Abstract
Compared with thin films, nanoparticle layers as coatings for QCM offer substantially increased interaction areas and sensitivities with favourable response times. Molybdenum disulphide (MoS
2), e.g. has turned out to be a highly suitable material for interacting with thiols. The resulting materials are sufficiently soft according to Pearson to bind sulphur containing compounds reversibly. Depositing MoS
2 nanoparticle submonolayers (particle size 200–300
nm) leads to an increase in sensor response by a factor of ten compared to a pure gold layer. Additionally, the nanoparticle layers show fully reversible sensor signals. Particle synthesis can also be combined with the molecular imprinting approach: by a precipitation technique, it is possible to generate molecularly imprinted TiO
2 particles for engine oil degradation measurements. Compared with deposited thin layers, particles incorporate oxidised compounds from lubricants by a factor of two better.