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 determining a sensitivity of a continuous analyte sensor, the method comprising:
applying a bias voltage to an analyte sensor;
applying a voltage step above the bias voltage to the analyte sensor;
measuring, using sensor electronics, a signal response of the voltage step from the analyte sensor;
determining, using the sensor electronics, a peak current of the signal response;
determining, using the sensor electronics, a sensitivity of the analyte sensor by correlating the peak current to a predetermined relationship of the peak current to sensor sensitivity, wherein the predetermined relationship is based at least in part on time of use of the analyte sensor;
receiving, using the sensor electronics, from the analyte sensor sensor data indicative of analyte concentration;
compensating, using the sensor electronics, the sensor data using the determined sensitivity of the analyte sensor;
determining, using the sensor electronics, an analyte concentration value based at least in part on the compensated sensor data; and
displaying, using a display, the determined analyte concentration value.
2. The method of claim 1 , wherein correlating the peak current to the predetermined relationship comprises calculating an impedance of the analyte sensor based on the peak current and correlating the impedance of the analyte sensor to the predetermined relationship.
3. The method of claim 1 , wherein the sensitivity of the sensor is a sensitivity of the analyte sensor or a temperature of the analyte sensor.
4. The method of claim 1 , wherein the peak current is a difference between a magnitude of the response prior to the voltage step and a magnitude of the largest measured response resulting from the voltage step.
5. The method of claim 1 , wherein the predetermined relationship is an impedance-to-sensor sensitivity relationship.
6. The method of claim 1 , wherein the compensating comprises correlating a predetermined relationship of the peak current to sensor sensitivity or change in sensor sensitivity and modifying a value or values of the sensor data responsive to the correlated sensor sensitivity or change in sensor sensitivity.
7. The method of claim 6 , wherein the predetermined relationship is a linear relationship over time of use of the analyte sensor.
8. The method of claim 6 , wherein the predetermined relationship is a non-linear relationship over time of use of the analyte sensor.
9. The method claim 6 , wherein the predetermined relationship is determined by prior testing of sensors similar to the analyte sensor.
10. A system for determining a sensitivity of a continuous analyte sensor, the system comprising:
sensor electronics configured to be operably connected to a continuous analyte sensor, the sensor electronics configured to:
apply a bias voltage to an analyte sensor;
apply a voltage step above the bias voltage to the analyte sensor;
measure a signal response of the voltage step from the analyte sensor;
determine a peak current of the signal response;
determine a sensitivity of the analyte sensor by correlating the peak current to a predetermined relationship of the peak current to sensor sensitivity, wherein the predetermined relationship is based at least in part on time of use of the analyte sensor;
receive from the analyte sensor sensor data indicative of analyte concentration;
compensate the sensor data using the determined sensitivity of the analyte sensor; and
determine an analyte concentration value based at least in part on the compensated sensor data; and
a display configured to display the determined analyte concentration value.
11. The system of claim 8 , wherein the sensor electronics are configured to correlate the peak current to the predetermined relationship by calculating an impedance of the analyte sensor based on the peak current and correlating the impedance of the analyte sensor to the predetermined relationship.
12. The system of claim 8 , wherein the sensitivity of the analyte sensor is a sensitivity of the analyte sensor or a temperature of the analyte sensor.
13. The system of claim 8 , wherein the peak current is a difference between a magnitude of the response prior to the voltage step and a magnitude of the largest measured response resulting from the voltage step.
14. The system of claim 8 , wherein the predetermined relationship is an impedance-to-sensor sensitivity relationship.
15. The system of claim 8 , wherein the sensor electronics are configured to compensate sensor data by correlating a predetermined relationship of the peak current to sensor sensitivity or change in sensor sensitivity and modifying a value or values of the sensor data responsive to the correlated sensor sensitivity or change in sensor sensitivity.
16. The system of claim 15 , wherein the predetermined relationship is a linear relationship over time of use of the analyte sensor.
17. The system of claim 15 , wherein the predetermined relationship is a non-linear relationship over time of use of the analyte sensor.
18. The system of claim 15 , wherein the predetermined relationship is determined by prior testing of sensors similar to the analyte sensor.