A sensor system, comprises a subcutaneous or implanted sensor, said sensor having a plurality of independent working electrodes (4310), a counter electrode (4320), and a reference electrode (4330); and sensor electronics operably coupled to said sensor and including: electronic circuitry (4255) configured to selectively perform an electrochemical impedance spectroscopy (EIS) procedure for one or more of said plurality of independent working electrodes (4310) to generate impedance-related data for said one or more working electrodes (4310); a programmable sequencer (4266) configured to provide a start stimulus and a stop stimulus for performing said EIS procedure; and a microcontroller interface configured to operably couple the sensor electronics to a microcontroller.