Design and analysis of piezoelectric cantilevers with enhanced higher eigenmodes for atomic force microscopy

Atomic force microscope (AFM) cantilevers with integrated actuation and sensing provide several distinct advantages over conventional cantilever instrumentation such as clean frequency responses, the possibility of down-scaling and parallelization to cantilever arrays as well as the absence of optical interferences. However, for multifrequency AFM techniques involving higher eigenmodes of the cantilever, optimization of the transducer location and layout has to be taken into account. This work proposes multiple integrated piezoelectric regions on the cantilever which maximize the deflection of the cantilever and the piezoelectric charge response for a given higher eigenmode based on the spatial strain distribution. Finite element analysis is performed to find the optimal transducer topology and experimental results are presented which highlight an actuation gain improvement up to 42 dB on the third mode and sensor sensitivity improvement up to 38 dB on the second mode.