U.S. patent application number 14/281614 was filed with the patent office on 2014-09-11 for fluid transfer system and method.
This patent application is currently assigned to INTELLECTUAL INSPIRATIONS, LLC. The applicant listed for this patent is Intellectual Inspirations, LLC. Invention is credited to Daniel BLOOM, Edward Paul DONLON, Morten J. JENSEN, Nicholas A. NELSON, Laurence R. SHEA, Stuart TAYLOR, Joseph Anthony VIVOLO.
Application Number | 20140257137 14/281614 |
Document ID | / |
Family ID | 43781091 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140257137 |
Kind Code |
A1 |
BLOOM; Daniel ; et
al. |
September 11, 2014 |
FLUID TRANSFER SYSTEM AND METHOD
Abstract
Devices and methods for automatic monitoring of fluid of a
patient are disclosed, comprising a patient line, a transfer disk
which receives the fluid and controllably transfers the fluid to
test substrates, and a sensor disk which houses the test
substrates. The sterile transfer disk may be configured to maintain
the sterility of the patient sampling assembly while transferring
samples to non-sterile components, such as the sensor disk.
Inventors: |
BLOOM; Daniel; (Alameda,
CA) ; NELSON; Nicholas A.; (San Francisco, CA)
; JENSEN; Morten J.; (Santa Clara, CA) ; SHEA;
Laurence R.; (San Francisco, CA) ; DONLON; Edward
Paul; (San Jose, CA) ; VIVOLO; Joseph Anthony;
(San Francisco, CA) ; TAYLOR; Stuart; (Santa
Clara, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intellectual Inspirations, LLC |
Austin |
TX |
US |
|
|
Assignee: |
INTELLECTUAL INSPIRATIONS,
LLC
Austin
TX
|
Family ID: |
43781091 |
Appl. No.: |
14/281614 |
Filed: |
May 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12731010 |
Mar 24, 2010 |
8753290 |
|
|
14281614 |
|
|
|
|
61164285 |
Mar 27, 2009 |
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Current U.S.
Class: |
600/582 |
Current CPC
Class: |
A61B 5/150236 20130101;
A61B 5/15087 20130101; A61B 5/6866 20130101; A61B 5/150213
20130101; A61B 5/155 20130101; A61B 5/150961 20130101; A61B
5/150992 20130101; A61B 5/1535 20130101; A61B 5/15003 20130101;
A61B 5/150358 20130101; A61B 5/150793 20130101; A61B 5/150229
20130101; A61B 5/150755 20130101; A61B 5/150809 20130101; A61B
5/150221 20130101; A61B 5/150946 20130101; A61B 5/150824 20130101;
A61B 5/14532 20130101; A61B 5/157 20130101 |
Class at
Publication: |
600/582 |
International
Class: |
A61B 5/15 20060101
A61B005/15; A61B 5/157 20060101 A61B005/157 |
Claims
1. A fluid monitoring system, comprising: a patient access
interface configured to receive fluid from a patient; a fluid pump
configured to transfer fluid in the patient access interface; a
valve coupled to the patient access interface and the fluid pump
and comprising a fluid dispensing opening, wherein the valve is
configured to dispense a fluid sample at the fluid dispensing
opening; and a fluid inlet blocking structure adjacent to the fluid
dispensing opening.
2. The fluid monitoring system of claim 1, wherein the patient
access interface, fluid pump, valve and fluid inlet blocking
structure are coupled to a patient line housing.
3. The fluid monitoring system of claim 1, further comprising an
external fluid access interface configured to receive fluid from an
external fluid source.
4. A method of performing fluid monitoring in a patient,
comprising: withdrawing fluid from a patient into a first housing
coupled to a fluid monitoring system; transferring a fluid sample
from the withdrawn fluid in the first housing to a second housing;
changing the orientation of the second housing relative to the
first housing; pumping the fluid sample from the second housing to
a test substrate.
5. The method of claim 4, wherein pumping the fluid sample from the
second housing to the test substrate comprises pumping the fluid
sample across an air gap between a fluid opening of the second
housing and the test substrate.
6. The method of claim 4, wherein pumping the fluid sample from the
second housing to the test substrate comprises pumping the fluid
sample from the second housing to a third housing, wherein the test
substrate is located in the third housing.
7. The method of claim 4, further comprising wiping a dispensing
region of the second housing.
8. The method of claim 6, further comprising blocking an opening of
the second housing the first housing.
9. A method for performing fluid monitoring in a patient,
comprising: transferring fluid along a first fluid pathway from a
patient to a fluid dispenser; transferring a fluid sample from the
fluid dispenser to a transfer reservoir along a second fluid
pathway; severing the second fluid pathway by displacing the
transfer reservoir; actively transferring at least a portion of the
fluid sample from the transfer reservoir to a test substrate along
a third fluid pathway.
10. The method of claim 9, further comprising crossing an air gap
between the transfer reservoir and the test substrate with the
fluid sample.
11. The method of claim 9, wherein at least portion of the
cross-sectional shape of the fluid sample is unrestrained in a
transverse plane along a movement axis of the third fluid
pathway.
12. A method for performing blood monitoring of a patient,
comprising: withdrawing blood from a patient into a fluid control
system; dispensing a blood sample from the sterile fluid control
system to a sterile transfer reservoir; transferring the blood
sample from the sterile transfer reservoir to an non-sterile test
substrate.
13. The method of claim 12, moving the sterile transfer reservoir
with respect to the fluid control system after dispensing the blood
sample.
14. The method of claim 13, wherein moving the sterile reservoir
occurs before transferring the blood sample.
15. The method of claim 12, wherein transferring the blood sample
comprises pumping the blood sample from the sterile transfer
reservoir to a non-sterile test substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/731,010, filed Mar. 24, 2010, which claims benefit
under 35 U.S.C. .sctn.119(e) to U.S. Provisional Ser. No.
61/164,285, filed on Mar. 27, 2009, the contents of which are
herein incorporated by reference in their entirety for all
purposes.
BACKGROUND
[0002] In the health-care industry, diagnostic testing of
physiological or biological samples, such as blood, is a routine,
and often cumbersome, task, with physicians requiring a wide
variety of specialized tests on patients' samples to support their
diagnoses. With in-patient and critical care settings, the
frequency of blood sampling places additional demands on hospital
staff.
[0003] To satisfy this ever increasing demand for analytical data
from samples, sophisticated chemical analyzers have been developed
over the past 20 years to perform a multiplicity of physical and
chemical tests on specially prepared patients' samples. Sample
volume requirements have also been reduced substantially, to 100
.mu.L or less for some tests.
BRIEF SUMMARY
[0004] Devices and methods for automatic monitoring of fluid of a
patient are disclosed, comprising a patient line, a transfer disk
which receives the fluid and controllably transfers the fluid to
test substrates, and a sensor disk which houses the test
substrates. The sterile transfer disk may be configured to maintain
the sterility of the patient sampling assembly while transferring
samples to non-sterile components, such as the sensor disk.
[0005] One embodiment of a fluid sensor device may comprise at
least one transfer reservoir, wherein each transfer reservoir
comprises an inlet, and outlet, and a cavity comprising a
displaceable region and a light-reflecting structure. The transfer
device may also comprise at least one alignment structure
associated with each transfer reservoir.
[0006] Certain variations of a fluid sensor device may also
comprise a plurality of transfer reservoirs located in a transfer
structure. Other variations may comprise a plurality of test
substrates that are located inside a sensor structure, and/or
outside the transfer structure. In some embodiments, the sensor
structure is configured to attach to the transfer structure.
[0007] One embodiment of a fluid sensor device may comprise a
plurality of transfer reservoirs, where each reservoir may comprise
an optically transmissive material, an inlet opening, an outlet
opening, and a cavity comprising a deformable wall and a
light-reflecting structure, as well as a plurality of alignment
structures, wherein at least one alignment structure is associated
with each transfer reservoir.
[0008] In some embodiments of a fluid transfer reservoir, the
deformable walls of the plurality of transfer reservoirs are
deformable membranes. Optionally, the cavities of the plurality of
transfer reservoirs further comprise a fixed wall. Certain
embodiments of a fluid transfer reservoir are located in a circular
transfer housing wherein the inlet openings of the plurality of
transfer reservoirs are located on the outer circumferential
surface of the circular transfer housing. In some embodiments, the
transfer housing may be a circular transfer cartridge.
[0009] Additionally, the fluid sensor device may further comprise a
sensor housing interface, wherein the interface may comprise an
alignment structure and at least one locking structure. The sensor
housing interface may further comprise a plurality of sensor
substrate access apertures. In some embodiments, the fluid sensor
device may further comprise a sensor cartridge comprising a
transfer cartridge interface complementary to the sensor cartridge
of the transfer cartridge. Certain embodiments of the fluid sensor
device also comprise a plurality of test sensors.
[0010] Some embodiments of the sensor cartridge further comprise a
plurality of fluid sample receiving regions, a plurality of sensor
substrates and a plurality of sensor electrode contacts. The
plurality of fluid sample receiving regions are oriented to
correspond to inlet openings of transfer reservoirs when the
transfer cartridge and sensor cartridge are attached.
[0011] Another variation of a fluid monitoring system may comprise
a patient access interface configured to receive fluid from a
patient, a fluid pump configured to transfer fluid in the patient
access interface, and a valve coupled to the patient access
interface and the fluid pump and comprising a fluid dispensing
opening, wherein the valve is configured to dispose a fluid sample
at the fluid dispensing opening and a fluid inlet blocking
structure adjacent to the fluid dispensing opening.
[0012] The patient access interface, fluid pump, valve, and fluid
inlet blocking structure are coupled to a patient line housing. In
some embodiments, the fluid monitoring system further comprises an
external fluid access interface configured to receive fluid from an
external fluid source.
[0013] Several methods may be employed to monitor the fluid of a
patient, for example, the method may comprise withdrawing fluid
from a patient into a first housing coupled to a fluid monitoring
system, transferring a fluid sample from the withdrawn fluid in the
first housing to a second housing, changing the orientation of the
second housing relative to the first housing, pumping the fluid
sample from the second housing to a test substrate. Pumping the
fluid sample from the second housing to the test substrate may
comprise pumping the fluid sample across an air gap between a fluid
opening of the second housing and the test substrate. In other
variations, pumping the fluid sample from the second housing to the
test substrate may comprise pumping the fluid sample from the
second housing to a third housing, wherein the test substrate is
located in the third housing. The method may further comprise
wiping a dispensing region of the second housing, and may comprise
blocking an opening of the second housing the first housing.
[0014] Other methods for performing fluid monitoring in a patient
may comprise transferring fluid along a first fluid pathway from a
patient to a fluid dispenser, transferring a fluid sample from the
fluid dispenser to a transfer reservoir along a second fluid
pathway, severing the second fluid pathway by displacing the
transfer reservoir, and actively transferring at least a portion of
the fluid sample from the transfer reservoir to a test substrate
along a third fluid pathway. The method may further comprise
crossing an air gap between the transfer reservoir and the test
substrate with the fluid sample. In some variations, at least
portion of the cross-sectional shape of the fluid sample is
unrestrained in a transverse plane along a movement axis of the
third fluid pathway.
[0015] An alternate method for performing blood monitoring of a
patient may comprise withdrawing blood from a patient into a fluid
control system, dispensing a blood sample from the sterile fluid
control system to a sterile transfer reservoir, and transferring
the blood sample from the sterile transfer reservoir to a
non-sterile test substrate. The method may comprise moving the
sterile transfer reservoir with respect to the fluid control system
after dispensing the blood sample, wherein moving the sterile
reservoir occurs before transferring the blood sample. Transferring
the blood sample may comprise pumping the blood sample from the
sterile transfer reservoir to a non-sterile test substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 depicts a fluid monitoring system used to monitor
blood glucose levels in a patient.
[0017] FIGS. 2A-2C depict one embodiment of the housing of a
patient line (PL) cartridge.
[0018] FIGS. 2D-2F depict the arrangement of fluidic devices in the
PL cartridge of FIGS. 2A-2C.
[0019] FIGS. 2G-H depict one embodiment of a pressure sensor used
in the PL cartridge.
[0020] FIGS. 2I-2M depict one embodiment of a multiplexing valve
used in the PL cartridge.
[0021] FIG. 2M-1 illustrates one variation of the dispense nozzle
shape.
[0022] FIGS. 2N-2O depict a sequence of fluidic connections that
may be used by the fluid monitoring system during initialization,
sample collection, and sample dispensing.
[0023] FIG. 3 depicts one embodiment of a multi-component disk
assembly.
[0024] FIGS. 4A-4B depict one embodiment of the transfer disk that
may be used in a multi-component disk assembly.
[0025] FIGS. 4C-4E depict one embodiment of the transfer disk
structure.
[0026] FIGS. 4F-4G depict a pump mechanism that may be used to urge
a fluid sample in a transfer reservoir.
[0027] FIGS. 4H-4L depict various aspects and components of the
transfer disk structure, including the transfer reservoir, inlets
and outlets, and the total internal reflection minors and light
path for optical sensing of a fluid sample (e.g. blood).
[0028] FIGS. 5A-5B depict the components of one embodiment of a
sensor disk.
[0029] FIGS. 5C-5E depict one embodiment of the sensor disk
structure.
[0030] FIGS. 5F-5J depict various aspects of the sensor disk and
sensor interface.
[0031] FIG. 5K depicts an example of a shelf-life vs. humidity
curve.
[0032] FIG. 5L depicts an integration routine that may be used to
estimate the shelf-life of test sensors under changing humidity
conditions.
[0033] FIGS. 6A-6D depict various aspects of the interface between
a transfer disk and sensor disk.
[0034] FIG. 7 depicts a possible load configuration of the PL
cartridge and disk assembly.
[0035] FIGS. 8A-D depict different functional configurations (such
as dispense, withdraw, index, and wipe) of the PL cartridge and
disk assembly.
