Lorentz‐force‐induced excitation of cantilevers for oscillation‐mode scanning probe microscopy

In the field of scanning probe microscopy, imaging modes with oscillating cantilevers are used to image soft samples with high resolution. The tapping mode is most frequently realized by a vibrating chip‐holder, which is coupled to the cantilever chip to excite the cantilever acoustically. A new promising approach is a direct excitation of a V‐shaped cantilever by a Lorentz force acting on the V‐shaped cantilever. The Lorentz force is generated by an alternating current flowing through the cantilever while being placed in a static magnetic field. Here we show an appropriate method, to microstructure the reflective coating of commercial cantilever chips for a current flow through the cantilever, that is based on a laser system. The laser microstructuring method allows chips to be processed without changing the mechanical properties of the cantilever itself, leading to excellent dynamic properties of the vibrating cantilever. Because the cantilever is excited directly, no peripheral resonances except the eigen‐resonance of the cantilever were apparent in the frequency spectrum. For a current of high amplitude at a static magnetic field of low intensity it is observed that the bimetal properties of the cantilever cause an additional thermal excitation. The results show that commercial cantilevers can be microstructured to implement this new excitation method for a frequency spectrum with a high‐quality factor of oscillation.