54 is
larger than the smallest width of tapered slot 65, the filament
cannot pass through the slot and is permanently captured within
center holes 63 of the ball segments 36.
[0045] In another alternative embodiment, the components of drive
train 34, that is, ball segments 36, plunger 32, and cursor 33, are
interconnected using a tongue and groove system 72. FIG. 7A
illustrates drive train 34 having a tongue and groove system 72,
and FIG. 7B shows a cross-sectional view of a ball segment 36
having a tongue 74 and a groove 76. In one such embodiment,
filament 54 is not required; the components of the drive train are
interconnected by inserting the tongue of one ball segment 36 into
the groove of the successive ball segment. In exemplary
embodiments, tongue and groove system 72 is incorporated into
plunger 32 and cursor 33 to connect them to adjoining ball
segments.
[0046] In yet another alternative embodiment, the drive train
comprises a single component instead of multiple components
assembled together. Such an embodiment is referred to hereinafter
as a single-piece drive train 80. In certain embodiments, drive
train 80 is injection molded using a polymeric material that
resists axial compression while providing sufficient flexibility to
the drive train to steer through curved reservoir 20. Drive train
80 comprises a threaded spine 82, and plunger 32 and cursor 33
connected to the proximal and distal ends, respectively, of
threaded spine 82. Threaded spine 82 comprises a center structure
84 with a continuous thread 88 on top of the structure. In some
embodiments, drive train 80 further comprises centering elements 86
on each side of center structure 84, as shown in FIG. 8A. In
another embodiment, centering elements 86 are present on only one
side of center structure 84. The number of centering elements
required and their location is entirely dependent on the inner
profile of curved reservoir 20 and the mechanical properties of
drive train 80. Centering elements 86 help to position threaded
spine 82 within the curved reservoir 20. FIG. 5B shows a close-up
view of an exemplary drive train 80 in engagement with a lead screw
89 specifically intended for threaded spine 82. As shown in the
figure, drive train 80 further comprises an alignment rail 87
located at the bottom of threaded spine 82. Alignment rail 87 is
used to ensure that drive train 80 is properly positioned as it
passes under lead screw 89 and that threads 88 align with the
grooves of the lead screw.
[0047] FIG. 9A shows an alternative embodiment of centering
elements 86 of single-piece drive train 80. This particular design
makes centering elements 86 more flexible in lateral displacement,
and therefore, more tolerant to slight variations in the shape or
dimension of curved reservoir 20. FIG. 9B shows a cross-section of
drive train 80 positioned within curved reservoir 20. To minimize
friction with the inner surface of reservoir 20, and to optimize
the centering of drive train 80, the number of contact points 92 is
limited to three (3) for any given cross-section, and the contact
points are located approximately 120.degree. apart.
[0048] Another aspect of the present disclosure is an infusion pump
encompassing a long, curved reservoir and a delivery mechanism
comprising a flexible drive train for controlled, accurate delivery
of small amounts of fluidic medication from the reservoir. The
configuration of an exemplary infusion pump will be described with
reference to curved reservoir 20, drive train 80, and lead screw
89. It is contemplated that the infusion pump of the present
disclosure can utilize a long, curved reservoir and a flexible
drive train of any configuration, including, but not limited to
drive train 34 and lead screw 38.
[0049] FIG. 10A demonstrates a general configuration of a modular
infusion pump 100 comprising a control module 110, a reservoir
module 120, and a cradle 130. FIG. 10B is an exploded view of the
embodiment depicted in FIG. 10A and shows control module 110,
reservoir module 120 and cradle 130 separated from one another. In
exemplary embodiments, control module 110 and reservoir module 120
are mated and locked together to form a pump unit, which is then
connected to cradle 130. Cradle 130 is configured to adhere
directly to the skin of a user. A flexible cannula 140 extends
below the bottom surface of the cradle and penetrates the skin of
the user to deliver the medication. In exemplary embodiments,
control module 110 comprises the electronics and the motor of
infusion pump 100, including lead screw 89, and reservoir module
120 includes curved reservoir 20, drive train 80, and a battery to
power the infusion pump. In some embodiments, lead screw 89 is
included in the reservoir module 120 instead of control module 110.
