Method of strip insertion detection

• US 20020117639A1
• Filed: 02/28/2001
• Published: 08/29/2002
• Est. Priority Date: 02/28/2001
• Status: Active Grant

• Current Assignee: Trividia Health, Inc. (Sinocare, Inc.)
• Original Assignee: Home Diagnostics Incorporated
• Inventors: Paolini, Gregory P., Modzelewski, Brent E., Roth, G. Thomas
• Granted Patent: US 6,525,330 B2
• Time in Patent Office: Days
• US Class Current: 250/559.1
• 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

Abstract

A method an apparatus for strip insertion detection in an analytical meter system. The invention allows for individual meter calibration, adaptive thresholding and ambient light correction. Increased performance is economically realized, while providing enhanced meter accuracy in varying light conditions.

Claims

1. A method for calibrating a strip sensor in an analytical meter device, the strip sensor having a photodetector and a light source, the method comprising the steps of:

a. measuring the voltage output difference of said photodetector between when said light source is on and off using a standard having relatively high reflectance;

b. measuring the voltage output difference of said photodetector between when said light source is on and off using a standard having relatively low reflectance;

c. calculating a voltage threshold VTH produced by the strip sensor to be used by said analytical meter device to indicate when a test element has been inserted therein according to the formula;

V_TH=K_TH[(V_High−

V<sub>High—

Off</sub>)−

(V_Low−

V<sub>Low—

Off</sub>)]+(V_Low−

V<sub>Low—

Off</sub>)

where K_TH is a constant;

d. evaluating the value of V_TH calculated in step (c) for acceptability according to predetermined criteria;

e. permanently storing V_TH in said analytical meter device if evaluated as acceptable in step (d).

2. The method of claim 1, wherein said standard of relatively high reflectance is a white calibrator.

3. The method of claim 1, wherein said standard of relatively low reflectance is a light grey calibrator.

4. The method of claim 1, wherein said value of KTH is in the range of about 0.2 to 0.4.

5. A method of detecting a strip inserted into an analytical meter device calibrated according to the method of claim 1, wherein said method of detecting a strip comprises the step of monitoring said strip sensor for proximity of strip through adaptive thresholding.

6. The method of claim 5, wherein said step of monitoring further comprises the steps of:

a. measuring the output of the photodetector with the light source turned off (V<sub>SS—

OFF</sub>);

b. comparing V<sub>SS—

OFF</sub> to a threshold voltage, and if V<sub>SS—

OFF</sub> is greater than said threshold voltage, indicating a fault condition;

c. measuring the output of the photodetector with the light source turned on (V_SS);

d. determining a strip to be inserted if V_SS−

V<sub>SS—

OFF</sub>>

V_TH.

7. A method of performing an analytical test on a strip inserted into an analytical meter device calibrated according to the method of claim 1, wherein said method of running an analytical test comprises the step of monitoring ambient light conditions with said strip sensor.

8. A method of performing an analytical test on a strip inserted into an analytical meter device calibrated according to the method of claim 5, wherein said method of running an analytical test comprises the step of monitoring ambient light conditions by periodically repeating said step of monitoring said strip sensor for proximity of strip.

9. A method of performing an analytical test on a strip inserted into an analytical meter device calibrated according to the method of claim 6, wherein said method of running an analytical test comprises the step of monitoring ambient light conditions by periodically repeating said step of monitoring said strip sensor for proximity of strip.

10. The method of claim 9, wherein said fault condition is determined by the analytic test device to indicate that there is no strip in place.

11. The method of claim 9, wherein said fault condition is determined by the analytic test device to indicate that there is a standard strip in place.

12. The method of claim 9, wherein said fault condition is determined by the analytic test device to indicate that there is a chemistry strip in place under adverse ambient lighting conditions.

13. The method of claim 12, wherein said fault condition is determined by the analytic test device after an analytical test has been started, and further comprising the step of aborting the analytical test.