Eqs. (1), (2) and (3) demonstrate the importance of geometrical aspects when materials are deposited onto mechanical string resonators by non-diffusion limited sampling. The geometry of the resonators is equally important for their sensitivity, when measuring photothermal frequency detunings. The relative resonance frequency change of a mechanical string resonator with cross sectional area A and length L, which is exposed to a certain laser power P in its center, can be written as [13]