System and method for quality assurance of a biosensor test strip

• US 9,410,915 B2
• Filed: 07/14/2014
• Issued: 08/09/2016
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diabetes Care Inc. (Roche Holding AG), Roche Operations Limited (Roche Holding AG)
• Inventors: Celentano, Michael J., Groll, Henning, Pauley, James L., Moore, Steven K.
• Primary Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US14/330,610
• Publication Number:
  US 20140318991A1
• Time in Patent Office: 757 Days
• US Class Current: 1/1
• CPC Class Codes: G01N 27/327 Biochemical electrodes , e.g. electrical or mechanical details for in vitro measurements
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence

Abstract

The present invention provides a test strip for measuring a signal of interest in a biological fluid when the test strip is mated to an appropriate test meter, wherein the test strip and the test meter include structures to verify the integrity of the test strip traces, to measure the parasitic resistance of the test strip traces, and to provide compensation in the voltage applied to the test strip to account for parasitic resistive losses in the test strip traces.

Claims

1. A circuit for a test meter adapted to be operatively coupled to a biosensor strip, the circuit comprising:

a difference amplifier having first and second difference amplifier inputs and a difference amplifier output, wherein the first difference amplifier input is operatively coupled to a first connector contact of the test meter and the second difference amplifier input is operatively coupled to a second connector contact of the test meter;

a commanded voltage signal source;

a voltage follower amplifier having first and second voltage follower inputs and a voltage follower output, wherein the first voltage follower input is coupled to the commanded voltage signal source, the second voltage follower input is coupled to the difference amplifier output, and the voltage follower output is configured to be operatively coupled to a third connector contact of the test meter; and

a fourth connector contact of the meter operatively coupled to a microprocessor of the circuit configured to receive and process signals from a biosensor strip;

wherein the first, second, third, and fourth connector contacts are configured to be operatively coupled to respective first, second, third, and fourth contact pads of a corresponding biosensor strip inserted into the test meter, and wherein the difference amplifier output represents a voltage difference between the first and second connector contacts of the test meter, and wherein the voltage follower amplifier is operatively configured to generate a voltage from the voltage follower output such that the voltage at the second voltage follower input is generally equal to the voltage at the first voltage follower input.

2. The circuit of claim 1, wherein the microprocessor comprises the commanded voltage signal source and is operatively coupled to the first voltage follower input, wherein the microprocessor is configured to generate a signal indicative of a desired voltage potential to be applied from the voltage follower output.

3. The circuit of claim 2, wherein the signal generated by the microprocessor comprises a digital signal, the circuit further comprising a converter having a digital input operatively coupled to the microprocessor and an analog output operatively coupled to the first voltage follower input, the converter configured to receive the digital signal at the digital input, convert the digital signal to an analog signal, and output the analog signal.

4. The circuit of claim 2, wherein the desired voltage potential comprises a voltage potential to be applied across a measurement cell of the biosensor strip, wherein the measurement cell is operatively coupled to first, second, third and fourth contact pads of the biosensor strip via separate respective traces, the first, second, third, and fourth contact pads further being operatively coupled to the first, second, third, and fourth connector contacts of the test meter, and wherein the separate respective traces are subject to parasitic resistance and wherein the operative couplings of the first, second, third and fourth contact pads of the biosensor strip to the respective first, second, third and fourth connector contacts of the test meter are subject to contact resistance.

5. The circuit of claim 1, wherein the first and second difference amplifier inputs comprise high impedance inputs wherein substantially no current flows therein.

6. A method for generating a voltage substantially compensated for voltage potential drops caused by one or more of parasitic resistance in conductive traces of a biosensor test strip and contact resistance in the coupling of biosensor test strip contact pads to connector contacts of a test meter, the method comprising the steps of:

operatively coupling a biosensor test strip to a test meter, the biosensor test strip comprising a first measurement electrode and a second measurement electrode, a first conductive trace operatively coupling a first contact pad and the first measurement electrode, a second conductive trace operatively coupling a second contact pad and the first measurement electrode, a third conductive trace operatively coupling a third contact pad and the second measurement electrode, and a fourth conductive trace operatively coupling a fourth contact pad and the second measurement electrode;

the test meter having a circuit comprising a difference amplifier having first and second difference amplifier inputs and a difference amplifier output, wherein the first difference amplifier input is operatively coupled to a first connector contact of the test meter and the second difference amplifier input is operatively coupled to a second connector contact of the test meter, the first and second connector contacts of the test meter being operatively coupled respectively to the second and fourth contact pads of the biosensor test strip when the biosensor test strip is operatively coupled to the test meter, the first and second difference amplifier inputs comprising high impedance inputs so that substantially no current flows from the second contact pad to the first connector contact or from the fourth contact pad to the second connector contact, the circuit further comprising a commanded voltage signal source and a voltage follower amplifier having first and second voltage follower inputs and a voltage follower output, wherein the first voltage follower input is coupled to the commanded voltage signal source, the second voltage follower input is coupled to the difference amplifier output, and the voltage follower output is operatively coupled to a third connector contact of the test meter being operatively coupled to the first contact pad of the biosensor test strip when the biosensor test strip is operatively coupled to the test meter;

outputting from the commanded voltage signal source a signal indicative of a desired voltage potential to be applied across the first measurement electrode and the second measurement electrode;

applying from the voltage follower output a voltage potential to the third connector contact of the test meter and producing a current between the first measurement electrode and the second measurement electrode;

by the voltage follower amplifier, adjusting an output from the voltage follower output until a voltage potential at the second voltage follower input is substantially equal to the desired voltage potential;

wherein the voltage potential at the second voltage follower input represents the voltage potential across the first and second measurement electrodes, and wherein when the adjusted output from the voltage follower output is such that the voltage potential at the second voltage follower input is substantially equal to the desired voltage potential then the voltage potential across the first and second measurement electrodes is substantially equal to the desired voltage potential and the adjusted output is substantially compensated for voltage drop caused by one or more of parasitic resistance in the first and third conductive traces and contact resistance in the coupling of the biosensor test strip contact pads to the connector contacts of a test meter.

7. The method of claim 6, further comprising the step of measuring the current produced between the first and second measurement electrodes, said measuring comprising transmitting the current through the third conductive trace to a microprocessor of the test meter and determining a concentration of an analyte the amount of which is proportional to the current produced.

8. The method of claim 7, wherein the measuring step further comprises providing the current to a current-to-voltage amplifier generating an analog output voltage, providing the analog output voltage to an analog-to-digital converter converting the analog output voltage to a digital signal, and providing the digital signal to the microprocessor.

9. The method of claim 7, further comprising the step of displaying the concentration to a user by means of an LCD output device operatively coupled to the microprocessor.