Flow sensing for determination of assay results

• US 20050037511A1
• Filed: 12/19/2003
• Published: 02/17/2005
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Original Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Inventors: Sharrock, Stephen P.
• Granted Patent: US 7,317,532 B2
• Time in Patent Office: Days
• US Class Current: 436/164
• CPC Class Codes: G01N 2021/8488 the band presenting reference patches
• CPC Class Codes: G01N 2021/8494 Measuring or storing parameters of the band
• CPC Class Codes: G01N 21/251 Colorimeters; Construction thereof
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/78 producing a change of colour
• 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 2201/06106 Plural sources used for calibration
• CPC Class Codes: G01N 2201/062 LED's

Abstract

An assay result reading device for reading the result of an assay performed using a liquid transport carrier may include at least one light source capable of emitting light incident upon at least one of two or more spatially separated zones of the carrier, a photodetector so positioned as to be capable of detecting light emanating from each of the two said zones and generating signals representing the presence or absence of a fluid sample in the respective zone, and a computation circuit. The computation circuit may be responsive to the signals to calculate a flow rate for a fluid flowing along the carrier, compare the calculated flow rate to upper and lower limits, and reject the assay result if the calculated flow rate is outside the upper and lower limits.

Claims

1. An assay result reading device for reading the result of an assay performed using a liquid transport carrier, the device comprising:

at least one light source capable of emitting light incident upon at least one of two or more spatially separated zones of the carrier;

a photodetector so positioned as to be capable of detecting light emanating from each of the two said zones and generating signals representing the presence or absence of a fluid sample in the respective zone; and

a computation circuit responsive to the signals to;

calculate a flow rate for a fluid flowing along the carrier;

compare the calculated flow rate to upper and lower limits; and

reject the assay result if the calculated flow rate is outside the upper and lower limits.

2. A device according to claim 1, wherein the carrier comprises a porous carrier.

3. A device according to claim 1, wherein the at least one light source comprises a light emitting diode.

4. A device according to claim 1, wherein the at least one photodetector comprises a photodiode.

5. A device according to claim 1, wherein the at least one light source comprises at least two light sources, and the at least one photodetector comprises at least two photodetectors.

6. A device according to claim 5, wherein:

the first light source is capable of emitting light incident on the first zone, and the first photodetector detects light emanating from the first zone; and

the second light source is capable of emitting light incident on the second zone, and the second photodetector detects light emanating from the second zone.

7. A device according to claim 1, wherein the at least one light source comprises at least two light emitting diodes, and the at least one photodetector comprises at least two photodiodes.

8. A device according to claim 1, wherein the signal representing the presence or absence of a fluid sample in a zone is calculated based upon the optical reflectance, the transmissivity, or both, of the carrier.

9. A device according to claim 1, further comprising a housing enclosing the at least one light source and the at least one photodetector.

10. A device according to claim 9, wherein the housing is no larger than about 12 cm long, about 2.5 cm wide, and about 2.2 cm tall.

11. A device according to claim 1, wherein the at least one light source and the at least one photodetector are disposed within an area no larger than about 1 square centimeter.

12. A device according to claim 1, wherein the at least one light source and the at least one photodetector are disposed within an area no larger than about 0.7 square centimeter.

13. A device according to claim 1, wherein signals generated by the at least one photodetector represent an amount of analyte present in a zone.

14. A method of performing an assay for an analyte of interest in a liquid sample, the method comprising:

positioning a liquid transport carrier in relation to an assay result reader, the carrier having at least two spatially-separated zones, the reader comprising a housing enclosing at least one light source and at least one photodetector, and the carrier positioned so that the at least one light source emits light incident on at least one of the zones, and so that light emanating from at least one of the zones is incident on the photodetector;

applying or introducing the liquid sample to the liquid transport carrier;

calculating a flow rate of the liquid sample along the carrier in response to signals generated by the at least one photodetector representing the presence or absence of the liquid sample in a respective zone; and

determining whether the calculated flow rate is within predetermined acceptable limits.

15. A method according to claim 14, further comprising rejecting an assay result if the calculated flow rate is not within the predetermined acceptable limits.

16. A method according to claim 14, wherein the test strip is positioned at least party inside the assay result reader.

17. A method according to claim 14, wherein the assay result reader further comprises a second photodetector, the at least one light source comprises first and second, and third light sources, the test strip has three spatially separated zones, and wherein:

each light source is aligned with and laterally offset from a corresponding test strip zone;

the first photodetector is so positioned as to receive light emanating from the first zone and the second zone; and

the second photodetector is so positioned as to receive light emanating from the second zone and the third zone.