Directly heated quartz crystal microbalance with an integrated dielectric sensor

Cross-sensitivity, especially to humidity, is a common problem in the analysis of chemical gas-sensor signals. To identify the contributions of two gas components at least two suitable signals are needed. This article presents a new chemical sensor unit which is a combination of a quartz crystal microbalance and a dielectric sensor. Thus it yields information about both the mass and the dielectricity of the same chemically sensitive film. The differences in absorption isotherms and drift behaviour are discussed. To make this a universal element for gas sensing, a heater and a temperature gauge are also integrated directly on the quartz by thin-film technology. This allows the application of temperature modulation techniques to the quartz microbalance principle. (C) 1998 Elsevier Science S.A. All rights reserved.