U.S. patent application number 09/737601 was filed with the patent office on 2002-04-11 for liquid sample assay device.
Invention is credited to Forsberg, Bengt Erik.
Application Number | 20020042145 09/737601 |
Document ID | / |
Family ID | 25522261 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042145 |
Kind Code |
A1 |
Forsberg, Bengt Erik |
April 11, 2002 |
Liquid sample assay device
Abstract
An assay device for determining the presence of specific
analytes in a liquid sample comprises a container for collecting
the sample liquid and a removable cap for sealing the container.
The cap includes one or more test strips, such as chromatography
strips, supported thereon for visually displaying the results of
the assay. A chamber in the cap, collects, through an inlet, a
volume of liquid from the container when it is inverted by
depressing and subsequently releasing a piston located in the
chamber. The liquid collected in the chamber is transferred to the
chromatography strips by a wicking system. The piston frictionally
engages a seal pad made of resilient material. The seal pad closes
the inlet and forms a hermetic seal between the liquid contained
within the container and the outside thereby preventing such liquid
from becoming contaminated and any leakage of the contained
liquid.
Inventors: |
Forsberg, Bengt Erik;
(Caledon East, CA) |
Correspondence
Address: |
Orange & Chari
Suite 4900, Box 190
Toronto Dominion Bank Tower
Toronto-Dominion Centre
Toronto
ON
M5K 1H6
CA
|
Family ID: |
25522261 |
Appl. No.: |
09/737601 |
Filed: |
December 18, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09737601 |
Dec 18, 2000 |
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08974617 |
Nov 19, 1997 |
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6168758 |
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Current U.S.
Class: |
436/165 ;
422/400 |
Current CPC
Class: |
B01L 2300/0663 20130101;
B01L 2400/0633 20130101; G01N 33/54366 20130101; A61B 10/007
20130101; B01L 3/502 20130101; B01L 2200/0605 20130101; B01L
2300/069 20130101; A61B 2010/0009 20130101 |
Class at
Publication: |
436/165 ;
422/58 |
International
Class: |
G01N 031/22 |
Claims
The Embodiment of the ivnention in which an exclusive property or
is claimed are defined as follows:
1. An apparatus for conducting an assay on a liquid located in a
container, the apparatus comprising: a removable cap for closing
the container; at least one assaying device located on the cap for
visual observation thereof, the assaying device having means for
analyzing said liquid and visually displaying the presence of
specific analytes in the sample liquid; a chamber defined by an
inner and outer wall, attached to the cap and communicating with
the assaying device, the chamber having a piston located therein
and an inlet for collecting a volume of sample liquid inside the
chamber; said piston contacting the wall of said chamber and moving
between a first operating position where said inlet is sealed and a
second operating position where said inlet is open and allows for
the collection of sample liquid is said chamber upon submergence; a
means for supplying said liquid collected in said chamber to said
assaying device; a resilient seal pad extending at least the
diameter of said chamber; whereby said seal pad, when in the first
operating position, prevents fluid from passing through said
inlet.
2. A method of conducting an assay on a liquid comprising the steps
of: a) collecting a sample liquid to be assayed in a container
having a removable cap wherein said cap includes a chamber and an
assaying device having a means for chemically analyzing a liquid
for a specific analyte; wherein said cap includes a inlet for
connecting the chamber with said container, and a means for sealing
said inlet; wherein said means for sealing said inlet includes a
piston engaging a seal pad, said piston moving said seal pad
between a first closed position and a second open position; b)
segregating a portion of said liquid into said chamber; c) sealing
said inlet so as to provide a hermetic barrier between said chamber
and the container; d) contacting said portion of the liquid with
said assaying device whereby said sample is assayed for said
analyte.
Description
[0001] This application is a continuation in part of application
Ser. No. 08/974,617, which was allowed on Jul. 26, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to liquid assay devices, and
in particular, to liquid sample containers which include a self
contained means of assaying such liquid.
DESCRIPTION OF THE PRIOR ART
[0003] There is presently a great demand for safe, reliable and
easy to use liquid assaying devices. Such devices have uses in a
variety of areas such as diagnostic testing of biological fluids,
testing of water samples, etc. An example of one such application
of the device is in diagnostic and drug testing purposes of urine
samples at the screening stage. Screening apparatus are used by
health practitioners as a diagnostic aid. A preliminary assay will
help the practitioner to determine the presence of various antigens
in a patient's bodily liquids which could potentially be causing an
illness. There is even a greater demand for such diagnostic
screening apparatuses due to a widespread fear which has been
aroused in the general population by the growing number of people
being infected with HIV. Due to the long incubation period of this
disease many people have chosen to be screened so that early
treatment can be obtained and the spread of this deadly disease can
be reduced.
[0004] In society at large, there is also a growing concern about
drug abuse. It is the policy of many employers to screen employees
for the use of illegal drugs. Similarly, athletes are now routinely
screened for the presence of banned substances both before and
after competitions. To address the need to quickly screen people
for these illegal substances, various screening devices have been
produced which require manual transfer of a sample liquid from a
collecting vessel to an assaying device. A positive test at the
screening stage would require the sample to be sealed and then
forwarded to a laboratory for more rigorous and complete testing to
verify the results of the screening test.
[0005] One such device for specifically testing for the presence of
non-protein antigens such as most drugs of abuse is taught by U.S.
Pat. No. 5,238,652. This device utilizes a thin layer
chromatography membrane for testing for the presence of certain
illegal drugs. The assaying device taught makes use of colored
latex spheres combined with a specific antibody for binding to a
specific antigen (i.e. drug). The latex spheres are applied to a
chromatography membrane upstream of an immobilized drug conjugate
probe. The antibody/latex complex is picked up by the test liquid
and is used to indicate the presence or absence of a specific
antigen drug. A positive test is indicated by the absence of a
colored line in the area of the drug conjugate probe on the
chromatography membrane due to the fact that the antibody will have
bound the antigen rendering it unable to bind the drug conjugate
probe. A negative test is indicated by a colored line corresponding
to the binding of the latex/antibody complex to the drug conjugate
probe.
[0006] In use, urine drops are withdrawn manually from a collection
vial and added drop-wise to a reception cavity on the device. The
urine is then absorbed by a pad and moves along the chromatography
membrane by capillary action. This particular device is problematic
in that the sample liquid must be manually transferred from the
collection device to the assay device, being the chromatography
membrane. This is dangerous to those conducting the assay as there
is exposure to the sample which could include harmful materials.
Also, the test sample is subject to contamination in the
transferring process which reduces the reliability of the
assay.
[0007] U.S. Pat. No. 5,403,551 teaches an assaying apparatus which
also uses a chromatography membrane to indicate the presence or
absence of specific antigens. As before the use of a latex/antibody
complex will display a colored line in the absence of a specific
analyte.
[0008] This assaying apparatus comprises a collecting vessel and an
assaying device as one unit. A sample is introduced into a
collecting chamber which is then sealed with a cap. The sample is
then introduced into a reservoir through a flow path which is only
accessible to the liquid sample when the device is inverted. The
reservoir communicates with chromatography test strips and is sized
to contain only enough samples to wet the chromatography membranes
without flooding them. A mechanical valve is operated by twisting
the cap of the device in order to close the flow path of the sample
into the reservoir. In this way the sample liquid in the container
is sealed off from the ambient air surrounding the container.
[0009] This apparatus has a drawback in that it is necessary for a
person conducting the assay to remember to twist the cap and
thereby close the mechanical valve after inverting the device. A
failure to carry out this third step will result in the sample
liquid in the container being contaminated by impurities in the
ambient air surrounding the apparatus. This apparatus also has a
further problem in that it is possible to inadvertently close the
mechanical valve prior to inverting the apparatus to start the
test. This results in the test not being properly started upon
inverting the apparatus. The operator will then waste time waiting
for the test to begin before realizing that the valve has been
closed. The structure taught by U.S. Pat. No. 5,403,511 suffers
from a further drawback in that it is complicated, involving
several structural parts. This apparatus is therefore difficult and
expensive to manufacture.
