Fully Digital QCM using Twin Quartz Sensor

In this paper, we propose a new method to improve measurement resolution of QCM (quartz crystal microbalances). In the proposed method, the oscillation waveform of the crystal oscillator is directly captured by an analog to digital converters, and the phase is calculated by digital computation. The mass of the object is detected by calculating the instantaneous frequency by time differentiation of the time-series phase information. Therefore, compared to the method using a frequency counter, there is no waiting time due to the gate time, therefore high-speed mass detection is possible. As a result of the experiment, it was confirmed that the measurement resolution was improved compared to the method using the frequency counter.