Apparatus for shuttling a test element from a discharge path to a wash station

A shuttle apparatus and method for catching a test element ejected from an incubator, for carrying it to a station outside the incubator, e.g., a wash station, and for returning it to a loading station. Preferably, the apparatus comprises a simplified catcher plate and a device for moving the plate in an arcuate path around a portion of the circumference of the incubator. The plate cooperates with a stop disposed above said arcuate path, to capture a washed element upon reloading, so that the washed element can be reloaded by returning it to the original path used to load elements into the incubator in the first instance.

FIELD OF THE INVENTION 
The invention relates to an analyzer for ascertaining analyte 
concentrations in body liquids dispensed onto test elements, particularly 
such analyzers that need a wash station to allow immunoassays to be 
conducted. 
BACKGROUND OF THE INVENTION 
Analyzer mechanisms have been provided for receiving slide test elements 
from incubators, to carry them on to additional stations, e.g., a wash 
station. Such a mechanism is described in U.S. Pat. No. 4,857,471. 
Although this mechanism functions admirably, it uses a platform that 
lowers into the "dump" path of the ejected slide element to catch the 
slide element, FIG. 2. The platform cannot move on to the wash station but 
provides a stationary support. As a result, a claw must then be used to 
transfer the slide element from this stationary support to a movable train 
104. Thus, the noted mechanism does have the disadvantage of requiring a 
transfer claw and means other than the catching surface to move the slide 
element to the wash station. Furthermore, the train that is used for the 
wash step transfer is of substantial size and complexity. 
Thus, prior to this invention, there has been a need for an improved 
transfer mechanism off-line of the incubator, to allow a slide element to 
be removed from the incubator, washed and reinserted, using simpler and 
less expensive parts. 
SUMMARY OF THE INVENTION 
We have constructed a shuttle mechanism and method that solve the aforesaid 
problems, with a catcher plate that provides the needed movement of a 
"caught" test element ejected from an incubator, to a wash station and 
back into a loading station for reinsertion into the incubator. Further, 
the catcher plate is constructed to provide other important features, all 
in one simplified piece. 
More specifically, in accord with one aspect of the invention, there is 
provided an analyzer having processing stations including an incubator and 
a wash station outside of said incubator, means for ejecting a test 
element from one of the processing stations, and means defining a 
discharge path to carry the ejected element out of the analyzer. The 
analyzer is improved in that it further includes a catcher plate for 
catching test elements ejected from the one processing station by the 
ejecting means, and means for moving the plate into a position in the 
discharge path to intercept an ejected element moving along the path, the 
moving means including means defining a track constructed to move the 
catcher plate and an intercepted test element from the path to the wash 
station. 
In accord with another aspect of the invention, there is provided an 
analyzer comprising processing stations including an incubator, means for 
injecting a test element bearing a sample liquid along a first path into 
one of the processing stations, means for ejecting a test element from the 
one station, and discharge means defining a second path for carrying an 
ejected test element away from the one station. The analyzer is improved 
in that it further includes a stop mechanism between the first path and 
the second path, the mechanism including a) a shoulder adjacent the first 
path to prevent a test element on the first path from moving off the first 
path towards the second path, and b) a camming surface under and adjacent 
to the stop shoulder, the camming surface being shaped to cause the stop 
mechanism to ride up over a test element moved from the vicinity of the 
second path to the first path, so that a test element can be moved only 
from the second path to the first path, and not from the first path to the 
second path. 
In accord with yet another aspect of the invention, there is provided a 
test element support for use in an analyzer that analyzes analytes of a 
body liquid contained in a test element, the support comprising a plate 
having a frame, a central portion within and flexibly secured to the 
frame, and raised shoulders on opposite edges of the frame dimensioned to 
retain a test element between the shoulders to prevent a held element from 
being displaced off the support, the central portion being cantilevered 
from the frame at only one side thereof, so as to be capable of flexing in 
an out of the plane of the frame. 