[0010] As such, there is a need for an assaying apparatus
transferred to an assaying device included in the apparatus,
without having to remove the sample liquid from the apparatus. A
device is needed which has an automatic shut-off valve for
preventing contamination of the sample liquid after the assay has
been commenced. The automatic properties of such a valve would
effectively eliminate the potential for human error in operating
such a valve.
[0011] There is also a need for a simpler assaying device which is
easier and less expensive to manufacture, which accomplishes the
function of transferring liquid from a collecting medium to an
assaying system without having to manually transfer the sample
liquid, thereby exposing the sample liquid to the external
environment.
SUMMARY OF THE INVENTION
[0012] The present invention is an apparatus, having an assaying
device for conducting an assay on a sample liquid. The apparatus
has means for collecting a sample liquid and means for transferring
a predetermined volume of the collected sample liquid to the
assaying device. The apparatus has an automatic valve for sealing
the sample liquid in the apparatus from the external environment
after the assay has been commenced.
[0013] According to one aspect of the invention, an apparatus is
provided for conducting an assay on a sample liquid. The apparatus
includes a container defining a chamber, the container having an
open end for collecting a sample liquid. The apparatus has a
removable cap for closing the container. An assaying device is
included in the apparatus located on one of the cap and the
container for visual observation thereof, the assaying device
leaving means for receiving and chemically analyzing the sample
liquid and visually displaying the presence of a specific analyte
in the sample liquid. The apparatus further includes a defines a
sub-chamber communicating with the assaying device. The reservoir
has a wall which defines at least one opening located to collect a
predetermined volume of sample liquid inside the sub-chamber upon
submerging the reservoir in the sample liquid in the container. The
apparatus also includes a valve member which is located between the
reservoir sub-chamber and the assaying device, the valve member is
formed of a material that absorbs sample liquid and swells thereby
closing off the assaying device from the sub-chamber.
[0014] According to another aspect of the invention, there is
provided an apparatus for conducting an assay on a liquid located
in a container. The apparatus comprises a cap for closing the
container. The apparatus includes an assaying device located on the
cap for visual observation thereof. The assaying device has means
for receiving and chemically analyzing a sample liquid and visually
displaying the presence of a specific analyte in the sample liquid.
A reservoir is attached to the cap. The reservoir defines a chamber
communicating with the assaying device, the reservoir having a wall
defining at least one opening located to collect a predetermined
volume of sample liquid inside the chamber upon submerging the
reservoir in the sample liquid. The apparatus has a valve member
located between the reservoir chamber and the assaying device, the
valve member being formed of a material that absorbs sample liquid
and swells thereby closing off the assaying device from the chamber
after a predetermined amount of sample liquid is received by the
assaying device.
[0015] According to another aspect of the invention there is
provided a method of conducting an assay on a liquid comprising the
step of providing a container for collecting a liquid sample to be
assayed. The method includes the further step of segregating a
predetermined amount of the liquid to be assayed from the remainder
of the collected sample liquid by providing a barrier between the
predetermined amount of liquid and the remainder of the collected
sample liquid, the barrier being expandable upon contact with the
liquid. The method includes the further step of contacting the
predetermined amount of liquid with an assaying device including a
chromatography strip having means for chemically analyzing a liquid
for a specific analyte. The method includes the further step of
expanding the barrier to hermetically seal off the remainder of the
collected liquid.
[0016] According to another aspect of the present invention, there
is provided an apparatus for conducting an assay on a liquid
located in a container. The apparatus comprises a cap for closing
the container. The apparatus includes an assaying device located on
the cap for visual observation thereof. The assaying device has a
means for receiving and chemically analyzing a liquid sample and
visually displaying the presence of a specific analyte in the
sample liquid. The cap further includes a chamber defined by an
inner and outer wall, attached to the cap and communicating with
the assaying device. The chamber further includes a piston
positioned with the chamber and an inlet for providing a passage to
collect a volume of sample liquid inside the chamber. The piston
contacts the inner wall of the chamber and moves between a first
operating position where the inlet is sealed, and a second
operating position where said inlet is open and allows for the
collection of sample liquid is said chamber upon submergence. The
cap further includes wicking system for supplying the liquid
collected in said chamber to the assaying device. A valve member or
seal pad comprising a generally annular disc forms a seal on the
inlet. A frictional fit between the piston and the seal pad ensures
that the movement of the piston effects the movement of the seal
pad. A second seal maintains contact between the piston and said
chamber wall such that when the container is inverted the seal
prevents the leakage of liquid from the chamber.
[0017] According to yet another aspect of the invention, there is
provided a method of conducting an assay on a liquid comprising the
step of providing a container for collecting a liquid sample to be
assayed. The method includes the further step of segregating a
predetermined amount of the liquid to be assayed from the remainder
of the collected sample liquid by providing a seal between the
portion amount of liquid and the remainder of the collective sample
liquid. Wherein the method for segregating this portion of liquid
includes inverting the container and depressing the piston within
the chamber thereby moving the seal pad away from the inlet and the
closed position, to the open position thereby evacuating the air
from the chamber. The piston is then released and in turn allows
liquid sample to enter the chamber through the inlet through both
gravity and suction. The piston returns to the first operating
thereby closing the inlet. The container is then returned to an
upright position. The method includes the further step of
contacting the predetermined amount of liquid with an assaying
device including a chromatography strip having means for chemically
analyzing a liquid for a specific analyte.
[0018] In another embodiment, the invention provides an assay
device for a liquid contained within a container, the device
comprising a removable cap for the container, the cap having:
[0019] a reservoir to receive a sample of the liquid from the
container;
[0020] a passage for transferring the sample of liquid from the
container to the reservoir;
[0021] a means for closing the passage;
[0022] a means for assaying the liquid sample;
[0023] a means for transferring the liquid sample from the
reservoir to the means for assaying.
[0024] More particularly, the invention provides in one embodiment
an assay device for a liquid contained within a container, the
device comprising a removable cap for the container, the cap
having:
[0025] a reservoir to receive a sample of the liquid from the
container;
[0026] a passage for transferring the sample of liquid from the
container to the reservoir;
[0027] a valve for closing the passage;
[0028] a plurality of chromatographic test strips for assaying the
liquid sample;
[0029] a wick for transferring the liquid sample from the reservoir
to the test strips.
[0030] The invention also provides a method of using such
device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] These and other features of the preferred embodiments of the
invention will become more apparent in the following detailed
description in which reference is made to the appended drawings
wherein:
[0032] FIG. 1 is a perspective view of a preferred embodiment of an
apparatus according to the present invention;
[0033] FIG. 2 is an exploded perspective view of the cap used in
the apparatus of FIG. 1;
[0034] FIG. 3 is a cross-sectional view of the apparatus taken
along lines 3-3 of FIG. 1 depicting the apparatus in a first
operating position;
[0035] FIG. 4 is a cross-sectional view of the apparatus taken
along lines 3-3 of FIG. 1 depicting the apparatus in a second
operating position;
[0036] FIG. 5 is a cross-sectional view of the apparatus taken
along lines 3-3 of FIG. 1 depicting the apparatus in a third
operating position; and
[0037] FIG. 6 is an enlarged cross-sectional view of a portion of
the cap taken along lines 3-3 of FIG. 1 the apparatus in a fourth
operating position;
[0038] FIG. 7 is a side cross sectional view of a further
embodiment of the invention;
[0039] FIG. 8 is a bottom view of the embodiment of FIG. 7;
[0040] FIG. 9 is a plan view of the middle portion of the
embodiment of FIG. 7;
[0041] FIG. 10 is a plan view of a test strip for the embodiment of
FIG. 7;
[0042] FIG. 11 is a side elevation of the test strip of FIG.
10;
[0043] FIG. 12 is a plan view of the embodiment of FIG. 7
illustrating the cover portion;
[0044] FIG. 13 is a side cross sectional view through A-A of FIG.
