2002 Volume 45 Issue 4 Pages 567-572
In dynamic atomic force microscopy (AFM) for detecting local elastic properties of samples, it is desirable that the contact resonance of an AFM cantilever is sensitive to tip-sample contact stiffness. This paper presents a unique cantilever with its mass concentrated as a way of enhancing the sensitivity. The cantilever is made up of a commercially available normal cantilever and a tungsten particle adhesively attached to the free end. Spectra of the contact vibrations are measured for three sample materials. The mass-concentrating cantilever whose tip is in contact with a sample exhibits a distinguishing spectrum containing a meaningful resonant peak affected significantly by contact stiffness. If the attached mass is about four times larger than the distributed (cantilever) mass, the resonant peak obeys a spring-mass model. This means that the cantilever with its mass concentrated can provide the maximum sensitivity even for stiff materials.