In accord with still another aspect of the invention, there is provided a 
method of washing an incubated test element and comprising the steps of 
loading a test element at a first station into an incubator, ejecting at a 
second station a loaded test element from the incubator, catching the 
ejected test element, shuttling the caught element to a wash station, 
washing the shuttled test element at the wash station, and returning the 
washed element to the incubator. The method is improved in that the 
returning step comprieses moving the washed element back to the first 
station, and reloading it into the incubator. 
Accordingly, it is an advantageous feature of this invention that the same 
means that catches a test element ejected from the incubator, is used to 
transport such test element to a wash station. 
It is a related advantageous feature of the invention that the means for 
transporting a test element from its ejected location to an additional 
station, is simplified. 
It is another advantageous feature of the invention that a removed and 
washed test element is returned to the original loading mechanism, for 
reloading into the incubator, to avoid the use of a separate loader. 
Other advantageous features will become apparent upon reference to the 
following Description of the Preferred Embodiments, when read in light of 
the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention is hereinafter described in connection with the preferred 
embodiments, in which the transfer mechanism that catches and transfers 
slide-like test elements is disposed outside of an incubator particularly 
positioned in an analyzer, to transfer the test element to a wash station 
and back to the incubator, and in which the test elements are of a type 
similar to those obtained from Eastman Kodak Company under the trademark 
"Ektachem" slides, or from Fuji Photo under the tradename "Drychem". In 
addition, such a transfer mechanism is useful adjacent any processing 
station of an analyzer, whether or not it is the incubator and regardless 
of the position of that station, to take the slide-like test element to 
any other processing station and back to the first processing station from 
which the test element is received. Still further, such a transfer 
mechanism is useful regardless of the construction of the test element, 
although generally planar elements are preferred since the transfer 
mechanism is shaped preferably to handle such planar elements. 
An analyzer 10 in which this shuttle invention is useful comprises, FIG. 1, 
preferably a station 20 for loading a slide-like test element E into a 
sample dispensing station 30, and for loading such an element, along path 
32, now bearing patient sample, into an incubator 40. Preferably, loading 
station 20 includes a pusher blade 22 that pushes an element E along path 
29 so as to be injected into station 30. The loading station includes tip 
locator 34, FIG. 2, with two apertures 36, 37 as is conventional for 
patient sample metering, and an aperture 38 for reference liquid metering, 
as is also conventional. Also preferably, the incubator is the rotating 
type, arrow 42 and includes a reflectometer 50, FIG. 1, for scanning 
colorimetric test elements while they are held at a plurality of stations 
44, etc., FIG. 2, as defined by a rotor 46. Such an analyzer includes an 
electrometer 52, FIG. 1, for reading potentiometric test elements after 
they are removed from the incubator by, e.g., a pusher blade 48, FIG. 2. A 
wide variety of incubators is useful for this purpose, for example, that 
shown in, e.g., U.S. Pat. No. 4,935,374. 
Similar to the construction of the analyzer in U.S. Pat. No. 4,857,471, a 
wash station 70 is disposed outside of incubator 40, displaced 
circumferentially from station 30. The wash station comprises a boss 72 
and aperture 74 that serve to hold a dispensing tip in proper orientation 
with respect to a test element to be washed. In between stations 30 and 70 
is an eject station 80, including a discharge path defined by aperture 82, 
FIG. 1, into which a test element is ejected, arrow 84, when its readings 
are completed. Shuttle apparatus is then provided to allow test elements 
to be intercepted at station 80, taken to wash station 70, and reinserted 
into the incubator, as in the '471 patent. In accord with one aspect of 
the invention, it is the improvement of this apparatus to which the 
invention is addressed. 
More specifically, the shuttle apparatus 100, FIG. 2, comprises a catcher 
plate 110, means 160 for supporting plate 110 for movement along a path 
112, FIG. 1 that is preferably curvilinear, and means 140, FIG. 2, for 
driving plate 110 along path 112, FIG. 1. Importantly, path 112 is 
constructed to extend back to station 30 to intersect path 32, so that a 
test element washed at station 70 can be reinserted into the loading path 
32. 