9;
[0045] FIG. 14 is a side cross sectional view of the seal pad of
FIG. 7;
[0046] FIG. 15 is a front view of the pad of FIG. 14;
[0047] FIG. 16 is a perspective view of the embodiment of FIG.
7;
[0048] FIG. 17 is a side cross-sectional view of a further
embodiment of the invention; and
[0049] FIG. 18 is a plan view of the embodiment of FIG. 17 cut
along line 1-1 illustrating the cover portion;
[0050] FIG. 19 is a plan view of the embodiment of FIG. 17
illustrating the valve member in a alternative position;
[0051] FIG. 20 is a plan view of the embodiment of FIG. 17 cut
along line 2-2 illustrating the cover portion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0052] Referring to the drawings, an apparatus according to the
present invention is generally indicated by numeral 10 as shown in
FIGS. 1 to 3. Apparatus 10 includes a container 25 which defines a
chamber 33. The chamber 33 functions to hold a quantity of a sample
liquid 30 as depicted in FIGS. 3, 4 and 5.
[0053] Apparatus 10 includes a removable cap 7 which screws onto
the container 25 in order to close the container. Preferably, the
container has screw threads formed into it near an opening at the
top of the container. The cap has a cylindrical portion 8 which
extends downwardly from a bottom central portion of the cap. The
cylindrical portion 8 is molded to the cap to form a single molded
part including the cap and the cylindrical portion 8. In an
alternate embodiment the cylindrical portion and the cap can
comprise two separate parts which are tightly attached
together.
[0054] A reservoir 18 is attached to a bottom surface of the cap
when the cap 7 is screwed onto the container 25, the reservoir 18
defines a sub-chamber 23 in the chamber 33 as shown in FIGS. 3, 4
and 5. The cylindrical portion 8 of the cap 7 is located in the
sub-chamber. The reservoir has four openings 20 formed in a wall 21
of the reservoir 18. The openings 20 are of a sufficient size to
allow a sample liquid 30 to flow into the reservoir 18 when the
reservoir is submerged in the sample liquid 30. It is possible to
have one or more openings 20 in the wall 21 of the reservoir. A
greater number of openings will increase the rate at which liquid
will flow into the sub-chamber 23 upon submerging the sub-chamber
in the sample liquid in the container. Similarly the rate at which
the sample liquid will flow out of the sub-chamber through the
openings 20 will be proportional to the number of openings and the
size of the openings formed in the wall 21.
[0055] The openings 20 on the reservoir wall 21 are located at a
common level with respect to a base 22 of the reservoir 18. It is
not necessary that the openings 20 all be at the same level on the
wall 21 with respect to the base 22, and other embodiments are
possible where the openings are at varying levels on the wall 21
with respect to the base. However, the location of the opening 20
nearest to the base 22 will determine the ultimate level of the
sample liquid 30 which will be collected in the sub-chamber 23
after inverting the apparatus, as discussed in more detail below.
Hence, it is possible to predetermine the amount of sample liquid
which will be collected in the sub-chamber 23, upon submersion of
the reservoir in the sample liquid, by selecting the location of
openings 20 on the wall 21. By placing the openings further
upwardly from the base 22, more sample liquid will be collected in
the sub-chamber 23. Conversely, less liquid will be collected in
the sub-chamber when the openings 20 are located closer to the base
22. As will be discussed below, the volume of liquid collected in
the sub-chamber will also be related to the air pressure which
within the reservoir 18 during filling of the sub-chamber.
[0056] The openings 20 are positioned on the wall 21 relative to
the base 22 such that a volume of sample liquid will be collected
in the sub-chamber 23 which will be sufficient to allow the assay
to be conducted reliably. However, the volume of sample liquid
collected will be sufficiently small so that an assaying device
will not become flooded thereby adversely affecting the test
results.
[0057] The reservoir 18 is attached to the cap 7. Many methods of
attachment known in the art are possible for attaching the
reservoir to the cap. The cylindrical portion 8 of the cap 7 has a
plurality of passageways 14 formed therein (see FIG. 1). These
passageways 14 extend from a bottom end of the cylindrical potion 8
of the cap through a top surface the cap 7.
[0058] At least one liquid permeable wick 3 is provided for
transporting the sample liquid through the passageway 14. The wicks
3 transport the sample liquid 30, by capillary action, from the
reservoir to a plurality of wick pads 4, as discussed in more
detail below. The wicks 3 are formed of a cellulose based porous
material, such as cellulose fibers which allows an aqueous liquid
to be absorbed by the wicks and move through the wicks 3 by
capillary action. Alternate embodiments are contemplated where the
wicks are formed of other materials which will absorb and transport
a liquid through capillary action.
[0059] The wicks are impregnated with colored latex spheres for the
purpose of conducting an assay which is explained below. Since the
material with which the wicks are impregnated is assay specific,
alternate embodiments are contemplated in which the wicks are
impregnated with materials other than latex spheres for the
purposes of conducting different assays. Depending on the assay
being performed in an alternate embodiment, it may not be necessary
to impregnate the wicks with any material.
[0060] As discussed below, the composition of the wicks is
dependent upon the type of tests being conducted on the sample. If
only a single type of test is being conducted, it will be
understood that only one wick would be required. Similarly, one
wick can be used to supply liquid to a plurality of test strips. In
such case, the cylindrical portion 8 would require only one
passageway 14 located, preferably, in the center thereof.
[0061] An indentation 12 is formed over each of the passageways 14
on the top surface of the cap 7. The indentations 12 are each sized
to accept a wick pad 4 which is formed of a non-woven glass fiber
material through which the sample liquid will move by capillary
faction. The wick pads 4 are located adjacent to the assaying
device which may comprise a plurality of known liquid test strips
5, and function to draw liquid up through the wicks 3 and to
transfer sample liquid 30 to the test strips 5 which are located on
the cap 7, as discussed further below. Other materials which can
absorb and transfer a liquid via capillary action can comprise the
wick pads in alternate embodiments. A perimeter wick 6 is located
in a groove 9 on the top surface of the cap. The perimeter wick is
comprised of a liquid absorbent material such as cellulose paper
and is located adjacent to the test strips 5. The perimeter wick 6
functions to absorb sample liquid 30 from the test strips 5 thereby
drawing the sample liquid 30 along the test strips 5. Further,
perimeter wick 6 also serves to prevent the strips 5 from being
flooded by the liquid being assayed. A wicking system comprising
the wicks 3, the wick pads 4 and the perimeter wick 6 provides
transferring means for transferring sample liquid 30 from the
reservoir 18 to the test strips 5.
[0062] A valve member 15 is located adjacent to the base 22 of the
reservoir 18, inside the sub-chamber 23. The valve member 15 is
located adjacent to the cylindrical portion 8, and therefore the
valve member 15 is located adjacent to the wicks 3. When the valve
member is in a valve open position, a gap 35 exists between the
cylindrical portion 8 of the cap and the valve member 15, as
indicated in FIGS. 3 and 5.
[0063] The valve member 15 is formed of a cross-linked polymer
which is hydrophilic. In one embodiment, the cross-linked polymer
comprising the valve member is chosen from the family of polymers
known as polyether block amides available from ATOCHEM under the
trade-mark PEBAX. Other cross-linked polymers which are hydrophilic
and which swell upon absorbing water could also be used to comprise
the valve member. It is not necessary that the material comprising
the valve member be a cross-linked polymer. Any material which
absorbs liquid and swells and thus prevents further flow of sample
liquid through cylindrical portion 8, can comprise the valve member
in alternate embodiments of the invention. Other materials are also
possible for the valve member depending upon the liquid being
tested and the substance being assayed. For example, PEBAX
functions sufficiently well with aqueous liquids. However, this
material has been shown to absorb the active ingredient in
marijuana, THC, and, therefore, a device using such valve would
give a false negative result. A valve made from balsa wood on the
other hand can also be used for aqueous liquids and does not bind
with THC.
[0064] Other embodiments of the invention are contemplated which
include a valve member constructed of a lyophilic sol or gel which
can absorb either aqueous solvents or non-aqueous organic solvents.
