U.S. patent application number 14/004775 was filed with the patent office on 2013-12-26 for sample metering.
This patent application is currently assigned to Carclo Technical Plastics Lmited. The applicant listed for this patent is Philip Robertson, Richard Swainson, Patrick Ward. Invention is credited to Philip Robertson, Richard Swainson, Patrick Ward.
Application Number | 20130344617 14/004775 |
Document ID | / |
Family ID | 45937435 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130344617 |
Kind Code |
A1 |
Robertson; Philip ; et
al. |
December 26, 2013 |
SAMPLE METERING
Abstract
A sample metering device for a liquid sample comprises at least
one capillary passage with an inlet and an outlet; a side passage
extending from the capillary passage part way along the length
thereof and leading to an outlet; a fluid application region for
receiving a liquid sample to be tested, for entry to the capillary
passage via the inlet; first sealing means operable releasably to
seal the outlet of the capillary passage; and second sealing means
operable releasably to seal the outlet of the side passage.
Inventors: |
Robertson; Philip;
(Weybridge Surrey, GB) ; Swainson; Richard;
(Chessington Surrey, GB) ; Ward; Patrick; (Croydon
Surrey, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Robertson; Philip
Swainson; Richard
Ward; Patrick |
Weybridge Surrey
Chessington Surrey
Croydon Surrey |
|
GB
GB
GB |
|
|
Assignee: |
Carclo Technical Plastics
Lmited
Ossett Yorkshire
GB
|
Family ID: |
45937435 |
Appl. No.: |
14/004775 |
Filed: |
March 15, 2012 |
PCT Filed: |
March 15, 2012 |
PCT NO: |
PCT/GB2012/050575 |
371 Date: |
September 12, 2013 |
Current U.S.
Class: |
436/180 ;
422/520 |
Current CPC
Class: |
B01L 2400/0694 20130101;
B01L 2300/161 20130101; B01L 2400/0406 20130101; B01L 3/50273
20130101; B01L 2200/0689 20130101; B01L 2200/16 20130101; B01L
3/561 20130101; B01L 2300/042 20130101; B01L 2400/0683 20130101;
B01L 2400/082 20130101; B01L 3/5027 20130101; B01L 2300/0672
20130101; B01L 3/502738 20130101; B01L 2400/049 20130101; Y10T
436/2575 20150115; B01L 3/502707 20130101; B01L 3/56 20130101 |
Class at
Publication: |
436/180 ;
422/520 |
International
Class: |
B01L 3/00 20060101
B01L003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2011 |
GB |
1104354.4 |
Mar 15, 2011 |
GB |
1104357.7 |
Mar 15, 2011 |
GB |
1104358.5 |
Mar 15, 2011 |
GB |
1104359.3 |
Claims
1. A sample metering device for a liquid sample, the device
comprising at least one capillary passage with an inlet and an
outlet; a side passage extending from the capillary passage part
way along the length thereof and leading to an outlet; a fluid
application region for receiving a liquid sample to be tested, for
entry to the capillary passage via the inlet; first sealing means
operable releasably to seal the outlet of the capillary passage;
and second sealing means operable releasably to seal the outlet of
the side passage.
2. A sample metering device according to claim 1 wherein the
sealing means are capable of controlling flow of liquid sample in a
passage without contact between the sealing means and liquid
sample.
3. A sample metering device according to claim 1, having more than
one capillary passage, each with an associated side passage and
sealing means.
4. A sample metering device according to claim 3, wherein the
capillary passages have a common inlet.
5. A sample metering device according to claim 1, wherein the side
passage is a capillary passage.
6. A sample metering device according to claim 1, wherein the side
passage has a larger cross-sectional area than the capillary
passage.
7. A sample metering device according to claim 1, wherein the
sample application region is designed to receive a larger volume of
liquid sample than the test volume.
8. A device according to claim 1, wherein an outlet is provided at
a distal end of a capillary passage or side passage.
9. A device according to claim 1, wherein a capillary passage
comprises one or more additional outlets, removed from a distal or
proximal end of a capillary passage, and first sealing means
operable to releasably seal an additional outlet, to control flow
of liquid sample in a device.
10. A device according to claim 1, wherein the fluid application
region comprises a well.
11. A device according to claim 10 wherein the well is formed
within a planar element forming the capillary pathway device.
12. A device according to claim 11, preferably as a concave region
leading to a sample application hole.
13. A device according to claim 10, wherein the base of the well
comprises the fluid application region.
14. A device according to claim 10 wherein the base of the well is
configured such that it slopes toward a sample inlet hole from all
directions.
15. A device according to claim 10, wherein the sample well
comprises features to aid flow of sample liquid into a capillary
passage.
16. A device according to claim 1 wherein the sealing means (and
additional sealing means if present) may be located on a control
element, movable to cause operation of the sealing means.
17. A device according to claim 16 wherein the control element is
arranged for rotary or linear motion.
18. A device according to claim 16, with the outlets of the
capillary passages, and optionally the outlets of any side passages
if present, being located in the vicinity of the fluid application
region and wherein the control element surrounds the fluid
application region.
19-34. (canceled)
35. A sample testing device comprising a sample metering device as
defined in claim 1.
36. A method of metering a liquid sample, comprising a) applying a
liquid sample to a sample application region of a sample metering
device which comprises a capillary passage having an outlet and a
side passage extending from the capillary passage part way along
the length thereof and leading to an outlet; b) operating first
sealing means to seal the outlet of the capillary passage and
operating second sealing means not to seal the outlet of the side
passage; c) allowing liquid sample to flow along the capillary
passage by capillary action, and into the side passage; d)
operating first sealing means to not seal the outlet of the
capillary passage and second sealing means to seal the outlet of
the side passage.
37. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to a sample metering device, for
providing a predetermined quantity of a liquid sample.
BACKGROUND TO THE INVENTION
[0002] There are many situations in which it is necessary to
provide a predetermined quantity of a liquid sample, e.g. for
testing purposes, and difficulties can arise in achieving this
accurately and reliably in an easy manner not requiring complex
equipment and/or skilled operators, particularly where very small
quantities of liquid are involved such as microfluidic devices.
This applies e.g. with sample testing devices having one or more
capillary passages for testing for the presence or amount of a
component of interest in a liquid sample, commonly a body fluid
such as blood (whole blood or plasma), urine, saliva, etc.
[0003] For a Point of Care assay system, it is desirable for an
unskilled operator to add an unmeasured volume of sample to the
device, and for the device to automatically abstract the required
volume and sequester any excess in a secure manner to prevent
contamination.
[0004] Many systems are based on "capturing" a defined volume from
the start of flow and restricting the volume drawn into the assay
capillary (e.g. using a wick region with a defined volume, such as
pregnancy tests). However, such approaches do have drawbacks. If
the metering zone is fluidically connected to the rest of the
device then unless care is exercised by the user, or some
interruption is interposed in the pathway, an excess of fluid can
be drawn through the metering zone and an incorrect volume
obtained. With devices based on lumen-type capillaries it can be
difficult to cause the fluid to leave the wick as the capillary
forces in the wick are stronger than in the lumen.
[0005] Another approach has been to "capture" a defined volume from
the fluid front, then use an overflow to discard excess sample from
the rear of the sample flow. The defined volume is then transferred
to the reaction area. US patent application no. 2011/0003286 uses
such an approach. By using a combination of pressure and
restrictions in the flow path, sample is caused to enter a metering
zone but cannot exit due to a reduction in capillary dimension at
the outflow. Excess sample is purged out of the feed channel and
then a higher pressure applied to force the defined volume of
sample from the sampling region past the restriction and into the
reaction zone. Such systems are thus complex and rely on an
additional motive force to capillary action for fluid flow. They
are thus not suited to pure capillary systems.
[0006] The present invention aims to overcome or ameliorate
problems associated with the prior art.
SUMMARY OF THE INVENTION
[0007] The present invention provides a sample metering device for
a liquid sample, the device comprising at least one capillary
passage with an inlet and an outlet; a side passage extending from
the capillary passage part way along the length thereof and leading
to an outlet; a fluid application region for receiving a liquid
sample to be tested, for entry to the capillary passage via the
inlet; first sealing means operable releasably to seal the outlet
of the capillary passage; and second sealing means operable
releasably to seal the outlet of the side passage.