[0036] FIGS. 9A-9C depict the various mechanisms that regulate
fluid flow from the PL cartridge to the transfer disk to the sensor
disk.
[0037] FIGS. 10A-10C depict an example of sterile packaging for a
disk assembly component.
[0038] FIGS. 11A-11B depict a variation of the system interface for
the patient line and housing and disk assembly.
DETAILED DESCRIPTION
[0039] FIG. 1 schematically depicts one embodiment of an automated
fluid monitoring system. In this particular embodiment, the fluid
monitoring system is a blood monitoring system (165), but in other
embodiments, a fluid monitoring system may be used with other body
fluids or organ systems. The blood monitoring system (165) may be
organized into several components: a patient line (PL) and housing
assembly (195), a monitor assembly (167), a transfer and sensor
element such as disk assembly (188), and a flush and KVO ("keep
vein open" or "keep vessel open") fluid system (169). The patient
line and housing assembly (195), which may also be called the
patient access line (PAL) and housing assembly, comprises a fluid
access device (171) attachable to the patient (50) and a series of
fluid channels or pathways connecting the fluid access device (171)
to a fluid sample dispenser or dispense valve (173), a pump (198),
fluid system and other components. The fluid access device (171)
may be configured to access any of a variety of sites, including
but not limited to peripheral and central vascular access sites,
arterial and venous vascular sites, lymphatic sites, urinary tract
sites, cerebral spinal fluid sites in the spine and cranium,
intraabdominal and intrapleural fluid sites, etc.
[0040] A transfer element is a portion of the system that is
configured to transfer (either directly or indirectly through an
intermediary) a sample from a patient line to a sensor element. A
sensor element is a portion of the system that is configured to
sense at least one parameter of a transferred sample. One
embodiment of a transfer and sensor element is disk assembly (188)
in FIG. 1, comprising a transfer disk (196) and a sensor disk (190)
which includes a plurality of test sensors (161) with test
substrates (199). The transfer disk (196) may be locked into
engagement with sensor disk (190) when in use. Once locked
together, the transfer disk (196) and sensor disk (190) may not be
separated so that they cannot be reused and are generally disposed
of together after use. In other embodiments, the transfer and
sensor element may be an assembly of cassettes, cartridges, or may
be enclosed in a single housing. The transfer element or transfer
disk, or sensor element or sensor disk may comprise a variety of
shapes and/or configurations of test sensors or test substrates not
limited to a disk shape.
[0041] The transfer disk (196) in FIG. 1 provides a plurality of
fluid sample cavities or conduits (189) that separate and transport
a fluid sample (175) from the fluid sample dispenser (173) to a
test sensor substrate (199) of the sensor disk (190). The transfer
disk (196) further comprises a plurality of transfer pumps (197)
each corresponding to a conduit or cavity (189) and configured to
pump a sample from the conduit or cavity to a corresponding test
substrate. According to some embodiments, the transfer pumps
comprise deformable members which communicate with the conduit or
cavity (189). An enclosed cavity containing a sample opens towards
a test substrate (199). Upon deformation of the transfer pump
(197), the sample is pumped, displaced, transported or pushed
towards a test substrate (199). A pump actuator (197a) may be
separately controlled. In some embodiments, e.g., as illustrated,
the pump actuator is located on the monitor (167) and may be
mechanical or electrical in nature. It communicates via interface 1
with the control system (185).
[0042] By using a transfer disk (196) instead of directly
dispensing a fluid sample (175) to the test substrate (199), the
risk of contamination spreading or bridging back from the non
sterile sensor disk (190) to the sterile (or non-contaminated)
patient line and housing assembly (195) or the patient (50) may be
reduced. Also, by providing sterile, single-use intermediate
structures between the fluid sample dispenser (173) and the test
substrates (199), the test substrates (199) do not require
sterilization themselves, which may improve the shelf-life,
operating range, and/or operating performance of the chemicals or
reagents, if any, comprising the test substrates (199).
[0043] After transferring a fluid sample (175) to the sensor disk
(190), the fluid sample (175) may react with the chemicals,
reagents, or other components of a test substrate (199) and the
resulting end product is produced in proportion to the analyte
level in the fluid sample, which can then be analyzed by the
monitor assembly (167) to determine the analyte level or other
fluid parameter measurements. In the particular embodiment depicted
in FIG. 1, the blood monitoring system (165) is configured to
measure blood glucose using a blood glucose monitor ("BGM")
assembly of the monitor assembly (167), but in other embodiments,
other analyte or parameter measurement components may be provided
in addition or in lieu of the BGM.
[0044] As mentioned previously, the transfer disk and/or sensor
disk may comprise any of a variety of designs, including but not
limited to drums, carousels, clips, cassettes, or any other module
configured to interface or insert into another component. In some
embodiments, the patient line and housing assembly (195), the flush
and KVO fluid system (169), and/or the monitor assembly (167) may
also be in a cartridge or other swappable or modular form factor.
In some embodiments, two or more components may be integrated into
a single chassis or structure. In some embodiments, for example,
the transfer disk (196) and the sensor disk (190) may be integrated
into a single cartridge (disk assembly (188)), while in other
embodiments, the patient line and housing assembly (195) may be
integrated with one or more components of the flush and KVO fluid
system (169).
[0045] As depicted schematically in FIG. 1, the patient line and
housing assembly (195) comprises a main access line (177) from
which fluid may be withdrawn and/or infused with respect to the
patient (50). The main access line may include a luer lock (177a)
that may be connectable to a variety of types of fluid access
devices (171) or catheters such as peripherally inserted venous
catheters, peripherally inserted central catheters, central venous
catheters, or arterial lines. Accordingly the system may be
adaptable to connect to a catheter or other blood access device
already positioned in the patient. In this particular embodiment,
the main access line (177) includes an air in line detector (178).
The air in line detector (178) may be useful for safety purposes to
make sure that during any infusion or reinfusion procedures through
the main access line (177), limited air is being infused. The
patient line and housing assembly (195) may include a bubble
removal port which can be used to manually remove air bubbles or
take fluid samples from the patient line fluid circuit. The air in
line detector (178) may be an optical, acoustic, chemical, or
impedance-based detector, but any other detector design may also be
used.
[0046] The fluid dispenser (173) is used to dispense a fluid sample
or fluid droplet to the transfer disk. In the particular embodiment
depicted in FIG. 1, the fluid sample dispenser (173) is a dispense
valve, but in other embodiments, the fluid sample dispenser (173)
may comprise a membrane or a spray nozzle, for example. The fluid
sample dispenser (173) may be combined into one unit with a fluid
selector valve (181) as represented by bracket (111) in FIG. 1.
Fluid dispense valve (173) and fluid selector valve (181) may be
combined in a way that permits certain connection configurations
while prohibiting others. For example, the configuration of the
dispense-selector combination valve that allows the volume
reservoir (183) to be connected to the dispense valve nozzle would
simultaneously prevent any fluid connections between the syringe
and the KVO flush solution. The dispense-selector combination valve
may be arranged in any way to permit or prohibit fluid connections
as required by the operation of the fluid monitoring system.
[0047] The fluid sample dispenser (173) is connected to an optional
blood detector (180). The blood detector (180) may be used by the
monitor assembly (167) to determine whether blood has been
adequately withdrawn from the patient (50). For example, the
monitor assembly (167) may use blood detection as a pre-condition
for dispensing a fluid sample from the fluid sample dispenser
(173). This may be necessary to ensure that non-diluted blood has
reached the fluid sample dispenser (173) because the patient line
may be filled with flush solution prior to withdrawing a patient
sample. Also, in some instances, flow resistance and/or clotting
may reduce the blood flow in the blood monitoring system (165). By
providing a blood detector (180), the action of the pump (198) may
be adjusted to compensate for changes in fluid flow and/or to
provide a warning signal. In some instances, the monitor assembly
(167) may be configured to cease operation or initiate an
unclogging or other corrective procedure when certain operating
states are identified by the blood detector (180) or air in line
detector (178), for example. This is described in U.S. application
Ser. No. 11/386,078, which is hereby incorporated by reference in
its entirety. The blood detector may be an optical blood detector,
a chemical-based, acoustic-based, impedance-based, or other type of
detector. The fluid sample dispenser (173) also comprises an
actuator or motor for controlling the configuration or state (e.g.
open or closed) of the dispenser (173), and may also include one or
more sensors that may be used to detect dispenser malfunction or to
provide feedback to control valve function.
[0048] The blood detector (180) is connected to a fluid selector
valve (181) which is in fluid communication with a pressure sensor
(182). The fluid selector valve (181) is configured to selectively
provide communication between two or more of its ports. In this
embodiment, the pressure sensor (182) is shown positioned between
the syringe (198) and the valve (181). Various embodiments of the
fluid selector valve are described in greater detail below. In the
particular embodiment depicted in FIG. 1, the fluid selector valve
(181) in combination with the dispense valve (as indicated by
bracket (111)) comprises at least five ports. However, in other
embodiments, a greater or less number of ports and/or valves may be
provided and/or used. A pressure sensor (182) is positioned in the
tubing that runs between the syringe (198), selector valve (181)
and volume reservoir (183), but in other embodiments, one or more
pressure sensors may be connected in other locations in proximity
to the fluid selector valve (181), may be integrated with the
syringe pump, or may be positioned in-line along other portions of
the blood monitoring system (165) including but not limited to at
the catheter or fluid access site (171). As depicted, the ports of
the fluid selector valve (181) are connected to a pump (198) and a
flush and KVO solution (169). An optional fluid reservoir (183) is
also provided between the pressure sensor (182) and the blood
detector (180). In some instances, the fluid reservoir (183) may be
used to ensure that a sufficient volume within the patient line
fluid circuit exists to ensure that samples from the patient are
not able to contact the pump (198), pressure sensor (182) or fluid
selector valve (181). In other instances, the fluid reservoir (183)
may act as a sump which may reduce the precision needed for one or
more processes. In some embodiments, an additional port may be
provided for a waste disposal line or component. The waste disposal
line may be used, for example, for expelling clots or bubbles in
the blood monitoring system (165), and/or for clearing certain
types of fluids out of the fluid lines. The waste disposal may take
blood saline mixture out that is created when blood is drawn. This
may be used in particularly fluid sensitive patients or to avoid
infusing excess solution back into a patient. In one specific
example, the blood monitoring system (165) may include a cleansing
solution that is periodically infused into the system to resist
biofilm buildup and/or clot formation but is preferably not infused
into the patient. The waste disposal line may be used to expel the
cleansing solution from the system, along with additional flush
solution, from the fluid channels before restarting any KVO
infusion or fluid sampling. In other embodiments, a separate waste
disposal line and/or valve may be provided elsewhere along the
system.
[0049] The fluid selector valve (181) and/or the fluid sample
dispenser (173) may be manipulated by the monitor assembly (167)
using any of a variety of actuating mechanisms. These mechanisms
include but are not limited to a stepper motor, servo motor or
electromagnetic motor. The motor may be electric, hydraulic,
pneumatic or magnetic-based, or electro-magnetic, for example.
[0050] The pump (198) connected to the fluid selector valve (181)
may be any of a variety of pumps, including but not limited to a
syringe pumps, piston pumps, diaphragm pumps, peristaltic pumps,
and the like. The pump (198) may be bidirectional or
multidirectional. The pump (198) may be disposable. The pump (198)
may comprise an opening with which fluid may be withdrawn and
infused. In other embodiments, however, separate inlet and openings
may be provided.
[0051] In the particular embodiment illustrated in FIG. 1, a single
solution source is provided, comprising a flush and KVO solution
(169) to be used with the flush and KVO solution set (169). The
solution source may be connected to the blood monitoring system
(165) using a spike drip chamber (184) which is used with standard
intravenous fluid bags, but in other embodiments, any of a variety
of other fluid connectors may be used and multiple fluid sources
for multiple fluids or solutions may be used. The solutions that
may be used with the blood monitoring system (165) include but are
not limited to distilled water, normal saline, half-normal saline,
D5W, and Lactated Ringer's solution. In some embodiments, the
solution may contain one or more additives, including but not
limited to heparin, a heparinoid, potassium, magnesium, sodium
bicarbonate, multi-vitamin solution, anti-infectives such as
antibiotics and anti-fungal agents, for example, provided the
solution does not significantly interfere with the analyte to be
measured or provided the solution can be adequately be compensated
for when the analyte is measured.
[0052] The flush and KVO solution set (169) may be used to infuse
intravenous fluids into the patient (50) in between blood sampling
procedures. It may also be used to open an occlusion or venous
valve to improve blood draw. As noted previously, the flush and KVO
solution bag or source may be accessed using a spike drip chamber
(184) or other type of access device. Although characterized as a
"Keep-Vein-Open" solution set, higher infusion rates may be
provided also. For example, typical KVO (or TKO "To-Keep-Open")
infusion rates are about 50 mL/hour or less, but infusion rates
greater than 50 mL/hour may be provided. The higher rates may be
about 75 mL/hour, about 100 mL/hour, about 125 mL/hour, about 150
mL/hour, or more. The infusion rate may be an average rate or may
be delivered as a bolus or a plurality of boli over a period of
time.
