Preliminary Development of an upgrade of a chamber to measure the response of quartz crystal resonators

Abstract

Quartz crystal microbalance (QCM) sensors have been frequently used as weighing devices, since they have proven to be sensitive due to shifts in their resonant frequency due to increments in the mass attached to their surface. These, are normally used as sensor arrays for systems known as "Electronic Noses", to detect and analyze gases, fluids, medical and environmental applications, and biological compounds, among others. For the implementation of such systems, it is necessary to characterize the response of the sensors at different types of compounds, primarily in temperature-controlled environments, which implies the use of control systems with a high cost. This work presents the preliminary design of a static system to measure the response of quartz crystal gas sensors, as a lower cost proposal, using an open-loop controlled temperature environment, through an electronic communication system with the computer and a virtual instrumentation software to monitoring and manipulating the temperature. To observe the effectiveness of the system, real QCM gas sensors with a coat of sensing film of ethyl cellulose were used, applying concentrations of ethanol. In addition, temperatures of 25°C, 35°C and 45°C were adjusted, obtaining typical results of the response of this type of sensors.