[0008] The present invention is typically applicable to capillary
devices in which fluid flow is passive, i.e. it is not controlled
by an external force. The sealing means of the device act as remote
(off-line) valves, which control passive flow of sample liquid
through a passage of the device. Thus, the sealing means are
releasably movable between a position in which the sealing means
are positioned to seal an outlet and a position in which the outlet
is not sealed, to stop or allow liquid sample flow, respectively.
By remote or off-line is meant that the valve (sealing means) is
capable of controlling flow of a liquid sample (i.e. stopping or
slowing, or resuming flow) without requiring contact between the
sealing means and liquid sample. When a liquid sample is applied to
the fluid application region, liquid will flow along the capillary
passage only when the first sealing means is operated not to seal
the outlet of the capillary passage. When the first sealing means
is operated to seal the outlet, then fluid flow along the capillary
passage is not possible. Thus operation of the sealing means can be
used to control fluid flow in the capillary passage.
[0009] The invention is used by applying a liquid sample to the
fluid application region, with the first sealing means operated to
seal the capillary passage outlet and the second sealing means
operated not to seal the outlet of the side passage. Liquid sample
flows along the capillary passage by capillary action only as far
as the intersection with the side passage, because the outlet of
capillary passage is sealed. Liquid is, however, able to flow into
and along the side passage because the side passage outlet is not
sealed. The capillary will fill until all sample has been drawn in,
and the well is depleted of sample liquid. Any excess liquid above
the test volume will begin to fill the side passage. Flow stops
when all sample has drawn in from the fluid application region into
the capillary passage (the back pull in the capillary then
equalling the forward pull). In this way, the capillary passage is
filled with sample liquid to a defined point (the intersection with
the side passage). The volume of sample liquid from the capillary
passage inlet to the intersection with the side passage is referred
to herein as a test volume. Any excess sample over the test volume
is contained within the side channel. If the sample volume is too
small, liquid sample will not reach the side passage. Thus, it is
preferred that sample in excess of the test volume is added to the
device. Preferably, the test volume is a pre-determined volume,
appropriate to the assay type. The conditions of the sealing means
are then reversed, with the first sealing means functioning not to
seal the capillary passage outlet and the second sealing means
functioning to seal the side passage outlet. The liquid in the
capillary passage is then free to flow further along the capillary
passage, for example by capillary action. No further flow will take
place along the side passage, including back-flow towards the
capillary passage. Where the liquid sample moves by capillary
action it is usually desirable to add a chase buffer to the
proximal part of the capillary, e.g. via the inlet. Where other
motive forces are used to cause the liquid sample to flow, the
addition of a chase buffer may not be necessary.
[0010] The above embodiment has the advantage that the leading edge
of the sample liquid is not used as the test fluid, but is removed
into a side passage as excess fluid. This is different to the
assays of the prior art, where the leading volume is used as the
test volume. This has benefit in applications where mid-sample
liquid is preferred, for example urine for pregnancy test. Further,
the arrangement means that the defined sample does not leave the
main capillary, and so can continue to flow along the capillary
channel for the assay. No complex fluidics or additional sources of
motive force are required other than capillary force. Further, the
design is such that excess sample is contained safely within the
device preventing any external contamination.
[0011] The invention can thus provide a simple, convenient and
reliable means for obtaining a predetermined volume of a liquid
sample in a capillary passage (the test volume). The size of the
test volume depends on the cross-sectional area and length of the
capillary passage between the inlet and the side passage inlet. The
size of the capillary passage between the inlet and side passage
inlet (the test volume) may be of any suitable size, depending upon
the purpose of the assay. Preferred test volumes (and thus volume
of the capillary passage between the inlet and the intersection
with the side passage) range from 1 to 200 .mu.l, more preferably
between 1 and 150 .mu.l, more preferably between 1 and 50 .mu.l,
more preferably between 1 and 20 .mu.l, more preferably between 1
and 10 .mu.l.
[0012] Thus, the sealing means act, in the present invention, as
remote valves, operation of which serves to control flow in the
capillary and where provided, the side passages. The sealing means
are provided externally to the passages, and therefore are capable
of controlling flow of a liquid sample in the capillary passage
without contact of the sealing means with the liquid sample. Thus,
the sealing means are effectively off-line valves for control of
liquid sample flow, such that they are capable of controlling flow
of a liquid sample in a capillary passage without requiring contact
between the sealing means and liquid sample. (i.e. they operate at
a distance from the leading edge of the fluid).
[0013] Sealing means for use in the present invention must be
sufficient to provide an air tight seal to a passage, when in a
sealing relationship with an outlet. An air tight seal will
substantially or completely stop fluid flow in the capillary
passage to which the sealed outlet is related.
[0014] The device is preferably applicable to any capillary pathway
device, and finds application in a variety of microfluidic
applications that require delivery or control of one or more
liquids. Thus, it may be applicable to a microfluidic device,
including for example inkjet printheads, DNA chips, lab-on-a-chip
technology, biotechnology based arrays, and microfluidic based
sample assays, micro-propulsion, and micro-thermal technologies.
The device may be provided in combination with devices which rely
on other motive forces than capillary action to drive fluid flow,
preferably as an integrated device. In such embodiments, reference
to capillary action and capillary passages herein include within
their scope any applicable fluid flow action or passage.
[0015] The invention is preferably used for sampling based assays,
where a measured volume of liquid is removed from a larger volume
and assayed. The present invention is particularly suited for use
in assaying a sample liquid for a particular component. Whilst it
may be suited to biological and non-biological applications, it is
particularly suited to the former. Thus, the present invention is
preferably for use in assaying a biological sample for a particular
component, for example an analyte. Typically, assays for which the
present invention may be used are microfluidics-based assays,
including for example agglutination based assays, capture-based
assays such as ELISA assays, and coagulation based assays. The
assays may be quantitative or qualitative. The present invention
may be suitable for use with any liquid sample. Preferred
biological samples for assay using the present invention are blood
(whole blood or plasma) and urine.
[0016] The invention finds particular application in sample testing
devices having one or more capillary passages for testing for the
presence of a component of interest in a liquid sample, e.g. blood
or other body fluid, as is well known in the art, e.g. diagnostic
assays, such as the agglutination assays disclosed in WO
2004/083859 and WO 2006/046054.
[0017] The device may include more than one (i.e. two, three, four,
five or more) capillary passage, each with an associated side
passage. Sealing means may be provided for each capillary passage
outlet and side passage outlet. A sample testing device as
discussed above typically includes at least two side-by-side
capillary passages (and associated features), constituting a test
track and a control track, usually with a common inlet leading to
or constituting the inlet of the capillary passages. Multiple
similar test tracks may be provided, e.g. for simultaneous testing
of a single sample for multiple components of interest.
[0018] A device of the present invention may comprise reagent
deposited in one or more capillary passages. Preferably, reagent
may be deposited in test (assay) and/or control passages (i.e. main
capillary passages). Typically, side passages which are provided
for removal storage of excess sample do not require reagent
deposited therein. Any suitable methods may be used for deposition
of reagent in a capillary channel. Reagents laid down in a
capillary channel may include, for example, agglutination reagents,
antibodies, and labels. Other reagents include buffers, and any
other assay components. Particularly in a sample testing device,
reagent may be capable of causing a reaction with a component of
interest. In the case of the arrangement described above, the
reagent system is typically deposited in a capillary passage. Where
a side passage is provided for metering, any test reagent is
preferably deposited downstream thereof. Other sample treatment
reagents (for example, an anticoagulant) may be provided upstream
of the junction with a side passage.
[0019] In the present invention, a capillary passage may have any
suitable geometry, typically dictated by the array type. For
instance, the passage may be straight, curved, serpentine,
U-shaped, etc. The cross-sectional configuration of the capillary
passage may be selected from a range of possible forms, e.g.
triangular, trapezoidal, square, rectangular, circular, oval,
U-shaped, etc. The capillary passage may have any suitable
dimensions. Typical dimensions of a capillary passage for use in
the invention is a depth of 0.1 mm to 1 mm, more preferably 0.2
mm-0.7 mm. The width of a channel may be of similar dimensions to
the depth. Where the channel is V-shaped, for example, the profile
may be that of an equilateral triangle, each side having a length
of between 0.1 and 1 mm, more preferably between 0.2 and 0.7
mm.
[0020] Where more than one capillary passage is provided in a
device, the geometry of each may be independently selected and two
or more may be the same or different.