Referring now to FIGS. 4-6, catcher plate 110 comprises a frame 120 shaped 
to hold a test element E, shown in phantom. Accordingly, frame 120 is 
generally rectangular, and is provided with two opposed shoulders 122,124 
shaped and positioned, FIG. 6, to restrain element E from moving off plate 
110 as the latter moves on path 112, FIG. 4. Shoulder 122 is the leading 
shoulder and is preferably beveled, to allow shoulder 122 to cam under 
element E when the latter is returned to and retained at path 32, FIG. 1, 
as described hereinafter. 
A central support member 128 is flexibly connected to frame 120, FIG. 4, to 
do the principal carrying of element E. The flexibility is achieved by 
reason of the cantilever connection of support member 128 at one side 130 
of frame 120. As a result, member 128 is able to flex relative to frame 
120, in and out of the plane defined by frame 120. 
Plate 110 is preferably integrally connected to a drive tongue 132 that 
extends along a curvilinear arc that matches the curve of means 160 and 
path 112. The outside edge of tongue 132 has a raised ridge 134 provided 
with means, such as slots 136, to cooperate with a sensor. The inside edge 
138 of tongue 132 comprises a raised ridge that is provided with a rack 
139. Rack 139 is driven by gear 142 of drive means 140, FIG. 2. 
Support means 160 for plate 110 and its tongue 132 comprises two opposed 
track members 162 and 164, FIGS. 7-9, between which plate 110 and tongue 
132 reciprocate. Members 162 and 164 preferably have the same arcuate 
curvature as tongue 132. Most preferably, member 162 is generally flat, 
FIG. 8, and is apertured at 82 for element discharge, and at 166 to 
receive drive gear 142, FIG. 7. Opposed track member 164 is rail-shaped at 
170, 172 to accommodate ridge 134, and rack 139 of tongue 132, FIG. 8. 
Member 164 is secured to lower member 162 at bottom portions 174 and 176. 
Member 164 is apertured to accommodate gear 142, and further at 74, FIGS. 
1 and 2, to provide for wash station 70. 
In another aspect of the invention, there is provided stop means 180 that 
allow a washed test element to be returned and retained at station 30, 
FIG. 7. For this purpose, stop means 180 is disposed adjacent the 
injection path 29,32, at the intersection location of that path with path 
112. Most preferably, stop means 180 comprise a flexure plate 182, FIGS. 2 
and 7, that is cantilevered by arm 184 from the rest of upper member 164. 
The outer edge 186 of plate 182 provides a shoulder against which a test 
element abuts, when it moves along path 29,32. In addition, flexure plate 
182 includes on its undersurface 189, FIG. 9, one and preferably two 
camming feet 190, 192, FIGS. 7 and 9, which allow plate 182 to ride up 
over a test element, FIG. 12, being moved by plate 110 on path 112 to path 
29, 32. 
Optionally, a viewing port 196 can be provided, FIG. 4, adjacent station 
30, to allow a wetness detector to scan a slide element as liquid is 
dispensed thereon. 
The apparatus of the invention further includes bias means 200 at station 
30, FIG. 3, and locating surfaces 210, 212, FIG. 11, at wash station 70. 
In station 30, the bias means 200 acts to bias a test element up against 
the tip locator 34 at station 30. Means 200 comprise a platen 202 that is 
beveled at 203, FIG. 12, and a spring 204 exerting an upward force F, 
arrow 206, FIG. 3. Entrance slot 208 allows a test element to be inserted 
into station 30 and onto either platen 202 or shuttle plate 110, as shown 
in FIG. 3. 
