Film bulk acoustic resonators for DNA and protein detection and investigation of <em>in vitro</em> bacterial S-layer formation

We report investigations on the use of film bulk acoustic resonators for the label-free, multiplexed biosensing of DNA and proteins. The used acoustic resonators were operated in shear mode at about 800 MHz. From the measured changes of frequency and in dissipation, the mass and the viscoelasticity of biomolecular films formed at the top electrode of the device could be derived, respectively. A mass sensitivity of ∼2 kHz cm2/ng and a minimum detectable mass of ∼1 ng/cm2 were achieved. To demonstrate the highly sensitive detection of the time evolution of protein adsorption, the adsorption kinetics and recrystallisation of bacterial surface layer proteins on gold surfaces were investigated