Systems and methods for hematocrit impedance measurement using difference identity phase

1. A system for measuring a property of a sample, comprising:

a test strip for collecting the sample;

a diagnostic measuring device configured to receive the test strip and measure a concentration of an analyte in the sample received on the test strip; and

the diagnostic measuring device further comprising a processor programmed to execute an analyte correction for correcting a measurement of the sample due to one or more interferents, comprising:

calculating an interferent impedance measurement including a magnitude measurement and a phase measurement using a difference identity to generate a sinusoidal signal with an amplitude proportional to a phase difference; and

adjusting the measurement of the analyte in the sample using the calculated interferent impedance measurement.

2. The system of claim 1 , wherein the analyte is glucose and one of the one or more interferents is hematocrit.

3. The system of claim 1 , wherein the test strip comprises:

at least one electrically insulating layer with a proximal region and a distal region;

a conductive pattern including at least one electrode at the proximal region, electrical strip contacts disposed at a conductive region at the distal region, and conductive traces electrically connecting the at least one electrode to at least some of the electrical strip contacts;

a reagent layer contacting at least a portion of the at least one electrode; and

a chamber for receiving the sample.

4. The system of claim 1 , wherein the phase measurement includes a phase angle that is measured using the difference identity to provide a signal large enough for processing by the processor, the signal representing the phase angle.

5. The system of claim 4 , wherein the difference identity is a difference between a first sine wave and a second sine wave, with the first and second sine waves having a substantially equal amplitude.

6. The system of claim 5 , wherein a gain control circuit is configured to produce the substantially equal amplitude for the first and second sine waves.

7. The system of claim 6 , wherein a difference amplifier is configured to generate the signal as the difference between the first sine wave and the second sine wave.

8. The system of claim 1 , further comprising a peak detector circuit for generating a DC signal proportional to the phase measurement which can be read by the processor.

9. The system of claim 1 , wherein the difference identity can measure an impedance phase angle at high frequencies.

10. The system of claim 9 , wherein the high frequencies are up to 500 kHz.

11. A system for measuring a property of a sample, comprising:

a diagnostic measuring device configured to measure a concentration of an analyte in the sample; and

the diagnostic measuring device further comprising a processor programmed to execute an analyte correction for correcting a measurement of the sample due to one or more interferents, comprising:

calculating an interferent impedance measurement including a magnitude measurement and a phase measurement using a difference identity to generate a sinusoidal signal with an amplitude proportional to a phase difference; and

adjusting the measurement of the analyte in the sample using the calculated interferent impedance measurement.

12. The system of claim 11 , wherein the analyte is glucose and one of the one or more interferents is hematocrit.

13. The system of claim 11 , further comprising a test strip for collecting the sample, the test strip comprising two or more contacting pads, each contacting pad having a predefined electrical conductivity, and wherein the electrical conductivity of the two or more contacting pads form a code that represents information particular to the test strip.

14. A method of measuring a property of a sample comprising:

measuring an analyte in the sample; and

performing an analyte correction of the measured analyte due to one or more interferents, comprising:

calculating an interferent impedance measurement including a magnitude measurement and a phase measurement using a difference identity to generate a sinusoidal signal with an amplitude proportional to a phase difference; and

adjusting the measurement of the analyte in the sample using the calculated interferent impedance measurement.

15. The method of claim 14 , wherein the analyte is glucose and one of the one or more interferents is hematocrit.

16. The method of claim 14 , further comprising applying a temperature correction to the interferent impedance measurement.

17. The method of claim 14 , wherein the difference identity measures an impedance phase angle at high frequencies.

18. The method of claim 17 , wherein the high frequencies are up to 500 kHz.