Abstract

Advanced techniques in nanoscience now enable the creation of ultrasmall mechanical devices.  These nanoelectromechanical systems (NEMS) offer unprecedented opportunities for sensitive chemical, biological, and physical measurements.  I will describe three specific applications of NEMS that we are currently pursuing:  vacuum-based, force-detected magnetic resonance imaging; vacuum-based mass spectrometry; and fluid-based biochemical force assays for molecular recognition.  All three of these applications employ ultraminiature mechanical devices that offer potential functionality down to the single-molecule limit. Their reduced size yields extremely high fundamental vibrational frequencies while simultaneously preserving very high mechanical responsivity.  For vacuum-based applications this powerful combination of attributes translates directly into high force and mass sensitivity, ultimately below the attonewton and single-Dalton level respectively.  In fluidic media, even though the high quality factors attainable in vacuum become precipitously damped, the small device size and high compliance still yields response at the piconewton level -- the force required to break individual hydrogen bonds within a macromolecule.

Ultimately NEMS will enable us to access the regime where mesoscopic mechanics becomes dominated by quantum, rather than thermal, fluctuations, and measurement sensitivity approaches, or even exceeds, the standard quantum limit.  I will discuss the intriguing prospects of this realm -- from near-term possibilities of observing single-quantum jumps in vibratory and phonon systems, to longer-term objectives of quantum measurement and control in solid state nanodevices -- giving due respect to the practical obstacles to their attainment.