| CPC A61B 5/14532 (2013.01) [A61B 5/0002 (2013.01); A61B 5/1451 (2013.01); A61B 5/1486 (2013.01); A61B 5/6801 (2013.01); A61B 5/72 (2013.01); A61B 5/7228 (2013.01); G01N 33/48707 (2013.01); G01N 33/49 (2013.01); G16H 40/67 (2018.01); A61B 5/14865 (2013.01); A61B 5/1495 (2013.01); A61B 2560/0223 (2013.01); G16H 40/40 (2018.01); G16H 50/30 (2018.01); G16H 50/70 (2018.01)] | 20 Claims |
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9. A wearable continuous glucose monitoring (CGM) device comprising:
a working electrode for converting an analyte into a measurable species;
a sensor configured to be implanted subcutaneously into a user to produce current signals from interstitial fluid;
a display;
a bias circuit periodically establishing a non-steady state condition by applying a sequence of probing potential modulation (PPM) voltage signals to the working electrode;
a processor;
a transmitter circuitry coupled to the processor; and
a memory coupled to the processor;
wherein the memory includes a connection function and computer program code stored therein that, when executed by the processor, causes the CGM device to:
establish a steady-state condition by continuously applying, via the bias circuit, a constant voltage potential to the sensor;
wherein applying the constant voltage potential fully oxidizes the measurable species;
periodically measure a primary current signal generated by the constant voltage potential during a primary data cycle;
store the primary current signal in the memory;
periodically establish a non-steady-state condition by perturbing, via the bias circuit, the constant voltage potential during a PPM cycle, after the primary current signal is measured, with the sequence of PPM voltage signals that differ from the constant voltage potential,
wherein the sequence of PPM voltage signals comprises:
a first voltage potential greater than the constant voltage potential at a first time;
a second voltage potential less than the constant voltage potential at a second time after the first time;
a third voltage potential less than the second voltage potential at a third time after the second time; and
a fourth voltage potential greater than the third voltage potential at a fourth time after the third time;
wherein applying the second voltage potential of the sequence of PPM voltage signals decreases oxidation of the measurable species;
measure a plurality of PPM current signals for each PPM voltage signal generated in the sequence of PPM voltage signals;
store the plurality of PPM current signals in the memory,
wherein a first time duration of the PPM cycle is no more than half of a second time duration of the primary data cycle;
calculate a plurality of ratio parameters from the plurality of PPM current signals,
wherein the plurality of ratio parameters comprises a first ratio of a last current signal measured during the fourth voltage potential to a first current signal measured during the fourth voltage potential;
calculate an initial glucose concentration by applying at least one of the plurality of ratio parameters to a conversion function;
determine a connection function value based on the primary current signal and the plurality of ratio parameters;
calculate a final glucose concentration from the initial glucose concentration and the connection function value; and
cause the final glucose concentration to be displayed to the user.
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