CPC A61B 5/1473 (2013.01) [A61B 5/0002 (2013.01); A61B 5/053 (2013.01); A61B 5/14532 (2013.01); A61B 5/14865 (2013.01); A61B 5/1495 (2013.01); A61B 5/6849 (2013.01); A61B 5/7203 (2013.01); A61B 5/7225 (2013.01); A61B 2560/0214 (2013.01); A61B 2560/0223 (2013.01); A61B 2562/0214 (2013.01); A61B 2562/166 (2013.01); A61B 2562/227 (2013.01)] | 9 Claims |
1. 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.
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