[0053] The monitor assembly (167) comprises a control system (185)
or programmable logic controller that is configured to receive and
process sensor information and to control and coordinate a variety
of processes performed by the blood monitoring system (165). The
control system (185) receives data from a blood glucose monitor
("BGM") (186) through a BGM interface (16) which receives data from
read head (187) via interface (12). The BGM interface (16) and
other interfaces of the system (165) may be unidirectional (e.g.
input or output only, such as receiving data from the BGM) or
bi-directional (e.g. receiving data and transmitting control
signals to initiate a warm-up procedure or enter calibration or
maintenance mode, or to transmit other data, such as control
system, environmental, patient, or situational data, necessary for
the user or practitioner). The BGM (186) may be configured to
directly or indirectly analyze the test substrate (199). In the
embodiment depicted in FIG. 1, a read head (187) which is part of
the monitor (167) is positionable with respect to disk assembly
(188), to read the test substrate (199) and to communicate the
control system (185). According to some embodiments, an access
opening is provided for positioning the read head (187) adjacent
the test substrate (199). The interface (13) may be a connector or
a set of electrical contacts which allows the read head to read
from test substrate (199) when coupled thereto. The interface (11)
allows the control system (185) to control operation of the read
head (187). The BGM (186) may alternatively communicate with any
other system which would provide an intermediate structure between
the dispense valve (173) and the test substrates (199) or that
would allow reading of the test substrate (199) and communication
with the control system (185). According to some embodiments, a
humidity sensor (167j) is mounted in the monitor (167) adjacent to
the sensor disk (190). The humidity sensor communicates to control
system (185) via interface (27) which then may adjust the blood
glucose reading based on sensing humidity or humidity over time and
corresponding sensor sensitivity level. The humidity sensor (167j)
may also provide humidity sensor reading or readings that indicate
that a sensor is no longer sufficiently sensitive or accurate thus
signaling replacement of the disk assembly (188) is required.
According to some embodiments, the sensor life and/or accuracy
and/or precision is determined at different humidity levels. A
curve is created of the life or accuracy or precision of the sensor
based on humidity. Humidity at the sensor is monitored before and
during use. The humidity is integrated over time where the
integration is weighted depending on the sensitivity at the
different humidity levels. When the integrated humidity reaches a
level determined to be the limit where the sensor no longer
produces acceptable results, the monitor indicates replacement is
necessary. Alternatively, the monitor may adjust the output reading
to compensate for the humidity effects.
[0054] A disk assembly drive (191) is provided having an actuating
mechanism (e.g. a motor with a rotor) that provides movement and
positioning of the disk assembly (188) with respect to the monitor
(167) (including positioning of read head (187) and transfer pump
actuator (197a), with respect to a transfer pump (197) of a
transfer conduit or cavity (189) of the disk assembly (188)). The
disk assembly drive (191) advances, rotates, pivots or otherwise
manipulates the disk assembly (188) to select the desired conduit
or cavity (189) of the transfer disk (196) and corresponding test
substrate (199) of the sensor disk (190), into and out of a
dispensing position with respect to the fluid sample dispenser
(173). The disk assembly drive (191) provides for control and
selection of disk assembly (188) positions for purposes including
but not limited to dispensing to transfer conduit or cavity (189),
wiping or blotting the dispenser (173) with a wipe positioned on
the disk assembly (188), separating individual components from each
other or contacting individual components with each other, or
initiating a test sensor reading as well as checking test sensor
use status. In some embodiments, the interface (14) may also allow
the disk assembly drive (191) to transmit signals to the control
system (185) indicative of various operating parameters, for
example position of the disk assembly (188). The disk assembly
drive may be composed of a single acting mechanism driven directly
or indirectly by but not limited to a stepper motor, servo motor,
or DC motor. Alternatively the drive assembly may be comprised of
two or more assemblies, such as but not limited to a cam to provide
pivoting action and a spindle to provide rotary motion. Such
mechanism may be actuated by solenoids, DC motors, servo motors, or
stepper motors.
[0055] In the embodiment depicted in FIG. 1, the monitor assembly
(167) further comprises a electrical interface (4) between the
control system (185) and the pump (198). The configuration of the
software may vary, depending upon the desired functionality. For
example, the software may be configured to control the pump (198)
based upon plunger motion rate, plunger force, plunger home
position, plunger end position or any position therebetween. The
electrical interface may comprise any type of standardized
interface, or a proprietary interface. For some components, an
analog/digital converter may be provided in the component itself,
the signal interface and/or the control system (185). In
embodiments comprising an optional infusion pump for one or more
fluid sources connected to the blood monitoring system (165), an
infusion pump interface may also be provided.
[0056] The monitor assembly (167) may also comprise a distribution
valve interface (3) (or interface with multifunction valve, a
combination of distribution valve (181) and dispense valve (173)),
which transmits control signals to the mechanical drive of the
multi-port distribution valve or fluid selector valve (181), and
optionally transmits valve position information back to the control
system (185). A unidirectional or bidirectional interface may also
be provided for the fluid sample dispenser (173) to transmit
control signals and dispenser position information.
[0057] In embodiments comprising a stand-alone inline pressure
sensor or a pressure sensor integrated with the multi-port
distribution valve or fluid selector valve (181), a pressure sensor
interface (2) is provided to transmit pressure sensor information
to the control system (185). Other data input interfaces that may
be provided include but are not limited to the air detector
interface (6) and the blood detector interface (8).
[0058] In some embodiments, the monitor assembly (167) is
configured with sensors to detect the coupling and/or proper
seating of one or more components of the blood monitoring system
(165). For example, a patient line in place sensor (193) may be
provided to detect whether the patient line and housing assembly
(195) is in place. The control system (185) may use the sensor
(193) to check the status of the patient line and housing assembly
(195) before proceeding with its operation, or with certain
maintenance or corrective procedures. In some embodiments, a
releasable PL lock between the patient line and housing assembly
(195) and the monitor assembly (167) may be provided. The
releasable PL lock may form a mechanical interlock with the PL and
housing assembly (167) which is electronically releasable to
prevent removal of the patient line and housing assembly (195)
during operation or during certain procedures, and which may
protect the clinician, patient (50), and/or the blood monitoring
system (165) from damage. The transfer disk (196) may also be
provided with a transfer disk in place sensor (179) which
communicates with the control system (185) through signal interface
(15). The sensor disk (190) may also be provided with a sensor disk
in place sensor (192) which communicates with the control system
(185) through signal interface (7). An optional sensor or
communication interface may be provided between the PL and housing
assembly (195) and the disk assembly to confirm alignment between
the two components. Specific examples of the interface between the
disk assembly (188), the patient line and housing (195), and other
components are described below and also described in U.S.
application Ser. No. 12/057,245, which is hereby incorporated by
reference in its entirety.
[0059] In addition to detecting and identifying the placement of
modules in the blood monitoring system (165), a fill sensor (192a)
provided to detect when a cavity or conduit (189) has reached
maximum fill level. Conduit (189) may also be a cavity, conduit,
tube, well, sample reservoir, or other structure that may be used
to retain or contain a fluid sample. This prevents over and under
fill of the transfer conduit so that it is assured that the fluid
sample from the patient does not over fill the conduit and bridge
to a non-sterile component before the dispense valve (173) is
withdrawn from contact with the transfer disk (196). In addition,
the fill sensor may provide feedback that the well has been filled
adequately by the pump so as to ensure successful transfer of fluid
from the transfer disk to the test substrate or test sensor. In
addition, the pressure sensor may be used prior to dispensing to
determine if the fluid is at a pressure is stable and/or close to
ambient pressure or offset from ambient pressure by a given amount
thus providing a more controlled or reliable dispense of fluid.
[0060] A variety of sensors may be used including, e.g. an
optically transmissive, optically reflective, electrically
conductive or capacitive sensor. The sensors may be separate
elements, a plurality of elements, and/or may be integral with the
disk. The test sensor may be single use. It may be pre-calibrated,
e.g. to permit ease of use. A control solution, e.g., of a known
analyte concentration, may be positioned in one of the test sensor
locations and may be used to determine at time of used of sensor
element the efficacy of the sensors. For example, if the
sensitivity of a sensor has changed during transportation, or over
time, the sensor reading may be compared with sensitivity that is
input into the RFID tag at time of manufacture, packaging or
transport. The sensor readings may be corrected accordingly or an
indication may be provided if the sensor disk should be replaced.
The fill sensor (192a) may communicate via interface (15) with
control system (185). The fill sensor (192a) communicates with the
control system via interface (5).
[0061] In addition to detecting and identifying the placement of
modules in the blood monitoring system (165), door sensors (167f)
may also be provided to detect when one or more access doors of the
system (165) have been opened. In some embodiments, detection of
open access doors may stop or limit operation to protect against
danger to the patient, the clinician, or to the equipment or warn
the user to close the door to maintain the integrity of the chamber
within the monitoring system (165).
[0062] In some embodiments, one or more components or modules of
the blood monitoring system (165) may comprise machine readable
indicia that may be relayed to the control system (185) using an
indicia reader and may be used to provide information concerning
the particular component or module. The indicia reader may be, for
example, a barcode reader, a radiofrequency ID (RFID) chip reader
(194a), and/or an electrical connection to an EPROM or other chip
located on one of the consumable components (e.g., the transfer
disk, sensor disk or patient line). The machine readable indicia
may comprise graphical indicia such as a barcode, or intangible
indicia such as an RFID chip (194). In some embodiments, the
information may comprise serial numbers or arbitrary identification
information that may be compared to a database within the control
system (185) to confirm that the correct type of cartridge was
inserted, and/or to configure the blood monitoring system (165). In
other embodiments, the machine readable indicia may include
configuration information, such as calibration curves or threshold
values that may be used to configure the control system (185)
and/or BGM (186) without utilizing a look-up database. With the
latter embodiments, the software of the control system (185) does
not require updating in order to utilize a new type of test
substrate cartridge, because the configuration and/or calibration
information may be provided through the machine readable indicia.
In some embodiments, the monitoring system (165) may be configured
so that the machine readable indicia of a cartridge or module may
be read by the control system (185) before the cartridge is fully
seated and locked into place. If the control system (185)
identifies the particular cartridge or module as an incorrect
module (e.g. wrong patient, incompatible with the particular PL and
housing assembly (195) or with the selected monitoring function),
in some embodiments, the control system (185) may control the
module locks to block their seating or insertion into the
monitoring system (165), or by rejecting via a screen alarm is
detected after seating in place. In some embodiments, the control
system (185) may comprise a separate indicia writer, or a writing
function may be integrated into the indicia reader. The writing
function may permit, for example, an RFID chip to be programmed to
flag the cartridge as having been used, with or without patient
information or for patient-specific, operational use, or error
information to be written to the RFID chip for later analysis,
documentation, or troubleshooting by the user or manufacturer. The
writing function may also prevent inadvertent use of an incorrect
cartridge or module. In other embodiments, the writing function may
be provided by barcode printer which prints and applies printing,
e.g. inkjetting, a new barcode on the cartridge or module.
[0063] In addition to the interfacing with other components of the
blood monitoring system (165), the monitor assembly (167) may
further comprise one or more subcomponents for interfacing with
medical staff, medical information systems or other extrinsic
systems. In the embodiment depicted in FIG. 1, these subcomponents
may include a graphics display of text (167a) and/or pictorial
information (e.g. graphical plots) of patient related information
and/or system status information, other types of indicator lights
(167c) (e.g. LEDs), operator input devices (167b) (e.g. keyboard,
touch screen, joystick, mouse, buttons, dials, bar code reader), a
hospital information system port (167d) (e.g. for transmitting
information to a remote patient monitor at a nursing station and/or
for storing results in an electronic medical record), one or more
external patient sensors (194b) communicating with an external
sensor interface (167k) (e.g. wirelessly or through a connection or
other intermediate communication device), a diagnostic port to
perform maintenance updates or diagnostic checks of the system or
software, environmental sensors (167h) (e.g. temperature,
barometric pressure detectors), auditory/visual/tactile alarms for
patient/environmental/system-related warnings/fault states (167e),
and power/battery status monitors or sensors (167g). Data
interfaces (9, 10, 17, 18, 19, 20, 21, 22, 23, 24, 25 and 26) may
be provided for the respective components. The data interfaces for
these components may be unidirectional or bidirectional. The data
interface (26) for the hospital information system port, for
example, may transmit patient and/or system data out of the port,
but may also receive data from the external information system
(e.g. signal to change system function, or to alter the type or
presentation of patient and/or system data). The external patient
sensor may include a sensor apparatus that is configured to sense
or determine one or more parameter corresponding to a patient or
patient treatment, such as, e.g., patient temperature or limb
temperature, heart rate, pulse, EKG, blood pressure, respiration
rate, blood gas level (e.g., oxygen or carbon dioxide, e.g., via
pulse oximetry or an indwelling catheter), Hematocrit, blood
viscosity, drug type, drug dosing or infusion rates, or other
parameters. The sensed patient parameter and/or environmental, room
temperature, humidity information may be used to adjust patient
draw parameters, adjust glucose or other measurements made at
sensor disk or to improve accuracy or precision of readings by the
blood glucose or other analyte monitor.
[0064] In some embodiments, one or more of the subcomponents may
provide instructions or instructional indicia to a person, for
example, to perform a check or other procedure (e.g. check for a
clog or air in the fluid line, replace empty IV bag or test sensor
cartridge). In some embodiments of the blood monitoring system
where the manipulation of fluid samples or fluid droplets is
gravity dependent, the monitor assembly (167) may comprise a tilt
detector (167i) which may provide a warning when the system (165)
is not adequately level, or may even provide specific auditory
and/or visual instructions to adjust specific feet, or supports of
the system, up or down to achieve the desired leveling. In other
embodiments, the control system may comprise motors or other
mechanisms to automate procedures such as leveling, cartridge
change or IV bag change, for example.
Patient Line and Housing
[0065] As mentioned previously, certain components of the fluid
monitoring system may be provided in removable housings and/or
cartridges, which may facilitate replacement of disposable
components and/or sterilization of reusable components. A cartridge
may refer to any unit, cassette, drum, or assembly of parts, which
may be enclosed in a housing. Some variations of the patient line
and housing (195) in FIG. 1 may comprise a number of system
components found between the patient and the sensor substrate. One
specific embodiment of a PL and housing (200) is shown in FIGS. 2A
and 2B. The housing (201) is made of a co-polyester blend, but may
be made of any material with similar properties, such as
polycarbonate or acrylic. PL cartridge (200) may comprise one or
more connectors that transfer fluid in and/or out of the cartridge.