At station 70, FIG. 11, stop surface 210 is provided to stop the movement 
of a test element E' even as plate 110 continues to advance slightly 
further, arrow 112. Undersurface 212 at station 70 is the ceiling against 
which element E' is pushed by flexible support member 128. An opposite 
depression 220 is formed in lower track member 162 to receive frame 120 of 
plate 110, that is cammed downwardly due to camming surface 122 of frame 
120 pressing against element E'. In addition, a camming surface, not 
shown, extending diagonally from surface 210 ensures proper location of 
element E' in the direction out of the plane of FIG. 11. 
The wash method will be readily apparent from the previous description. In 
brief, plate 110 is moved by drive means 140 into position so as to 
intercept an ejected test element E', FIG. 10, thus preventing element E' 
from falling out discharge aperture 82. 
Next, plate 110 moves along path 112 due to the action of drive means 140, 
until element E' is at wash station 70, FIG. 11. A suitable pipette, not 
shown, is inserted into aperture 74, and boss 72 serves to hold the 
pipette the proper distance within station 70. At the same time, plate 110 
pulls element E' up against stop shoulder 210 and the flexure of support 
member 128 is such as to push element E' up against undersurface 212 of 
station 70. The proper spacing of the pipette and element E' is now 
defined, which can be, e.g., about 1.3 mm. About 10 .mu.L of wash liquid 
is preferably ejected onto the element E', preferably at a rate of about 
0.5 .mu.L per second, for 20 seconds. However, other rates can also be 
used, depending on the hydrophilicity of the element being washed. 
After washing, plate 110 is now returned towards station 30 and away from 
station 70, by reversing the direction of rotation of gear 142. 
In accord with another aspect of the invention, the wash method differs 
from that previously used in that the washed element is returned to the 
station from which elements that have just received sample are loaded into 
the incubator. This allows the analyzer to be simplified in that the same 
pusher blade used to initially load the element into the analyzer, is 
reused to re-load the element. More specifically, as plate 110 and element 
E' move from the vicinity of discharge path 82 into station 30 where path 
112 intersects path 29, 32, FIG. 12, camming surfaces 190 and 192 allow 
stop means flexure plate 182 to ride up over element E'. At the same time, 
platen 202 is cammed downwardly, due to the camming action caused by 
surface 203. 
Once element E' is returned to station 30, FIGS. 13A-13C, stop means 180 is 
effective to restrain element E' from leaving station 30 with plate 110. 
That is, shoulder 186 slips behind element E', FIG. 13A, and cam surface 
193 allows plate 110 to slip under element E', so that as plate 110 starts 
moving out of station 30 along the path of arrow 112, FIG. 13B, shoulder 
186 holds element E' from following plate 110. Plate 110 is carefully 
advanced into the position shown in FIG. 13A, by drive means 140, to 
ensure element E' is advanced past shoulder 186. The steps of travel of 
means 140 can be adjusted to ensure that this advance occurs. Meanwhile, 
platen 202 is pushed up by its spring 204, to further hold element E'. 
That is, plate 110 pushes element E' up due to the upward force of the 
platen. When plate 110 is completely withdrawn, FIG. 13C, element E' is 
positioned for reloading into incubator 40, using pusher blade 22. (The 
positioning of the parts in FIG. 13C is also their position when an 
element is first loaded into station 30 for dispensing patient sample 
and/or reference liquid via apertures 36, 37 and 38, of which 38 is not 
shown.) 
A bumper spring 300 is preferably included, FIG. 13A, against which plate 
110 pushes when element E' is being returned to station 30. This spring 
prevents over-travel of plate 110, but primarily it assists in holding 
test elements against stop shoulder 186, FIG. 13B. 
Following reloading of the washed slide into the incubator, which occurs 
after the events illustrated in FIG. 13C, further incubation and a reading 
of the element occur. When a read element is ready for disposal, ejection 
occurs using pusher blade 48, arrow 310, FIG. 2, except this time, plate 
110 is not in position at station 80 to catch the element. Instead, it 
falls through aperture 82, FIG. 1, into a suitable disposal container. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.