Optically readable strip for analyte detection having on-strip orientation index

• US 20020054827A1
• Filed: 11/26/2001
• Published: 05/09/2002
• Est. Priority Date: 09/08/1994
• Status: Active Grant

• Current Assignee: George Michael Daffern, Harshad Ishwarbhai Patel
• Original Assignee: George Michael Daffern, Harshad Ishwarbhai Patel
• Inventors: Patel, Harshad Ishwarbhai, Daffern, George Michael
• Granted Patent: US 6,491,870 B2
• Time in Patent Office: Days
• US Class Current: 422/56
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G01N 33/521 Single-layer analytical elements
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing

Abstract

A test strip is provided for determining the presence or quantity of an analyte in a liquid by inserting the strip into an optical reading apparatus. The test strip is provided with an orientation index zone having a reflectance that contrasts with the reflectance of areas contiguous thereto and such orientation index zone is employed to affirm that the test strip has not been inserted upside down with respect to the apparatus.

Claims

1. A test strip for determining the presence or quantity of an analyte in a liquid by inserting said test strip into an optical reading apparatus;

said test strip comprising;

a portion, for having liquid applied thereto, said portion having an area on a major surface of the strip defining a reaction zone, such reaction zone varying in reflectance as a function of the quantity of analyte in the applied liquid;

said test strip further comprising an area on said major surface defining an orientation index zone, said orientation index zone being positioned to lead said reaction zone as said strip is inserted into said apparatus;

said orientation index zone having a contrasting reflectance relative to that of the areas of the major surface contiguous to the orientation index zone;

whereby said apparatus may be provided with optical means for sequentially determining reflectance values of the major surface as the strip is inserted into the apparatus and with microprocessing means for detecting the presence of the orientation index zone or for reporting its absence.

2. The strip of claim 1 wherein said orientation index zone is positioned on said major surface to lead said contiguous area as the strip is to be inserted into said apparatus.

3. The strip of claim 2 wherein the reflectance of said contiguous area is at least 1.5 times the reflectance of said orientation index zone.

4. The strip of claim 3 wherein the reflectance of said contiguous area is at least two times the reflectance of said orientation index zone.

5. The strip of claim 2 wherein the reflectance of said contiguous area is no more than about 0.67 times the reflectance of said orientation index zone.

6. The strip of claim 5 wherein the reflectance of said contiguous areas is no more than about 0.5 times the reflectance of said orientation index zone.

7. The strip of claim 1 wherein the orientation index zone reflects no more than 0.9 times the light reflected when no strip is present in the apparatus.

8. The strip of claim 7 wherein the orientation index zone reflects no more than 0.5 times the light reflected when no strip is present in the apparatus.

9. The strip of claim 1 wherein the orientation index zone reflects at least 1.1 times the light reflected when no strip is present in the apparatus.

10. The strip of claim 9 wherein the orientation index zone reflects at least two times the light reflected when no strip is present in the apparatus.

11. An apparatus for determining the presence or quantity of an analyte in a liquid applied to a test strip and inserted into said apparatus, wherein said test strip comprises:

a portion for having said liquid applied thereto, said portion having an area on a major surface of said strip defining a reaction zone, said reaction zone varying in reflectance as a function of the quantity of analyte in the applied liquid, and an orientation index zone positioned to lead said reaction zone as said strip is inserted into said apparatus, said orientation index zone having a contrasting reflectance relative to that of the areas of the major surface contiguous to the orientation index zone;

said apparatus comprising;

a longitudinally extending strip passageway having an open end for receiving said strip and an opposed end;

optics comprising a light source for directing light into said passageway at a position between said open end and said opposed end and a light detector for detecting light reflected from said passageway;

conversion means for converting said detected reflected light into a signal;

microprocessing means for receiving said signal to detect the presence or absence of the orientation index zone in the passageway.

12. The apparatus of claim 11 wherein said orientation index zone has a lower reflectance than said contiguous areas and said orientation index zone is positioned to lead said contiguous areas as the strip is inserted into the passageway and the microprocessor is programmed to detect the passage of the orientation index zone by a signal indicating an increase in reflectance when the orientation index zone passes beyond said passageway position.

13. The apparatus of claim 11 wherein said contiguous areas have a lower reflectance than said orientation index zone and said contiguous areas are positioned to lead said orientation index zone as the strip is inserted into said passageway and the microprocessor is programmed to detect the presence of the orientation index zone by a signal indicating an increase in reflectance when the orientation index zone enters said position.

14. The apparatus of claim 11 wherein said orientation index zone has a higher reflectance than said contiguous areas and said orientation index zone is positioned to lead said contiguous areas as the strip is inserted into the passageway and the microprocessor is programmed to detect the passage of the orientation index zone by a signal indicating a decrease in reflectance when the orientation index zone passes beyond said passageway position.

15. The apparatus of claim 11 wherein said contiguous areas have a higher reflectance than said orientation index zone and said contiguous areas are positioned to lead said orientation index zone as the strip is inserted into said passageway and the microprocessor is programmed to detect the presence of the orientation index zone by a signal indicating a decrease in reflectance when the the orientation index zone enters said passageway position.

16. In a system for determining the presence or quantity of an analyte in a liquid applied to a test strip and inserted into an apparatus, a method for determining that the strip has been properly oriented in said apparatus, said method comprising:

inserting said strip into said apparatus, said strip comprising a portion having liquid applied thereto, said portion having an area on a major surface of said strip defining a reaction zone, said reaction zone varying in reflectance as a function of the quantity of analyte in the applied liquid and said strip further comprising an orientation index zone positioned to lead said strip as it is inserted into said apparatus, said orientation index zone having a contrasting reflectance relative to that of the area of the major surface contiguous to the orientation index zone;

determining the reflectance of the major surface of the strip by directing light at a fixed position in the pathway of the strip as it is inserted and detecting the reflected light;

detecting the presence or absence of reflected light corresponding to the passage of said orientation index zone past said fixed position as the strip is inserted into said passageway.