Development of a multi-sensor system using coated piezoelectric crystal detectors

Abstract

The development of a multi-sensor piezoelectric crystal detector system for the determination of airborne contaminants such as atmospheric ammonia is described. The system incorporates separate sensors for ammonia, moisture and temperature determination. The effects of variations in operating conditions such as analyte concentrations, humidity, gas flow-rate and coating area and mass were examined with the objective of developing a monitoring system that will operate under ambient conditions. The application of a microcomputer for data handling is described. The microcomputer was used to evaluate ammonia concentrations in air using the differential response from a pair of coated piezoelectric crystals, together with a series of correction routines that compensate for changes in environmental conditions.