Advanced analyte sensor calibration and error detection
Systems and methods for processing sensor data and self-calibration are provided. In some embodiments, systems and methods are provided which are capable of calibrating a continuous analyte sensor based on an initial sensitivity, and then continuously performing self-calibration without using, or with reduced use of, reference measurements. In certain embodiments, a sensitivity of the analyte sensor is determined by applying an estimative algorithm that is a function of certain parameters. Also described herein are systems and methods for determining a property of an analyte sensor using a stimulus signal. The sensor property can be used to compensate sensor data for sensitivity drift, or determine another property associated with the sensor, such as temperature, sensor membrane damage, moisture ingress in sensor electronics, and scaling factors.
1. A method for calibrating an analyte sensor, the method comprising:
applying a time-varying signal to the analyte sensor;
measuring a signal response to the applied signal;
determining, using sensor electronics, a sensitivity of the analyte sensor, the determining comprising correlating at least one property of the signal response to a predetermined sensor sensitivity profile; and
generating, using sensor electronics, estimated analyte concentration values using the determined sensitivity and sensor data generated by the analyte sensor.
2. The method of claim 1 , wherein the sensitivity profile comprises varying sensitivity values over time since implantation of the sensor.
3. The method of claim 1 , wherein the predetermined sensitivity profile comprises a plurality of sensitivity values.
4. The method of claim 1 , wherein the predetermined sensitivity profile is based on sensor sensitivity data generated from studying sensitivity changes of analyte sensors similar to the analyte sensor.
5. The method of claim 1 , further comprising applying a bias voltage to the sensor, wherein the time-varying signal comprises a step voltage above the bias voltage or a sine wave overlaying a voltage bias voltage.
6. The method of claim 1 , wherein the determining further comprises calculating an impedance value based on the measured signal response and correlating the impedance value to a sensitivity value of the predetermined sensitivity profile.
7. The method of claim 1 , further comprising applying a DC bias voltage to the sensor to generate sensor data, wherein the estimating analyte concentration values includes generating corrected sensor data using the determined sensitivity.
8. The method of claim 7 , further comprising applying a conversion function to the corrected sensor data to generate the estimated analyte concentration values.
9. The method of claim 7 , further comprising forming a conversion function based at least in part of the determined sensitivity, and wherein the conversion function is applied to the sensor data to generate the estimated analyte concentration values.
10. The method of claim 1 , wherein the property is a peak current value of the signal response.
11. The method of claim 1 , wherein the determining further comprises using at least one of performing a Fast Fourier Transform on the signal response data, integrating at least a portion of a curve of the signal response, and determining a peak current of the signal response.
12. The method of claim 11 , further comprising generating estimated analyte concentration values using the selected sensitivity profile.
13. The method of claim 1 , wherein the determining further comprises selecting the predetermined sensitivity profile based on the determined sensor property from a plurality of different predetermined sensitivity profiles.
14. The method of claim 13 , wherein the selecting includes performing a data association analysis to determine a correlation between the determined sensor property and each of the plurality of different predetermined sensitivity profiles and wherein the selected predetermined sensitivity profile has the highest correlation.
15. The method of claim 13 , further comprising generating estimated analyte concentration values using the selected sensitivity profile.
16. The method of claim 15 , further comprising determining a second sensitivity value using the selected sensitivity profile, wherein a first set of estimated analyte concentration values is generated using the determined sensitivity value and sensor data associated with a first time period, and wherein a second set of concentration values is generated using the second sensitivity value and sensor data associated with a second time period.
17. A system for measuring an analyte, the system comprising sensor electronics configured to be operably connected to a continuous analyte sensor, the sensor electronics configured to:
apply a time-varying signal to the analyte sensor;
measure a signal response to the applied signal;
determine a sensitivity of the analyte sensor, the determining comprising correlating at least one property of the signal response to a predetermined sensor sensitivity profile; and
generate estimated analyte concentration values using the determined sensitivity and sensor data generated by the analyte sensor.
18. The system of claim 17 , wherein the sensitivity profile comprises varying sensitivity values over time since implantation of the sensor.
19. The system of claim 17 , wherein the predetermined sensitivity profile comprises a plurality of sensitivity values.
20. The system of claim 17 , wherein the predetermined sensitivity profile is based on sensor sensitivity data generated from studying sensitivity changes of analyte sensors similar to the analyte sensor.