Reservoir module 120 is manually filled with medication by the user
before attaching it to control module 110. In one embodiment,
infusion pump 100 is a semi-disposable device, wherein reservoir
module 120 and cradle 130 are disposable while the control module
110 can be re-used multiple times with new reservoir modules 120
and cradles 130. In such an embodiment, the fluidic pathway is
contained entirely within the disposable reservoir module 120, and
therefore, multiple uses of control module 110 do not pose any risk
of cross-contamination or degradation of residual medication within
the reservoir. In another embodiment, all of the components of
infusion pump 100, including control module 110, are fully
disposable.
[0050] In exemplary embodiments, as illustrated in FIGS. 10A and
10B, control module 110 can further comprise at least one bolus
button 112 to signal the pump to provide a bolus of medication to
the user, and a visual indicator 114 to notify the user of certain
events or status. In select embodiments, control module 110 is
configured to communicate with an implantable and/or a
skin-attached disease-monitoring device to form a closed-loop
system that allows manual or automatic adjustment of dosage based
on the readings from the disease-monitoring device. For instance,
if modular infusion pump 100 is intended for continuous delivery of
insulin, then control module 100 can be configured to receive
feedback from a Continuous Glucose Monitor (CGM) and to adjust the
insulin dosage accordingly.
[0051] FIG. 11 illustrates the underside of control module 110 in
an exemplary embodiment of infusion pump 100. In one embodiment,
control module 110 comprises a locking pin 116 projecting beyond
the bottom surface of the control module. Locking pin 116
penetrates reservoir module 120 to secure the control module to the
reservoir module. FIG. 11 also illustrates an output mechanism 300
positioned within control module 110. Output mechanism 300 delivers
mechanical actuation to drive train 80 to dispense fluid from
curved reservoir 20. In exemplary embodiments, control module 110
comprises an electric motor and a gearbox (described in detail
later in this disclosure). An output shaft of the electric motor is
coupled to the gearbox, which increases the torque provided by the
electric motor and increases the rotational resolution. The output
of the gearbox is mechanically coupled to output mechanism 300,
which comprises a drive shaft and lead screw 89. The drive shaft
receives rotational motion from the gearbox and transmits it to
lead screw 89 which rotates along with the drive shaft. Lead screw
89 also has the ability to slide laterally along a flat surface on
the drive shaft, which allows the lead screw to self-align when
engaging the threaded spine of drive train 80, as described later
in this disclosure.
[0052] In exemplary embodiments, control module 110 can comprise
one or more annular seals 118 on the bottom surface of control
module 110 to form a hermetic seal between control module 110 and
reservoir module 120. As illustrated in FIG. 11, a first annular
seal 118 can be located around the periphery of the bottom surface
of control module 110 and a second annular seal 118 is located
around locking pin 116. In one embodiment, annular seals 118
comprise elastomeric gaskets (for example, O-rings or overmolded
features) that form a sealing contact between control module 110
and reservoir module 120. In certain embodiments, control module
110 can further comprise a sensor 115, such as a mechanical,
optical or magnetic sensor, to determine whether the pump unit
(control module and reservoir module) is installed on cradle 130 or
not.
[0053] FIG. 12 shows a top view of an exemplary reservoir module
120 having a lid 121 attached to its top surface. Several openings
in lid 121 provide access to components positioned within the
reservoir module, such as a battery 122 (shown with activation
tab), and latching tabs 123 used to latch onto locking pin 116 of
control module 110 when the control module is properly aligned on
the reservoir module. The locking mechanism (i.e., engagement of
locking pin 116 by latching tabs 123 of the reservoir module) helps
to orient and center the modules prior to mating and to prevent
accidental disconnection of the modules after full engagement of
the lock.
