USING THE QUARTZ-CRYSTAL MICROBALANCE PRINCIPLE FOR GAS-DETECTION WITH REVERSIBLE AND IRREVERSIBLE SENSORS

To improve the sensitivity and selective behaviour of the quartz cryst al microbalance (QCM) sensors we studied the specific interactions bet ween the usual sensor materials, as well as a monomolecular layer, a c omplex former, a biomolecule and a calix-n-arene, and different analyt es. First results for the application of these kinds of interactions t o detect reactants gases and solvents in chemical industry are shown. Beside typical reversible changes in the resonance frequency of the co ated quartz during gas exposure we found quasi-irreversible signals re sulting from complex forming reactions or hydrogen bonding. A brief de scription of the theory and experimental background is given.