Immunoassay test slide

A test slide for the performance of a series of immunoassay tests having: a substantially elongated and thin body of solid material; a plurality of individual test wells formed in said body; alignment means formed in said body in association with each of said wells; and movement facilitating means formed in said body; said slide being suitable for insertion into an automated testing device, said slide moving by said movement facilitating means, and said wells being aligned for detection by said alignment means.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to test slides for performing 
immunoassays and more particularly to an immunoassay test slide suitable 
for use in immunoassay testing which contains a series of test wells each 
having an immunosubstrate layer formed therein. 
2. Description of the Prior Art 
Immunoassay test slides having a series of test wells formed therein have 
been known in the industry for many years. Such test slides contain wells 
of varying shapes and sizes and are suitable for differing test 
procedures. Thus the prior art contains a test well shape consisting of a 
rounded bottom with diverging sidewalls, a test well shape consisting of a 
flat bottom and vertical sidewalls, and a test well shape consisting of a 
rounded dish shape having curved sidewalls. 
In recent years, it has been found that immunoassay test results may be 
enhanced through the utilization of an immunosubstrate. The 
immunosubstrate serves to provide substantially increased numbers of 
binding sites for immunoreagents utilized in the test procedures. The 
enhanced binding capacity has created greater sensitivity to immunoassay 
tests utilizing immunosubstrates. 
It therefore appeared innovative to place an immunosubstrate layer within 
individual test wells of the prior art test slides in order to enhance 
test results obtained therefrom. However, when tests were performed by the 
instant inventors utilizing an immunosubstrate in the various prior art 
test wells, inconsistent and inaccurate results were often obtained. It 
appeared that immunoreagents within the immunosubstrate layer gravitated 
to the sides of test wells having vertical sides. Test wells having 
rounded bottoms performed poorly and inconsistently for no obvious reason. 
It is the inventors hypothesis that the manner in which the 
immunosubstrate dries after wetting and the possible gravitation of 
immunoreagents during the drying process to particular areas of the 
immunosubstrate layer, such as to a ring towards the edge of the 
vertically sided well, contribute to the poor and unreliable results. 
SUMMARY OF THE PRESENT INVENTION 
It is therefore a primary objective of the present invention to provide an 
optimally shaped test well for performing immunoassays. 
It is another objective of the present invention to provide an immunoassay 
test slide having a series of optimally shaped test wells formed therein 
for the rapid and accurate performance of immunoassay tests. 
It is a further object of the present invention to provide an immunoassay 
test slide which is formed for automated testing within a immunoassay 
testing device. 
The optimally shaped test well of the present invention has a flat bottom 
and diverging side walls. The test well has sufficient depth to contain an 
immunosubstrate layer and liquid immunoreagents which will be placed in 
the test well to react within the immunosubstrate layer. 
The immunoassay test slide of the present invention contains a series of 
said optimally shaped test wells. Further embelishments of the test slide 
which aid in its utilization in an automated testing device include an 
edge formed as a rack for interaction with a pinion gear within the 
testing device and notches formed in an edge thereof for the accurate 
alignment of individual test wells with testing components within the 
testing device. 
An advantage of the present invention is that accurate, sensitive and 
reproducible results are now obtainable utilizing test wells of the 
particular shape described herein along with suitable immunosubstrate 
materials. 
Another advantage of the test slide of the present invention is that it may 
be utilized in an automated testing device such that accurate results for 
a series of tests may be obtained rapidly and inexpensively. 
These and other objects and advantages of the present invention will no 
doubt become apparent to those of ordinary skill in the art after having 
read the following detailed description of the preferred embodiments which 
are illustrated in the several figures of the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As depicted in FIGS. 1, 2 and 3, the preferred embodiment of the 
immunoassay test slide of the present invention 10 is basically a long 
thin strip of material having a series of test wells 12 formed therein. A 
suitable material is a polystyrene plastic however, other materials may be 
substituted therefore. When viewed from above, as in FIG. 1, it is seen 
that the test wells 12 are evenly spaced in a linear manner throughout the 
length of the slide 10. The spacing of the wells 12 from center line to 
center line is approximately 0.354 inches, such that standard industry 
microtiter equipment may be utilized therewith. 
The preferred embodiment of the immunoassay test slide 10 is formed for 
utilization in an automated testing system, not shown. The basic elements 
of the slide 10 which permit its movement within the automated testing 
system are a rack 14 which is formed along one of the elongated edges 16 
of the slide 10. The depiction of the rack 14 in FIGS. 4, 5 and 6, will 
aid in the understanding of this feature. The rack 14 is formed for 
engagement with a pinion gear within an automated testing device to permit 
the controlled movement of the slide 10 within the automated testing 
device. The invention is not to be limited to only this type of rack 14 
for the movement of the slide. 
