Everything moves! In a world dominated by electronic devices and instruments it is easy to forget that all measurements involve motion, whether it be the motion of electrons through a transistor, Cooper pairs or quasiparticles through a superconducting quantum interference device (SQUID), photons through an optical interferometer—or the simple displacement of a mechanical element. Nanoscience today is driving a resurgence of interest in mechanical devices, which have long been used as front ends for sensitive force detectors. Among prominent historical examples are Coulomb’s mechanical torsion balance, which allowed him in 1785 to establish the inverse-square force law of electric charges, and Cavendish’s mechanical instrument that allowed him in 1798 to measure the gravitational force between two lead spheres.
Today, micro- and nanoelectromechanical systems (MEMS and NEMS) are widely employed in ways similar to those early force detectors, yet with vastly greater force and mass sensitivity—now pushing into the realm of...
