A High‐Performance Miniaturized Frequency Shift Detection System for QCM‐Based Gravimetric Sensing

Abstract Micro‐gravimetric sensors, such as quartz crystal microbalance (QCM) are capable of detecting trace substances and even single nanoparticles in various fields due to their high sensitivity, selectivity, and stability. As a resonant sensor, the detection response of QCM requires frequency analysis instruments with high precision like a frequency counter and a vector network analyzer to measure its frequency shift during mass sensing. However, such bulky and high‐cost instruments undoubtedly hinder the applications of QCM‐based sensors outside the laboratory such as in situ and portable detection. In this paper, a high‐performance miniaturized frequency shift detection system based on a phase‐locked loop (PLL) circuit, is developed for QCM measurement. The designed system achieves high detection sensitivity of frequency shift as 1.859 mV Hz −1 with the Allan deviation of 0.49 mV at 0.15s and frequency resolution of 0.26 Hz, which is conducive to achieving the detection of trace substance by QCM. The excellent measuring performance is further validated by measuring the frequency response of QCM during mass sensing in a gaseous environment and aqueous solution. As a result, compared with a commercial frequency counter, the superior linearity and accuracy of over 98.4% were confirmed with a mean relative error (MRE) of less than 0.92%.