[0021] The side passage may also be a capillary passage. The size
and shape of a side passage is typically dictated by the volume of
sample it is required to accommodate. As the side passage is
provided for storage of surplus sample, the same requirements of a
test capillary passage, e.g. in terms of flow, reagent depositions,
surface preparation, may not necessarily apply. The geometric and
cross-sectional configurations of a side passage may be dictated by
required volume to be held and the overall configuration of the
device. The side passage may be wider or able to accommodate a
larger volume than the test volume. For reasons including flow of
sample, the side passage may be wider than the capillary passage.
Preferably, the side passage has a volume of between 1 and 100
.mu.l.
[0022] Typical dimensions of a side passage for use in the
invention is a depth of 0.1 mm to 1 mm, more preferably 0.2 mm-0.5
mm, most preferably approximately 0.4 mm. The width of a channel
may be of similar dimensions to the depth. Typically, a side
passage will have any length suitable depending upon the estimated
sample size and the metering requirement, and also dictated by the
shape and form of the device as a whole. Preferably, the side
passage may have a length of between 20 and 100 mm, more preferably
between 20 and 80 mm, more preferably approximately 60 mm.
[0023] The side passage may branch from the capillary passage in
any direction, and may adopt any geometric configuration, for
example it may be straight, curved, serpentine, U-shaped etc. It
may extend parallel to the capillary passage, or perpendicular
thereto. Preferably, the side passage is configured such that the
side passage outlet is in close proximity to the capillary passage
outlet, such that both may be operated by a single control element.
The cross-sectional configuration may be any suitable
configuration, for example trapezoidal, triangular, horizontal,
square, rectangular, circular, over, or U-shaped etc.
[0024] In a preferred embodiment, a capillary passage may comprise
means for detecting presence or absence of sample liquid. Such
means may be used to communicate to the user that further operation
of the device (e.g. sealing or not sealing an outlet) is necessary,
and/or to monitor flow for the purpose of obtaining assay results.
A side passage may comprise means for detecting the presence or
absence of sample liquid, preferably to confirm that sample liquid
has entered the side passage, and therefore the test volume is
present in the main capillary passage (i.e. the volume is not short
or insufficient). Suitable detection means for use in the invention
may include, in a simple form, for example a viewing window, or
other means such as an electronic or optical sensor. A detections
means may be operably linked to a control element, for operation of
a sealing means of the device.
[0025] Functionally, the configuration of the side passage must be
such that it supports capillary flow, such that flow into the side
passage can be remotely (i.e. without contacting the fluid)
controlled by sealing or opening the side passage outlet.
[0026] Inlets typically mean entry holes which are in fluid
communication with the sample application region, preferably in
direct fluid communication. If in indirect communication, this is
preferably via non-capillary passages or means. An inlet is
preferably provided at a proximal end of a capillary or side
passage of the invention, although inlets may also be provided at
one or more positions along the length of a capillary or side
passage, for example for deposition of reagents in a passage or
where branched (converging) channels or passages are provided. An
inlet must be of a dimension which enables it to receive liquid.
Preferably, for a sample testing device, an inlet will have an
opening diameter in the region of 2 and 4 mm, preferably between 1
and 2 mm. For other applications, larger or smaller inlets are
envisaged.
[0027] Typically, an outlet of a capillary passage or side passage
are provided to enable flow through a passage, for example by
capillary of by a motive force, typically so that air can leave the
passage. An outlet may be provided at a distal end of a capillary
or passage, although an outlet may be provided at one or more
positions along the length of a capillary or side passage. An
outlet may not need to accommodate liquid flow therethrough.
Preferably, it is able to accommodate air flow therethrough,
sufficient to maintain flow of a liquid through the respective
passage. For a sample testing device, an outlet may be of smaller
dimensions than an inlet. An outlet may typically have an opening
diameter of between 0.5 mm and 4 mm, more preferably between 0.75
and 2 mm. For other devices, larger or smaller outlets are
possible. An outlet is typically only in fluid communication with a
passage.
[0028] Outlets and inlets may have a raised skirt around
circumference, with the outlet being central thereto.
[0029] The device conveniently comprises a moulded plastics
component, e.g. in the form of a generally planar element having
grooves in one surface thereof to define the capillary passage(s)
and side passage(s) when sealed by a cover member.
[0030] The device conveniently comprises a well, in fluid
communication with the fluid application region, which may comprise
a sample application hole (the inlet) leading to a capillary
passage. The well may be any suitable shape and size, suitable for
receiving and retaining liquid sample. Preferably, the well may be
formed within, or as part of a planar element forming the device,
for example as a concave region leading to a sample application
hole, or may be formed upstanding therefrom, such as a collar. In
these embodiments, the base of the well may comprise the fluid
application region of the device. All or part of the well may be
provided with a device provided in combination with the sample
metering device, for example a fluid flow control device as
described herein.
[0031] Alternatively, the well may be defined by a separate
element, operably linked to the fluid application region by fluid
communication means. In such an embodiment, the base of the well
does not comprise the fluid application region.
[0032] The well is conveniently constituted by one or more side
walls, e.g. of generally circular cylindrical form. Preferably the
base of the well is funnel shaped, i.e. configured such that it
slopes toward a sample inlet hole from all directions. This
configuration aids drainage of sample into a capillary passage.
Preferably the well comprises a suitable form of cap or cover,
which is preferably removable, and may constitute one or more side
walls of the well.
[0033] A cap of a sample well may comprise a liquid inlet for
passage of liquid to the fluid application region, and thus the
sample application hole.
[0034] A well may comprise features, for example micropillars, to
aid sample liquid flow into a capillary passage. Suitable features
will be known to a person skilled in the art.
[0035] The sealing means (and additional sealing means if present)
may be located on a control element, movable to cause operation of
the sealing means. Each sealing means may be located on a
respective control element. Preferably, however, each pair of first
and second sealing means are located on a common control element.
Further pairs of first and second sealing means may be provided on
the same control element as first pair of first and second sealing
means, or on different control elements. In a preferred embodiment,
all sealing means for a device are provided on, or operably linked
to, a common control element.
[0036] The control element is typically arranged for rotary
movement or linear movement (axially, towards and away from the
outlet, or laterally, in a sliding action).
[0037] In embodiments having two or more capillary passages, one or
more of said capillary passages having a side passage, one or more
pairs of first and second sealing means may be provided. One or
more pairs of sealing means may be constituted by a single sealing
component or provided on a control element. A sealing component may
be provided on a control element. Such a component or control
element is moveable between a first position in which the first
sealing means is positioned to seal the outlet of the first
capillary passage and the second sealing means is positioned not to
seal the outlet of the side passage and a second position in which
the first sealing means is positioned not to seal the outlet of a
capillary passage and the second sealing means is positioned to
seal the outlet of the side passage. In an embodiment, two or more
first sealing means may be constituted by a single sealing
component or provided on a control element. A sealing component may
be provided on a control element. Such a component or control
element may be moveable between a first position in which the first
sealing means is positioned to seal the outlet of the first
capillary passage and a second position in which the sealing means
are positioned not to seal the outlet of a first capillary passage.
Two or more second sealing means may be constituted by a single
sealing component or provided on a control element. A sealing
component may be provided on a control element. Such a component or
control element may be moveable between a first position in which
the sealing means are positioned to not seal an outlet of a side
passage and a second position in which the sealing means are
positioned to seal an outlet of a side passage. In an embodiment,
two or more first sealing means and two or more second sealing
means, or two or more components may be provided on the same
control element, which is moveable between a first position in
which the first sealing means is positioned to seal the outlet of
the first capillary passage and the second sealing means is
positioned to not seal the outlet of the side passage; and a second
position in which the first sealing means are positioned not to
seal the outlet of a first capillary passage and the second sealing
means are positioned to seal the outlet of a side passage.
[0038] Alternatively, respective first and second (and possibly
further) sealing means may be provided for each of the capillary
passage outlets, each operable for sealing the associated outlet or
not. For instance, each sealing means may be located on a
respective control element, e.g. axially movable towards and away
from the associated outlet. As a further possibility, the sealing
components may be located on a common control element, e.g.
arranged for rotary or linear (lateral) motion, movable between a
first position in which the first sealing means is in sealing
relationship with the outlet of the first capillary passage, with
the second sealing means not in sealing relationship with the
outlet of the second capillary passage; and a second position in
which the second sealing means is in sealing relationship with the
outlet of the second capillary passage, and the first sealing means
is not in sealing relationship with the outlet of the first
capillary passage.
