Design of a multi-channel quartz crystal microbalance data acquisition system
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In this study a multi-channel data acquisition system has been designed, by which mass changes in small quantities can be monitored and recorded by means of a quartz crystal microbalance (QCM) technique. The whole system is controlled by an Arduino Atmega 2560 microcontroller and can be run independently or via a personal computer. A PIC16F628A microcontroller is used for each channel of the prototype device designed for the system, and frequency measurements of the QCM crystals to be used for sensor investigations have been performed by this microcontroller. The temperatures of sensor environments and ambient humidity can be measured at the same time as the frequency measurements. The frequency response performance of QCM crystal has been tested by experiment. The system is able to measure and monitor QCM frequencies in the 1-50 MHz range, at 1 ppm accuracy and 1 Hz precision. The front surface of a QCM crystal was coated with NiO by a physical vapor deposition technique, and the mass of the film layer grown on the QCM crystal surface was precisely calculated to be 26.53 mu g with an error rate of less than 1%. The mass value obtained in this way is in reasonably good agreement with the values obtained by oscilloscope and frequency meter methods.