A so far not considered energy loss mechanism in suspended micro- and nanoresonators due to noncontact acoustical energy loss is investigated theoretically. The mechanism consists on the conversion of the mechanical energy from the vibratory motion of the resonator into acoustic waves on large nearby structures, such as the substrate, due to the coupling between the resonator and those structures resulting from the Casimir force acting over the separation gaps. Analytical expressions for the resulting quality factor $Q$ for cantilever and bridge micro- and nanoresonators in close proximity to an underlying substrate are derived and the relevance of the mechanism is investigated, demonstrating its importance when nanometric gaps are involved.

• Received 5 July 2009

DOI:https://doi.org/10.1103/PhysRevB.81.035425