[0039] In an embodiment, sealing means may operate in a binary
manner between two positions, a position in which an outlet is
sealed and a position in which an outlet is not sealed. In another
embodiment, a sealing means may operate in a quantitative manner
such that the sealing means may be operated to partially close an
outlet, such that the rate of flow of the liquid sample in a
passage may be controlled depending upon the degree to which the
outlet is opened or closed. For example, the sealing means may be
operated to slide across the vent, such that the rate of flow of
the liquid sample is slowed as the outlet is in a partially closed
position. In an embodiment, the sealing means may adopt any one or
more positions which partially close an outlet to alter the rate of
flow in a passage. These embodiments may apply to both the first
and second sealing means of the invention.
[0040] Conveniently, one or more outlets may be grouped together.
Preferably the pair of outlets for the main passage and side
passage may be located within a close proximity so the respective
sealing means are operable by a single control element. In an
embodiment, two or more side passage outlets may be grouped in
close proximity, and two or more main capillary passage outlets may
be grouped in close proximity, so that each group may be
controllable by a single control element. Preferably, outlets or
groups of outlets may be located in close proximity to the fluid
application region.
[0041] Preferably, the control element conveniently surrounds the
fluid application region. A control element may be any suitable
shape or size, preferably easily manipulated by the user. A control
element may be manually operable by a user, or automatically
operable, for example prompted by one or more sensors associated
with detection means in the device, or a timer.
[0042] A control element is typically arranged for rotary movement
or linear movement (axially, towards and away from the outlet, or
laterally in a sliding action). A control element can move between
a first position in which the first sealing means is positioned to
seal the capillary passage outlet and the second sealing means is
positioned to not seal the side passage outlet; and a second
position in which the first sealing means is positioned to not seal
the capillary passage outlet and the second sealing means is
positioned to seal the side passage outlet. The control element may
be arranged for rotary or linear movement between positions.
[0043] The control element may be of any suitable shape, preferably
which allows it to move along or around the fluid application
region. For example, it may be a rotatable element, for rotational
movement about a pivot, or a formed for linear movement, e.g. a
sliding motion along the location of outlets. Preferably, it
desirably comprises a generally circular cylindrical element,
conveniently positioned for rotation with or around the fluid
application region, e.g. with or around a sample well, as discussed
above. Where the sample well is defined by the control element, the
side wall will rotate with the control element. Where the sample
well is a recess or indent in the capillary pathway device and a
control element forms a cover thereof, an underside of the control
element may form the cover of the sample well. The sample well is
exposed or covered depending on the position of the control
element. Other suitable shapes and forms of the control element and
fluid application region are included within the scope of the
invention. Grooves and elements may be provided on the control
element and upper surface of the device to permit limited movement
of the control element relative to the well.
[0044] The control element may comprise a sample well, or serve as
a cap for a sample well. It may include a liquid inlet for passage
of liquid to the fluid application region, and thus the sample
application hole. Preferably, the liquid inlet is in fluid
communication with the fluid application region or sample well only
when a control element is in selected positions, e.g. selected
rotary or linear positions, as further described below.
[0045] In an alternative embodiment, the sample well is constituted
by an element which is distinct from a control element of the
device. In an embodiment, the fluid application region or sample
well has a cap which is constituted by an element which is distinct
from a control element of the device.
[0046] In an embodiment, the well side wall desirably includes a
main cylindrical portion e.g. a part-cylindrical portion such as a
part circular cylindrical portion, with a wider extension portion,
e.g. a part-cylindrical portion such as a part circular cylindrical
portion, with the extension portion base including an opening
leading to the inlet of the capillary passage(s). The control
element, e.g. rotatable cap, desirably includes a cooperating
annular groove on the underside, dimensioned to fit around the well
side wall, with the annular groove having a widened portion to
accommodate the well side wall extension portion, with the control
element having a fluid entry opening overlying the widened portion
of the groove. The arcuate length of the widened portion of the
control element groove is larger than the arcuate length of the
well side wall extension portion, to permit limited rotary movement
of the control element relative to the well.
[0047] Sealing means or sealing components may carried on or
forming part of the control element, e.g. on the underside thereof.
The sealing means or components may be constituted by elements,
e.g. of soft material, e.g. a soft thermoplastic material such as
an elastomer, standing proud of or forming part of the control
element underside. Sealing means or a sealing component may be
provided on a flange which extends outward from a side wall of a
control element, preferably substantially perpendicular thereto.
Sealing means may be feet, provided on a flange.
[0048] Markings and/or stops are conveniently provided to indicate
the various positions of the control element, to facilitate
operation by a user. These may be provided preferably in the
capillary pathway device.
[0049] End stops are desirably provided to limit the movement of
the control element.
[0050] Desirably, a control element is movable between a first,
inactive position in which the liquid inlet is not in fluid
communication with the fluid application region and the first
sealing means do not seal the outlet(s) of the capillary passage(s)
and the second sealing means are positioned not to seal the
outlet(s) of any side passages; and a second position in which the
liquid inlet is in fluid communication with the fluid application
and the first sealing means are positioned to seal the outlet of
the first capillary passage and the second sealing means are
positioned not to seal the outlet(s) of a side passages.
[0051] The control element is moveable to a third position in which
the first sealing means do not seal the outlet(s) of the first
capillary passage(s), and the second sealing means seal the
outlet(s) of a side passage(s). Preferably, in the third position,
the liquid inlet is not in fluid communication with the fluid
application region.
[0052] More preferably the sealing means for the capillary passage
and side passage can be releasably operable.
[0053] In embodiments having two (or more) capillary passages,
additional sealing means or components may be provided as required,
conveniently located on a control element as discussed above.
[0054] The invention also provides a method of metering a liquid
sample, comprising
[0055] a) applying a liquid sample to a sample application region
of a sample metering device which comprises a capillary passage
having an outlet and a side passage extending from the capillary
passage part way along the length thereof and leading to an
outlet;
[0056] b) operating first sealing means to seal the outlet of the
capillary passage and operating second sealing means not to seal
the outlet of the side passage;
[0057] c) allowing liquid sample to flow along the capillary
passage by capillary action, and into the side passage;
[0058] d) operating first sealing means to not seal the outlet of
the capillary passage and second sealing means to seal the outlet
of the side passage. Preferably, the sample metering device is as
defined herein.
[0059] In an aspect, the present invention provides a fluid flow
control device for controlling flow of fluid in a capillary pathway
device having a first capillary passage with an inlet and an outlet
and a fluid application region for receiving a liquid sample for
entry to the capillary passage via the inlet, the fluid flow
control device comprising first sealing means operable for
releasably sealing the outlet of the first capillary passage.
[0060] The present invention provides a fluid flow control device,
as described herein, in combination with a capillary pathway
device, as described herein. A sample metering device may comprise
a fluid flow control device and capillary pathway device, as
described herein in embodiments.
[0061] Preferred features and embodiments of the sample metering
device (e.g. the reagents, control element, well, sealing means and
sealing components etc) may apply, mutatis mutandis, to the fluid
flow control device and capillary pathway device, or combined
device, as provided herein (e.g. features and embodiments relating
to reagents, capillary devices, inlets and outlets, wells, sealing
means, and the control element).
[0062] In an aspect of the invention there is provided a device
comprising a fluid flow control device for controlling flow of
fluid in a capillary pathway device, in combination with a
capillary pathway device comprising a first capillary passage with
an inlet and an outlet and a fluid application region for receiving
a liquid sample for entry to the capillary passage via the inlet,
the fluid flow control device comprising first sealing means
operable for releasably sealing the outlet of the first capillary
passage. Preferably, the fluid flow control device and capillary
pathway device are integrated to form a single device.
Alternatively, the fluid flow control device (or part thereof) may
be releasable from the capillary pathway device. In such an
embodiment, the fluid flow control device may be arranged to
cooperate with the capillary pathway device.
[0063] The capillary pathway device may comprise a single capillary
passage, but may have two or more capillary passages.
[0064] For instance the capillary pathway device may have a second
or further (third, fourth, fifth etc) capillary passage, each with
an inlet and an outlet, and the fluid flow control device may
comprise a second or further (third, fourth, fifth etc) first
sealing means operable for releasably sealing a respective outlet
of a second or further capillary passage. Thus, in a device
comprising a second or further capillary passage, flow of liquid
sample in each passage is controlled by (preferably separate) first
sealing means provided in respect of each passage.
