A High-Q Quartz Crystal Microbalance with Mass Sensitivity up to 1017 Hz/kg**Supported by the National Natural Science Foundation of China under Grant No 61871098.

Abstract

A high-Q quartz crystal microbalance (QCM) sensor with a fundamental resonance frequency of 210 MHz is developed based on inverted mesa technology. The mass sensitivity reaches 5.332 × 1017 Hz/kg at the center of the electrode, which is 5–7 orders of magnitude higher than the commonly used 5 MHz or 10 MHz QCMs (their mass sensitivity is 1010–1012 Hz/kg). This mass sensitivity is confirmed by an experiment of plating 1-ng rigid aluminium films on the surface of the QCM sensor. By comparing the changes in QCM equivalent parameters before and after coating the aluminum films, it is found that the QCM sensor maintains the high-Q characteristics of the quartz crystal while the mass sensitivity is significantly improved. Therefore, this QCM sensor may be used as a promising analytical tool for applications requiring high sensitivity detection.