Spectrophotometric apparatus for reducing fluid carryover

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Reexamination Certificate

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Details

C422S063000, C422S066000, C422S082050

Reexamination Certificate

active

06183694

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for performing optical inspection tests on reagent strips having samples of body fluid thereon which reduces the likelihood of carryover of body fluid from one reagent strip to another.
Conventional spectrophotometers may be used to perform a number of different urinalysis tests utilizing a reagent strip on which a number of different reagent pads are disposed. Each reagent pad may be provided with a different reagent which causes a color change in response to the presence of a certain type of constituent in urine, such as leukocytes (white blood cells) or erythrocytes (red blood cells). The color change is detected by the spectrophotometer by illuminating the pad and taking a number of reflectance readings from the pad, each having a magnitude relating to a different wavelength of light. The color may then be determined based upon the relative magnitudes of red, green and blue reflectance signals, for example.
In a conventional spectrophotometer, the process of inspecting a reagent strip is performed by dipping the reagent strip in a urine sample, blotting excess urine from the reagent strip, placing the reagent strip at a designated location in the spectrophotometer, and pressing a start button which causes the spectrophotometer to begin automatic processing and inspection of the reagent strip.
FIG. 1A
illustrates a prior art table
1
for supporting a reagent strip. The support table
1
has a receiving area
2
on which a reagent strip (not shown in
FIG. 1A
) is initially placed and an inspection area
3
to which the reagent strip is moved for optical inspection. Reagent strips are moved, one at a time, from the receiving area
2
to the inspection area
3
by a blotter arm
4
, shown in
FIG. 1B
, which makes contact with each reagent strip.
The support table
1
has a plurality of upwardly extending ribs
5
designed to support the reagent strips so that they are held above the upper surfaces of the support table
1
. The support table
1
has a first raised platform
6
, having the approximate shape of a reagent strip, on which a reagent strip is positioned when being read by a first readhead (not shown), and a second raised platform
7
on which a reagent strip is positioned when being read by a second readhead (not shown).
The blotter arm
4
shown in
FIG. 1B
was designed to extract or remove urine from a reagent strip when it makes contact with the reagent strip so that significant amounts of urine from one reagent strip will not contaminate, or be left on, the portions of the support tray
1
with which subsequent reagent strips make contact. To that end, the surface of the blotter arm
4
which makes contact with reagent strips is provided with small capillaries (not shown) which draw urine away from the reagent strip due to capillary action.
Other prior art spectrophotometers have been designed to extract urine from reagent strips to prevent fluid carry over from one reagent strip to another. For example, in one prior art spectrophotometer, reagent strips were moved through the device on a paper web which is designed to absorb excess urine from each of the reagent strips.
Conventional reagent strips used in the spectrophotometer having the support table
1
shown in
FIG. 1A
have multiple reagent pads which are provided with reagents to test for various conditions. One such reagent pad is designed to detect “occult blood” in urine. Such a reagent pad is impregnated with a conventional reagent which causes a blue color to be formed in the presence of very small concentrations of blood in urine.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus adapted to inspect reagent strips after having body fluid samples, such as urine samples, disposed thereon and to reduce the likelihood of contamination from one body fluid sample with another body fluid sample. The apparatus is provided with a reagent strip support, such as a support table, adapted to support a reagent strip having a plurality of reagent pads disposed in a longitudinal direction along the reagent strip, including, for example, an occult blood reagent pad which has a reagent that enables detection of occult blood. The apparatus also includes a reagent strip mover adapted to cause the reagent strip to be moved in a direction generally transverse to the longitudinal direction from an initial reagent strip location to an inspection location, a light emitter adapted to illuminate the reagent strip when the reagent strip is supported by the reagent strip support at an inspection location, and a detector adapted to receive light from the reagent strip when the reagent strip is being illuminated by the light emitter.
In one aspect of the invention, the reagent strip support and the reagent strip mover are designed not to remove excess body fluid from the reagent strips.
In another aspect of the invention, the occult blood reagent pad is located on the reagent strip at a reagent pad area, and the reagent strip support is adapted to support the reagent strip so that there is no significant physical contact between the reagent strip support and the reagent pad area when the reagent strip is located at the inspection location and when the reagent strip is moved between the initial reagent strip location and the inspection location.
In another aspect of the invention, the reagent strip support is adapted to support the reagent strip so that there is no physical contact between the reagent strip support and a no-contact area when the reagent strip is located at the inspection location and when the reagent strip is moved between the initial reagent strip location and the inspection location, the no-contact area being defined as the combined area of the reagent pad area, a first area extending at least about one-eighth of an inch from the reagent pad area in a first direction parallel to the longitudinal axis of the reagent strip, and a second area extending at least about one-eighth of an inch from the reagent pad area in a second direction parallel to the longitudinal axis of the strip.
The reagent strip mover may be provided with a first portion that makes physical contact with the reagent strip at a first point along the reagent strip and a second portion that makes physical contact with the reagent strip at a second point along the reagent strip, and the reagent pad area of the reagent strip may be disposed between the first and second points along the reagent strip so that the reagent strip mover does not make physical contact with the reagent pad area of the reagent strip.
The reagent strip support may be provided with a first upwardly extending elongated rib which makes physical contact with the reagent strip at a first contact point between the reagent pad area and a first end of the reagent strip and a second upwardly extending elongated rib which makes physical contact with the reagent strip at a second contact point between the reagent pad area and a second end of the reagent strip.
The apparatus may include a reagent strip pusher arm which is adapted to push the reagent strip along the reagent strip support while the reagent strip is being supported by the reagent strip support, the reagent strip pusher arm being shaped so that no portion of the reagent strip pusher arm makes contact with the reagent pad area of the reagent strip.
The features and advantages of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of the preferred embodiment, which is made with reference to the drawings, a brief description of which is provided below.


REFERENCES:
patent: 4689202 (1987-08-01), Khoja et al.
patent: 4820491 (1989-04-01), Khoja et al.
patent: 5055261 (1991-10-01), Khoja et al.
patent: 5143694 (1992-09-01), Schafer et al.
patent: 5654803 (1997-08-01), Howard, III et al.
patent: 5686047 (1997-11-01), Augstein
patent: 0997715 (2000-05-01), None

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