Effect of gold coating on the Q-factor of a resonant cantilever

The resonance frequency and the Q-factor of the fundamental and higher order flexural modes of silicon dioxide microcantilevers have been characterized at different pressures and for different thicknesses of gold coating. We present the experimental results and discuss the effect of the gold film on the performance and sensitivity of the cantilevers when used as mass sensors. An almost linear relationship between the Q-factor and the resonance frequency of the uncoated cantilevers is observed, implying that a higher sensitivity can be attained by actuation at higher order resonant modes. We also find that even a thin gold coating may reduce Q-factors by more than an order of magnitude.