Here, fluid connectors (202) and (204) are provided to connect PL
cartridge (200) to components of the fluid monitoring system, such
as the KVO and flush solution reservoir (169), or the fluid access
device (171), which is attached to the patient (50). In other
embodiments, additional connectors may be provided for additional
fluid lines, separate flush solutions, optional waste circuits,
and/or intravascular hemodynamic monitoring sensors, for example. A
dispensing valve (206) transfers fluid samples obtained from the
patient (50) to the other components of system, such as the
transfer cartridge or sensor cartridge that are described in
greater detail below. The PL cartridge (200) may also comprise
other structures which may facilitate or coordinate fluid transfer
to the other components or between other components, such as the
fluid channel plug (224), which is described in greater detail
below.
[0066] PL cartridge (200) may comprise several alignment features.
These alignment features may be used to ensure correction
positioning and alignment with respect to other system components.
For example, alignment protrusions (207b) and (207d) may be used to
mechanically align the PL cartridge to the monitor during
installation and use. In some embodiments, mechanical interlock
features may be temporary, so that the PL cartridge may be removed
and/or disposed after use. Apertures may also be provided for
alignment, which are described in detail below.
[0067] PL cartridge (200) may comprise mechanical and electrical
interfaces that allow the fluid monitoring system to control and
acquire data from certain components within the PL cartridge (200)
and acquire data from the cartridge (200). There may be various
apertures in the housing (201), for example, aperture (203) which
may facilitate the handling of the PL cartridge (200). Aperture
(205) may be sized and shaped to permit the insertion and actuation
of a pump, for example, a syringe pump. Additional apertures may be
included to allow actuators to manipulate the components of PL
cartridge (200) for example, as described in some variations
herein. In some variations, there may be apertures that allow
mechanical sub components within the PL cartridge to manipulate
external structures. Some variations of the PL cartridge may
comprise apertures in the back of the housing (201), as shown in
FIG. 2C. These apertures (227, 218, 220, 229) may provide access to
the internal components of the PL cartridge, as well as engage with
alignment protrusions. For example, apertures (227, 218, 220, 229)
may allow sensors (e.g. optical sensors) to access the contents of
the fluid channels in the housing (201). In some variations, access
apertures (227, 218, 220, 229) may be located in the front of the
housing (201). Apertures (207b) and (207d) may form a mechanical
interface with protrusions on the fluid monitoring system, to align
and secure the PL cartridge within the system. Access apertures
(227, 218, 220, 229) may also be used to aid in debugging the PL
cartridge (200) if a malfunction occurs. Assembly apertures, for
example, holes (207a) and (209b), may be provided as junction
points to secure multiple components together. Holes (207a) and
(209b) may be sized and shaped to accommodate screws and connectors
to secure the components of PL cartridge (200).
[0068] The PL cartridge (200) may also comprise an electrical
interface that provides power to the components in the cartridge.
This electrical interface may also allow commands to be issued from
the control system (185) to the PL cartridge, and for data readings
(e.g. from various sensors) to be transmitted back to the control
system. For example, control system (185) may probe an internal
sensor (e.g. a pressure sensor) using an electrical interface
(219), as shown in FIG. 2C. Different sensors may use a variety of
interfaces, e.g., any standard or proprietary interface, electrical
or otherwise, to communicate between the PL cartridge and the
control system, as shown in FIG. 1.
[0069] The connectors, apertures, and electrical interfaces
described above may be covered prior to their installation and use
within the fluid monitoring system. For example, cover (208) may be
locked onto the PL cartridge prior to installation by attaching to
retention features (223a) and (223b), and may only be unlocked when
properly installed in the fluid monitoring system. Covers may also
be temporarily attached to the housing (201) by adhesives,
hook-and-loop fasteners, static cling, or any suitable bonding
method. The covers may be rigid or flexible, depending on its
material composition. Covers (e.g. cover (208)) may optionally be
used to align the PL cartridge during assembly and installation.
Some variations of the PL cartridge (200) may include such covers
to reduce contaminants from entering the apertures, protect
connectors and other protruding features from damage, and to guard
against device tampering. Other fluid monitoring system components,
such as the disposable elements, may also comprise such covers.
[0070] Referring to FIGS. 2C and 2D, the fluid flow between the
patient and the sensor substrate may be managed using any number of
tubes, valves, connectors, and pumps arranged in any suitable
configuration. In PL cartridge (200), the fluid-regulating system
comprises a pump (210), tubing (214), a pressure sensor (216),
fluid reservoir (222), and fluid dispensing or multiplexing valve
(206). These fluidic devices may be placed in any suitable position
in the PL cartridge, an example of which is shown in FIG. 2D. These
devices may also be interconnected by a tubing assembly (214) in
any suitable configuration, as shown in FIG. 2E. In certain
variations, connector (202) and the tubing running from it may
connect the KVO and/or flush solution (169) to the multiplexing
valve (206). Connector (204) and the associated tubing may
connector the patient device (171) to the multiplexing valve (206).
The tubing assembly (214) may also provide connectivity between the
pump (210) and the fluid reservoir (222) and multiplexing valve
(206). Tubing assembly (214) may also provide connectivity between
the fluid reservoir (222) and the multiplexing valve (206). While
the tubing assembly (214) provides general connectivity between
these fluidic devices, the fluid connections may change during the
use of the monitoring system and is managed by the control system
(185). The control system may actuate the multiplexing valve (206)
to select for certain fluid connections, and may also actuate the
pump (210) to encourage fluid flow to or from the connected
components.
Syringe Pump
[0071] The fluid flow through the PL cartridge (200) may be
controlled by a variety of pumps, for example, infusion pumps,
centrifugal pumps, piston pumps, diaphragm pumps, syringe pumps,
peristaltic pumps, and the like. In one variation of a PL
cartridge, a syringe pump (210) is used to regulate fluid flow, as
shown in FIG. 2D. The plunger (211) of the syringe pump may extend
out of the housing through aperture (205) and may be actuated by
either an external or internal component, such as a lever or motor,
which is controlled by the control system (185). The size of the
syringe (210) may vary as needed. For example, a syringe pump in a
blood monitoring system that monitors one blood analyte may need to
regulate 5-10 mL of blood. A syringe pump in a blood monitoring
system that monitors multiple blood analytes or process several
fluids may need to regulate more than 10 mL of blood. The pressure
gradient created by the syringe (210) may be used to move fluid
into, out of, and within the tubing assembly (214). For example,
the pressure gradient created by the syringe pump (210) may be used
to draw fluid from (or pump fluid to) an external fluid source,
such as the patient (50) or the KVO solution (169). The syringe
pump (210) may also be used to move fluid from the fluid reservoir
(222) to the multiplexing valve (206). In certain variations, the
syringe pump may be sterilized prior to installation and use, and
made of materials that can withstand the sterilization procedure,
such that reliability is not compromised. The interface between the
pump and the fluid tubing may vary depending on the pump type. For
example, a luer lock (212) may act as the junction between syringe
pump (210) and PL cartridge tubing assembly (214), however any
locking interface that is fluid-tight (either through a locking
mechanism or by bonding) may be used. In the variation of the PL
cartridge shown in FIGS. 2D and 2E, the body of the syringe pump
(210) is enclosed by the fluid reservoir (222), however, the pump
(210) may be positioned elsewhere, and not necessarily enclosed by
the fluid reservoir (222).
Fluid Reservoir
[0072] Certain variations may have a fluid reservoir (222). In some
instances, the fluid reservoir (222) is used to ensure that
sufficient volume within the PL fluid circuit exists to ensure that
samples from the patient are not able to contact the pump (210),
pressure sensor (216), or other components. Alternatively, fluid
reservoir (222) may act as a sump and reduce the precision needed
for one or more processes. The fluid reservoir may be of any
suitable configuration such that an excess of fluid may be stored
therein and readily drawn for testing. In some variations, the
fluid reservoir may be a container, and in other variations, the
fluid reservoir may be an extension of tubing assembly (214), for
example, a coil of tubing. As shown in FIG. 2E, the fluid reservoir
is connected by the tubing assembly (214) to the multiplexing valve
(206) and the pressure sensor (216), however in other variations,
the fluid reservoir may be connected to any number of PL cartridge
components in any suitable way. Fluid reservoir (222) and PL
cartridge tubing (214) may be manufactured from any of a variety of
biocompatible material, such as a variety of polymers (e.g. PVC,
polycarbonate, polyethylene, polypropylene, polyurethane, silicone,
etc) and/or metal alloys (e.g. stainless steel, Nitinol, cobalt
chrome, etc), and may optionally be medical grade and sterile. In
some variations, tubing assembly (214) and/or reservoir (222) may
be pre-molded from polymeric or metallic materials. The interior of
tubing assembly (214) and reservoir (222) may be formed to
facilitate fluid flow. For example, the interior of the tubing and
the reservoir may contain microstructures that reduce fluid
resistance and drag. The interior may also be coated with an agent
(e.g. an anti-thrombotic agent) to reduce the likelihood of tube
obstructions, and/or reduce the friction of the internal surface of
the tube.
Blood Sensor, Air-in-Line Sensor and Humidity Sensor
[0073] In some variations, several types of sensors may be used
with the PL cartridge, including but not limited to optical
sensors. As described previously and shown in FIG. 1, a fluid
monitoring system may include sensors that detect the presence of
fluid or air in the tubing, or sensors that may discern one fluid
from another. For example, in a blood monitoring system, there may
be blood detectors (180) and air-in-line sensors (178). In other
variations, there may be a sensor that detects specific analytes in
the blood and can detect blood hematocrit. Furthermore, there may
be a sensor that determines when whole, undiluted blood has reached
a specific point in the fluid circuit. In some embodiments, this
sensor may be an optical blood sensor, though alternate devices and
methods may be used to detect whole, undiluted blood. These sensors
are accommodated either within the PL or in the fluid monitoring
system external to the cartridge. External sensors (such as optical
sensors) may access the environment in PL cartridge and the fluid
sample through access apertures, such as the ones described in FIG.
2C (apertures (218), (220), and (229)). Non-optical sensors that
detect temperature, humidity, and the like may also be used to
measure any number of conditions in the PL cartridge. The data from
these sensors may be transmitted to the control system (185) so
that the appropriate parameters may be adjusted according to the
changing conditions.
Pressure Sensor
[0074] The PL cartridge (200) may also comprise at least one sensor
that is in direct contact with the fluid in tubing assembly (214),
for example, a pressure sensor (216). As shown in FIGS. 2G and 2H,
pressure sensor (216) contacts the fluid sample via an aperture
(213) of a T-shape tubing connector (215). An O-ring (217) is used
to secure the junction between tubing connector (215) and pressure
sensor (216) to prevent fluid leakage. Latches (221) may be used to
connect or couple the T-shape tubing connector (215), O-ring (217)
and pressure sensor (216) together, though other methods of secure
attachment may be used. Other methods of providing fluid access to
a pressure sensor may be used, such as bonding the tubing directly
to the pressure sensor, or using a pressure sensor that may be
placed in-line with the tubing. The pressure sensor (216) in FIG.
2G also has an electrical interface (219) that allows the control
system (185) to read an electrical measurement from the pressure
sensor. The electrical measurement is then correlated to a known
pressure value, by means of the monitor (167), to determine a
pressure measurement from the PL cartridge. Any interface,
mechanical or electrical, may be used to send a signal that
indicates system pressure to the control system. In other
variations of the PL cartridge, other types of sensors may also
utilize direct contact with the fluid in the tubing assembly, for
example, electrochemical, pH, and temperature sensors.
Dispense/Selector Valve
[0075] The connectivity between the components of the PL cartridge
may be regulated by at least one multiplexing valve. As previously
described, the multiplexing valve may be a combination (111) of the
fluid selector valve (181) and dispense valve (173) shown in FIG.
1. A multiplexing valve may be adjusted to different configurations
to allow the application of positive or negative pressure from a
pump to distribute fluid to various regions of the tubing assembly.
In some variations, there may be a plurality of multiplexing
valves. One example of a multiplexing valve (206) is illustrated in
FIGS. 2I-2M.
[0076] Some variations of a multiplexing valve are formed from an
assembly of components. For example, multiplexing valve (206) in
FIG. 2J comprises a valve body (240), valve core (250), and valve
plug (260). The valve body (240) has plurality of ports that may
interface with tubing, for example, inlet ports (241), (242),
(243), and (244), a dispense nozzle (246). Some variations may have
an alignment protrusion (248) to precisely position the valve body
with respect to other components of the fluid monitoring system.
Valve body (240) in FIGS. 2I and 2J is tubular, and contains the
valve core (250) within its lumen. The valve core (250) is tubular,
and contains a valve plug (260) within its lumen. In some
variations of a multiplexing valve assembly, the valve plug (260)
is not rotatable within the lumen of the valve core (250), but the
valve core (250) is rotatable within the lumen of the valve body
(240). The rotation of the valve core (250) within the valve body
determines the connectivity between the inlets (241), (242), (243),
(244), and dispense nozzle (246).
[0077] In certain variations, grooves or conduits on the valve core
(250) and/or valve plug (260) form conduits that connected the
inlets on the valve body. For example, in FIG. 2K, groove (252) on
the valve core forms the conduit between inlets (241) and (242).
Bores (254a) and (254b) of valve core (250) are aligned in a fixed
position with groove (262) on the valve plug (260) and form a
conduit between inlets (243) and (244). The orientation of groove
(252) is offset with respect to the conduit formed by bores (254a),
(254b), and groove (262) so that only one fluid connection is made
at a time (e.g. either inlets (241) and (242) are connected, or
inlets (243) and (244) are connected). However, in other variations
of a valve assembly, the orientation of the plurality of conduits
with respect to each other may vary such that one or more
connections may be made at a time depending on the particular
embodiment of fluid transfer system.