[0054] Referring again to FIG. 12, another opening in lid 121
exposes a few threads of drive train 80 that are engaged by lead
screw 89 when control module 110 and reservoir module 120 are mated
together. In exemplary embodiments, the housing of reservoir module
120 is equipped with a few raised (or recessed) structures 124 that
can be used to secure the reservoir module to cradle 130. In
exemplary embodiments, reservoir module 120 further comprises a
port 125, which can be used to fill curved reservoir 20 with
medication and also to connect reservoir module 120 to cradle 130
for delivery of medication to the user.
[0055] In some exemplary embodiments, the port used for dispensing
medication is separate and distinct from a fill port used for
loading medication into curved reservoir 20. FIGS. 13A, 13B, and
13C illustrate such an embodiment having two separate ports in
reservoir module 120--an output port 125A used to deliver
medication to a user and a fill port 125B used for loading
medication into reservoir 20. In select embodiments, fill port 1251
is a self-sealing port designed to avoid leakage of medication
through the fill port during operation. FIG. 13A shows a bottom
view and FIG. 138 shows a bottom isometric view of an exemplary
reservoir module 120 having output port 125A and fill port 125B. In
exemplary embodiments, output port 125A comprises a terminal
junction needle 132 that can connect with a cradle 130 for delivery
of medication to the user. In select embodiments, fill port 125B
comprises a fill septum 138 that can be used to infuse medication
into curved reservoir 20. The needle of a fill syringe containing
the necessary volume of medication is inserted into fill septum 138
to inject the medication into the curved reservoir. In some
embodiments, output port 125A is configured to attach to an
infusion set 150 in place of cradle 130, as illustrated in FIG.
13C. Infusion set 150 comprises a tubing 152 with a
cannula/insertion needle (not shown) at its proximal end for
subcutaneous delivery of medication to a user. In certain
embodiments, port 125 or output port 125A is capped with a
protective plug 136 until it is connected to cradle 130 or infusion
set 150. FIGS. 13D and 13E show a bottom view and side view,
respectively, of an exemplary reservoir module having protective
plug 136 over output port 125A. In select embodiments having a
single port 125, protective plug 136 can function as a fill septum
for loading medication into curved reservoir 20. In those
embodiments that have discrete output port 125A and fill port 1251,
protective plug 136 is used to prevent medication from escaping
through output port 125A when medication is introduced into
reservoir 20 through fill port 125B.
[0056] Once the reservoir is filled with the required volume of
medication, reservoir module 120 is mated with control module 110
to form a pump unit. Protective plug 136 is then removed from the
base of reservoir module 120. Cradle 130 or infusion set 150, which
is already attached to the skin of the user, is then connected to
port 125 or output port 125A to begin delivery of medication.
[0057] In exemplary embodiments, as illustrated in FIGS. 13C and
13D, the base of reservoir module 120 further comprises a
hydrophobic vent 134. Vent 134 is provided to equalize the pressure
inside and outside the reservoir module. In some embodiments, vent
134 is composed of a hydrophobic membrane hermetically affixed to
the interior surface of the reservoir module. In one such
embodiment, the vent membrane is ultrasonically welded to the base
of the reservoir module directly over the holes of vent 134. In an
alternative embodiment, the membrane can be replaced by a plug of
hydrophobic porous (breathable) material held within a
receptacle.
[0058] FIGS. 14A and 14B show the interior components of an
exemplary reservoir module 120 comprising curved reservoir 20,
drive train 80, and having a single port 125 used for both loading
medication into reservoir 20 and to dispense medication to the
user. Lid 121 of the reservoir module is removed to show the
interior components of the reservoir module. FIG. 14A illustrates
the interior of reservoir module 120 before curved reservoir 20 is
filled with medication. Infusion pump 100 is delivered to a user
with plunger 32 bottomed out at the proximal end (the end of the
reservoir that is proximate to the port that delivers medication to
the user) of curved reservoir 20, as shown in FIG. 14A. In this
configuration, drive train 80 is contained almost entirely within
the curved reservoir. As the user fills curved reservoir 20 with
medication via port 125, plunger 32 and drive train 80 are driven
back towards the distal end of curved reservoir 20, as shown in
FIG. 14B. Depending on the position of plunger 32 within curved
reservoir 20, drive train 80 is located either within the reservoir
20, or in feeder track 31. In exemplary embodiments, feeder track
31 comprises a continuous, curved wall structure that serves as a
low friction track for guiding drive train 80. When reservoir 20 is
completely filled with the medication, drive train 80 is located
almost entirely on the feeder track 31, as depicted in FIG.
