Online Quartz Crystal Microbalance Analyzing Device of Mass Concentration of Formaldehyde Gas Based On FPGA

Abstract

Abstract As one of the main indoor gas pollutants, formaldehyde gas (HCHO) seriously threatens human health and ranks second among toxic chemicals in China. In order to monitor the concentration of formaldehyde in the environment in real time, an online Quartz Crystal Microbalance (QCM) analyzing device based on FPGA is developed in this paper. This device is composed of QCM sensor module and FPGA signal processor. Firstly, graphene oxide film is prepared on QCM chip to adsorb formaldehyde, which causes the change of resonance frequency. Secondly, to monitor the quality of adsorbed formaldehyde through frequency change, FPGA signal processor is mainly integrated with Direct Digital Synthesis module, Analogue-to-Digital Conversion module, Low-Pass Filter module and Frequency Domain Analysis module. These modules have the characteristics of high speed, low power consumption and parallel processing, which provide the best solution for the online implementation of the analyzing device. Finally, the standard gas experiment shows that the device is feasible and reliable for the analysis of formaldehyde gas mass concentration, with a resolution of about 10 counts per 1% concentration.