In either case, absorption of the liquid will result in swelling
and closing of the valve member. Hence, materials which swell upon
absorbing an oil based or organic liquid and which are impermeable
to these liquids when fully swollen, can comprise the valve member
in alternate embodiments. In another embodiment, the valve member
15 is made of a laminate having an expanding layer of balsa wood
and a sealing layer of a polymer such as cross linked polyolefin.
The choice of balsa wood is preferred in the case of aqueous
liquids and where materials discussed above may bind with the
analytes being tested for.
[0065] The valve member 15 according to one embodiment of the
present invention will absorb a water-based sample liquid 30 such
as urine. Upon being submerged in the sample liquid the valve
member will begin absorbing sample liquid 30. The valve member will
swell gradually to a maximum expansion. This maximum expansion will
be reached in approximately ten minutes. The valve member 15 is in
a valve open position prior to the absorption of any liquid by the
valve member 15. Before the valve member 15 has swelled to its
maximum expansion, the gap 35 is present between the valve member
15 and the wicks 3. As such, sample liquid in the reservoir 18 will
come into contact with the wicks 3 when the valve member is in the
valve open position. When the valve member 15 has absorbed a
sufficient amount of sample liquid to swell to its maximum
expansion the valve member 15 will reach a valve closed position
thereby closing the gap 35 as depicted in FIG. 6.
[0066] The valve member 15 serves various functions in the device.
For example, when the valve member is in the valve closed position,
it hermetically seals the sample liquid 30 in the chamber 33 and in
the sub-chamber 23, from the ambient air outside of the apparatus
10. This prevents any contamination of the sample liquid located in
the chamber 33, which may be required for testing at a later time.
Such further testing may be required in the event that the results
of the present testing device are to be verified. Such a hermetic
seal, also prevents any more sample liquid from the reservoir from
coming into contact with the wicks 3. As such, the movement of any
sample liquid, remaining in the sub-chamber 23, to the test strips
5 is halted. Such sealing is also required in an embodiment of the
invention where an air outlet is provided on the top surface of the
cap. Such outlet is provided to relieve any pressure which may
accumulate as the liquid is transported across the test strip. As
will be appreciated, in an embodiment as shown in the figures, such
pressure accumulation will occur along the outer perimeter of the
cap. Therefore, the outlet would preferably comprise a gap along
such outer perimeter. It will also be appreciated that such
pressure may be quite minimal and, therefore, an outlet as
described is required only as a contingency basis.
[0067] In another embodiment of the invention, the air outlet may
comprise one or more holes (not shown) in the reservoir 18. Such
holes will be designed such as to permit the passage of air
therethrough while being small enough to prevent the passage of
liquid. It will be appreciated that the sizing of such holes will
be dependent upon the surface tension of the liquid being tested.
It will also be appreciated that if such holes are provided in the
reservoir 18, no additional air outlets would be required in the
cap thereby resulting in the device being completely sealed without
any leakage of the contents.
[0068] The valve member also functions to prevent any sample liquid
in the container from being suctioned out of the container when the
apparatus is stored in a low pressure compartment. This would
otherwise be problematic in situations such as where the apparatus
is stored in the cargo bay of an aircraft upon shipment of the
apparatus to a laboratory for further testing. To relieve the
pressure differential between the outside of the container and the
inside of the container, it is contemplated to place a small
pressure equalizing opening in the cap above the test strips, in an
alternate embodiment. In such a case, an overcap could be placed
above the cap.
[0069] In another alternate embodiment, it is contemplated to
laminate a top surface of the valve member with a rubber or a
lacquer coating in order to prevent the valve member from drying
out in arid conditions.
[0070] A plurality of test strips 5 are located on the cap 7 and
are thus readily visible. The test strips 5 provide an assaying
device located on the cap of the container for visual observation
thereof. In an alternate embodiment, as described below, the test
strips 5 can be located on the container 25. The test strips 5 may
comprise chromatographic, chemi-fluorescent or other known liquid
assay strips. The test strips 5 have means for receiving the sample
liquid 30. The means for receiving the sample liquid are ends of
the test strips 5 which are in direct contact with the wick pads 4.
In one embodiment, the test strips conduct chromatographic assays
and four separate chromatography membranes 38 are provided on the
cap. Each of the four chromatography membranes 38 comprise two
chromatography strips 5. Hence there are eight chromatography
strips 5 allowing for eight separate assays to be conducted on a
sample liquid. Hence, it is possible to test for the presence of
several different substances at the same time, while eight
chromatography strips are shown in FIG. 1, a greater or lesser
number of individual strips may be used depending on the desired
number of tests to be run on the sample liquid 30. The
chromatography membranes 38 are composed of a porous material
through which the sample liquid will move by capillary action.
Preferably the chromatography membranes are composed of a cellulose
nitrate material.
[0071] Each of the chromatography strips 5 is impregnated with a
test antigen conjugate probe which is immobilized at a fixed
location on the chromatography strip 5. The test chemical structure
to the specific antigen, such as cocaine or heroin, which is being
tested for by that particular chromatography strip 5. A test
antigen conjugate probe is a molecule having the same or similar
chemical structure as the substance which is being tested for. The
active site on a conjugate probe will generally be anchored to a
larger molecule but will be available to bind all antibody which
has been sensitized to the antigen for which the test is being
directed.
[0072] A second probe, or control or test valid probe, is
immobilized at a location downstream on the chromatography strip 5
of the test antigen conjugate probe. The second probe is a protein
antigen conjugate probe. The antibodies are sensitized to have a
second site which will bind the protein antigen conjugate probe. As
mentioned previously, the wicks 3 are soaked in latex which
consists of colored microscopic latex spheres which are coated with
the antibodies sensitized to bind the specific antigen and the
protein antigen conjugate probe. The latex spheres may be about 0.1
to about 1 micron in diameter and may be one of many colors. The
spheres are only visible when concentrated together in large
numbers. The latex spheres are impregnated on the wicks 3 such that
they are immobilized prior to coming into contact with the sample
liquid 30. As the sample liquid moves along the wicks 3, the sample
liquid 30 will eventually come into contact with the latex spheres.
The latex spheres become mobilized upon coming into contact with
the sample liquid 30 and are carried with the sample liquid as the
sample liquid moves along the wicks, through the wick pads, and
eventually along the chromatography strips 5.
[0073] If the sample liquid contains none of the specific antigen
being tested for, then the antibodies attached to the latex spheres
will bind the test antigen conjugate probe thereby forming a
complex consisting of the test antigen conjugate probe and the
latex spheres at the site of impregnation of the test antigen
conjugate probe on the chromatography strip 5. This will give rise
to the appearance of a colored line at the site of impregnation of
the test antigen conjugate probe.
[0074] The remaining latex spheres which pass the test antigen
conjugate probe after the binding sites on the test antigen
conjugate probe have become saturated, will bind to the protein
antigen conjugate probe located further downstream along the
chromatography strip 5. This will give rise to a second colored
line at the site of impregnation of the protein antigen conjugate
probe. The purpose of the second colored line is to indicate that
the test is active. Hence a negative test will give rise to two
colored lines on the chromatography strip.
[0075] In the event that the test antigen is present in the sample
liquid 30, then the antibodies on the latex spheres will bind to
the test antigen molecules immediately upon the sample liquid
coming into contact with the latex spheres on the wick 3. The
active site on the antibody for binding the test antigen will then
not be available for binding the test antigen conjugate probe on
the chromatography strip 5. As such, the latex spheres will pass
over the site of impregnation of the test antigen conjugate probe.
As a result, no line will be formed at that site. The antibodies
will however, bind to the protein antigen conjugate probe further
downstream to indicate that the test is active. Hence, a positive
test will be indicated by the presence of a single colored line
located at the site of impregnation of the protein antigen
conjugate probe on the chromatography strip 5.
[0076] It should be appreciated that an immunoassay can be
conducted with substances other than latex spheres. One alternative
is to use colloidal gold particles in the place of latex spheres.
It will be appreciated to those knowledgeable in the art that many
different types of assays may be conducted with the apparatus 10
which may or may not be immunoassays as described above. Such
assays will depend on the test strips used.
[0077] In the above example, a plurality of test strips are
provided on the device. In another embodiment, designed for a
specific application, only one test strip may be required. An
example of such embodiment is an assay device designed for testing
the presence of a particular substance in water or urine
samples.
[0078] A transparent protective cover 2 is placed over the
chromatography strips 5 on the cap 7 in order to provide a
protective barrier for the chromatography strips to prevent them
from becoming contaminated by substances which may be suspended in
the ambient air surrounding the chromatography strips. A label 1 is
placed over the protective cover 2 for indicating which specific
antigen is being tested for on each individual chromatography strip
5. The label also functions to emphasize the results of the assay.
The label has a plurality of openings 16 corresponding to the area
on each chromatography strip 5 where the test antigen conjugate
probe has been impregnated. Hence the appearance of a colored line
at this site will be emphasized by an opening 16 on the label 1. A
second group of openings 17 is formed in the label along the
periphery of the label. Openings 17 overlap with the sections of
the chromatography strips 5, which have been impregnated with the
protein antigen conjugate probe. The openings 17 will emphasize the
appearance of a colored band at this location on the chromatography
strips 5 thereby indicating that the test is active.
[0079] In an alternate embodiment, the cover 2 and the label 1 can
comprise a single integrally formed part. To achieve this result,
the label could be silk screened or otherwise embossed onto the
cover. Other methods known in the art are also possible for
imprinting the label onto the cover.
[0080] To operate the apparatus 10, it is necessary firstly to
remove the cap 7 from the container 25. The individual being tested
will then fill the chamber 33 with a sample liquid which would
normally be urine. Preferably, chamber 33 will be filled to
approximately half of its volume with sample liquid 30. Once the
chamber 33 has been filled with sample liquid, the cap 7 is screwed
on tightly to the container 25 so that a hermetic seal is formed
between the container 25 and the cap 7. The apparatus, in a first
operating position, after the initial filling of the chamber 33
with sample liquid 30 with the cap 7 securely attached to the
container 25, is depicted in FIG. 3. It is apparent that the
reservoir 18 defines a sub-chamber 23 in the chamber 33. At this
stage of operation, the valve member 15 is in the valve open
position. A gap 35 exists between the valve 15 and the wicks 3
which are supported in the cylindrical portion 8 of the cap.
[0081] After the chamber 33 has been filled with sample liquid 30,
it is then necessary to screw the cap onto the container and then
to invert the apparatus in order to submerge the reservoir 18 in
the sample liquid, in the chamber 33. FIG. 4 depicts the apparatus
in an inverted position. The reservoir 18 is submerged in the
sample liquid 30 upon the inversion of the apparatus 10. The sample
liquid 30 enters into the reservoir through the openings 20 in the
wall 21 of the reservoir 18. As the level of the sample liquid 30
in the reservoir sub-chamber 23 rises above the level of the
openings 20, air in the sub-chamber 23 can no longer escape out of
the sub-chamber through the openings 20. As such, a pressure-head
is created between the rising sample liquid in the sub-chamber 23
and the air between the sample liquid 30 and the base 22 of the
reservoir 18. The pressure-head created prevents the level of
liquid in the inverted sub-chamber 23 from rising to a level
sufficient to allow the wicks 3 to come into contact with the
sample liquid 30. As such, the 25 assay will not begin while the
apparatus is in the inverted position. At this stage, the valve
member 15 is also not brought into contact with the sample liquid
30, hence the valve member 15 will not yet begin to swell thus
remaining in the valve open position. As such there is still a gap
35 between the wicks 3 and the valve member 15.
[0082] As will be appreciated by those skilled in the art, the
pressure head discussed above also forces the air within the
reservoir through the wick 3 while the valve is still in the open
position. The rate of such air passing through the wick will be
dependent on the characteristics of the wick material such as its
porosity and on the number of wicks present.
[0083] It will be understood that if the apparatus is maintained in
the inverted position too long, enough air will be passed through
the wick to allow the liquid level within the sub-chamber 23 to
reach the bottom of the wick. In such case, the assay may commence
prior to righting the container which may not be desired. Further,
if the liquid is permitted to enter the wicks while the container
is inverted and if such container includes an externally venting
air outlet as described above, leakage of the liquid may result.
For an apparatus as described herein, the time inverted is
approximately fifteen to thirty seconds.
[0084] After maintaining the apparatus in the inverted position for
the time mentioned above, a predetermined amount of liquid is
collected in the sub-chamber 23, the apparatus is then reverted to
the upright position as shown in FIG. 5. As mentioned above, the
maximum time for maintaining the apparatus in such inverted
position is dependent upon the porosity of the wick. The level of
liquid retained in the sub-chamber will depend on the level of the
openings 20 on the wall 21 of the reservoir 18, as excess sample
liquid in the reservoir 18 will flow out of the sub-chamber 23
through openings 20. Hence the level of liquid remaining in the
sub-chamber 23 after reversion of the apparatus will be determined
by the location of the opening 20 on the wall 21 nearest to the
base 22 of the reservoir. The predetermined volume of sample liquid
collected inside the sub-chamber 23 is the volume of sample liquid
remaining in the sub-chamber after the sample liquid has filtered
out of openings 20 upon reversion of the apparatus to the upright
position.
[0085] After returning the apparatus to its upright position, the
valve member 15 becomes submerged in the sample liquid 30. Also,
the gap 35 becomes filled with sample liquid bringing the wicks 3
into contact with the sample liquid thereby commencing the transfer
of sample liquid to the chromatography strips. Once the valve
member 15 becomes submerged in the sample liquid it begins to
gradually absorb sample liquid and to swell. The valve member 15
will eventually seal off the gap 35. However, the valve will swell
slowly enough so that the gap 35 will not be sealed by the valve 15
until the predetermined volume of liquid collected in the reservoir
has been absorbed by wicks 3. The predetermined amount of sample
liquid, received by the assaying device before the valve member
seals off the sub-chamber 23 from the assaying device will be
determined by selecting the amount of sample liquid which can be
collected by the sub-chamber 23 upon submerging it in the sample
liquid in the chamber 33, as described above.
[0086] FIG. 6 depicts the valve member 15 in its fully expanded
position where the valve member has closed gap 35 forming a
hermetic seal between the reservoir sub-chamber 23 and the wicks 3.
As such, a hermetic seal is formed between the sample liquid in
chamber 33 and the ambient air outside the apparatus 10 so that the
sample liquid 30, which may be subject to further testing, cannot
be contaminated after the assay has been completed.
[0087] The reservoir 18, upon inverting the apparatus 10 and then
reverting the apparatus to its upright position, serves to
segregate a predetermined amount of liquid to be assayed from the
remainder of the collected sample liquid by providing a barrier
between the predetermined amount of liquid and the remainder of the
collected sample liquid. The barrier includes the valve member and
it may be attached to the base of the reservoir. The barrier is
therefore expandable upon contact with the liquid. The wicks 3 and
the wick pads 4 provide means for contacting the predetermined
amount of liquid with an assaying device including a chromatography
strip having means for chemically analyzing a liquid for a specific
analyte. The liquid absorbing and swelling properties of the valve
member provides means for expanding the barrier to hermetically
seal off the remainder of the collected sample liquid.
[0088] According to another embodiment of the present invention,
the chromatography strips 5 which constitute the assaying device
can be located on a sidewall 44 of the container 25 as indicated by
strips 5 shown in chain-dotted lines in FIG. 5. In this embodiment,
the sidewall 44 has cylindrical portion 8' extending into the
chamber 33. Attached to an interior surface of the sidewall 44 of
the container 25 over the cylindrical portion is the reservoir 18'.
As with the preferred embodiment, the cylindrical portion 8'
defines a plurality of passageways 14', each passageway 14'
supporting a wick which will extend from the reservoir sub-chamber
23' to the chromatography strips 5'. This embodiment is operated by
first tilting or inverting the apparatus 10 and then placing the
apparatus on its base 42 or can a side of the sidewall opposite to
the section of the sidewall to which the reservoir 18' is attached,
so that excess sample liquid can flow out of the reservoir
sub-chamber after it has been submerged in the sample liquid. If
the apparatus is to be placed on its side after submerging the
reservoir, the openings 20 in the reservoir would be in the
sidewall 21' of the reservoir. However, if the apparatus is to be
placed on the base of the container after submersion of the
reservoir then the openings in the reservoir will be in the base
22' of the reservoir as indicated in FIG. 5. A valve member 30' is
located in the reservoir sub-chamber between the cylindrical member
8' and the base 22' of the reservoir.
[0089] In yet another embodiment of the present invention, the
chromatography strips 5 can be located on the base 42 of the
apparatus 10. This embodiment would be like FIG. 4, but the cap
would be enlarged and become the container, and the container would
perform the function of the cap. To operate this embodiment, one
would fill the container with sample liquid and then seal the
container by putting on the cap. Inverting the apparatus would then
allow the assay to proceed to completion as described above. The
apparatus is not reverted to the upright position.
[0090] It will be appreciated by those skilled in the art that the
apparatus 10 can be used for many applications other than screening
bodily liquids for specific antigens. Among other applications, the
apparatus cart be used to test water samples from lakes and rivers
for various pollutants. Also, an alternate embodiment of this
invention can be used to test organic liquids such as oil samples
for the presence of toxins such as PCBs.
[0091] A further embodiment of the present invention is illustrated
in FIG. 7. As with the embodiments discussed previously, the
assaying device includes a container (not shown) as described
above. A cap for the container is shown generally at 100. The cap
100 includes a base 102 preferably having a thread 104 for engaging
a corresponding thread on the container as described above. The cap
100 further includes a middle portion 106 and a cover 108. The base
102 includes a bottom wall 113 which defines the bottom wall for a
reservoir or well 110 for receiving a sample of the liquid
contained within the container. Such sample of liquid is shown at
111. The base 102 also includes a liquid inlet portion 112. As
shown in FIGS. 7 and 8, the inlet portion 112 is preferably
rectangular in plan view and triangular in cross section. The inlet
portion 112 includes a plurality of windows 114 on a side wall 116
thereof. The windows 114 allow liquid from within the container
into the well 110. As will be explained below, in the preferred
embodiment, the windows 114 are located approximately mid way along
the height of the side wall 116 in order to permit a sufficient
volume of the liquid to be collected within the well 110.
[0092] As shown in FIGS. 7 and 9, the middle portion 106 of the cap
includes a bottom wall 115 which defines a top wall for the well
110. The middle portion 106 also includes an elongate wick chamber
118 containing a wick 120. The wick chamber 118 is located proximal
to the outer diameter of the cap 100. The bottom portion of the
chamber includes an opening from which depends a plurality of bars
119 preferably of a "U" shape which supports the wick 120. This
arrangement is shown in FIG. 13. The opening in the bottom of the
chamber 118 allowing the wick 120 to contact the sample of liquid
111 within the well 110 while the bars 119 maintain the wick in a
fixed position. The wick 120 is made of a material which absorbs
the liquid sample and transfers same by capillary action. Wick 120
is preferably in the form of a rectangular slab which extends
across the length of the chamber 118. The appropriate material for
the wick is dependent upon the liquid sample and the type of tests
being conducted. The possible materials which can form the wick
were discussed above.
[0093] The middle portion 106 supports, on the top surface 122, a
plurality of test strips 124 for conducting the desired assays. As
best shown in FIGS. 10 and 11, the test strips 124 include assay
surface 126 and first and second wick pads 128 and 130,
respectively. The assays surface 126 of the test strip are
conventional and are treated with various reagents depending upon
the assay being conducted. Various conventional forms of test
strips are possible for use in the present invention. Examples of
such strips are provided above. In the usual case, the test
comprises a chromatographic assay for the presence of a particular
analyte in the liquid. In a preferred embodiment, the strips
include an assay region 127 and a control region 129. The assay
region 127 is provided with the reagents discussed above for
conducting the desired assay. The control region 129 is provided
with different reagents for ensuring that the test was conducted
properly in that a sufficient volume of liquid was absorbed and
contacted with the reagents. The test strips are made of an
appropriately absorbent material which draws liquid across its
surface thereby bringing such liquid into contact with the various
reagents. By providing the assay device with a plurality of
different test strips, various assays can be conducted
simultaneously on a given sample. In one embodiment as shown in
FIG. 11, the wick pads 128 and 130 are provided below the assay
surface 126. In another embodiment, such wicks can be provided
above the assay surface. In such case, the first wick 128 functions
as a bridge linking the wick 120 to the assay surface 126 of the
test strip 124.
[0094] Wick pads 128 and 130 are contained within first and second
recesses 132 and 134 on the upper surface of the middle portion
106. First recess 132 is located above and opens into the wick
chamber 118. In this manner, first wick pad 128 contacts the wick
120 and is wetted by same thereby drawing such liquid. In such
manner, liquid 111 from the well 110 is supplied to the first wick
pad 128 which then transfers the liquid to the test strip which, in
turn, transfers the liquid to the second wick pad 130 where it is
collected. In the preferred embodiment, second wick pad 130 for
each test strip is provided proximal to the outer diameter of the
cap 100 and opposite from the first wick pad 128. In this way, the
length of the test strips is maximized over the surface of the cap
100. Second wick pad 130 draws liquid along the length of the test
strip 124 and prevents flooding of same.
[0095] It will be understood that test strips as described above
are generally known in the art. Accordingly, a variety of test
strips can be utilized in the present invention. Such strips can,
for example, be of a chromatographic or a chemi-luminescent assay
nature, and can be used to test for a variety substances in either
aqueous or non-aqueous liquids.
[0096] As shown in FIGS. 7 and 12, the cover 108 is provided over
the test strips 12.4 and protects such strips from contamination.
The cover includes a plurality of first and second windows 136 and
138, respectively. First windows 136 are provided over the assay
region 127 of the test strips 124 while second windows 138 are
provided over the control region 129 of the test strips. In one
embodiment, a transparent covering 140 is provided to enable
viewing of the windows 136 and 138 without contamination of the
test strips.
[0097] As described previously, an air outlet (not shown) is
preferably provided on the cap to dissipate any pressure which may
build up as the liquid moves along the test strip and deposited in
second wick pads 130. Such air outlet may comprise a gap along the
perimeter of the covering 140, or one or more holes therein. In one
embodiment, the cover 140 is omitted thereby exposing the cover 108
of the cap. In such case, the test strips are exposed to the
outside by means of windows 136 and 138 which, therefore, provide
the air outlet for the device. In another embodiment, an outlet for
the air being displaced during the assay may be achieved by
providing one or more holes 154 in the bottom wall 115 of the
middle portion 106. Such holes will allow the passage of air while
preventing passage of the liquid (due to its surface tension)
therethrough. In such arrangement, the holes in the wall 115 will
allow the displaced air to enter the well 110 thereby avoiding the
necessity for air outlets exposed to the outside. Such holes will
therefore result in a sealed container and avoid the possibility of
the liquid leaking therefrom.
[0098] A valve member, or seal pad 142 is provided between the base
102 and the middle portion 106. The seal pad 142 is positioned
within a space 144 bounded by the wall 116 of the base 102 and an
opposing bearing surface 146 formed by a plurality of indentations
148 formed in the middle portion 106 of the cap as shown in FIGS. 1
and 13. The space 144 for the seal pad is also bounded by
oppositely facing comers 148 on the top surface of the base 102 as
shown in FIGS. 7 and 8. Such comers prevent movement of the seal
pad 142 by engaging the lower comers thereof. To further immobilize
the seal pad, there may be provided further comers etc. The seal
pad 142 is placed adjacent the window 114 on wall 116. The seal pad
is generally made of a swellable material which absorbs the liquid
entering the well 110 and begins swelling. As the seal pad 142
expands, bearing wall 146 forces the pad against the opposite wall
116 and, therefore, against the window 114. It will be appreciated
that the wall 116 and, the comers 148 and the upper wall 115 force
the seal pad to expand only in the direction of the window 114.
Upon expanding a sufficient amount, the seal pad 142 thereby closes
the window 114 and prevents further liquid from entering the well
110 and effectively seals the liquid contents of the container from
contamination. In the preferred embodiment as shown in FIG. 7, the
wall 116 is sloped and the bearing surface 146 is parallel to same.
In such arrangement, when the container is in the upright position,
the seal pad 142 rests upon the wall 116, and, therefore against
the window 114. Similarly, when in the upside down position, the
seal pad, when in the non-expanded form, rests against the bearing
surface 146. In the preferred embodiment, the wall 116 is angled at
30.degree..
[0099] As shown in FIGS. 7 and 14, the seal pad 142 is laminated
and comprises of first and second layers 150 and 152, respectively.
First, or sealing layer 150 is preferably a foam material such as
cross-linked polyolefin foam. The second, or expanding layer 152 is
formed from an absorbent and expanding material. Preferably, the
material forming the second layer 152 undergoes an irreversible
expansion whereby its expanded form is maintained when the absorbed
liquid is evaporated over time. The choice of the material for the
second layer 152 will depend upon the nature of the liquid being
assayed. In the case of an aqueous liquid, the preferred material
for such second layer is balsa wood. It will be appreciated that
some materials cannot be used for certain assays as they may bind
with the analytes being tested and, therefore, render a false
negative result. The material for the first layer 150 is chosen to
provide an adequate seal to close the window 114 and, thereby,
preventing liquid from entering or leaving the well 110.
[0100] It will be appreciated that the thickness of the seal pad
depends upon various factors. For example, a pad that is too thick
after expansion will seal the window before a sufficient volume of
the liquid is collected in the well. Similarly, a pad that is too
thin after expansion will not effectively seal the window.
Therefore, the thickness of the seal pad is based on the
swellability of the pad material and the width of the space 144 in
which it is placed. For example, the following table illustrates
the swellability of various materials which may be used in forming
the seal pad:
1 Material Condition Swelling PEBAX Natural 18% PEBAX Natural 18%
PEBAX Natural 17% Balsa wood Natural 3% Balsa wood Hot pressed 31%
Balsa wood Hot pressed (with foam layer) 8% Balsa wood Hot pressed
(with foam layer) 8% Balsa wood Cold pressed (with foam layer) 36%
Balsa wood Cold pressed (with foam layer) 37%
[0101] In a cap for a conventional container, a seal pad, as shown
in FIG. 14, is a total of 0.125" in width, and has a sealing layer
comprised of cross linked polyolefin of width 0.03" and an
expanding layer comprised of balsa wood of width 0.095". Further,
in the case of balsa wood being used as the expanding layer, full
swelling of the seal pad normally takes approximately 15
minutes.
[0102] In a preferred embodiment, the various portions of the cap
100, the base 102, the middle portion 106 and the cover 108, are
attached together by conventional means. In such manner, the
various non-structural elements, the wick 120, the wick pads 128
and 130, the test strips 124 and the seal pad 142, are maintained
in a fixed position.
[0103] FIG. 16 illustrates the positioning of the cap 100 on a
conventional container 200 for specimens containing liquid 202 to
be tested.
[0104] In another embodiment, a raised portion 156 is provided on
the side wall 116 on the surface facing the seal pad 142. Raised
portion 156 serves to prevent the seal pad from floating upwards
against window 114 while the well 110 is being filled. Such raised
portion is not, however, so large as to prevent closure of the
window after expansion of the seal pad. During the swelling of the
pad, the flexible nature thereof will surround the raised portion
156.
[0105] The use of the assay device of FIG. 7 is similar to that
discussed above. Firstly, the cap is removed and a volume of the
liquid to be tested in added to the container. The cap 100 is then
replaced onto the container. When the assay is required, the
container in the closed position is turned upside down thereby
causing the liquid to collect on the cap 100 and enter the inlet
portion 112 of the base 102. The liquid then passes through the
window 114, over the seal pad 142 and onto the top wall 115 of the
well 110 where it is collected. It will be appreciated that the top
wall 115 prevents the liquid sample from contacting the test strips
124. While the top portion of the well 110 is filling, the seal pad
gradually expands and, as discussed above, eventually seals window
114 thereby preventing further liquid from entering the well 110.
Also as mentioned above, the window 114 is positioned a sufficient
distance from the bottom surface 115 of the middle portion 106 so
that a sufficient volume of liquid can be collected within the
well.
[0106] After the window is sealed, the container is turned right
side up and the collected liquid 111 is maintained within the well
110. As will be appreciated, a smaller volume of liquid will be
collected within the well if the window 114 is close to the bottom
wall 115, that is, the upper surface of the well, than if the
window is closer to the bottom wall 113 of the well.
[0107] The wick 120 is then allowed to absorb the liquid and, by
capillary action, transfer such liquid to the first wick pad 128.
The liquid is then transferred, again by capillary action, across
the test strip 124 and is collected at the second wick pad 130. As
mentioned above, the test strip is treated with various reagents
depending upon the assay being conducted. Further, in the preferred
embodiment, a plurality of different test strips can be provided on
the cap 100 thereby permitting various assays to be simultaneously
conducted on a given sample.
[0108] In a preferred embodiment, the position of the window along
the wall 116 can be determined based on the volume of liquid to be
collected. As mentioned above, if the window is positioned close to
wall 115, a lesser volume will be collected than if the window is
positioned close to the bottom wall 113 of the well. Therefore, it
is possible to pre-determine the volume of the sample collected by
the appropriate positioning of the window. Further, in the
preferred embodiment, the window is positioned above the bottom of
the chamber 118 when in the upright position. In such arrangement,
when the reservoir is being filled, the liquid sample level will be
maintained below the opening of the wick chamber 118 thereby
preventing the liquid from contacting the wick. Therefore, with
this type of arrangement the wick is wetted, and the assay begun,
only after the device is turned upright.
[0109] As discussed previously, the embodiment described above can
be used in various applications where testing of a liquid is
required. For example, the device can be used for analyzing body
fluids such as urine for the presence of various substances.
Similarly, the device can be used for testing of water samples for
pollutants, toxins and other such substances.
[0110] It will be appreciated that the volume of liquid collected
within the reservoir will be dependent upon the number of test
strips contained within the assay device since each strip absorbs a
volume of the liquid. Therefore, a device having one strip will
require less of a liquid sample than a device having five strips as
shown in the drawings of the preferred embodiments. The volume of
the sample collected in the reservoir is based on various criteria.
For example, as mentioned above, the positioning of the window 114
along the wall 116 is one such factor. In addition, the depth of
the reservoir would also affect the quantity of the liquid
available for the assay procedure.
[0111] In a further embodiment of the invention, the container is
sealed thereby preventing leakage of the liquid contents and is
provided with holes in the middle portion 106 as described above.
In this embodiment, the seal pad 142 is omitted. Such a version of
the invention can be utilized where a segregation of the liquid in
the container and that being assayed is not required. An example of
such use is in the testing of samples from bodies of water.
[0112] A further embodiment of the present invention is illustrated
in FIGS. 17 through 20. As with the embodiments previously
discussed, the assaying device includes a container (not shown) as
described above. A cap for the container is generally shown at
300.
[0113] FIG. 17 illustrates a top view of cap 300 having a generally
cylindrical chamber 332 defined by inner wall 328 and outer wall
326. Positioned within the chamber 332 is a disc 346 of generally
annular configuration having a plurality of radiating arms 348
extending therefrom toward the inner wall 328 of chamber 332. Inlet
360 provides a passage located between radiating arms 348 such that
liquid within the container passes into chamber 332 of cap 300 as
described below.
[0114] FIG. 18 details the cross-sectional view of the embodiment
shown in FIG. 17 along the line 1-1. The cap 300 includes a cover
314 and a base 312 preferably having a thread 304 for engaging a
corresponding thread on the container as described above. The cap
300 further includes a compartment 311, and a piston 340 positioned
within chamber 332. The piston 340 contacts the inner wall 328 and
moves between a first operating position where inlet 360 is sealed,
ad a second operating position where inlet 360 is open and allows
contents of the container to enter the cap, as will be described
below.
[0115] The piston 340 is generally cylindrical and comprises a
button 341 having first and second surfaces 337, 339, and a flange
343 perpendicular to and extending away from the outer most edge of
the second surface 339 of button 341. Flange 343 having an inner
wall 345 and an outer wall 353 includes a channel 321 formed in the
outer wall 353 of flange 343 having an o-ring 330 located therein.
The o-ring ensures a seal is maintained between the piston 340 and
the inner wall 328 of cylinder 332. The piston 340 further includes
arm or shaft 345 generally perpendicular to surface 337 of button
341 and extending away from the second surface 339 of button 341. A
helical spring 342 is provided, generally coaxial with piston shaft
345, such that piston shaft 345 extends therethough. The annular
disc 346 is defined by a first surface 347, and a second surface
349 and is diametrically opposed to button 341. Piston shaft 345
passes through a central aperture 350 of disc 346. Spring 342 is in
compression when the piston is in the first operating position and
bears on each of the first surface 347 of disc 346 and the second
surface 339 of button 341 whereby, as will be described below, the
piston 340 is maintained in the first operating position. Disc 346
further includes a plurality of radiating arms 348 described above,
preferably extending in all directions for connecting disc 346 to
the inner wall 328 of chamber 332. In the preferred embodiment, as
shown in FIG. 17, four radiating arms 348 are provided to ensure
secure attachment of the disc 346 to the chamber wall 328 and also
to ensure an adequate size for inlet 360. Each of the radiating
arms 348 provide support for disc 346 such that the annulus is
coaxial with the piston shaft 345. In this manner, disc 346 and
arms 348 present a "wheel and spokes" configuration.
[0116] A valve member, or seal pad 344 comprising a generally
annular disc is defined by inner wall 331, outer wall 333, first
surface 335, second surface 337 and a central aperture 351. Seal
pad 344 is made of a resilient material so as to form a seal on
inlet 360 whereby, when in the first operating position, fluid is
prevented from passing through inlet 360. Piston shaft 345 passes
through the central aperture 351 of seal pad 344. A frictional fit
between piston shaft 345 and inner wall 331 of seal pad 344 ensures
that movement of the piston arm 345 effects movement of seal pad
344. It will be understood by persons skilled in the art that
various other means of attaching the seal pad 344 to the piston arm
345 are possible. A pin 336 fastened to piston shaft 345 applies
pressure to the second surface 337 of seal pad 344. When the piston
340 is in the first operating position, the first surface 335 of
seal pad 344 abuts the second surface 349 of disc 346 and base 312.
The seal pad 344 extends at least the diameter of chamber 332 to
the edge of base 312. In the first operating position, the pin 336
impinges on resilient seal pad 344 so as to apply pressure on the
seat pad thereby ensuring an adequate seal of the inlet 360. In the
preferred embodiment, as shown in FIG. 19, the aperture of disc 346
has a greater diameter than aperture 351 of seal pad 344.
[0117] In the preferred embodiment, the piston shaft 345, includes
a terminal end 308 having a smaller diameter than the rest of shaft
345. The diameter of terminal end 308 is sufficient to frictionally
engage central aperture 351 of seal pad 344, once terminal end 308
is passed through aperture 351. The diameter of the rest of shaft
345 ensures a sliding fit through aperture 350 of disc 346. In this
manner, a portion of seal pad 344 proximal to the central aperture
351 overlaps aperture 350 of disc 346 thereby preventing any fluid
from inadvertently passing through aperture 350 when in the first
operating position.
[0118] In an alternative embodiment, the piston shaft 345 shown in
FIG. 18 may further include a circumferential channel (not shown)
located at the distal end of piston shaft 345 from button 341. The
channel having the inner wall 331 of seal pad 344 located therein
such that a frictional fit is ensured between the channel and the
seal pad 344.
[0119] In a further embodiment, seal pad 344 may have a conical
shape (not shown) having a central aperture 351 as described
above.
[0120] Piston 340 moves between a first operating position shown in
FIG. 18 and a second operating position as depicted in FIG. 19.
Prior to collecting a sample in cap 300, the container is upright
and piston 340 is in the first operating position and seal pad 344
maintains inlet 360 in a closed state. When button 341 is
depressed, piston 340 moves within chamber 332 toward the second
operating position where seal pad 344, being connected to piston
shaft 345, is moved away from base 312. Spring 342, on depressing
the piston 340, is further compressed from its original position as
shown in FIG. 18 to the position shown in FIG. 19. On releasing the
button 341, spring 342 forces piston 340 to move within chamber 332
away from opening 360, returning piston 340 to the original first
operating position shown in FIG. 18. As the piston 340 returns to
the first operating position, the seal pad 344 through its
engagement with piston shaft 345, also moves to the original closed
position closing inlet 360 such that the chamber 332 is sealed from
the container.
[0121] The assay device of FIGS. 17-20 is used in a similar to
those embodiments previously discussed. The cap 300 is removed and
a volume of liquid sample is added to the container. The cap 300 is
replaced onto the container. To conduct an assay, the container in
the closed position, is first inverted. Once inverted, the button
341 of cap 300 is depressed by the user thereby moving seal pad 344
from the closed, sealed position to the open position and
evacuating air within chamber 332. The button 341 is then released
and liquid 310 flows by gravity and suction through inlet 360 and
collects in chamber 332 of cap 300 as depicted in FIG. 20. 0-ring
seal 330 of button 341 prevents leakage of the liquid 310 from
chamber 332 of cap 300 onto the user of the assay device. The
piston 340 returns to the first operating position, due to the
pressure exerted by spring 342 thereby closing inlet 360. After the
chamber 332 is sealed, the container is turned right side up and
the collected liquid 310, as shown in FIG. 18, is maintained in
chamber 332.
[0122] As shown in FIG. 18, a first wick 321 extends along base 312
of compartment 311 and is preferably in the form of a rectangular
slab. One end of first wick 321 is passed through an opening 313 in
chamber 332 and provides a point of contact between a first wick
321 and the contents of chamber 332.
[0123] The cap 300 further includes an elongate wick chamber 323
containing a second wick 320. The wick chamber 323 is proximal to
the outer edge of the cap 300. The arrangement of elongate wick 320
is similar to the arrangement of wick 120 shown in FIG. 7. The each
of the first and second wick 321, 320 is made of a material which
facilitates capillary action.
[0124] Wick pad 318 is located in a first recess 322 of an upper
surface 315 of compartment 311. The first recess 322 is located
above and opens into the wick chamber 323 such that wick pad 318
contacts wick 320 and is wetted by same thereby drawing such
liquid. In such a manner, liquid 310 from chamber 332 is supplied
to first wick 321 which then transfers the liquid to elongate wick
320, to wick pad 318. Liquid absorbed by wick pad 318 contacts one
or more test strips 333 and in turn transfers the liquid to that
test strip 338. The test strips 338 may be any commonly known strip
as described previously. Liquid travels along the test strip and
lastly, the test strip 338 transfers the liquid to a second wick
pad 329, located in second recess 324 on upper surface 315 of
compartment 311, where the liquid is collected. Pressure pads 316a
and 316b are preferably provided proximate to the wick pads 318 and
329 respectively. Test strip 338 is located between the pressure
pad and the wick pad. These pressure pads not only apply pressure
to the wick pad to ensure contact between test strip 338 and wick
pads 318 and 329 respectively. The appropriate material for each of
the wicks previously described is dependent upon the liquid sample
and the type of tests being conducted. The possible materials which
can form the wick were discussed above.
[0125] As will be apparent to those skilled in the art in the light
of the foregoing disclosure, many alterations and modifications are
possible in the practice of this invention without departing from
the spirit or scope thereof. Accordingly, the scope of the
invention is to be construed in accordance with the substance
defined by the following claims.
* * * * *