System and method for determining an abused sensor during analyte measurement
View Patent ↗A method of measuring an analyte in a biological fluid comprises applying an excitation signal having a DC component and an AC component. The AC and DC responses are measured; a corrected DC response is determined using the AC response; and a concentration of the analyte is determined based upon the corrected DC response. Other methods and devices are disclosed.
1. A method for detecting an abused sensor for determining a concentration of a medically significant component of a biological fluid placed upon the sensor, comprising the steps of:
a) placing the biological fluid sample upon the sensor;
b) applying a first signal to the biological fluid;
c) measuring a current response to the first signal;
d) repeating step (c) at least once;
e) calculating a normalized Cottrell Failsafe Ratio using the current response data;
f) applying a second signal having an AC component to the biological fluid;
g) measuring an AC response to the second signal; and
h) combining the normalized Cottrell Failsafe Ratio and the AC response to produce an indication of whether the sensor has been abused.
2. The method of claim 1 , wherein the second signal is an AC signal.
3. The method of claim 1 , wherein the first signal and the second signal are applied at least partially simultaneously.
4. The method of claim 1 , wherein the AC response comprises admittance magnitude and phase angle information.
5. The method of claim 1 , wherein the AC response comprises admittance phase angle information.
6. The method of claim 1 , wherein the second signal comprises a number of frequencies, wherein the number is greater than one.
7. The method of claim 6 , wherein the number is not less than two and not greater than five.
8. The method of claim 6 , wherein the number is not less than two and not greater than ten.
9. The method of claim 6 , wherein the number is greater than ten.
10. The method of claim 1 , wherein the AC component of the signal has a frequency not less than 1 Hz and not greater than 20 kHz.
11. A method of determining a failure condition indicating an abused sensor in a blood glucose concentration test, comprising the steps of:
a) applying a first test signal having an AC component to a test sample;
b) measuring a first phase angle response to the first test signal;
c) applying a second test signal having an AC component to the test sample;
d) measuring a second phase angle response to the second test signal; and
e) determining a failure condition value based upon the first phase angle response the second phase angle response and a predetermined Cottrell Failsafe Ratio.
12. The method of claim 11 , further comprising the steps of:
f) applying a test signal to the test sample;
g) measuring at least two current responses; and
h) determining the predetermined Cottrell Failsafe Raito based upon the sum of the current responses and a final current response.