QCR response to attachment processes of particles

This work engages in interfacial effects when particles in liquids are measured with quartz crystal resonators (QCR). Basic strategy is the excitation of the QCR sensor not only in fundamental but also in overtone mode for more information about the attachment process. Particles with diameters of 100 nm up to 2 μm and liposomes with diameters up to 1200 nm have been measured. Particles and quartz surfaces have been functionalized to get different binding strengths. We assume that interfacial effects between film and gold electrode as well as lateral distribution of particles/liposomes determine the data measured with the QCR. Theoretical calculations predict a dramatic dependence on interfacial properties. Indeed, experiments performed under equivalent conditions with macroscopically similar properties show variations, which prove the theoretical predictions.