Methods, systems, and devices for electrode capacitance calculation and application

A method for real-time monitoring of a subcutaneous glucose sensor, said subcutaneous glucose sensor including physical sensor electronics, a microcontroller, and a working electrode (WE), the method comprising:

• (a) measuring, by said physical sensor electronics, a first current level for the working electrode;
• (b) after measuring said first current level, open circuiting, by said microcontroller, the working electrode by discontinuing input current to the working electrode for a time period having a predefined duration;
• (c) during said time period, measuring, by said physical sensor electronics, a first WE voltage value and a second WE voltage value, said first WE voltage value being measured at a first point in time after open circuiting the working electrode, said second WE voltage value being measured at a second point in time after open circuiting the working electrode, and said first and second WE voltage values being measured when a current level for the working electrode is substantially zero;
• (d) calculating, by said physical sensor electronics or said microcontroller, the working electrode's capacitance by a relation C=(I)/(dV/dT), wherein I is the first current level, dV is a difference between said first and second WE voltage values, and dT is a difference between said first and second points in time;
• (e) repeating operations of (a)-(d) periodically;
• (f) determining, by said physical sensor electronics or said microcontroller, a change in the working electrode's capacitance over a time period;
• (g) determining, by said physical sensor electronics or said microcontroller, whether the subcutaneous glucose sensor is previously used based on the change in the working electrode's capacitance over the time period;
• and
• (h) responsive to determining that the subcutaneous glucose sensor is previously used, causing replacement of the subcutaneous glucose sensor.