Switchable molecule-based materials for micro- and nanoscale actuating applications: Achievements and prospects

•The interest of molecule-based switches for MEMS/NEMS applications is highlighted.•An overview of current smart actuator materials is provided.•Actuating examples of different families of molecular switches are discussed.•Prospects and challenges are analyzed. Molecular switches rely on various physico-chemical phenomena, and in most cases the switching event is accompanied by a significant rearrangement of atomic positions. At the macroscopic level the long range order of switching molecules usually results in a collective, or even cooperative, volume change, which can be readily exploited for actuating purposes. These molecular (or molecule-based) systems can provide multiple advantages for this type of application due, primarily, to their intrinsic chemical and functional versatility and the small size of their functional units. This review provides an overview of advances and presents the prospects for integrating switchable molecular materials as active elements into actuator devices, with particular emphasis on micro- and nanoscale systems.