Monolithic sensor array based on a quartz microbalance transducer with enhanced sensitivity for monitoring agricultural emissions

A low-cost sensor array system for agricultural applications is presented. The sensor array is based on a quartz crystal microbalance (QMB) transducer with a novel heating structure. Selective host molecules are used as gas-s ensitive layers. The gas-sensitive layers were optimized for the selective detection of ammonia at varying humidity concentrations. A mode of operatio n is presented which allows on-line monitoring of ammonia without a referen ce gas (RG). In addition, this temperature modulation (TM) mode improves th e signal-to-noise ratio of the sensors compared to the usually applied RG m ode. Multivariate regression models are applied on the sensor array data to selectively predict the ammonia concentration in agricultural emissions. ( C) 2000 Elsevier Science B.V. All rights reserved.