I. INTRODUCTION Electromechanical nano-switches as integral parts of nanoelectromechanical systems (NEMS) find numerous technological applications as, e.g., mass memory storage, high- frequency electrical switches, and mass or force sensors. Such high technological applications demand combined efforts of engineering and science through modelling and simulations. Hence, to design state-of-the-art nanotechnological devices with predetermined character- istics, engineers need in addition to experimental techniques not only new formulas and computational methods but also improved electromechanical models. The new models must account for the nonlocal properties of the materials and new physical phenomena. The nonlocality appears due to the noticeable role of interatomic forces in nano-objects. In nonlocal theories, the constitutive equations take into account microstructure of real materials and microscopic interaction length between, e.g., molecules in a lattice. From the physical point of view, the nonlocality exhibits through special size-dependent effects such as, for example, flexoelectricity - induced polarization due to the strain gradient. It is well known that conventional continuum theories are size-independent and therefore cannot be applied automatically for the analysis of NEMS devices. The most suitable tools for their analysis are atomic and molecular models, but they are restricted by their computational capacity. One of the ways to resolve this contradiction consists in the employment of improved, size- dependent classical theories [1]. In the present work, we consider both piezoelectric and flexoelectric cases. In the latter case, a nonuniform strain field may locally break inversion symmetry and induce polarization. To take into account this effect, similar to [1], we assume that the electric enthalpy density depends not only on strain, electric field, and polarization but also on strain gradient. Then, we replace the polarization by its linear representations through the electric field and strain. Using Hamilton’s principle, we obtain the equations of motion for Euler-Bernoulli and Timoshenko beams as well as for 2-D plate. The higher order terms in the strain from the electric enthalpy density give additional contribution to the bending rigidity of the beam compared to classical solution. The analysis shows that taking into account the strain gradient increases the elastic characteristics of the nano-switch considered in this work. From the obtained formulas it is seen that at reducing dimensions to the nanoscale the flexoelectric effect plays more significant role than piezoelectric effect. In the dynamic 2