Improved Capacitive Detection Method for Coriolis Mass Flow Sensors Enabling Range/sensitivity Tuning

We report on a novel capacitive detection principle for Coriolis mass flow sensors which allows for three times increased sensitivity. Capacitive Coriolis mass flow sensors are normally read out by two electrodes that measure the ratio between the actuation mode and the Coriolis mode, which is induced by the mass flow. This ratio results in a phase shift between the two electrodes. By adding two additional read out electrodes, the actuation mode signal is partially cancelled, allowing for higher sensitivity to the Coriolis mode, and thus larger phase shifts for the same mass flows. An analytical model is derived and correspond with the measurements. It is also proven that the range and sensitivity of the sensor can be tuned by changing the size of the additional readout electrodes. This readout method does not increase the readout time.