A High-Sensitivity Frequency Shift Detector for QCM-Based Miniaturized Sensing System

As a micro-gravimetric sensor, QCM is widely used in gas, particle, and virus detection. However, due to its high resonant frequency, the detection response (frequency shift) of QCM often requires expensive and bulky high-frequency analysis equipment such as vector network analyzer. In order to realize the simplicity and convenience of QCM analysis, so as to realize the ability of in-situ and real-time detection based on QCM, a miniaturized frequency shift detector based on a PLL circuit is developed., with a size of 40 mm×40mm. The proposed detector achieves a high frequency shift detection sensitivity of 1.859 mV/Hz by calibration. The developed detection system demonstrated an ability to detect two kinds of heavy metal ions, which also represents the potential applications for outdoors detection.