14B.
[0059] FIGS. 14A and 14B further illustrate battery 122, terminal
junction needle 132, and a window 147 positioned within an
illustrative embodiment of reservoir module 120. In some
embodiments, battery 122 is placed on elastic support structures to
elevate it and bring it in contact with control module 110.
Junction needle 132 couples reservoir terminal 26 of the curved
reservoir to port 125/output port 125A for delivery of medication
to the user. Window 147 is provided to allow ingress of locking pin
116, which is used to secure reservoir module 120 and control
module 110. Further, in some exemplary embodiments, overmolded
gaskets 148 are provided around the periphery of window 147 and
around the margin of reservoir module 120 to provide a hermetic
seal between control module 110 and reservoir module 120. The
locking mechanism of infusion pump 100 (engagement of locking pin
116 of the control module by latching tabs 123 of the reservoir
module) helps to provide uniform compression around gaskets 148 and
improve hermeticity of the pump.
[0060] Consistent with exemplary embodiments of the present
disclosure, area 144 in FIG. 14B identifies the segment of drive
train 80 that is engaged by lead screw 89 when reservoir module 120
is mated with control module 110. In exemplary embodiments, area
144 is a straight segment, which facilitates mechanical coupling
between the drive train and the lead screw. In one such embodiment,
drive train 80 is permitted to advance only in the proximal
direction, i.e., towards output port 125A or port 125, once drive
train 80 is engaged by lead screw 89.
[0061] A yet another aspect of the present disclosure is a method
and system for measuring the amount of medication contained within
curved reservoir 20 of modular infusion pump 100. In exemplary
embodiments, modular infusion pump 100 comprises a level sensing
system 200 comprising two parallel resistive traces 210 a (outer
trace) and 210 b (inner trace) on the underside of lid 121 of
reservoir module 120, as illustrated in FIG. 15A. In some
embodiments, resistive traces 210 a and 210 b comprise an
electrically conductive polymeric material. In select embodiments,
resistive traces 210 a and 210 b can be manufactured using a pad
printing process. In such embodiments, pad printing is used to
deposit a conductive ink on the underside of lid 121 to form the
parallel resistive traces. In some other embodiments, resistive
traces 210 a and 210 b comprise 3D circuitry formed directly on the
underside of lid 121 using a molding process. In such embodiments,
lid 121 is formed of a thermoplastic material. The plastic
substrate (i.e., lid 121) is combined with circuit traces into a
single part through selective metallization and 3D molding of the
plastic material.
[0062] The parallel resistive traces 210 a and 210 b are connected
to the electronics inside control module 110 via electrical
terminals 212, 214, and 216. The outer trace 210 a terminates at
each end at terminals 212 and 216, and the inner trace 210 a
terminates at only one end 214. In one embodiment, terminal 216 is
shared by the negative electrode (GND) of battery 122. In exemplary
embodiments, electrical terminals 212, 214, and 216 are in the form
of electrical spring contacts that are positioned on elevated
support structures 217 formed on the base of reservoir module 120,
as illustrated in FIG. 15B. The electrical spring contacts bring
the resistive traces at the bottom of lid 121 to the top surface of
the lid so that the electronics inside control module 110 can
connect to them. FIG. 15C illustrates how the electrical contacts
extend out of the top of reservoir module 120 when lid 121 is
placed on it.