[0065] In one arrangement, the capillary pathway device comprises
first and second (and possibly more) similar capillary passages,
typically in a side-by-side arrangement. The passages may have a
common inlet and respective outlets. By appropriate operation of
the first sealing means, liquid applied at the fluid application
region may be caused to flow along each of the capillary passages
as required, for desired time intervals (and hence in desired
quantities). In this way, the fluid flow control device may be
used, for instance, to dispense liquid from a common source to
different outlets in desired quantities at desired times.
[0066] The invention is used by applying a sample to the fluid
application region, with the first sealing means operated to not
seal the capillary passage. Liquid sample will flow from the fluid
application region into a first or second or further capillary
passage. Flow of liquid sample can be slowed or stopped at any
point during the assay, by operating the first sealing means to
partially or fully close the outlet(s) of the capillary passage.
Preferably, the first sealing means may then be operated to not
seal the outlet(s) of the capillary passage, allowing liquid sample
to flow along the capillary passage. Flow of the liquid sample may
be slowed, stopped and caused to resume flow by appropriate
movement of the first sealing means, any number of times (one or
more) during a single assay.
[0067] This aspect of the present invention also has the advantage
of providing a simple mechanism by which flow of liquid sample can
be slowed or stopped. This may be desirable in a multi-step assay,
for example at a predetermined point to enable a reaction to occur
before allowing the fluid to proceed to the next step. The
invention can also be used to direct fluid, or a portion of fluid,
along different capillary passages in a device.
[0068] In this aspect of the invention, substantially all liquid
sample will flow from the fluid application region into a capillary
passage. Typically, for a sampling based assay, a defined volume of
liquid sample may be required for optimal functioning of the assay.
Thus, in a preferred embodiment, sample metering means may be
provided, which service to provide a predetermined, measured volume
of liquid to a capillary passage for the assay. Any suitable sample
metering means may be used, which may vary depending upon the form
and purpose of the assay and device.
[0069] Preferably, the fluid flow control device, capillary pathway
device and metering means are integrated to form a single device.
Preferably, sample metering means may be provided either in the
fluid flow control device or the capillary pathway device.
[0070] Preferably, the device comprises a sample metering device as
described herein. In a preferred arrangement, the capillary pathway
device comprises a first capillary passage (or second or further
capillary passage, as defined above) and a side passage, extending
from the first capillary passage part way along the length thereof
and leading to an outlet, the inlet to the side passage being
constituted by the junction with the first capillary passage. The
fluid flow control device comprises first sealing means operable
for releasably sealing the outlet of a first capillary passage and
second sealing means operable for releasably sealing the outlet of
the side passage.
[0071] The two arrangements discussed above may be used together.
Thus, for example, the capillary pathway device may include two or
more sets of a main (first) capillary passage with an associated
side passage. First sealing means are provided to releasably
operate the outlet of a main passage. Second sealing means are
provided to releasably seal the outlet of a side capillary
passage.
[0072] In an embodiment, a device of the invention comprises fluid
dispensing means, comprising a rupturable, sealed container of
fluid to be dispensed, rupturing means for rupturing the container
and releasing the contents, the container and/or rupturing means
being arranged for relative movement between a first position in
which the container is intact and a second position in which the
container is ruptured.
[0073] The device may comprise a well, as hereinbefore described.
Where the well of the device is provided in a fluid flow control
device, the base of the well may comprise a fluid application
region. In embodiments, the well may be formed by a combination of
one or more elements forming the fluid flow control device,
capillary pathway device and a separate element. For example, a
base of the well may be formed by a portion of a capillary pathway
device, and side walls of a well may be formed by a portion of a
fluid flow control device, with a further, optionally separable,
element provided to form a cap or cover for the well.
[0074] The sealing means, sealing components and control elements
may preferably be as hereinbefore described.
[0075] In embodiments having more than one capillary passage, each
with associated sealing means, two or more sealing means (and
additional sealing means if present) may be constituted by a single
sealing component provided by the fluid flow control device. A
sealing component may be movable between a first position in which
a sealing means of the sealing component seals an outlet; and a
second position in which a first sealing means of a sealing
component does not seal an outlet and a second or further sealing
means of a sealing component seals an outlet. Alternatively, the
sealing component is movable between a first position where two or
more sealing means of the sealing component seal the outlets of the
capillary passages; and a second position in which two or more
sealing means of the sealing component do not seal the outlet of
the capillary passages. Preferably, such a sealing component is
conveniently located on a control element, e.g. arranged for rotary
or linear (lateral) motion, movable to bring the sealing component
into and out of a sealing relationship with each of the
outlets.
[0076] Alternatively, one or more (and possibly further) sealing
means may be provided for each of the capillary passage outlets,
each operable for sealing the associated outlet or not. For
instance, each sealing means may be located on a respective control
element, e.g. arranged for linear or rotary movement towards and
away from the associated outlet. As a further possibility, one or
more sealing components may be located on a common control element,
e.g. arranged for rotary or linear (lateral) motion, towards and
away from one or more outlets.
[0077] Desirably, a control element is movable between a first,
inactive position in which the liquid inlet is not in fluid
communication with the fluid application region and the first
sealing means do not seal the outlet(s) of the capillary passage(s)
and a second position in which the liquid inlet is in fluid
communication with the fluid application and the first sealing
means seal the outlet of the first capillary passage. If side
passages are present, second sealing means are positioned not to
seal the outlet(s) of any side passages in the first, inactive
position; and not to seal the outlet(s) of any side passages in the
second position.
[0078] In embodiments having a side passage, the control element is
moveable to a third position in which the first sealing means do
not seal the outlet(s) of the first capillary passage(s), and the
second sealing means seal the outlet(s) of a side passage(s).
Preferably, in the third position, the liquid inlet is not in fluid
communication with the fluid application region.
[0079] In embodiments of the invention, for example where capillary
action is used to move liquid sample in the passages, fluid
dispensing means may be provided. Preferably, fluid dispensing
means comprise a rupturable, sealed container of fluid to be
dispensed, rupturing means for rupturing the container and
releasing the contents, the container and rupturing means being
arranged for relative movement between a first position in which
the container is intact and a second position in which the
container is ruptured.
[0080] Preferably, the fluid is a buffer, which serves to assist
movement of the liquid sample in the passages, although the fluid
may be any fluid required for performance of the assay. Where it is
used to assist movement in a capillary based assay, the buffer may
be referred to as a chase buffer. Any suitable buffer may be used,
for example, a solution of Ficoll polymer, preferably a 1% by
weight solution of Ficoll polymer in deionised or distilled water
(Ficoll is a Trade Mark), which enables the reaction to be carried
out with a smaller volume of sample than is required to flow around
the entire capillary system to determine a test result.
[0081] The rupturable, sealed container of fluid may be movable
with respect to rupturing means, e.g. in the form of projections in
the vicinity of the fluid application region, for release of fluid
for passage to the capillary pathway device. Operating means serve
to move the container, rupturing means or both into a second
position in which the container is ruptured. The operating means
may be a plunger, carrying at one end either the container or
rupturing means. Operating means may be arranged for rotary
movement e.g. about a pivot, or linear movement (axially or
laterally).
[0082] Preferably, at least a portion of the container wall is
rupturable, e.g. being formed of rupturable foil such as a
polyolefin film. The container may be made entirely of rupturable
material e.g. being in the form of a capsule. As a further
possibility, the container may mainly or partly comprise rigid
material, e.g. a rigid plastics material, with a rupturable
portion, such as a rupturable wall or base, e.g. of rupturable foil
such as polyolefin film.
[0083] Any suitable rupturing means may be provided. Preferably,
the rupturing means conveniently comprise one or more projections,
preferably having sharp tips. The projections are desirably
tapered, and preferably have features to facilitate fluid release
e.g. being of scalloped configuration. Desirably a plurality of
projections are provided.
[0084] Second rupturing means may similarly be provided, arranged
to rupture an opposing portion of the container, to allow air to
pass into the container. This aids flow of fluid out of the
container. The second rupturing means may be provided as for the
first rupturing means, provided they are arranged to rupture an
opposing portion of the container.
[0085] Preferably, the rupturable container, at least when in a
ruptured position, is in fluid communication with the fluid
application region or sample well. Preferably, fluid communication
means are provided to pass fluid from the container to the sample
well or fluid application region. The fluid enters the capillary
passage via the sample inlet hole, as defined above.
