An easy-to-implement method for evaluation of capacitive resonant sensors

A novel method that can be used to characterize resonant capacitive sensors is presented. The method is based on measurement of the third harmonic of the current through the capacitor; thus the detection signal is frequency separated from the excitation signal. The measurement is time-continuous and only requires a very simple resonant structure where a single electrode is simultaneously used for excitation and detection. The readout circuit is easily implemented with a single operational amplifier and standard equipment such as a lock-in amplifier or a function generator and a spectrum analyzer. Measurements of a resonant structure confirm the feasibility of the concept.

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