Integrated Microgravimetric Set-up for Chemical Sensing

It is a well known fact that stability and reproducibility of measurement are crucial topics for chemical sensing. Most problems are intrinsically associated with the sensor chemico-physical characteristics and with the fabrication techniques, but often the measurement set-up must carefully be designed. In this paper we addressed the development of an integrated microgravimetric set-up able to perform fast and accurate measurements with an array of quartz crystal microbalances (QCMs). In order to guarantee measurement accuracy, reliability and repeatability, the sampling system was designed to control and optimise factors capable of influencing the generation of sensor transduction signals. The system comprises a dedicated electronic interface for measuring the QCM resonance frequency by using a novel technique. This technique allows reducing the measurement time while maintaining a high frequency resolution. The system was simulated in the range of frequencies covered by prototypal PVA-coated QCMs. The resonance frequency was estimated for a six elements sensor array with a resolution lower than 0.2Hz when the input signal presents a SNR near 40dB at a 1sec scan rate.