Self-sensitive torsional microresonators based on a charge-density wave system

Recently, there have been dramatic advances in the miniaturization of electromechanical devices. Most of the micro- and nanoelectromechanical systems (MEMS-NEMS) operate in the resonant modes1. The micron-, and, the more, the submicron-sizes devices, are driven usually by electrostatic forces, as piezoelectric and electromagnetic engines are powerless over this size range. Such engines could play the role of external actuators for the NEMS, being, however, macro devices in their own. Apart from actuation, an objective of NEMS is getting the output signal characterizing the oscillations1, so, actuators sensing their own motion are rather topical (see 2 for example). Not long ago, several works appeared demonstrating high sensitivity of the sizes3,4 and form5 of quasi one-dimensional conductors to the deformations of the charge-density wave (CDW). Here we demonstrate electrically driven torsional resonators based on whiskers of the quasi one-dimensional conductor with CDW, TaS3. The driving force for the torsional deformation is peculiar to the CDW systems and reflects the transmission of the CDW deformation to the crystalline lattice. In comparison with the piezoelectrics, the effect of electric field on the crystal deformation is 3-4 orders of magnitude larger. The resonator is found to provide also a torsion-induced electrical feed-back (output signal) from the oscillations. We discuss the CDW systems as promising elements for NEMS-MEMS.