Quality control of automotive engine oils with mass-sensitive chemical sensors - QCMs and molecularly imprinted polymers

Molecularly imprinted polyurethanes were used as sensor materials for monit oring the degradation of automotive engine oils. Imprinting with characteri stic oils permits the analysis of these complex mixtures without accurately knowing their composition. Mass-sensitive quartz crystal microbalances (QC Ms) coated with such layers exhibit mass effects in addition to frequency s hifts caused by viscosity, which can be compensated by an uncoated quartz o r a non-imprint layer. Incorporation of degradation products into the impri nted coatings is a bulk phenomenon, which is proven by variation of the sen sor layer height. Therefore, the resulting sensor effects are determined by the degradation products in the oil.