[0078] The connectivity between inlets (241) and (242) may be
adjusted by rotating the valve core (250), as shown in the Y-Y
cross-section of the valve assembly (250) in FIG. 2L. Inlets (241)
and (242) are connected when groove (252) on valve core (250) is
positioned to contact both inlets, such that the groove space is
continuous with the inlets. When the groove (252) is in a position
where only one or none of the inlets are contacted, then the inlets
are not connected. In this variation, inlet (241) is connected to
the syringe pump (211), and inlet (242) is connected to the KVO and
flush solution (169), as shown in FIG. 2E. When inlets (241) and
(242) are connected via groove (252), the syringe pump is connected
to the KVO and flush solution reservoir. In other variations of the
PL cartridge, the inlets may be connected to fluidic components as
appropriate.
[0079] The connectivity between inlets (243), (244), and dispense
nozzle (246) may be adjusted by rotating the valve core (250), as
shown in the X-X cross-section in FIG. 2M. There are three
connection states for this multiplexing function: inlet (243) and
inlet (244) are connected, or inlet (243) and dispense nozzle (246)
are connected, or none of them are connected. Note that in this
variation of the multiplexing valve (206), during operation, the
dispense nozzle (246) may not be connected to inlet (244), however,
in other variations, this connection state may be used. The
connection state is adjusted by rotating the valve core (250) so
that the bores (254a) and (254b) (which are aligned with groove
(262) in the valve plug) contact the desired inlets. In this
variation, inlet (243) is connected to fluid reservoir (222) and
inlet (244) is connected to the fluid access device (171), and the
dispense nozzle (246) transfers fluid to the disk assembly. In
alternate variations, other fluidic components may be connected to
the inlets.
[0080] The tip of a dispense nozzle may be any suitable geometry
that is configured to limit fluid sample adhesion to the dispense
nozzle surface. The tip of the nozzle may be configured to reduce
wetting of the outside of the nozzle and/or to maintain a sterile
fluid path with the patient or avoid contamination of one or more
components of the system. FIG. 2M-1 is an enlarged view of the
dispense nozzle (246) shown in FIG. 2M. In this variation, the tip
(233) of the nozzle (246) is hemispheric, intersecting with a
straight edge to form an abrupt sharp edge (231). The sharp edge
(231) may break the fluid tension relative to the hemispheric
surface, which may provide a controlled delivery of fluid, and
reduce loss of fluid or sterility by wetting out. Optionally, the
dispense valve and/or nozzle may be coated with an anti-adhesion
agent, e.g. an anti-coagulant agent, to ensure effective throughput
of the fluid sample.
[0081] In this variation of the PL cartridge and several of its
components shown in FIGS. 2E-2M, the multiplexing valve (206)
regulates the connection between the syringe pump (210), KVO and
flush solution (169), fluid access device (171), fluid reservoir
(222), and dispense nozzle (246), as schematically represented in
FIG. 2N. FIG. 2O illustrates an example of a series of connections
(270) that may be made to obtain a blood sample from a patient via
fluid access device (171) for glucose testing. In step (271a), the
system is primed by drawing KVO solution (169) into the syringe
(210). Then at step (271b), the fluid is pumped from the syringe
(210) through the reservoir (222) to the patient access interface
of the tubing. These steps (271a) and (271b) be may be repeated
until the system is primed. At step (271c), the KVO solution is
drawn into the syringe. In step (272), the fluid access device
(171) and syringe are connected through reservoir (222), and a
blood sample is drawn from the patient towards and some times into
the reservoir (222). In this connection configuration, the
monitoring system may poll the blood detector to determine if the
fluid in the tubing assembly (214) is undiluted blood. If not, then
the system may draw more blood from the patient until the blood
detector indicates that the blood sample in the fluid circuit is an
undiluted sample. If so, then the monitoring system may proceed to
step (274). At step (274), the syringe (210) is connected to the
dispense valve through the reservoir (222), and the blood sample is
dispensed for testing by pumping KVO solution towards the reservoir
(222) to move the blood sample out of the dispense nozzle. In step
(276), the syringe (210) is coupled to the fluid access device
(171) through the reservoir (222) and any excess blood and solution
mixed with blood that may be in the reservoir is returned to the
patient (or alternatively or in part, moved to a waste port through
a valve in the tubing path (not shown)). At step (278), more saline
fluid is pulled into the syringe. At step (280), the fluid is
pushed from the syringe (210) through the reservoir (222) to the
fluid access device at a selected KVO rate until blood is to be
drawn again. When blood is to be drawn again, the system may return
to step (272). Other connection and pump sequences may also be used
to perform analogous tasks.
[0082] Some variations of the multiplexing valve may be rotated to
a load configuration after it is manufactured, but before it is
used in a fluid monitoring system for the first time. The load
configuration is a valve configuration that is not used (and not
rotated through) in normal operation of the fluid monitoring
system. During the manufacturing process, the multiplexing valve
may be imposed into this load configuration using hard stops molded
into the valve components. In some variations of a fluid monitoring
system, the PL cartridge may be loaded only if the multiplexing
valve is in the load configuration. In the absence of a PL
cartridge, the fluid monitoring system will transition to a load
state, which is a pre-programmed and known configuration that will
only interlock with a PL cartridge where the multiplexing valve is
also in a load configuration. If the multiplexing valve of the PL
cartridge is not a load configuration, then the cartridge cannot be
installed in the system. Such a mechanical interlock between the
multiplexing valve and the fluid monitoring system in the load
state may act to prevent inappropriate installation of the PL
cartridge. For example, this feature may prevent the reuse of a PL
cartridge, since the multiplexing valve of a used PL cartridge is
not in a load configuration. In some variations, the multiplexing
valve may contain a "lock-out" feature which prevents the valve
from inappropriately being rotated back to the load configuration
after it has been removed from the fluid monitoring device.
Fluid Channel Plug
[0083] Some variations of a PL cartridge may also comprise a
mechanism that ensures that the fluid sample transferred from the
dispense nozzle to the input port of the disk assembly proceeds
towards the test substrate in the disk assembly, and does not flow
back through the fluid channel in the transfer disk. One variation
of such a mechanism is a fluid channel plug (224), shown in FIGS.
2A-2F, which is sized and shaped to obstruct the input port of the
transfer disk. The fluid channel plug (224) may be made of any
fluid impermeable material, and may be actuated in any suitable
direction. Other mechanisms may also be used to obstruct the input
port of the disk assembly. For example, the input port may be
sealed off with an impermeable membrane, pinched shut with a clip,
blocked with a rigid cover, or occluded with an inflatable member.
Obstruction of the input port may prevent the spread of any
contaminants between the disk assembly and PL cartridge, and may
acts to urge the blood sample towards the test substrate.
Disk Assembly
[0084] As shown in FIG. 1, some variations of the automated fluid
monitoring system may comprise a transfer and sensor element, such
as disk assembly (188) that receives the fluid sample from the PL
cartridge and directs the fluid to sensors (161) which may be
provided in the disk assembly (188). Disk assembly (188) may
contain any number of functional modules that perform some or all
of the tasks used to receive the sample for testing. For example,
the disk assembly may comprise a single cartridge or housing that
receives the sample from the PL cartridge and channels it to the
test substrate, which may have an interface suitable for the
control system to read out the test result. In some variations, the
disk assembly may comprise two or more functional elements, such as
individual cassettes, drums, cartridges, or disks. Multiple
functional elements may be provided to house and separate
components undergoing sterilization or those with other different
handling requirements, for example. Thus, individual components
that require sterilization may be sterilized, without sterilizing
the entire disk assembly. For example, a portion of the disk
assembly that may be momentarily in fluid contact with a patient's
circulatory system may be sterilized, but other components of the
disk assembly that do not come into fluid contact with a patient
may or may not be sterilized. In some examples, limiting or
avoiding sterilization of the sensors (or other components) may
prolong the shelf-life or maintain the accuracy of a sensor or a
test substrate. A multi-disk assembly may maintain test substrate
and/or sensor sensitivity while reducing the risk of contamination
to the patient. An example of such a disk assembly is illustrated
in FIG. 3. In certain variations, as depicted in FIG. 3, the disk
assembly (300) may comprise at least two components, such as a
fluid transfer disk (302) and a test sensor disk (304). The
transfer disk (302) and the sensor disk (304) are configured to
work in concert to receive a sample for testing. The transfer disk
(302) receives the fluid sample from the PL cartridge, and
transfers it to the sensor disk (304) for testing.
Transfer Disk
[0085] As shown in FIG. 1, the transfer disk (196) may be a
separate component of the disk assembly (188). A fluid transfer
component of the disk assembly, such as the transfer disk (302)
shown in FIGS. 4A and 4B, is configured to receive the fluid sample
from the PL cartridge, and may be particularly configured to
transfer fluid from a sterile source to a non sterile environment
without contaminating the sterile source. In other embodiments of
the disk assembly, the transfer component may also be a cassette or
cartridge. The transfer disk may comprise a pump and pump actuator
that may be a deformable member. As depicted in FIG. 4A, the
transfer disk (302) comprises a deformable membrane (402), a wipe
assembly (404), and a transfer disk structure (406). These three
components may be bonded together with an adhesive, where the wipes
(405) may be bonded to the outer perimeter of the transfer disk
structure (406). Alternatively, the three components may be bonded
together by means such as welding or vulcanizing one or more
materials to the other materials. The deformable membrane (402) is
overlaid in a way to provide a fluid-tight seal to the transfer
reservoirs (408), and may be made of any fluid impermeable,
compliant material, such as silicone, latex, urethane, and/or
thinly hammered metal alloy or polymer. In some variations, the
transfer reservoirs (408) are arranged around the outer
circumference of the transfer disk structure (406), and the
membrane is sized and shaped to cover the open side of the transfer
reservoirs (408), which may form individual fluid displacement
elements operatively coupled to each reservoir (408). The transfer
disk structure (406) is made of molded acrylic, but may be made of
any material with similar structural and optical properties. Wipes
(405) may be evenly spaced around the outer edge of transfer disk
structure (406), and arranged to contact the dispense nozzle (246)
during use. The transfer disk structure (406) may comprise an
interface that allows the control system to read out from the test
sensors of the sensor disk, for example, apertures (410) may be
sized and positioned according to the size and positions of the
test sensors on the sensor disk, which may be adjacent to the
transfer disk. Apertures (412a-b), indentation (413), and latches
(415) are structures that may be used to align the transfer disk to
the other components of the fluid monitoring system, and to secure
and lock the transfer disk in place for use. These features will be
described in detail below.
[0086] As shown in FIG. 1, transfer disk (196) may comprise a
plurality of fluid sample cavities (189) that separate and
transport a fluid sample. One variation of a transfer disk
comprises a transfer disk structure (406) as shown in FIG. 4C.
Transfer disk structure (406) may comprise a plurality of transfer
reservoirs (408), such as the 25 transfer reservoirs, but in other
variations, any other number of transfer reservoirs may be
provided, including but not limited to at least (or no more than)
about 5, about 10, about 15, about 20, or about 30 transfer
reservoirs. Reservoirs may be disposed in a circular pattern on the
disk or may be disposed in 2 or more coaxial circular patterns so
that multiple reservoirs exist at 2 or more radial positions along
each radius line, thus increasing the capacity of reservoirs on the
disk by two fold or three fold. Each transfer reservoir (408) may
have an inlet (416), which receives the fluid sample from the PL
cartridge dispense nozzle (246), and an outlet (418) which allows
the sample to be transferred to the sensor disk for testing, as
shown in FIGS. 4D and 4E. Inlet (416) and outlet (418) may be
openings or channels. In some variations, the transfer reservoir
may also comprise an outlet neck (417), which may be a shallow
channel from the transfer reservoir to the outlet. Optionally,
transfer reservoir (408) may comprise a plurality of ridges (420)
that discourages fluid adhesion to the surface of the transfer
reservoir, thus facilitating the movement of the fluid from inlet
(416) to outlet (418). The ridges (420) may be arranged in series
(in any orientation) along the fluid flow from the inlet (416) to
the outlet (418). For example, the ridges (420) may be oriented
parallel to the fluid flow into the reservoir. The fluid flow from
the inlet to the outlet may vary depending on the orientation of
the transfer disk. For example, in some variations of a fluid
monitoring device, the transfer disk may be mounted vertically,
i.e. on its side. In this variation, if the fluid sample is
dispensed to a transfer reservoir at location (419) shown in FIG.
4C, the fluid sample entering the inlet would need to be urged
upward towards the outlet. Alternatively, if the fluid sample is
dispensed to a transfer reservoir at location (421), the fluid
sample entering the inlet would flow downward towards the outlet
due to gravity. In some variations, the transfer disk may be
mounted horizontally. In some variations of a horizontally mounted
disk, the reservoir and fluid channels would be positioned so that
fluid entering the inlet would need to be urged across the transfer
reservoir in order to exit through the outlet.
[0087] The fluid sample may be transferred from the inlet (416) to
the outlet (418) in various ways. In some variations, the transfer
may not take place until after the dispensing of the fluid ceases
entirely, i.e. there is no fluid that connects the PL cartridge
and/or dispense nozzle to the disk assembly. A number of variations
may be used to help move a sample from inlet (416) into the
transfer reservoir. For example, the transfer reservoir (408) (or
the portion of the disk assembly) that contains the fluid sample
may be tilted, allowing the sample is directed to the outlet (418)
by gravity feed. Alternatively, the transfer reservoir (408) may be
made of a material that facilitates capillary action. The direction
of the capillary action may be configured by machining different
micro patterns on the surface of the transfer reservoir that allows
fluid migration in one direction but not in the opposite direction.