[0086] The fluid dispensing device may be a separate element,
distinct from the capillary pathway device and fluid flow control
device. If separate, it is preferably arranged to cooperate (be
compatible with) with the capillary pathway device and/or the fluid
flow control device. The fluid dispensing device may be provided on
the capillary pathway device.
[0087] Alternatively, the fluid dispensing device may be provided
by the fluid flow control device. Preferably, it is provided by the
control element carrying the sealing means or a sealing component,
as defined herein. Preferably, the rupturing means are provided on
an inner surface of the base of the fluid flow control device. In
such an embodiment, the rupturable container may be provided by the
fluid flow control device (preferably the control element).
[0088] Alternatively, the fluid dispensing device may be composed
of parts of the capillary pathway device and the fluid flow control
device. For example, rupturing means may be provided by the
capillary pathway device (for example, as moulded upstanding
projections), and the rupturable container and operating means may
be provided by the fluid flow control device.
[0089] In an embodiment, a single control element may be provided
comprising sealing means (e.g. constituted by a sealing component),
carrying means for a rupturable, sealed container of fluid (and
optionally the container of fluid) and/or rupturing means and
optionally operating means for bringing into contact a rupturable,
sealed contained and rupturing means. Such a control element
preferably also defines a portion of a sample well or fluid
application region, for example as defined above.
[0090] In such an embodiment, movement of the control element to
operate the sealing means may be combined with movement to rupture
the container. Thus, for example, movement of the control element
to operate the sealing means may also cause the container to be
brought into contact with rupturing means. For example, in a
preferred embodiment, rotational movement of the control element to
operate the sealing means may also serve to drive operating means
such that the container is brought into contact with rupturing
means. In such an embodiment, a cam may be provided to operably
link the rotational movement of the control element with a linear
movement of the operating means.
[0091] Alternatively, movement of the control element to operate
sealing means may be independent from the operating means to bring
the container into contact with the rupturing means. Thus, separate
actions are required.
[0092] Preferably, the control element is a control element
comprising sealing means, as described herein.
[0093] The container is preferably movable relative to the
rupturing means, although other arrangements are possible, such as
the rupturing means being movable relative to the container, or
both being movable to come into contact.
[0094] In one preferred arrangement, the container is arranged for
downwards movement, to be brought into contact with rupturing
means. In this embodiment, the rupturing means are preferably
provided on the device, and preferably are in fluid communication
with a sample well or fluid application region. The rupturing means
may comprise projections, and the container is impaled onto
upstanding projections. In another preferred embodiment, the
container is arranged for impaling on projections and being pierced
by spikes.
[0095] Preferably, the container or rupturing means are movable
within the control element between the first and second positions,
e.g. either being carried by or constituting a plunger operable
from the exterior of the control element by simple application of
force, e.g. manually by a user or in automated manner. The relative
movement between the rupturing means and the container may be axial
or linear (i.e. the movement of the operating means may be linear
or axial). Activation brings the rupturing means and container into
contact, thus releasing fluid from the container. Preferably, the
same action brings second rupturing means into contact with the
container, to allow air to pass into the container. Thus,
preferably, fluid passes passively from the container.
[0096] In a preferred embodiment, the operating means comprise a
plunger. The plunger may be initially retained in the first
position, spaced from the rupturing means, e.g. by rupturable webs.
On removal of the spacing means, for example, rupturing of the
webs, the plunger is freed and can be moved to the second position
in which the container is brought into contact with the rupturing
means, and the contents are released. Preferably, the container is
carried by the plunger. Preferably, the plunger is carried, or is
part of, a control element. Preferably, the rupturing means are
carried by the device, or a control element, or a distinct element.
Instead of rupturable webs, a removable collar may be provided to
prevent premature operation of the plunger. In a preferred
embodiment, the removable collar includes a cap to cover the sample
application region.
[0097] The fluid flow control device is conveniently used to
dispense fluid to a fluid receptacle, e.g. for reaction therein, or
to the inlet of a fluid flow passage.
[0098] This embodiment of the device of the invention is
conveniently used in such sample test devices for supplying a known
volume of reagent, e.g. a chase buffer, to the system. This enables
the assay to be carried out using a smaller quantity of sample than
would otherwise be required.
[0099] The invention can enable fluid to be dispensed reliably in
known quantities, determined by the container contents, even small
volumes such as 1000 microlitres or less, 500 microlitres or even
less.
[0100] A device of the invention can thus be easy to operate, to
deliver a predetermined volume of fluid, and can be used reliably
by relatively unskilled personnel.
[0101] A control element as discussed above can be easily
manipulated by a user, and can be used reliably by relatively
unskilled personnel to deliver accurately controlled quantities of
liquids.
[0102] Optionally, a timer is associated with a device of the
invention. The timer may be used to indicate the time for moving
the sealing means or a control element between positions, and/or
for rupturing the container.
[0103] Preferably, one or more detection regions are provided in a
capillary or side passage, to determine presence or absence of
liquid sample at a detection region. Detection regions may be
provided in a side passage, as described herein, and preferably one
or more detection regions in a first capillary passage. Presence or
absence of liquid sample at a detection region may prompt the user
to move the sealing means (e.g. operate the control element) or
otherwise control the flow of liquid sample, or rupture the sealed
container.
[0104] Preferably, a capillary passage of the device, and
optionally a side passage, may be treated to improve flow of liquid
sample therethrough, by passing treatment fluid through the passage
to leave a surface coating on the internal surface of the passage.
Thus, a capillary passage of the device and optionally a side
passage comprise a coating on the inner surface thereof, of a
treatment fluid.
[0105] The coating typically acts by minimising any repulsion
between the inner surface of the passage and sample fluid, whilst
preferably not actively binding or substantially reacting with any
sample, fluid or component thereof. Preferably, the surface coating
increases the hydrophilicity of the passage, as compared to an
untreated passage. The coating may, for example, act by forming a
layer on the inner surface of the treated passage, polymerising
with the surface of the treated passage, or soaking into the
material of the treated passage.
[0106] The treatment fluid may be a liquid or a gas, but typically
is a liquid. Preferably, the treatment fluid, when passing through
the passage, coats the inner surface of the passage (as discussed
above, by leaving behind a layer of material, soaking into the
passage material or polymerising therewith, for example). This
coating has the effect of altering the surface properties of the
passage, for example to improve fluid (e.g. sample) flow though the
passage, for example by improving the hydrophilicity of the
passage. Thus, the treatment fluid is preferably a liquid which
improves flow of a liquid sample, and does not bind the sample.
Preferably, it imparts hydrophilic properties.
[0107] Alternatively, the treatment fluid may be a reagent, for
deposition in a passage. The treatment fluid may be a reagent,
preferably an assay reagent, including for example reagents
comprising agglutination reagents, antibodies, and labels. Other
reagents include buffers, and any other assay components.
[0108] The thickness of the coating will depend upon the type of
treatment fluid, the purpose of the coating, and the dimensions of
the capillary passage. Where a layer of treatment fluid is left on
the inner surface of the passage, it is preferably multi-molecular
or mono-molecular layer. Preferably, the method of the invention
causes substantially the entire inner surface of the treated
passage to be coated with treatment fluid. Preferably, the inner
surface comprises an open-topped channel formed within a component,
and the cover member thereof.
[0109] Where it is desired to improve flow through a passage, this
can be achieved by use of a treatment fluid with suitable
hydrophilic properties, e.g. a surfactants. Suitable materials are
well known to those skilled in the art, and include for example
polysorbates, commonly being used for this purpose, particularly
polyoxyethylene sorbitan materials known as Tween (Tween is a Trade
Mark), e.g. Tween 20 (polyoxyethylene (20) sorbitan monolaurate),
Tween 60 (polyoxyethylene (20) sorbitan monostearate), Tween 80
(polyoxyethylene (20) sorbitan monooleate). Such materials are
typically used in the form of dilute aqueous solutions, e.g. 0.1 to
10%, typically. 1% by volume or less, typically in deionised water,
although other solvents such as isopropanol (IPA) may alternatively
be used.
[0110] The present invention provides a fluid flow control device,
as described herein. The fluid control device may comprise a
control element, as defined herein.
[0111] The present invention provides a capillary pathway device,
as described herein.
[0112] The present invention provides a fluid dispensing device, as
described herein.
[0113] It is appreciated that any preferred features of embodiments
of a device described herein may apply to another device described
herein, and such embodiments are within the scope of the
invention.