[0063] In exemplary embodiments, the parallel resistive traces 210
a and 210 b are located immediately above the feeder track 31,
which contains drive train 80 in its entirety when curved reservoir
20 is completely filled with medication. As described earlier in
this disclosure, and further demonstrated in FIG. 16, plunger 32 is
located at the proximal end of drive train 80 and cursor 33 forms
the most distal element of drive train 80. Cursor 33 and the
parallel resistive traces 210 a and 210 b together form level
sensing system 200. The purpose of cursor 33 is to provide a moving
electrical short between the outer trace 210 a and inner trace 210
b. When curved reservoir 20 is not filled with medication, drive
train 80 is located within the curved reservoir in its entirety,
except for cursor 33 and segment 144 of the drive train which
engages lead screw 89. When the reservoir is filled (in full or in
part) with medication, drive train 80 along with cursor 33 is
driven backwards into the feeder track 31, thus pushing backwards
the electrical short between the resistive traces 210 a and 210 b.
When reservoir 120 is mated with control module 110, the
electronics of the control module can determine the amount of
medication in the reservoir by measuring the resistance value
between terminals 212, 214, and 216. As drive train 80 is driven
forward by lead screw 89 to dispense medication from curved
reservoir 20, cursor 33 moves forward as well under the resistive
traces 210 a and 210 b, and thereby changes the location of the
electrical short between the two resistive traces. In exemplary
embodiments, the changing location of the electrical short produces
different resistive values, which alters the voltage signal
measured by control module 110 via electrical terminations 212,
214, and 216. The voltage signal is converted into a corresponding
volume of medication present in curved reservoir 20.
[0064] Thus, level sensing system 200 functions as a potentiometer
to determine the amount of medication contained within reservoir
20. In illustrative embodiments, as depicted in FIGS. 15 and 16,
outer track 210 a functions as the potentiometer track and the
inner track 210 b serves to transmit the voltage sensed by cursor
33 to control module 110 where the sensed voltage is converted into
a corresponding level of medication within reservoir 20. In
exemplary embodiments, level sensing system 200 can be used not
only to sense the level of medication in the reservoir, but also as
a safety feature to cross-check the accuracy of the medication
delivery mechanism.
[0065] Another aspect of the present disclosure is an actuation
mechanism for delivering medication from the curved reservoir 20 to
a user. In exemplary embodiments of infusion pump 100, control
module 110 provides mechanical actuation to reservoir module 120,
which enables the reservoir module to deliver medication to a user.
FIGS. 17A and 17B illustrates the mechanical components of an
exemplary control module 110 (with the top cover removed). As shown
in FIG. 17A, control module 110 includes an electric motor 220. In
some embodiments, motor 220 is coupled to a motor shaft encoder
225, which provides rotational information about the motor. An
output shaft of motor 220 is coupled to a gearbox 230, which
increases the torque provided by the motor. In select embodiments,
motor shaft encoder 225 is mounted on any of the gears of gearbox
230 instead of being connected directly to motor 220. This helps in
preserving the torque of the motor and conserve battery energy. In
one such embodiment, an extra gear is added to gearbox 230 and the
motor shaft encoder is mounted on the extra gear, which is mated
with one of the bigger gears in gearbox 230. The output of gearbox
230 is coupled to actuation device 300, which is located under a
lead screw enclosure 240 which forms part of the control module
housing. An occlusion sensor 250 is connected to actuation device
300 to detect any blockage in the medication delivery path.
[0066] FIG. 17B shows a cross-sectional view of control module 110
providing more details on actuation device 300. FIG. 17C shows a
cross-sectional view of actuation device 300. The output of gearbox
230 is mechanically coupled to a drive shaft 310, which receives
rotational motion from gearbox 230. In exemplary embodiments, gear
box 230 is coupled to the drive shaft via a spur gear 335.
[0067] Lead screw 89 slides on drive shaft 310 and rotates with it.
In exemplary embodiments, a flat surface 320 is located on drive
shaft 310 and the lead screw travels laterally along the flat
surface 320, as illustrated by lateral movement. Lm in FIG. 17C. A
centering spring 330, which can be used in both compression and
elongation, keeps lead screw 89 centered on the flat 310 of the
drive shaft when control module 110 is not connected to reservoir
module 120. When the control module 110 and reservoir module 120
are mated together, the ability of the spring-loaded lead screw to
slide back and forth allows the lead screw to find a suitable
location for its threads between the threads of drive train 80 and
thus facilitate proper engagement of the lead screw and the drive
train.
