Abstract: The results of a study of the oscillations of microcantilevers (MCs) made of nanoporous anodic aluminum oxide and constituting the base of biochemical sensors are described. Finite-element modeling of an MC’s vibrations reveal the sources of resonances in the frequency spectrum that do not correspond to the cantilever’s oscillations and complicate the development of sensors. It is shown for the first time that such sources are resonances of vibrations of the base of the MC on the elastic layer of the compound used to attach the base to the substrate. Approximate relationships between the parameters of the MC, base, and compound layer are obtained, which ensure that only the working modes of MC vibrations are present in the spectrum. To ensure a clean spectrum, one of two conditions must be observed or a combination of both: a sufficiently rigid MC attachment to the substrate and a sufficiently small base size. Ensuring a clean spectrum is achieved regardless of the rigidity of the MC’s fastening as long as the base length does not exceed 0.6, 0.43, and 0.33 MC lengths, respectively, for the 3rd, 4th, and 5th harmonics of the MC’s working mode. © 2021, Pleiades Publishing, Ltd.