DESCRIPTION OF THE DRAWINGS
[0114] A preferred embodiment of a sample testing device will now
be described, by way of illustration, with reference to the
accompanying drawings, in which:
[0115] FIG. 1 is a perspective view from above of a sample
collection element;
[0116] FIG. 2 is a plan view of the underside of the element of
FIG. 1;
[0117] FIG. 2A is an enlarged scale sectional view of part of the
element of FIGS. 1 and 2;
[0118] FIG. 3 shows to an enlarged scale part of the upper face of
the device as shown in FIG. 1;
[0119] FIG. 4 shows to an enlarged scale part of the lower face of
the device as shown in FIG. 2;
[0120] FIG. 5 is a perspective view from above of the element of
FIGS. 1 to 4, carrying a simplified cap (with the plunger omitted
for clarity);
[0121] FIG. 6 is a top plan view of a preferred cap for use with
the element of FIGS. 1 to 4;
[0122] FIG. 7 is a perspective view of the underside of the cap
shown in FIG. 6;
[0123] FIG. 8 is a perspective view from above of the cap of FIGS.
6 and 7, with the plunger in an upper, ready position;
[0124] FIG. 9 is a sectional view of the cap of FIG. 8 with the
plunger in the upper, ready position;
[0125] FIG. 10 is a cutaway perspective view of the cap of FIG. 8,
with the plunger in the upper, ready position;
[0126] FIG. 11 is a sectional view, to an enlarged scale, showing
the cap of FIGS. 6 to 10 located on the element of FIGS. 1 to 5,
with the plunger in the upper, ready position;
[0127] FIGS. 12 to 15 are a series of views corresponding to FIGS.
8 to 11, showing the plunger in a lower, depressed, activated
condition position;
[0128] FIG. 15A is a schematic representation of a step in the
production of the illustrated device;
[0129] FIGS. 16A and 16B are top plan and underside plan views,
respectively, of part of the element of FIGS. 1 to 5 with the
simplified cap of FIG. 5 (with the plunger omitted for clarity),
with the cap in a first position, with the top view also showing
the position of parts in the element and the underside view also
showing the underside of the cap;
[0130] FIGS. 17A and 17B are views similar to FIGS. 16A and 16B,
with the cap in a second position;
[0131] FIGS. 18A and 18B are views similar to FIGS. 16A and 16B,
with the cap in a third position; and
[0132] FIGS. 19 and 20 are schematic views of the underside of the
element of FIGS. 1 to 5, representing operation with the cap in the
second and third positions, respectively.
[0133] FIG. 21 is a view of the underside of a preferred combined
control element of the invention, comprising sealing means, a
plunger for a rupturable container, rupturing means, and serving as
a cap for a sample well. FIG. 22 is a top view of the same control
element.
DETAILED DESCRIPTION OF THE DRAWINGS
[0134] The drawings illustrate a sample testing device having
capillary passages or pathways for performing an agglutination
assay, e.g. generally as disclosed in WO 2004/083859 and WO
2006/046054.
[0135] The device comprises two main components: a sample
collection element 10, and a cap 12. FIGS. 5 and 16 to 18 show a
simplified version of the cap 12' for ease of understanding, with
the plunger omitted for clarity. FIGS. 6 to 15 show a currently
preferred version of cap 12. The caps 12 and 12' are functionally
identical.
[0136] As shown in FIGS. 1 to 5, element 10 comprises a rigid,
planar rectangular plate of injection moulded polycarbonate having
dimensions 136 mm.times.57 mm.times.2.5 mm. The element is formed
with an upstanding collar 14 on the upper face 16 thereof, with a
series of grooves constituting open-topped channels 18 formed in
the lower face 20 of the element. A series of holes, to be
described below, extend through the element, opening onto the upper
and lower faces.
[0137] As seen best in FIG. 3, the collar 14 is located near one
corner of the element and includes a main part-circular portion 24
constituting part of a circle having a radius of about 10 mm and a
minor part-circular portion 26 constituting part of a circle having
a radius of about 6 mm. The collar 14 defines a generally
cylindrical sample collection well 27 on the upper face of the
element 10. A pair of ribs 28 extend outwardly over a portion of
the outer surface of portion 24, with arcuate slot-shaped openings
30 extending through the element below the ribs. The openings do
not perform any function in use of the device, and are present for
moulding production reasons. The upper face of the element within
the collar includes a circular funnel-like recessed portion 32
within collar minor portion 26, leading to a sample hole 34
extending through the element, with the remainder of the upper face
of the element within the collar being slightly dished and
downwardly inclined as shown at 36, as seen also in FIGS. 11 and
15. Four spikes 40 of scalloped configuration extend upwardly from
the dished portion 36 of the upper face.
[0138] The channels 18 define two similar side-by-side capillary
tracks, arranged as mirror images, constituting a test track and a
control track. Each track comprises a main channel 42, 42' arranged
in a U-shaped configuration, with major limbs about 100 mm long.
These channels extend from the sample entry hole 34 to respective
main channel vent holes 44, 44' that pass through the element 10.
Each track also includes an overflow channel 46, 46' extending as a
side branch from the associated main channel and turning through
90.degree. to extend back towards the sample entry hole, and
terminating in respective overflow channel vent holes 48, 48'
extending through the element 10. The overflow channels are wider
than the main channels. A short side channel 50, 50' extends from
each of the main channels, slightly downstream of the junction with
the overflow channels, terminating in respective side channel
openings 52,52' extending through the element 10 and being
countersunk on the element upper face.
[0139] The main channels 42, 42' are V-shaped in section and have
the cross-sectional profile of an equilateral triangle with sides
0.435 mm long. The depth of these channels is 0.377 mm. The overall
length of each main channel is approximately 200 mm. The overflow
channels 46, 46' are trapezoidal in cross section, having a flat
base 0.3 mm in length with outwardly inclined side walls defining
an angle of 60.degree. therebetween. The depth of these channels is
0.38 mm. The overall length of each overflow channel is
approximately 62 mm. The cross-sectional profile of the channels is
shown in FIG. 2A.
[0140] The cap 12, 12' comprises a generally circular cylindrical,
rigid body 60 of injection-moulded acrylonitrile butadiene styrene
(ABS) with a diameter of about 34 mm and a height of about 10 mm.
The body 60 has a circular upper wall 62 with a central opening 64,
and a side wall 66 with a ribbed outer face 68. An inner
cylindrical skirt 70 extends from the lower face of the upper wall
62, being centrally located with respect thereto, surrounding the
central opening 64 and having a diameter greater than that of the
opening 64. An annular trough 72 is formed between the inner face
of side wall 66 and the outer face of skirt 70. A major, narrower
portion 74 of the trough 72 has parallel side walls, defined in
part by a part-circular thicker section 76 of side wall, with this
portion 74 being configured and dimensioned to fit over the main
portion 24 of the collar of element 10. The remaining minor, wider
portion 78 of the trough 72 is defined in part by a thinner, curved
section 80 of the side wall, with this portion 78 being
sufficiently wide to fit over the minor portion 24 of the collar of
element 10. The arcuate length of cap portion 78 is longer than the
arcuate length of collar portion 26, so that when the cap 12 is
located on the element 10 with the trough 72 located over the
collar, a limited degree of rotary movement of about 90.degree. of
the cap 12 relative to the element 10 is possible, with the extent
of movement determined by abutment of the ends of the inner face of
thinner side wall section 80 with the outer face of the minor
collar portion 26.
[0141] The upper wall 62 of the cap 12 includes a recessed portion
82 that has a sample entry hole 84 therethrough that is centrally
and symmetrically located in the wider trough portion 78. Hole 84
cooperates with the sample entry hole 34 in the element 10, as will
be described below.
[0142] The lower face of the cap thinner side wall section 80
includes two elongate part-circular grooves 86,88, each terminating
in a circular recess. A cylindrical soft rubber insert 90, 92, 94,
96 of thermoplastic elastomer (TPE) with a Shore hardness of 40A is
fitted into each of the recesses, with the inserts standing
slightly proud of the lower face of the side wall, forming four
sealing members that cooperate with the capillary channel vent
holes 44, 44', 48, 48', as will be described below.
