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 defective sensor, the method comprising:
generating sensor data using an implantable analyte sensor;
generating, using sensor electronics, analyte concentration values using the implantable sensor data generated by the continuous analyte sensor;
applying, to the implantable analyte sensor, a stimulus signal having a particular frequency, multiple stimulus signals having different frequencies, or a stimulus signal comprising a spectrum of frequencies;
measuring a signal response of the implantable analyte sensor to the stimulus signal;
determining a value associated with the signal response;
determining whether the value is within a predefined level;
determining that the implantable analyte sensor has a condition associated with membrane damage when the value exceeds the predefined level; and
notifying a user that the implantable analyte sensor is defective responsive to the determining that the implantable analyte sensor has the condition associated with membrane damage.
2. The method of claim 1 , wherein determining the value associated with the signal response of the implantable analyte sensor is performed iteratively.
3. The method of claim 1 , wherein determining the value associated with the signal response of the implantable analyte sensor is performed in substantially real time.
4. The method of claim 1 , wherein the value associated with the signal response is electrical impedance determined by electrochemical impedance spectroscopy.
5. The method of claim 1 , further comprising determining a sensitivity of the implantable analyte sensor during sensor use.
6. The method of claim 5 , wherein determining the sensitivity is performed in substantially real time.
7. The method of claim 5 , wherein determining the sensitivity of the implantable analyte sensor is performed iteratively.
8. The method of claim 7 , wherein determining the sensitivity of the implantable analyte sensor is performed throughout a substantially entire sensor session.
9. The method of claim 1 , wherein the value associated with the signal response is electrical impedance, and wherein the determined electrical impedance is compared to an established impedance-to-sensor sensitivity relationship.
10. The method of claim 9 , further comprising determining sensor sensitivity by using the impedance-to-sensor sensitivity relationship.
11. The method of claim 9 , further comprising determining a change in sensitivity over time by using the impedance-to-sensor sensitivity relationship.
12. The method of claim 1 , wherein the defective implantable analyte sensor is detected by an unstable sensor sensitivity.