Advanced techniques in nanoscience now enable the creation of ultrasmall mechanical devices. These nanoelectromechanical systems (NEMS) offer unprecedentedopportunities for sensitive biochemical measurements. I will describe three specific applications of NEMS that we are currently pursuing: vacuum-based mass spectrometry, fluid-based/ /biochemical force assays for molecular recognition, and number-state measurements on a NEMS device at ultralow temperatures.

The first two applications employ ultraminiature mechanical devices that offer sensitivity 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 in to high force and mass sensitivity, ultimately below the attonewton and single-Dalton levels, 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 below the piconewton level – roughly the force required to break individual hydrogen bonds within a macromolecule. The latter experiments require ultrasensitive measurements on high frequency devices which enable number state measurements while avoiding linear coupling – an class of measurements that are novel for mechanical systems.