Self-Sensing Structures for Control of Micro and Nano-cantilevers

摘要

A sensing approach, based on resonance frequency shifts of an oscillating micro- or nano- cantilever, can potentially provide ultimate sensitivity for detection of a single molecule. However, implementation of this sensing technology on a micro-scale has intrinsic limitations: The quality, Q, of an oscillating microcantilever vibrating in air is approximately in the 30-100 range and this value dramatically drops in a liquid environment. Feedback control of the oscillations can improve the quality of the system but multiple challenges are encountered with the sensing and actuation. Traditional data acquisition approaches, which include optical, piezoresistance, piezoelectric and capacitance methods, have very limited application in signal transduction from micro- or nano- cantilever beams. In addition, electrostatic and thermal actuations are not appropriate for liquid environments. A novel approach, utilizing the self-sensing and self-actuation response of electroactive materials is proposed for control of cantilever beam vibration. As far as sensing is concerned, we exploit the fact that any dielectric material exhibits dielectrostriction effect; this is defined as variation of dielectric properties of the material with deformation. Similarly, on the actuation side electrostriction response can also be used. In this work, control challenges and approaches for such nonlinear systems with self-sensing and self-actuation capabilities will be discussed.