Thumbnail image of graphical abstract

The structural phase transition in vanadium dioxide and its inherent hysteretic behavior are used in the work by Cabrera et al. (pp. 1704–1711) to program multiple mechanical states in a micrometer-sized structure through electrical pulses. The background image on the cover shows one of the lithography masks used for the fabrication of the device. In the top-left 3D scheme of the micro-actuator a two-end arrow at the tip emphasizes the fact that bi-directional mechanical states were programmed. The gray part of the actuator represents the metal traces used for Joule heating, and the cantilever made of SiO2 (glass) is shown as transparent. The bottom plots are a graphical representation of the mechanical states (deflection) that can be programmed with the electrical pulses (voltage). Two horizontal rectangles in the deflection graph represent the windows for programming an “on-state” and an “off-state”. Finally, the monoclinic and tetragonal lattice diagrams emphasize that the phenomena that allow for the mechanical states to be programmed are the crystallographic changes in the VO2 thin film that occur across the phase transition and are completely reversible.