In some variations, this material may be substantially contacted
with the test substrate, allowing the fluid to be conveyed by
capillary action entirely within the material. Fluid may also be
drawn towards the outlet (418) by setting up a pressure gradient
across the transfer reservoir (408), such that the outlet (418) is
in a region of lower pressure. Pressure gradients may be created
through the use of a vacuum bulb, drawing the fluid into the
transfer reservoir, and expelling the fluid towards the outlet. For
example, it may urge, push, or direct the fluid towards the outlet
with a fluid displacing element or fluid directing element. Other
methods of directing the fluid sample to the transfer reservoir
outlet may utilize deformable or displaceable structures. For
example, the transfer reservoirs made be made of a deformable
material, such as silicone or a sheet of malleable metal alloy, and
tubular shaped, so once the fluid has been dispensed and
dissociated from the PL cartridge, the tubular transfer reservoir
is pinched shut, and the pinching mechanism gradually moves towards
the outlet, essentially "squeezing" the fluid sample to the outlet
(418). In other embodiments, the fluid may be urged through the
transfer reservoir by a slidable seal or piston, which may act to
pressurize the transfer reservoir cavity. In another variation, the
volume of the transfer reservoir (408) may be adjusted, e.g. from
large to small, to displace the sample fluid towards the outlet
neck (417). The volume of a transfer reservoir may be changed by
constricting or dilating the transfer reservoir lumen and/or
introducing an external element that displaces a sufficient volume
in the transfer reservoir that forces the fluid sample to move
towards the outlet. One example is shown in FIGS. 4F and 4G. The
deformable membrane (402) is sealed across the transfer reservoir
(408) which creates a liquid-tight enclosure. Once a desired
quantity of fluid is deposited into the transfer reservoir (408),
the membrane (402) is deformed with a piston (476). The deformation
in the membrane (402) created by the piston (476) acts to displace
the fluid into the outlet (418). The initial volume of the transfer
reservoir (408) may be of any suitable quantity, for example,
between approximately 1.2-10.0 .mu.L, or approximately 1.0-100
.mu.L, or approximately 1.0 .mu.L to more than 100 .mu.L, however,
when the membrane (402) is deformed, the volume of the transfer
reservoir is reduced from the initial volume. The volume of the
transfer reservoir before and during membrane deformation may vary
widely. This method of fluid transfer may allow for a greater
degree of flow control (as compared to gravity feed or capillary
action) and may be done more rapidly (as compared to "squeezing"
the fluid in a tubular transfer reservoir). In alternate
embodiments, a displaceable seal or piston with a generally fixed
configuration may be provided to push the fluid sample out of the
transfer reservoir. Furthermore, positioning the outlet neck (417)
at a higher plane than the inlet (416) buffers the downstream
sensor substrate from fluid overflow, which allows the control
system (185) additional time to remedy the overflow condition. The
inlet (416) may be occluded, covered, sealed or blocked to prevent
the fluid sample contained in the transfer reservoir from flowing
backwards when the piston (476) acts on the membrane (402). For
instance, the fluid transfer plug (224) shown in FIGS. 2A-2E may be
used to block the inlet (416). Other suitable means of occluding
the inlet may also be used, for example, the inlet may be
constricted by a clip, or sealed off with a thin film material or
flap.
[0088] The membrane (402) may be shaped such that a deformation in
the membrane (402) will displace the fluid sample within the
transfer reservoir (408). In some configurations, the membrane
(402) may have a plurality of folds and/or creases, which may allow
for a greater degree of membrane compression and fluid
displacement. For example, the folds may be evenly formed in a
pleated configuration, but may also assume any suitable geometry.
In other variations, the membrane (402) is stretched over the
transfer reservoir (408) with a certain degree of tension, with few
if any folds or creases. This configuration may reduce or minimize
the surface area of the membrane that contacts the fluid sample,
which may increase the quantity of fluid that is transferred to the
sensor substrate. Each portion of the membrane is isolated from
each other by chemical bonds, mechanical bonds, or a combination
thereof, or interference plastic fit parts to ensure that the fluid
within each reservoir is maintained within that reservoir without
leaking or transferring to other reservoir. These features may act
to isolate the sample to one and only one transfer reservoir. This
may reduce or eliminate cross contamination between samples.
[0089] The fluid input channel to transfer reservoir (408) may be
any shape or size that efficiently accepts a fluid sample. A
variation of fluid input channel is shown in FIGS. 4I and 4K. The
fluid input channel comprises an input aperture (424) that is
connected to a bore (423) shown in FIG. 4I. Some variations of a
fluid input channel may have a tapered input aperture (424) to
better mate with the shape of the dispense nozzle of the PL
cartridge, which may funnel fluid into the transfer reservoir (408)
more efficiently, however the shape and size of the input aperture
(424) may be varied according to the characteristics of the system
and/or fluid viscosity. The size and shape of the input aperture
(424) may also facilitate the dissociation of the fluid from the
dispense nozzle from the fluid in bore (423). Breaking the fluid
connection between the dispense nozzle and the fluid input channel
may reduce the risk that contamination which may have entered the
transfer disk from other sources is then transferred to the
patient. Optionally, the surface of the input aperture (424) and
bore (423) may be coated to prevent the fluid from adhering to the
surface. The coating may be an anti-coagulant agent, surfactant, or
charge-neutral coating that may reduce the influence of
electrostatic forces on fluid flow.
[0090] FIG. 4J depicts section B-B taken across the transfer
reservoir (408) and outlet neck (417) shown in FIG. 4H. In a
horizontal position (such as the orientation shown in FIG. 4J), the
outlet neck and outlet of the transfer reservoir (408) may be
located at a higher plane than the inlet (416). Such an arrangement
may prevent a direct and immediate fluid flow-through from the
inlet to the outlet. In a vertical position, where the outlet neck
(417) points up and the inlet (416) points down, a fluid sample
entering the inlet would be prevented from directly and immediately
flowing through to the outlet (418). In these arrangements, the
transfer reservoir acts as a buffer intermediate between the inlet
and outlet, and may allow for increased control of fluid flow
between the transfer disk and sensor disk. Features that allow for
precise regulation of the fluid flow may reduce the possibility of
a continuous fluid connection from the sensor disk to the transfer
disk to the patient. This may safeguard the patient against
contamination from any non-sterile components of the disk
assembly.
[0091] Transfer reservoirs may also comprise a fluid detector to
indicate when the transfer reservoir has reached a maximum or
minimum fill level. A variety of sensors may be used, such as
optically reflective, electrically conductive, or capacitive
sensors. Certain variations of transfer reservoirs (408) are formed
of molded acrylic, which allows sensors optical access to the
contents within the transfer reservoir. For example, as shown in
FIGS. 4I and 4L, total internal reflection minors (414) are molded
into the transfer disk structure, and may channel the optical
characteristics of the transfer reservoir contents to a sensor that
detects for the presence or absence of fluids. In some variations,
an infrared beam enters into the transfer disk and is reflected
back to the transfer reservoir along a light path, for example
light path (427), until a fluid (such as blood) interferes with the
beam. In this embodiment, as shown in FIG. 4L, the infrared beam
emitter and receiver may be located on the fluid monitoring system,
directly across from the total internal reflection minors in the
transfer reservoir, configured to transmit and receive light, e.g.
infrared, along light path (427). Some embodiments of an infrared
sensor can detect quantities of fluid between about 50 .mu.L to
about 80 .mu.L, but sensors with other ranges of fluid sensitivity
may also be used. Fluid sensor output may be used as a feedback
signal to the control system (185) to regulate various aspects of
the fluid monitoring system, such as adjusting the fluid flow and
quantity (e.g. to prevent under fill and overfill conditions), and
to signal if fluid is unexpectedly in the transfer reservoir.
[0092] As shown in FIGS. 4B and 4H, the transfer disk structure
(406) may comprise a number of alignment features, such as notches,
interlocking structures, apertures, and protrusions. Appropriate
alignment of the transfer disk with respect to the other components
of the fluid monitoring system may ensure precise fluid transfer
from one component to the other. Such alignment features may also
be used to provide clearance between the individual components of
the disk assembly, and may include locking mechanisms to secure one
component to another. For example, apertures (412a) and (412b)
shown in FIG. 4B on the transfer disk (302) may be aligned to
protrusions on other parts of the fluid monitoring system, so that
the monitoring system can precisely dispense the fluid sample,
locate the sensor outputs, and correctly index the individual
transfer reservoir units on the transfer disk. Indentation (413)
may be sized and shaped to mate with other components of the
monitoring system to ensure consistent and precise alignment.
Latches (415) may be mechanically interlocked with complementary
structures, e.g. notches, on the monitoring system, to secure and
lock the transfer disk to the overall system. Transfer disk
structure (406) may also comprise alignment aperture (426) that
mates with the alignment protrusion (248) to ensure precise
positioning of the dispense nozzle (246) into input aperture (424).
The transfer disk structure (406) may also have an alignment notch
(422) to mate with an alignment protrusion on the PL cartridge to
precisely position dispense nozzle (246) in contact with wipe (405)
in between dispense cycles. The transfer disk (302) may have any
number and variety of alignment features to precisely position and
secure it to the fluid monitoring system.
[0093] The transfer disk (302) may comprise cleaning pads or wipes
(405) similar to those shown in FIG. 4H to wick away excess fluid
from the dispense nozzle (246) in between dispense cycles. The
wipes (405) may be made of any absorbent material, for example, a
polyester/cellulose non-woven blend, which has a high affinity for
the fluid that is being monitored so that the fluid may be wicked
away quickly and evenly. The wipes (405) may be positioned or
shaped in any way that optimizes its contact with the dispense
nozzle (246). For example, some wipes (405) may comprise
protrusions and/or micro structures to increase surface area
contact with the dispense nozzle, the protrusions may be shaped to
be complementary to the shape of the dispense nozzle. In some
variations, the wipe (405) may be positioned on a mechanism that
can be actuated to wipe the dispense nozzle, for example, the wipe
may be moved laterally across the dispense nozzle, or plunged into
and out of the lumen of the nozzle to absorb excess fluid. In other
variations, wipes may contact the dispense nozzle without any
lateral movement, i.e. the wipe may "blot" the dispense nozzle to
wick away excess fluid. Excess fluid may contaminate any sterile
components in the PL cartridge or transfer disk, as well as
possibly skewing the test results of later fluid samples. In the
case where blood is the fluid that is monitored, excess blood on
the dispense nozzle (246) may clot and occlude the transfer of
latter blood samples for testing, and may contaminate the latter
samples which may result in an inaccurate test result.
Sensor Disk
[0094] As described in FIG. 1, sensor disk (190) may be a separate
component from the transfer disk (196), but configured to interface
with the transfer disk (196) via a mechanical lock. Some variations
of the disk assembly (300) shown in FIG. 3 may comprise a sensor
element, such as sensor disk (304). In other embodiments of the
disk assembly, the sensor component may also be any assembly
enclosed in a housing, or may be an assembly of multiple cassettes,
cartridges, or disks. FIG. 5A depicts one variation of a sensor
disk (304). Sensor disk (304) includes a plurality of test
substrates (each configured to receive a sample) and/or test
sensors (each configured and analyze a fluid when it mixes with
chemicals, reagents or interacts with other components of a test
sensor or test substrate). The sensor may be electrical,
electrochemical, optical, or optoelectronic, for example. In some
variations, sensor disk retains an array of test sensors such that
each test sensor is configured to receive a fluid sample from a
single transfer reservoir. A sensor disk (304) may comprise test
sensors (502), a sensor disk structure (504), and an absorbent
lamina (506). The sensor disk structure (504) is made of molded
acrylic, but may be made of any material with similar structural
and optical properties. Some or all components of the sensor disk
(304) may be sterilized, however, in some variations, the test
sensors (502) may not be able to be sterilized without compromising
shelf-life, reliability, and/or accuracy. Some variations of the
sensor disk (304) may comprise absorbent lamina (506) to retain any
excess fluid that may be transferred from the transfer reservoir to
the sensor disk. This may prevent cross-contamination between test
sensors (502). The absorbent lamina (506) may be comprised of any
absorbent material (505), for example a polyester/cellulose
non-woven blend, and be secured by a rigid structure (507) that is
sized and shaped to fit with the sensor disk structure (504). The
sensor disk structure (504) comprises apertures that allow the
fluid sample to contact the absorbent material (505), for quick and
even absorption, without contacting the transfer reservoir outlet
or test substrate of other test sensors (502).
[0095] Certain types of test sensors (502) may be maintained in a
relatively moisture-free environment to extend shelf-life and test
accuracy. Some variations of a sensor disk (304) may comprise
desiccating features, for example, a desiccating material (508) and
a desiccant cap (510) to maintain a moisture-free environment in
the sensor disk. The desiccant material, such as molecular sieve,
silica gel, or any clay-based granular desiccant, may be contained
in the airspace between the desiccant sieve (508) and desiccant cap
(510). The quantity and type of desiccant to include may be
determined by the anticipated moisture influx that the sensor disk
may be expose to during its course of its shelf-life and use. Some
variations of the sensor disk (304) may also comprise a humidity
sensor (167j), as depicted in FIG. 1, that communicates humidity
data to the control system (185) so that the test sensor reading
may be adjusted according to the humidity in the sensor disk (304).
For example, the readings from glucose test sensors may need to be
adjusted according to the humidity level over time. Excessively
humid or excessively dry sensor disk environments may render the
test sensors (502) inaccurate, and the control system (185) may
instruct the user to replace the sensor disk (304).
RFID Feature
[0096] As described previously, some variations of the sensor disk
(304) may also comprise machine readable indicia that may be
relayed to the control system (185) using an indicia reader. The
indicia reader may be, for example, a barcode reader, a
radiofrequency identification (RFID) reader, and/or an electrical
connection to an EPROM or other chip located on the sensor disk
(304). For example, as shown in FIG. 5B, the sensor disk may
comprise an RFID chip (512) that communicates with the control
system through an RFID serial interface. The RFID chip may contain
information, such as the disk type, manufacturing date and time
(including batch tracking numers, factory and operation data), test
sensor codes (indicating test sensor quantity, type and expiration
date), calibration codes, and sensor disk expiration date. Data may
also be written to the RFID. In some embodiments, the RFID may be
secured so that it can only be written to by a specific type of
fluid monitoring system, and may only be written to once, and
optionally encrypted. The types of data that may be written to an
RFID by the monitoring system may be the first time of use, any
indicators and identifiers of malfunctioning or adverse events
(e.g. damage sustained during use), temperature and humidity
conditions under which the sensor disk was used. Patient data may
also be written to the RFID. In some cases, the data on the RFID
may indicate to the fluid monitoring system that the sensor disk is
defective or error-prone, and should be replaced. The RFID (512)
may also indicate to the control system if the sensor disk is
properly installed, aligned, and locked into place. The RFID may
also be used to relay calibration curves and other analysis or
configuration data to the controller in multiple analyte systems.
