QCM-based liquid media sensing system design

Today, our environment is still contaminated with chemicals during industrial processes consciously or unconsciously. The atmosphere and drinking / using water quality should be supervised continuously. Determination and supervision of pollutants in waters are essential for environmental controls. The possible chemical contaminants have been known. Systems are needed to determine the quality and quantity of these pollutants.In this study, a system consisting of the sensor array has been designed to identify contaminants in liquids. The system consists of a liquid vessel which provides sensors to contact with liquid and allows the circulation of liquid and a sensor array which consists of eight Quartz Crystal Microbalance (QCM) sensors. Oscillator circuits have been used in interface circuits to detect the changing frequency of oscillation of QCM sensor in contact with contaminated liquid. Coating each sensor with different sensing material provides each sensor to generate different frequency responses to the same pollutant. The frequency shifts from all the sensors include quality and quantity information of the pollutant. With a microcontroller, frequency information of each oscillator circuit is transferred to PC by scanning with 1 s intervals. Thus the developed system can determine the pollutants in water and can be used in controls.This work was supported by fund with the project number of 2010-11, Dumlupınar University Scientific Research Projects.Keywords: Frequency Shifts, QCM Sensor Array, Liquid Vessel.