To accomplish the accurate alignment of individual test wells 12 within an 
automated testing device a series of notches 18 are formed in the other 
elongated edge 20 of the slide 10. An enhanced understanding of the 
notches 18 in edge 20 is to be gained from FIGS. 4, 5 and 7. Each of the 
notches 18 is formed in a prearranged accurate alignment with the wells 12 
such that when the slide 10 is inserted within an automated testing device 
a suitable sensing device can detect the presence of a notch 18 along edge 
20 to accurately align each individual test well 12 with a test detection 
system within the automated testing device. It is crucial to the creation 
of accurate and reproducible results from an automated test system 
utilizing the slide 10 that each test well be accurately and identically 
aligned relative to the test detection system within the automated testing 
device. The instant invention is not to be limited to the type of 
alignment system described herein, as equivalent systems may be easily 
substituted therefor. 
A detailed depiction of the shape of each test well 12 of the slide 10 is 
presented in FIG. 5. As depicted therein, each test well is formed with a 
flat bottom 30 and has diverging sidewalls 32. The acute angle between the 
plane of the base 30 and the sidewall 32 in the preferred embodiment is 
formed to be approximately 68.degree.. In the preferred embodiment, the 
diameter of the upper opening of each test well is approximately 0.250 
inches, the diameter of the flat bottom 30 of each test well is 
approximately 0.188 inches and the depth of each test well is 
approximately 0.080 inches. 
An immunosubstrate layer 34 is shown in the test well 12 of FIG. 5. A 
typical immunosubstrate layer 34 would have a thickness of approximately 
0.004 inches and would exhibit a slight creeping 36 up the diverging sides 
32 of the test well 12. The immunosubstrate layer 34 is utilized to 
provide a substantially increased number of binding sites for 
immunoreagents utilized in performing tests within the test well 12. The 
utilization of an immunosubstrate greatly increases the sensitivity and 
accuracy of immunoassays. 
The above-described test well of the preferred embodiment, having a flat 
bottom and diverging sidewalls, when used with an immunosubstrate, has 
demonstrated in testing that it provides test results which are more 
consistent and accurate than test results obtained using preexisting test 
wells of differing shapes and the identical immunosubstrate. 
More specifically, one type of prior art test well, possessing a rounded 
bottom together with diverging sidewalls was examined. When an 
immunosubstrate, consisting of latex polymer bead emulsion in water, was 
placed in the bottom of this test well and testing was conducted, the 
results were inconsistent from test well to test well and generally 
inaccurate. The inventors are unsure of the precise reasons for the 
inconsistency and inaccuracy, but believe that the rounded bottom of the 
test well created a deep pocket of immunosubstrate material which dried 
more slowly than the outer regions. It is believed that the uneven drying 
resulted in uneven concentrations of immunoreagents within the 
immunosubstrate and produced the inconsistent and inaccurate results. 
Additionally, it is believed that the rounded geometry of the well 
inhibits effective washing of unbound reagents from the immunosubstrate 
prior to the testing thereof. This effect also would tend to create poor 
results. 
Further testing was conducted utilizing the prior art test wells which have 
a flat bottom and vertical sidewalls; the identical immunosubstrate was 
utilized to form a layer therein. Again, inconsistent and inaccurate 
results were obtained, as compared with those of the preferred embodiment. 
The inventors are unsure of the cause of the poor results, but it appeared 
that substantial creeping of the immunosubstrate up the walls of the test 
well was occurring. It is hypothesized that the vertical test walls create 
a shielding or shadowing effect such that the optical instruments utilized 
to perform the immunoassay testing could not accurately detect 
immunoreagents which had crept up the side walls. Additionally, the 
vertical sidewalls appeared to inhibit effective washing of the outer 
edges of the immunosubstrate. This would tend to permit unbound reagents 
to remain in the immunosubstrate and lead to inconsistent and inaccurate 
results. Again, the inventors were uncertain of the cause of the poor 
results and confirmed that the test well shape of the preferred embodiment 
is substantially superior. 
A third prior art test well in the shape of a fully rounded depression was 
also examined. Test results utilizing this prior art shape with the 
immunosubstrate also proved inconsistent and inaccurate. The inventors 
believe the source thereof to be the rounded bottom which creates uneven 
drying and difficulty of washing of the immunosubstrate in the bottom of 
the test well, as was described hereinabove. 
The instant invention achieves consistent and accurate immunoassay testing 
results through the utilization of a specially shaped test well 12 having 
a flat bottom and diverging sidewalls. The placement of a series of such 
test wells 12 in the instant test slide along with the utilization of the 
alignment notches 18 and rack 14 permit the slide 10 to be utilized in an 
automated immunoassay testing system to produce accurate results rapidly 
and inexpensively. 
Whereas the preferred embodiment of the present invention has been 
described above, it is contemplated that other alterations and 
modifications may become apparent to those skilled in the art after having 
read the above disclosure. It is therfore intended that the appended 
claims be interpreted as covering all such alterations and modifications 
as fall within the true spirit and scope of the invention.