For example, the rotational/axial position of different analyte
sensors may be stored in the RFID so the monitoring system can
coordinate the application of appropriate firmware, analytical
algorithms, or calibration data to each type of sensor.
Sensor Disk Structure
[0097] Some variations of the sensor disk structure (504) may
comprise several alignment features as shown in FIG. 5C.
Protrusions or pins may pass through apertures (528a) and (528b) to
align components of the sensor disk (304) to the fluid monitoring
system. The sensor disk structure (504) may also comprise a
protrusion (533) that may engage the sensor disk (304) with other
disk components, e.g. the transfer disk. To engage with other disk
assembly components, such as the transfer disk, the protrusion
(533) for each disk must be sized and shaped to mate with the
grooves and protrusions of the other disks. Additionally, these
alignment features may also comprise locking features, such as
hooks or snap locks (531a-c), which secure the sensor disk (304) to
the transfer disk. These locking features may reversibly or
irreversibly engage other disk assembly components.
[0098] The sensor disk structure (504) may comprise additional
apertures for purposes other than alignment, as shown in FIGS. 5D
and 5E. For example, aperture (530) is arrayed throughout the
sensor disk structure (504) to provide ventilation to facilitate
the capillary of the test sensor. Apertures of other sizes and
shapes may aid in the precise manufacturing of the sensor disk
structure (504), the loading of sensors (502), and may also provide
exposure to a desiccant. For example, aperture (524) may expose
underlying layers of the sensor disk (304), such as the absorbent
material (505), so that the absorbent material (505) may be
contacted by fluid that is present in aperture (524).
[0099] The sensor disk (304) may be configured to retain 25 test
sensors (502) as shown in FIG. 5F, but in other embodiments, any
other number of sensors may be retained, include but not limited to
at least (or no more than) about 5, about 10, about 15, about 20,
or about 30 test sensors (502). Additionally, test sensors may be
disposed on the sensor disk in multiple coaxial circular patters to
double or triple the number of sensors to match a higher density
transfer disk as described above. Each test sensor (502) is
retained in a semi-enclosed subunit (514) of the sensor disk
structure (504). Each sensor disk subunit (514) is separated from
the adjacent subunit by a wall (515), which may be of sufficient
height to prevent fluid transfer (cross-contamination) between
subunits, as shown in FIG. 5H. The test sensors (502) are secured
within each sensor disk subunit (514) by several retainer
protrusions (516). As shown in FIG. 5G, there are also alignment
protrusions (518) that ensure the position of the test sensor
(502). In some variations, the alignment protrusion (518) may be
sized and shaped to fit a complementary groove (519) in the test
sensor (502). For example, a cylindrical alignment protrusion (518)
may be used to align a sensor (502) with a semi-circular groove
(519).
[0100] Test sensors (502) may comprise a sensor substrate (503) and
electrode contacts (532), depicted in FIGS. 5I and 5J. The sensor
substrate (503) reacts with the fluid sample, which forms an end
product that is indicative of the quantity of the analyte in the
sample. This measurement may be communicated to the control system
via electrode contacts (532). For example, blood glucose sensors
may receive blood which reacts with the sensor substrate (503)
reagent, and the monitoring system may analyze the glucose content
in the blood sample via the electrodes (532). Sensors that detect
different analytes may have different test substrates and electrode
configurations, and the sensor disk structure (504) may be modified
to accommodate the different location of the sensor substrate (503)
and electrodes (532). Some variations of sensors, such as certain
glucose sensors, may provide additional data to the control system.
For example, it may comprise an under-fill or over-fill detection
unit that indicates to the control system if a sufficient fluid
sample has been received by the substrate.
[0101] Each sensor disk structure subunit (514) comprises a fluid
sample receiving area (520), depicted in FIG. 5I. Receiving area
(520) comprises a groove (522) and an aperture (524). Aperture
(524) may open to expose absorbent material (505). In FIG. 5I, the
sensor substrate (503) is oriented over the groove (502), however
the sensor substrate may be oriented in any way that is suitable
for receiving blood from the transfer disk. In some variations of
the sensor disk structure (504), groove (522) may be a drain that
captures a portion of the fluid sample from the transfer disk
outlet, and aperture (524) which exposes absorbent material (505)
may wick up any overflow fluid from the groove (522). Positioning
the sensor substrate (503) over the groove (522) may permit
immediate access to the transferred fluid sample, before the fluid
sample is absorbed by material (505). In some variations, the test
sensor substrate (503) is not in direct contact with groove (522),
and takes up the dispensed fluid sample by capillary action.
[0102] The shelf-life of some types of test sensor substrates are
sensitive to humidity and/or temperature. Some variations of a
fluid monitoring system may comprise at least one humidity sensor,
as shown in FIG. 1 (for example, humidity sensor (167j)), near the
installation site of the sensor disk. However, in other variations
of a fluid monitoring system, the humidity sensor(s) may be located
anywhere in the system, for example, away from the installation
site of the sensor disk. Humidity sensors may be optionally
provided along the walls of the sensor disk or the transfer disk. A
variety of humidity sensors may be used, for example, chemical,
capacitive, resistive, or thermal conductivity humidity sensors.
The humidity sensors may measure absolute humidity, relative
humidity, or dew point, and may integrate any such measurements
over time to evaluate the moisture content in the air. For example,
a chemical humidity indicator, such as a silica gel desiccant, may
indicate the cumulative quantity of moisture in the air by changing
color. Other humidity sensors may communicate the moisture
measurement to the control system (185) through an electrical
interface, where the control system may compute the expected test
sensor life based on the humidity measurement. In some cases where
the humidity measurement may be affected by temperature, a
temperature indicator may also be included in the system, or
integrated with the humidity sensor. In certain embodiments, sensor
life can be plotted against relative humidity (% RH) integrated
over time, as shown in FIG. 5K. Temperature may also impact a
sensor's shelf-life, and plots similar to that shown in FIG. 5K may
be generated at different temperatures. The control system may
monitor the humidity of the sensor disk before use, and integrate
the humidity level over time, where the integration is weighted
depending on the sensitivity at the different humidity levels. At a
given humidity, the rate of sensor life degradation may be
determined according to the plot in FIG. 5K. For example, as each
hour passes (or any time unit), the control system may poll (at any
suitable frequency) the humidity measurement, and adjust its
evaluation of sensor life based on the current humidity
measurement. In some cases, the relationship between % RH and
sensor life may be linear, while in other cases, it is non-linear
(e.g. may contain a series of linear regions where the linearity
coefficient varies with relative humidity, or may be non-linear
across the entire range of % RH). For example, the shelf-life of a
sensor at 70% relative humidity (% RH) may be about 20 times
shorter than at 25% RH. If there is a non-negligible temperature
shift in the course of the use of the sensors, the relationship
between sensor life and % RH may be altered, e.g. % RH axis shift,
and/or linearity coefficient shift, etc, and the computation for
the expected shelf-life may incorporate this temperature effect. An
example of a humidity integration routine (550) the system may
perform to evaluate test sensor life is depicted in FIG. 5L. After
the sensor disk is installed in the system (552), the integrated
humidity level is reset to zero and the first humidity measurement
is taken (554, 556). Another humidity measurement is performed
after a certain period of time. The control system then determines
how much time has elapsed since the previous humidity measurement
(558). Based on the humidity measurement, the sensitivity factor is
computed based on a plot of sensor life as a function of humidity,
shown in FIG. 5K. The sensitivity factor at a given % RH is 100%
divided by total sensor life at that % RH. The routine (550) then
computes the product of current humidity measurement, elapsed time,
and sensitivity factor (562). This result is added to the
integrated humidity level (which is initially zero) in step (564).
At that point, the routine will compare the integrated humidity
level against the maximum limit, e.g. at or around 100% (566). If
the integrated humidity is below the maximum limit, then the
routine will loops back to step (556) and iterate at a
pre-determined frequency, e.g. once per minute, once per 10
minutes, etc, until the sensor life expires due to elapsed time or
increased humidity. If the integrated humidity is near 100%, the
system may issue a warning signal to the user. When the integrated
humidity is at or exceeds 100%, then the sensor will be considered
inaccurate and/or unfit for use, since the expected shelf-life has
been exceeded (which may be due to, for example, elapsed time, or
changes in humidity or temperature). Once the sensors have exceeded
their shelf-life, the system may issue an alert or alarm to remove
or discard the sensor disk. Other computational methods and
routines may be used to dynamically update the expected shelf-life
of the sensors. The control system may poll the humidity sensor
when the sensor disk is installed and determine if the sensor disk
is suitable for use, given the measured humidity (and temperature,
for certain embodiments). If the sensor disk is determined to be
unsuitable for use, the system may issue an alarm to remove the
sensor disk. The relative humidity may also be plotted against
other sensor factors, such as sensitivity, accuracy, and/or
precision. For example, a plot similar to FIG. 5K may be generated
that relates % RH to sensor sensitivity, which may be used to
adjust the readings from the sensors to compensate for shifts in
humidity and/or temperature. In certain embodiments, humidity
sensors as described above are provided in a plurality of locations
throughout the fluid monitoring system, such as the PL cartridge,
the transfer disk, the sensor disk, etc. If excessive humidity is a
result of moisture that originates from within the system, a
plurality of humidity sensors in the system may provide sufficient
information to the control system to localize the source of
humidity and flag an indicator to remove the moisture source.
Interface Between Transfer Disk and Sensor Disk
[0103] As described previously, in some variations of a fluid
monitoring device, the disk assembly may comprise a transfer
element and a sensor element, either enclosed in a single housing,
or separated as individual cassettes, cartridges, or disks. The
variation of disk assembly shown in FIG. 6A comprises a transfer
disk and a sensor disk which are secured and actuated together.
FIG. 6A depicts features such as slots (602), apertures (606), and
protrusions (604) that are configured to secure the transfer disk
and sensor disk together. Either or both the transfer disk and
sensor disk may be sterilized individually or in combination. The
transfer disk and the sensor disk may be permanently secured
together, and may be removed from the system and disposed between
patients. The sensor disk may be disposed of when the sensors have
expired (i.e. exceeded their shelf-life) or all of the sensors have
been used. Either the sensor disk or transfer disk may be disposed
of (individually or together) if contaminated or previously
used.
[0104] In certain variations of the disk assembly (300) as shown in
FIG. 6B, the outer edge of the transfer disk (302) juts out or
protrudes from the sensor disk (304). The gap (613) provides
clearance for alignment features. Edge (621a) on the transfer disk
articulates with edge (621b) on the sensor disk, which aligns the
two disks and ensures that there is adequate clearance between the
two disks. In the variation shown in FIGS. 6B and 6C, there is
sufficient clearance such that no portion of the transfer disk
contacts the test sensors (502). In FIG. 6C, the outlet (418) from
the transfer disk (302) is positioned directly over, but not
touching, the sensor substrate (503), separated by gap (623). The
gap (623) may be between the transfer disk and the sensor disk for
a portion of the fluid path to a test location of the test
substrate or test sensor. The disk assembly (300) may also include
an access interface for the system to contact the test sensor
electrodes (532). In some variations, an aperture is provided for
external reading elements to access electrodes (532), while in
other variations, the electrode reading elements may remain
entirely internal to the disk assembly (300). As shown in FIGS. 6B
and 6C, the test sensor (502) is not in contact with the transfer
disk (302). The disk assembly (300) may comprise a membrane (402)
depicted in FIGS. 6B-6D. In some variations, the membrane (402) is
silicone, and stretched over the perimeter of the disk assembly
(300) such that the membrane forms a fluid-tight seal with the
transfer disk transfer reservoir (408), however, the membrane (402)
may be made of any other material with similar properties, such as
a malleable metal alloy. The membrane (402) may have varying
degrees of elasticity and may be stretched over the transfer
reservoir (408) with varying degrees of tension.
Interface Between Disk Assembly and Patient Line Cartridge
[0105] In some fluid monitoring systems, the disk assembly (300) is
installed with minimal contact with other system elements as shown
in FIG. 7. For example, disk assembly (300) may be installed to
maintain an air space or gap between the alignment aperture (426)
and alignment protrusion (248) of the PL cartridge (200). This
ensures that the dispense nozzle (246) of PL cartridge and the
inlet of the disk assembly (300) (not shown in FIG. 7) also
maintain an air space. Such a load configuration may be useful for
some variations to maintain the sterility of either the PL
cartridge (200) or the disk assembly (300). Other load
configurations may be used as appropriate for other disk assemblies
and PL cartridges, depending on the degree of sterility that is
desired.
[0106] Some variations of a fluid monitoring system may include
mechanisms that prevent the installation and use of an
inappropriate PL cartridge (200), such as an incompatible part, or
a previously used PL cartridge. For example, when there is no PL
cartridge the fluid monitoring system, the alignment and/or lock
features of the fluid monitoring system may be in a "load"
configuration. Only PL cartridges that are also in a matching
"load" configuration can be installed in the system. This mechanism
may be implemented in the dispense valve, where the "load"
configuration is one that is not used during the operation of the
PL cartridge. Other sub components may carry out this lock-out
function.