[0068] Referring again to FIG. 17C, drive shaft 310 is further
coupled to a force sensor 255 via a ball 340. Force sensor 255 is
part of the occlusion sensor 250 in the control module. Ball 340
transmits to the sensor any lateral force Fs applied to it by the
rotating drive shaft. In exemplary embodiments, ball 340 is made of
metal or ceramic.
[0069] A light force, which acts as a preload force Fpl, is applied
on the drive shaft to keep it in contact with ball 340, and the
ball in contact with force sensor 255. In exemplary embodiments, a
leaf spring 350 is used to apply a light force on drive shaft 310
to ensure that no gap exists between the drive shaft and force
sensor 255. Force sensor 255 continuously monitors the force on the
drive shaft during operation. Any force build-up or spike in force
can indicate that there is an occlusion in the medication delivery
pathway and the user can be alerted to take remedial measures. In
exemplary embodiments, ball 340 applies force Fs to a front plate
260, which in turn applies the force to sensor 255. The purpose of
the front plate is to distribute the concentrated force applied by
ball 340 over the entire surface of force sensor 255. A rigid back
plate 270 ensures that force sensor 255 can measure the load
without being affected by any deformation of the back plate. In
exemplary embodiments, as illustrated in FIG. 17C, occlusion sensor
250, including force sensor 255, front plate 260 and back plate
270, are positioned at a 45' angle with respect to the axis of the
shaft. The angled placement reduces the total height of the
occlusion sensor and amplifies the force measured by force sensor
255 by a factor of 1.4142. When the lead screw reaches the "drive"
position, with the "drive" position being defined as the position
assumed by lead screw 89 when it transmits mechanical actuation to
drive train 80 in reservoir module 120, centering spring 330
becomes elongated and the lead screw is pressed against retaining
ring 380. In this position, the lateral force applied to the lead
screw (when actuating the drive train) will be transmitted to force
sensor 255 via a retaining ring 380 and shaft 310. In some
embodiments, retaining ring 380 is snapped into a groove in drive
shaft 310. The retaining ring forms a hard stop to the lateral
displacement of lead screw 89 when travelling in the direction of
force sensor 255.
[0070] Referring again to FIG. 17C, an exemplary occlusion
mechanism 300 includes a pair of bearings 360 at each end of drive
shaft 310 to support the drive shaft and allow it to rotate freely.
Further, in some embodiments, occlusion mechanism 300 includes
O-rings 370 at each end of drive shaft 310 to form barriers between
the interior and exterior of control module 110 so as to avoid
contamination of the interior of the control module.
[0071] When control module 110 and reservoir module 120 are mated
together, lead screw 89 is positioned randomly on drive train 80.
For instance, in the process of positioning the threads of lead
screw 89 between the threads of drive train 80, the lead screw can
move towards the spur gear 335 and compress centering spring 330.
In such a case, a gap separates lead screw 89 from retaining ring
380. To close the gap, actuation device 300 is primed by rotating
drive shaft 310. As the drive shaft rotates, lead screw moves
laterally over the immobilized drive train 80 (the drive train is
immobilized because the medication in the reservoir is
incompressible and the medication output port is closed) towards
retaining ring 380. The gap is closed when lead screw 89 makes
contact with the retaining ring and the lead screw cannot move
further. As rotation of drive shaft 310 continues, lead screw 89
presses against retaining ring 380 and results in a push force on
drive train 80. If the medication output port (port 125/output port
125A) is open, the push force results in a forward motion of drive
train 80 which leads to delivery of medication. As the push force
is applied to drive train 80, a corresponding equal and opposite
reaction force (under Newton's third law) is applied to ball 340,
which is turn transmits a force Fs to force sensor 255 that is
proportional to the force required to move drive train 80 forward.
In exemplary embodiments, the push force on drive train 80 is
registered by force sensor 255, which triggers the electronics in
the control module to stop rotating drive shaft 310 and to indicate
to the user that the system is primed.
[0072] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *