US20040228761A1

US20040228761A1 - Lateral flow test strip

Info

Publication number: US20040228761A1
Application number: US10/868,734
Authority: US
Inventors: Mitchell Owens; Norman Reddick; Michael Turanchik
Original assignee: Medtox Scientific Inc
Current assignee: Medtox Scientific Inc
Priority date: 1999-01-15
Filing date: 2004-06-15
Publication date: 2004-11-18
Also published as: WO2000042430A1; WO2000042430A9; US20040023364A1; CA2360044A1; EP1159611A1; WO2000042430A8; US6566051B1; US20050208677A1

Abstract

The present invention provides a test strip having a first layer comprising a wicking member and a second layer comprising a capillary transfer plane member. The capillary transfer plane has a plurality of capillary transfer passages. The capillary transfer passages can comprise a hole, channel, or other shape to control sample flow rate. Located above the one or more capillary transfer passages are a plurality of testing members. The test strip can include a third layer next to the wicking member, the third layer comprising a backing member for providing support to the wicking member. Another aspect of the present invention provides a sample testing device, which includes a housing having a plurality of openings, and a test strip as described above, wherein a sample application area of the test strip is accessible through one of the openings in the housing, and each of the testing members is viewable through one of the openings of the housing.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No. 10/347,951, filed Jan. 21, 2003, which in turn is a continuation of U.S. application Ser. No. 09/889,270, now U.S. Pat. No. 6,566,051, which claims the benefit under 35 U.S.C. 120 to PCT application No. WO 00/42430, filed on Jan. 14, 2000, published in English as per PCT article 21(2), which in turn claims priority to provisional U.S. application Ser. No. 60/115,984, filed on Jan. 15, 1999.[0001]

BACKGROUND

Testing of bodily fluids for drugs is an increasingly important field because of increased recognition of the need for safety. For example, employers have the need to test employees in dangerous jobs such as construction, truck driving or piloting. Also, testing bodily fluid samples for other purposes, such as disease detection and other diagnostic purposes, is also important.

In the past, assorted systems for collecting and testing samples have been used. For example in one method, when a test is needed, a sample, usually urine, blood, or another bodily fluid, is deposited into a cup. Currently, the user places a dipstick into the collection cup, assuring that all test sites on the dipstick are submerged within the fluid. The dipstick remains in the sample fluid for approximately one second. The dipstick is then removed by dragging it along the edge of the specimen cup to remove excess urine or other fluid. Some type of absorbent paper must be placed on a flat surface, upon which the dipstick will be placed, with test sites up, to absorb all excess fluid. The dipstick must not be left in the collection cup any longer than one second because the chemicals used in the test area will begin to dissolve into the sample, coming off the test area, thereby providing inaccurate test results because of cross-contamination.

Overall, this is an unsanitary process that can result in urine getting onto counter-tops, clothes, instruments, etc. Also, if multiple samples are being tested, as is the case in a laboratory environment, it is difficult to efficiently identify multiple samples once they are removed from the collection cup.

For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a better method and apparatus for performing testing of samples.

SUMMARY

Embodiments of the present invention answer the need described. For example, in one embodiment, a test strip for testing for at least one substance in a sample, including a wicking member having a sample application area and an absorbent area, is disclosed, the sample application area and the absorbent area defining therebetween a central portion of the wicking member, the wicking member adapted to draw a sample from the sample application area through the central portion and towards the absorbent area. This test strip also provides a testing member containing a testing reagent, a transfer member formed of a material through which fluid will not flow, in which the transfer member located between the central portion of the wicking member and the testing member, and a transfer path from the wicking member to the testing member, in which the transfer path is adapted to draw a portion of the sample from the central portion of the wicking member to the testing member via capillary force action, the transfer path being small enough to reduce backflow from the testing member to the wicking member.

In further embodiments of the test strip described above, the transfer member is a planar member, and/or the transfer path is a channel between two transfer members, and/or the transfer path is a channel between two sections of the transfer member, and/or the testing member is positioned adjacent to the central portion of the wicking member. In additional embodiments, the transfer path is the only fluid path from the wicking member to the testing member, and/or a plurality of testing members is included, each containing reagents for separate testing of the sample. For this embodiment, the respective transfer paths may draw a portion of the sample from the central portion of the wicking member to each testing member. In an additional embodiment, the testing member receives the sample only from the central portion of the wicking member.

An alternate embodiment provides a test strip for testing for a plurality of substances in a sample that includes: a wicking member having a sample application area and an absorbent area, the sample application area and the absorbent area defining therebetween a central portion of the wicking member, the wicking member adapted to draw a sample from the sample application area through the central portion and towards the absorbent area; a plurality of adulterant testing members each containing a testing reagent for separate testing of the sample for adulterants; and a plurality of transfer paths, each transfer path extending from the central portion of the wicking member to a respective testing member, each transfer path adapted to draw a portion of the sample from the central portion of the wicking member to the respective testing member via capillary force action, the transfer paths being small enough to reduce backflow from the testing members to the wicking member.

In further embodiments of the test strip described above, the testing members receive the sample only from the central portion of the wicking member. Alternately, or in addition, an embodiment may further include a transfer member formed of a material through which fluid will not flow, the transfer member located between the central portion of the wicking member and the testing members. In further embodiments, the transfer paths are formed from passages within a transfer member, the transfer member formed of a material through which fluid will not flow, and the transfer member is located between the central portion of the wicking member and the testing members, and/or the testing members are separated and isolated from each other, and/or the transfer paths are separate and isolated from each other.

Advantageously, a test strip is provided that separates the testing member holding the testing reagent from the sample holding member itself. This provides a simpler testing process that helps prevent unsanitary conditions and cross-contamination. The test strip can be placed into a carrier device or instrument to assist in handling and containing the sample being tested, such as urine, blood, body fluids or any other type of sample extraction. The test strip and associated methods make the testing process easier, more sanitary, and less confusing when processing multiple samples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of one embodiment of a test strip. [0011]
FIG. 2 shows a top view of the test strip of FIG. 1. [0012]
FIG. 3 is a side view of the test strip of FIG. 1. [0013]
FIG. 4 is a front view of the test strip of FIG. 1. [0014]
FIG. 5 is an isometric view of the test strip of FIG. 1. [0015]
FIG. 6 is an exploded view of the test strip of FIG. 1. [0016]
FIG. 7 is a top view of another embodiment of a test strip. [0017]
FIG. 8 is a top view of another embodiment of a test strip. [0018]
FIG. 9 is a top view of another embodiment of a test strip. [0019]
FIG. 10 is a front isometric view of one embodiment of a housing. [0020]
FIG. 11 is a back isometric view of the housing of FIG. 10. [0021]
FIG. 12 is a back view of the housing of FIG. 10. [0022]
FIG. 13 is a front view of the housing of FIG. 10. [0023]
FIG. 14 is a sectional view of the housing of FIG. 10. [0024]
FIG. 15 is another sectional view of the housing of FIG. 10.[0025]

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. [0026]
FIGS. 1-6 show one embodiment of a lateral [0027] flow test strip 100. Test strip 100 includes a first layer, such as a wicking member 101, for holding and carrying the sample. Wicking member 101 includes a sample application area 115 and an absorbent area 113. In one embodiment, wicking member 101 is fabricated from an efficient liquid transferring material, such as a wicking membrane material, that allows a sample placed on the sample application area 115 to freely flow to the absorbent area 113. Test strip 100 also includes a capillary transfer plane member 102 and a plurality of assorted test pads or testing members 108-112. In one embodiment, test strip 100 can include a backing layer 114 to provide support for wicking member 101. The backing member 114 may be Mylar or other rigid support material.
Capillary [0028] transfer plane member 102 is adhesively attached to one side of the first layer of wicking member 101. It is located so that it is sandwiched between the first layer and the testing members 108-112. In one embodiment, the wicking member is longer than the capillary transfer plane member so that sample application area 115 of wicking member 101 is exposed so that a sample can be placed thereon. In one embodiment, capillary transfer plane member 102 is fabricated from Mylar or other suitable material.
[0029] Member 102 includes a plurality of capillary transfer passages 103-107. These passages provide a capillary force action to draw a portion of a sample placed on wicking member 101 to be drawn upwards through the passage and into contact with the testing members 108-112. Each of the capillary transfer passages are of a suitable size for providing correct flow rate of the sample. In one embodiment, the passages are holes of approximately 0.5 to 2.5 millimeters in diameter. In another embodiment, each passage is a hole approximately 2 millimeters in diameter. Those skilled in the art will appreciate that the exact size of the hole is determined by the viscosity of the liquid and the desired flow rate. Moreover, it is noted that if the passage is too small, surface tension of the sample fluid will prevent flow and if the passage is too large, the capillary action will not be activated. Alternatively, the passages can be channels, such as channels 801-805 shown in FIG. 8. Alternatively, any other transfer means may be used instead of holes or channels, such as star-shaped holes or other shapes.
Furthermore, more than one hole, channel, or other shaped passage may be located under each test area, as shown in FIG. 9, which shows a [0030] test strip 100 which includes a pair of holes 901 and 902 beneath each testing member 108-112. As noted above, the exact size, shape, and number of the capillary transfer passages depends on the viscosity of the fluid sample and the desired flow rate. Advantageously, the pressure at the inlet of a given capillary transfer passage 108-112 is sufficient to prevent an immediate back-flushing effect into the wicking member 101. This prevents any cross-contamination of or between the separate testing members 108-112. Such cross-contamination can be caused by the cross-mixing of the reagents on the pads or a combination of reagent and sample being reintroduced back to the main sample in the wicking member. Also, the passages provide that test strip 100 does not have any testing reagents located on the wicking member 101 or on any material in direct contact with the wicking member. The testing reagents on the testing members 108-112 are isolated from the first layer containing the sample and they receive the necessary sample volume intermittently as the sample runs along the first layer material. Advantageously, this also prevents cross contamination which would result from a contrary system. In one embodiment, capillary transfer plane member 102 also includes an indexing hole 610 (see FIGS. 6 and 7). Indexing hole 610 provides a means during manufacturing for aligning passages 103-107 so that they are the proper distance apart.
The size of the layers may vary considerably, as will be appreciated by those skilled in the art. However, by way of example, but not limitation, in one embodiment, the first layer, such as [0031] wicking member 101, is approximately 70 millimeters long by 5 millimeters wide and 0.20 millimeters thick. Also, way of example, but not limitation, in one embodiment, member 102 is approximately 56 millimeters long by 5 millimeters wide and 0.50 millimeters thick.
Testing members [0032] 108-112 are testing areas or test pads which are fabricated from porous materials that will hold specific testing reagents. The testing reagents in the testing members 108-112 can provide for separate testing of a single sample. In one embodiment, the testing members can include a color coded, positive or negative, test result. The testing members are located over the capillary transfer passages 103-107 in the capillary transfer plane member 102. In one embodiment, member 102 includes adhesive zones 601-605 for attaching testing members 108-112 over its capillary transfer passages 103-107 (see FIG. 6). It is noted that the number of testing members shown in the Figures is exemplary, and that embodiments could include more or less, depending on the need.
As a sample flows along the wicking [0033] member 101, some of the sample will be pulled through the first capillary transfer passage 103 and saturate the first testing member 108. As noted above, the capillary transfer passages 103-107 are shaped and designed a suitable size for providing correct flow rate of the sample. The sample will continue on to each adjacent capillary transfer passage 104-107 in the same manner until it reaches the absorbent area 113. This system provides that a user need only add a few drops to the application area 115. This lessens the complexity of doing multiple tests since there is no need to carefully time the immersion of the test strip in the fluid sample. Also, since immersion is not required, the present system provides for a neater, more sanitary testing system.
FIGS. 10-15 show one embodiment of a sample testing device comprising a carrier device or [0034] housing 1200 having a plurality of openings and a test strip 100 located within the housing (the test strip is shown in outline in FIG. 12. The test strip 100 is substantially as described above, and will not be described further). Housing 1200 includes a first, front member 1201 and a second member (not shown) which provides a backing for the housing. The front and back members can be attached by attaching members 1301. Housing 1200 also includes a plurality of openings, such as viewing openings 1205-1209 and sample application openings 1202 and 1203. The test strip is contained within carrier device 1200 so that each of the testing members 108-112 is viewable through at least one of the plurality of openings 1205-1209 of the housing 1200. In one example of using the present system for performing a test of a sample, the sample is deposited on the sample application area 115 of the test strip 100 through opening 1202 of the housing. In one embodiment, carrier device or housing 1200 can also include another sample opening 1203 and another viewing opening 1204. This provides that another type of testing system can be incorporated into the carrier device.
As will be recognized by one skilled in the art, embodiments of the test strip and its associated methods represent an advance over dipstick format tests in which the sample is introduced to the testing area by submerging the dipstick into the sample being tested or have the sample introduced directly onto the test areas. Advantageously, the lateral [0035] flow test strip 100 placed within the carrier device 1200 provides that a sample can be tightly controlled, isolated and identified, even after introducing the sample into the sample application area 115. For example, if multiple samples are being tested, as is the case in a laboratory environment, it is difficult to efficiently identify multiple samples from different patients once the samples are removed from a collection cup. Advantageously, in the present system, the lateral flow test strip in a carrier device provides an area for permanent and efficient sample/patient identification. Moreover, the present system can be used for the conversion of adulterant or urinalysis dipsticks that screen for adulterants in urine samples or uranalysis tests that screen for Ph factors, for example.
A sample testing system has been described. In one embodiment, the system includes a [0036] test strip 100 for testing a sample. Test strip 100 having a first layer, such as a wicking member 101, for holding and carrying the sample. The test strip includes a second layer next to the first layer comprising a capillary transfer plane member 102 having a plurality of capillary transfer passages 103-107 for drawing a portion of the sample away from the wicking member 101. The test strip also includes and a plurality of testing members 108-112, each testing member located over at least one of the plurality of capillary transfer passages, each testing member 108-112 for receiving the portion of the sample from the capillary passage(s) beneath the testing member. In one embodiment, the wicking member 101 comprises a first end having a sample application area 115 and a second end comprising an absorbent area 113. In one embodiment, the capillary transfer passages comprises a hole of approximately 0.5 to 2.5 millimeters in diameter. Alternatively, the capillary passage can be shaped as a channel, star, or other shape to provide the correct flow depending on the flow rate desired by the designer. Each of the plurality of testing members 108-112 comprise a porous material holding a testing reagent.
In another aspect, the present system provides a lateral [0037] flow test strip 100 that can be placed into a carrier device 1200 or instrument to assist in handling and containing the sample being tested, such as urine, blood, body fluids or any other type of sample extraction. The lateral flow test strip 100 provides a method for converting any type of dipstick style test, such as adulterants, glucose, urinalysis, etc. to an easy and sanitary format by enclosing and controlling the sample. The various embodiments of the test strip and associated methods generally make the testing process easier, more sanitary, and less confusing when processing multiple samples.
It is understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. [0038]

Claims

1-25 (cancelled)

26. A test strip for testing for at least one substance in a sample, comprising:

a wicking member having a sample application area and an absorbent area, the sample application area and the absorbent area defining therebetween a central portion of the wicking member, the wicking member adapted to draw a sample from the sample application area through the central portion and towards the absorbent area;

a testing member containing a testing reagent;

a transfer member formed of a material through which fluid will not flow, the transfer member located between the central portion of the wicking member and the testing member; and

a transfer path from the wicking member to the testing member, the transfer path adapted to draw a portion of the sample from the central portion of the wicking member to the testing member via capillary force action, the transfer path being small enough to reduce backflow from the testing member to the wicking member.

27. The test strip of claim 26, wherein the transfer member is a planar member.

28. The test strip of claim 26, wherein the transfer path is a channel between two transfer members.

29. The test strip of claim 26, wherein the transfer path is a channel between two sections of the transfer member.

30. The test strip of claim 26, wherein the testing member is positioned adjacent to the central portion of the wicking member.

31. The test strip of claim 26, wherein the transfer path is the only fluid path from the wicking member to the testing member.

32. The test strip of claim 26, further including a plurality of testing members each containing reagents for separate testing of the sample.

33. The test strip of claim 32, wherein respective transfer paths draw a portion of the sample from the central portion of the wicking member to each testing member.

34. The test strip of claim 26, wherein the testing member receives the sample only from the central portion of the wicking member.

35. A test strip for testing for a plurality of substances in a sample, comprising:

a plurality of adulterant testing members each containing a testing reagent for separate testing of the sample for adulterants; and

a plurality of transfer paths, each transfer path extending from the central portion of the wicking member to a respective testing member, each transfer path adapted to draw a portion of the sample from the central portion of the wicking member to the respective testing member via capillary force action, the transfer paths being small enough to reduce backflow from the testing members to the wicking member.

36. The test strip of claim 35, wherein the testing members receive the sample only from the central portion of the wicking member.

37. The test strip of claim 35, further including a transfer member formed of a material through which fluid will not flow, the transfer member located between the central portion of the wicking member and the testing members.

38. The test strip of claim 35, wherein the transfer paths are formed from passages within a transfer member, the transfer member formed of a material through which fluid will not flow, the transfer member located between the central portion of the wicking member and the testing members.

39. The test strip of claim 35, wherein the testing members are separated and isolated from each other.

40. The test strip of claim 35, wherein the transfer paths are separate and isolated from each other.