Operational Configurations
[0107] Once the PL cartridge and disk assembly have been installed
into the system according to the various alignment and locking
features, the system may undergo an initialization and/or
diagnostic procedure. The initialization or diagnostic procedure
may involve polling and testing all system sensors (temperature,
humidity, pressure, air-in-line detector, blood detector, etc) to
ensure that every sensor is properly calibrated, installed, and
initialized. Initialization may also include priming the tubing
system within the PL cartridge, for instance, perfusing a cleaning
solution or saline into all the tubing. This perfusion step may
serve to reduce or eliminate the air in tubing and may rinse away
any residual manufacturing agent. The perfusate may then be flushed
out of the system through a waste portal. The initialization
procedure may also include reading the RFID components of the PL
cartridge and disk assembly as previously described. The
information read from the RFID components may be incorporated by
the control system to adjust the operation of the fluid monitoring
system, and may also confirm that the PL cartridge and disk
assembly have been properly aligned and installed. The control
system may also have data from a look up table, e.g. provided by
disk assembler, manufacturer or transporter concerning lot numbers,
initial lot calibration information, dates of assembly, production
or transport information, etc. This information may be downloadable
or otherwise provided to a user of the instrument.
Dispense Configuration
[0108] After the initialization procedure has successfully
completed, PL cartridge (200) and disk assembly (300) may be placed
in a fluid dispense configuration (803), as shown in FIG. 8A. In
the dispense configuration (803), the alignment protrusion (248) on
the PL dispense valve is inserted in the alignment aperture (426),
which ensures that the dispense nozzle positioned to deliver a
fluid sample to the transfer disk inlet (not shown) to the transfer
disk transfer reservoir (408). Once such alignment is confirmed,
the control system may signal to the PL cartridge to dispense a
fluid sample to the transfer reservoir (408) of disk assembly
(300). The asterisk in FIGS. 8A-8D marks the transfer reservoir
that received the sample in FIG. 8A. The fluid channel plug (224)
may or may not be aligned with transfer disk inlet. In dispense
configuration (803), the PL cartridge (200) and the disk assembly
(300) may be in close proximity (812) to each other.
Withdrawal Configuration
[0109] After a desired quantity of fluid has been dispensed to the
disk assembly (300), as sensed by a fluid sensor in the system,
e.g. within the transfer disk transfer reservoir (408), the control
system (185) may issue a command to the PL cartridge to cease the
fluid flow. Then, the PL cartridge (200) and/or the disk assembly
(300) may be manipulated so that the distance between then is
increased (813). In the withdraw configuration (804), the distance
(813) may be large enough to separate any fluid connection that may
remain between the PL cartridge and disk assembly after the PL
cartridge has ceased the fluid flow. In some variations, the
distance between the PL cartridge and disk assembly in the withdraw
configuration (804) may be small, but large enough so that the
individual components may be advanced or rotated without impacting
the other. In the withdraw configuration (804), the fluid channel
plug (224) may not be in contact with the disk assembly (300).
Indexing Intermediate Configuration
[0110] Some variations may have an indexing intermediate
configuration (805) where the disk assembly (300) is advanced with
respect to the dispense nozzle. An example of a position in the
intermediate configuration (805) is shown in FIG. 8C. This may be
achieved by rotating, translating, or pivoting the disk assembly
(300), and/or manipulating the PL cartridge, so that the dispense
nozzle (246) and alignment apertures (426) is moved towards a
transfer reservoir (408) other than the one just accessed. The
distance (815) between the PL cartridge and disk assembly may be
large enough so that the disk assembly and PL cartridge may be
rotated separately without substantial contact. The fluid channel
plug (224) may not be in contact with the disk assembly (300). The
indexing intermediate configuration (805) may rotate the disk
assembly (300) any number of steps to any transfer reservoir (408),
consecutive or otherwise, on the disk assembly. For example, the
disk assembly (300) may be rotated clockwise or counterclockwise,
in any order, and any number of degrees (e.g. about 10.degree.,
13.degree., 25.degree., etc). In some fluid monitoring systems, the
control system (185) may maintain a lookup table to track which
transfer reservoirs have already been accessed, and may be
programmed to access to a transfer reservoir only once. The
sequence and degree of rotation may be determined by the
positioning and number of transfer reservoirs on the disk assembly.
In certain variations, the sequence and degree of rotation may
prevent the contamination of wipes. The lookup table may also
contain information about the type of sensor located at each index
position, and based upon user input, (or upon information in a look
up table accessible by the controller and corresponding to RFID lot
number) may advance the disk assembly so that the fluid is
dispensed to the transfer reservoir that transfers the sample to
the desired sensor type.
Wipe Configuration
[0111] In some variations of a fluid monitoring system, a wipe
configuration (806) may follow the index configuration (805), as
shown in FIG. 8D. The wipe configuration (806) that positions the
alignment protrusion (248) in a notch (818), which may also
position the dispense nozzle in contact with a wipe (not shown). In
wipe configuration (806), the fluid channel plug (224) may be
occluding the inlet to a transfer reservoir (408) that may contain
a fluid sample, preventing any back flow of fluid from the transfer
reservoir. In this configuration (806), the fluid sample may be
transferred to the test sensor substrate by any mechanism, for
example, pumping, pushing, or gravity feed. The distance between
the PL cartridge and disk assembly may be reduced from the previous
configuration (e.g. the withdraw (804) and/or index intermediate
(805) configuration), such that the alignment protrusion (248) is
fully inserted into notch (818), and the dispense nozzle is in
substantial contact with a wipe (not shown). The control system
(185) may maintain a lookup table that tracks which wipes have been
previously used.
Fluid Transfer Path
[0112] As depicted in FIG. 9A, the control system (185) may
regulate the timing and fluid flow in various stages in the PL
cartridge and disk assembly. After the fluid sample (e.g. blood) is
obtained from the source (e.g. a patient), the sample is first
accumulated in the PL cartridge (200), for example, in fluid
channels or a reservoir. The control system (185) may hold the
sample in the PL cartridge (200) as long as desired, and may
withhold the sample from testing if sample contamination is
suspected. When the control system (185) configures the disk
assembly to receive the sample, the sample may be dispensed from
the dispense nozzle (246) to the transfer disk (302), where it may
enter a transfer reservoir (408) via an inlet (416). Once the
transfer reservoir (408) has received a sufficient quantity of
fluid sample, the control system (185) may then stop the fluid flow
from the PL cartridge (200) to the transfer reservoir (408), by
closing the dispense valve (206) or adjusting the pressure in the
PL cartridge (e.g. by adjusting the syringe pump (210)). Once the
fluid flow from the PL cartridge has ceased, the fluid in the PL
cartridge and the fluid in the transfer reservoir (408) may be
entirely separate fluid entities. However, for some fluids, such as
viscous fluids, there may be a fluid connection between the PL
cartridge (200) and the transfer reservoir (408) even after the
fluid flow from the PL cartridge has been stopped. In such a
circumstance, if complete fluid separation is desired, the control
system (185) may advance the disk assembly away from the dispense
valve (206), as described below. The control system (185) may hold
the sample in the transfer disk (302) as long as necessary, and may
withhold the sample from testing if sample contamination is
suspected. When the control system (185) determines that the sensor
disk (304) is ready to receive the fluid sample, the sample may be
transferred from the transfer reservoir (408) to the sensor
substrate (503). The fluid from the transfer reservoir (408) may be
transferred to the sensor substrate (503) through various methods,
for example, gravity feed or pumping or otherwise actively moving a
sample, as described previously.
[0113] As previously mentioned, the timing of fluid transfer from
the PL cartridge (200) to the transfer disk (302) to the sensor
disk (304) may be regulated by the control system (185). The
control system (185) may execute different system functions between
the stages of the fluid flow. For example, after the transfer of
fluid from the PL cartridge (200) to the transfer disk (302), the
transfer disk may be advanced so that a different transfer
reservoir (408) is positioned near the dispense valve (206). Before
the fluid is moved from the transfer disk (302) to the sensor disk
(304), the control system (185) may execute a calibration procedure
to ready the sensor substrate (503) for sample testing. Any system
configuration may be utilized to regulate the quantity, direction,
and rate of fluid flow to optimally monitor analytes in the fluid
sample. In some variations of a fluid monitoring device, the
movement of fluid from a first location to a second location may be
regulated so that the fluid connection between them is reduced or
eliminated. For example, the fluid flow may be regulated to avoid a
continuous fluid column from the sensor substrate (503) to the PL
cartridge (200). This type of fluid flow regulation may reduce or
eliminate the back flow of any contaminants from the sensor
substrate (503) to the patient line.
[0114] FIG. 9B illustrates an example of the path a fluid sample
may take from the PL cartridge to the sensor substrate. Arrow (903)
shows the path of the fluid sample from the PL cartridge, through
the inlet (901) to the transfer reservoir (408). The fluid is then
transferred (by a variety of means, such as gravity feed, by
actively moving, displacing or by pumping) in the direction of
arrow (906) to the outlet neck (417) to the outlet (418).
Cross-section T-T through the outlet (418) shows the path of the
fluid sample in the direction of arrow (907) down the outlet (418),
towards the test sensor (502). The test sensor substrate (503) may
be positioned to receive the fluid sample, for example, at a
location directly under or tangential to the outlet (418). Any
excess fluid may be captured in a drain (522), and then channeled
to an absorbent material that prevents the fluid from contaminating
unused test substrates. As previously described, various system
functions may be performed between the individual stages of this
fluid flow (i.e. the stages indicated by arrows (903), (906), and
(907)), such as advancing the disk assembly, calibration
procedures, and the like. The fluid sample may also be withheld
indefinitely in the PL cartridge or the transfer disk transfer
reservoir as desired.
Separation of Sterile & Non-Sterile Components
[0115] In some variations of a fluid monitoring system, the fluid
that is monitored is patient blood. In such variations, the
components that contact the patient's blood may be sterile to
reduce the risk of contamination to the patient. A component may be
manufactured using a sterile process and facility, or may undergo a
sterilization process post-manufacture. In either case, the
component may be packaged to preserve sterility. Some fluid
monitoring systems may be manufactured and assembled in a sterile
environment, or may be assembled, then sterilized. In some
variations, not all components of the fluid monitoring system are
sterilized. For example, the fluid lines in the PL and housing may
be sterile, but the transfer disk and/or the sensor disk may not be
sterile. A barrier, such as a sterile membrane or a gap, may be
imposed between sterile and non-sterile components to reduce and/or
eliminate contact between components. In some cases, the barrier
may be temporary, such as packaging that is removed upon
installation, or permanent, such as air space between components.
In other cases, the barrier gap may be permanent, such as
protrusions or spacers that provide permanent clearance between
sterile and non sterile components. Additional steps may be taken
during manufacture and installation to protect sterilized
components from contamination by non-sterile components. For
example, the packaging of a sterile PL and housing or disk assembly
may be sized and shaped so that the component can be handled and
installed without contamination, as shown in FIGS. 10A and 10B.
Packaging (1000) may be used to protect the sterility of any system
component, such as a PL cartridge or disk assembly. Packaging
(1000) may comprise a tray (1001) and lid (1003). The tray may be
molded into a shape that fits the contours of the component it is
intended to house, for example, the circular tray (1001) may be
suitable for housing a component of the disk assembly, such as the
transfer disk or sensor disk, and may be made of any material that
provides sufficient structural integrity to encase the enclosed
component, such as high-density polyethylene (HDPE) or poly
propylene. Some variations of a tray may comprise latches or snap
closures (1005) that retain the component within the tray, as shown
in FIG. 10C. Once the component is placed inside tray (1001), the
lid (1003) may be sealed over the component. The lid (1003) may be
made of any suitable material that can be effectively sealed and
bonded with the tray material, such as Tyvek for a HDPE tray, or
polycoated foil lid stock. The seal between lid (1003) and tray
(1001) may be a heat seal, or an adhesive seal, according to the
material composition of the lid and tray. Prior to installation,
the lid (1003) may be removed, exposing the alignment and locking
features of the component, while the component remains seated (and
engaged by latches (1005)) within the tray (1001). The latches
(1005) or any alternate coupling mechanism is configured to engage
the component to the tray (1001) in a manner that prevents a user
from separating the component from the tray, and thus preventing
use of the component in a manner that would compromise sterility.
The tray (1001) may then be gripped to guide the component to the
appropriate installation site, and manipulated so that the
alignment and locking features of the component are fully engaged
with the monitoring system. Full engagement and alignment with the
fluid monitoring system may urge the latches in the tray to
disengage the component. The tray (1001) may then be dissociated
from the component and discarded. Other variations of packaging
(1000) and methods of installation may be used as appropriate for
the component to be installed, where the packaging and method of
handling reduces the contact of non-sterile items with the sterile
component and may eliminate contamination by non-sterile components
along a sterile fluid pathway. During the manufacturing process,
the different components may be treated and packaged separately.
For example, the transfer disk may be sterilized via gamma
irradiation, however, the sensor disk may not be sterilized.
Directly prior to use, the transfer disk and sensor disk may be
assembled in the same clean room, even those they are packaged
separately.
[0116] The fluid monitoring system interface with the PL cartridge
and disk assembly may have any suitable shape and size, with the
appropriately aligned pins and recesses to accommodate the PL
cartridge and disk assembly. One variation of an interface (1100)
is shown in FIGS. 11A-11B. The system interface (1100) has a recess
(1101) for the installation of PL cartridge (200), and has a recess
(1103) for the installation of disk assembly (300). There may also
be additional recesses of varying shapes and sizes to accommodate
additional system components, as well as apertures and snap closure
to keep the PL cartridge and/or disk assembly components from
disengaging from the system during use. The interface (1100) may
also comprise sensor access apertures (1105) for ready access to
the disk assembly. The blood-in-line, air-in-line, humidity and
other sensor types may access the disk assembly through apertures
such as (1109), (1111), and (1113) respectively.
[0117] FIG. 11B shows the housing provided by the fluid monitoring
system, wherein the syringe may be installed prior to the PL
cartridge (200). The recess (1103) may also comprise a protrusion
that articulates with the alignment features in the transfer disk
(302). In this embodiment, the system interface (1100) is
configured for the vertical installation of the disk assembly, but
in other embodiments, the disk assembly may be oriented
horizontally, or any position between the two. The intersection
between recess (1101) and recess (1103) may be configured so that
the disk assembly (300) and the PL cartridge (200) may not contact
each other when first installed, however a variety of actuators may
be used to adjust the distance between the disk assembly and PL
cartridge.
* * * * *