[0143] The cap 12 includes a generally cylindrical rigid plunger
100 of ABS located in the central opening 64 of the cap body 60 and
connected to the body by a series of thin, rupturable webs 102. A
fluid filled cylindrical polypropylene capsule 104 with a capacity
of 400 microlitres is carried on the lower end of the plunger 100,
with the capsule being dimensioned to fit snugly within the skirt
70, for axial sliding movement therewithin. The plunger 100 and
capsule 104 are movable between an upper, ready position, as shown
in FIGS. 8 to 11, and a lower, activated position, as shown in
FIGS. 12 to 14, by application of a suitable downwards force to the
plunger to rupture the webs 102 and cause axial movement of the
plunger 100 and capsule 104 relative to the cap body 60 and element
10, causing the capsule 104 to be impaled on the spikes 40 with
consequential release of the fluid contents into the well 27 formed
within collar 14.
[0144] A sheet of flexible foil 106 (FIG. 15A) in the form of a
clear polycarbonate sheet 0.06 mm thick is secured by laser welding
to the lower face 20 of the element 10 to cover the channels 42,
42', 46, 46' and side channels 50, 50' and convert them into
enclosed capillary passages, also referred to herein as capillary
pathways.
[0145] Hydrocarbonates such as ABS or polycarbonates is hydrophobic
which means that aqueous fluids will not flow well within the
passages. To address this, the capillary passage internal surfaces
are treated to provide a thin coating of Tween 20 surfactant (Tween
is a Trade Mark) to impart hydrophilic properties to the capillary
surface. This can be done by any suitable means, for example using
a vacuum process to draw a solution of Tween 20 in deionised water
(comprising 0.25% by volume Tween 20) through the capillary
passages, by applying suction at an open end of the passages. This
is illustrated schematically in FIG. 15A. The Tween 20 solution is
applied via the sample entry hole 34, and a pair of suction cups
are applied to the vent holes at the ends of the capillary
passages, first to the main passages and then to the overflow
passages. A vacuum is applied by means of a vacuum generator, and
acts to suck the Tween 20 solution through the passages as
represented by the arrows in FIG. 15A. The element 10 is then left
to dry in an oven at low temperature to evaporate the water part of
the solution, leaving behind the Tween 20 deposited as a thin layer
on the internal capillary surfaces, thus making the surfaces
hydrophilic.
[0146] This treatment also performs a quality control function in
that it will reveal if any of the capillary passages are blocked,
e.g. as a result of imperfect moulding, imperfect sealing of the
foil, or the presence of debris or foreign matter in the passages,
enabling defective elements to be discarded at this stage.
[0147] The device is prepared for use in agglutination assay by
depositing a controlled amount of agglutination reagent, e.g. as
disclosed in WO 2004/083859 and WO 2006/046054, in the test track
passage 42. Any suitable method can be used for depositing the
reagent. A preferred method is via side channel 50, with reagent
being added via opening 52. A liquid comprising the reagent is
supplied via opening 52, and a vacuum applied to the vent hole 44.
This acts to suck the liquid through the side channel 50 and the
downstream part of test track passage 42, in the same manner as the
Tween treatment described above, resulting in deposition of reagent
on the capillary wall along the downstream part of the passage 42.
This is followed by drying as required. The openings 52, 52' are
then sealed by application of a foil covering to produce an
air-tight seal.
[0148] The cap 12 is then located on the collar 14 of the sample
collection element 10, with the plunger 100 in the ready position
and with the cap in a first position, as illustrated in FIGS. 16A
and 16B. In this first position, the device is in an inactive
state. The sample entry hole 84 of the cap is positioned so as not
to be in fluid communication with the sample collection well 27 of
the element, as shown in FIGS. 16A and 16B, so that the sample
entry hole 34 of the element is effectively blocked. None of the
channel vent holes is sealed.
[0149] The device in this condition may be packaged for
distribution and sale, e.g. being sealed in a foil pouch which is
impermeable to air and moisture.
[0150] When the device is required for use, the cap 12 is rotated
to a second position, as illustrated in FIGS. 17A and 17B. In this
position the sample entry hole 84 of the cap is positioned over the
portion 26 of the sample collection well 27, and is thus in fluid
communication with the sample entry hole 34 of the element. In
addition, the main channel vent holes 44, 44' are sealed by cap
inserts 96, 92, respectively, while the overflow channel vent holes
48, 48' are not sealed.
[0151] A quantity of fluid sample e.g. a blood sample to be tested
(possibly containing an analyte of interest) is added to the device
via sample entry hole 84. It is important that more sample is added
than is required for the test, with a sample of about 15
microlitres being appropriate in the present case. The sample fluid
flows along the initial portions of the main passages 42, 42' and
then into the overflow passages 46, 46', as illustrated in FIG. 19.
In this figure, the sample is represented by filled regions. The
sample cannot flow further along the main passages 42, 42' because
the main channel vent holes 44, 44' are sealed by the cap. In this
way, a defined quantity of sample is present in each of the main
passages (referred to as the test volume), with excess being
passing into the overflow passages. In the present embodiment, the
test volume in each main passage is about 5 microlitres.
[0152] The cap 12 is then rotated to a third position, as
illustrated in FIGS. 18A and 18B. In this position the sample entry
hole 84 of the cap is again positioned so as not to be in fluid
communication with the sample collection well 27 of the element, as
in the first position. However, the overflow channel vent holes 48,
48' are now sealed by cap inserts 94, 90, respectively, while the
main channel vent holes 44, 44' are not sealed.
[0153] Fluid in the capsule 104 is then introduced to the capillary
passages. Preferably, this is after a predetermined time, e.g. as
indicated by a timer associated with the device. Typically the
fluid is a chase buffer, e.g. a 1% by weight solution of Ficoll
polymer in deionised or distilled water (Ficoll is a Trade Mark),
which enables the reaction to be carried out with a smaller volume
of sample than is required to flow around the entire capillary
system to determine a test result. This is achieved by operation of
the cap plunger 100.
[0154] The plunger 100 of the cap 12 is depressed, e.g. by
application of force by an operator, to move it to the activated
position, as shown in FIGS. 12 to 15, resulting in piercing of the
capsule 104 by the spikes 40, as shown in FIG. 15, and release of
fluid from the capsule to flow into the well 27. As illustrated in
FIG. 20, the capsule fluid, e.g. chase buffer, which is represented
by hatched regions, pushes the test sample further along the main
passages.
[0155] Sample (followed by chase buffer) will flow along the main
passages 42, 42' by capillary flow. Because the overflow channel
vent holes 48, 48' are now sealed, no further flow will take place
along the overflow passages, including no back-flow towards the
main passages. Instead, fluid flow will be along the main passages
42, 42', towards the unsealed main channel vent holes 44, 44'. The
sample will thus flow past the deposited reagent in the test
passage. If the analyte of interest is present in the sample, this
will react with the reagent, affecting the flow properties compared
with unreacted sample in the control track.
[0156] The device includes a detector arrangement (not shown) near
the ends of the main passages to detect the presence (or otherwise)
of liquid in the test track and control track. From this, it can be
determined whether reaction has taken place with the agglutination
reagent, and information (qualitative or quantitative) can be
determined about the presence of the analyte of interest in the
test sample. Suitable detector arrangements are known, and are
outside the scope of this invention.
[0157] The device is easy to use, and can be used reliably by
relatively unskilled personnel, possibly at the point of care of
patients. In particular, the device functions to provide a
predetermined volume of sample into the capillary test system, by
the operation of the overflow passages, and a predetermined volume
of reagent such as chase buffer from the capsule. The device
requires only a very small volume of sample to be tested, e.g.
about 10 to 15 microlitres. The device is intended for single use,
being disposed of after use.
[0158] FIGS. 21 and 22 show an alternative embodiment of a control
element according to the invention. In these embodiments, the
control element is formed by a generally oval shaped member,
comprising an underside portion on which sealing components are
provided on the feet of the control element, such that the sealing
components contact the upper surface of the planar capillary
pathway device. A generally cylindrical well is formed within the
upper surface of the control element, defined by side walls, and
having a base portion with an hole which is in fluid communication
with the sample entry hole of the capillary pathway device. The
base of the well comprises sharp tapered projections. A pivot point
is provided, enabling the control element to be rotated around the
pivot point. The control element sits on the upper surface of the
planar capillary pathway device, and is positioned such that in a
first position (as shown) a sample well in the capillary pathway
device is exposed. The sample well comprises a fluid application
region, and in use, a user inserts the sample into the sample well.
Operation of the control element enables it to be rotated about the
pivot, so that an underside portion of the control element sits
over the sample well.
* * * * *