Note: Double-hole cantilevers for harmonic atomic force microscopy.

To enhance the harmonic signals in intermittent contact atomic force microscopy, we proposed the double-hole structural modification. Finite element analyses and experiments demonstrated the capability and advantages of the developed method. An infinite set of harmonic cantilevers can be optimized by proper selections of hole size, position, and inter-distance. The second and third resonance frequencies are simultaneously regulated to be integer multiples of the fundamental frequency. In the meanwhile, the alteration of cantilever stiffness is kept minimum. The double-hole modifications have prominent advantages of regular geometry, flexible selection of cutting positions/dimensions, and easy-to-meet fabrication tolerances.