Simultaneous AFM and QCM measurements of biological and electrochemical processes

TL;DRAbstract

We focus on a better understanding of the interaction of the quartz crystal microbal-ance (QCM) resonator with fluid media while a biological layer is being adsorbed on the grounded sensing electrode. With this purpose in mind, we combined an atomic force microscope (AFM from Molecular Imaging, USA) working in liquid medium and a QCM based on the electronics provided by Q-Sense AB (Göteborg, Sweden). The advantage of this latter instrumentation is the ability to measure the evolution of the frequency of several overtones (first, third and fifth in our experiments) as well as the damping. The requirement of working with overtones in the AFM/QCM combination is manda-tory since the fundamental mode (4.7 MHz to 5 MHz in our setup) is so much disturbed by its fluctuating environment (liquid flow, cantilever holder motion) because of its wider energy distribution on the sensing electrode. We have identified the standing wave pattern of acoustic waves between the resonator and the cantilever

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