High Sensitivity Deflection Detection of Nanowires

A critical limitation of nanoelectromechanical systems (NEMS) is the lack of a high-sensitivity position detection mechanism. We introduce a noninterferometric optical approach to determine the position of nanowires with a high sensitivity and bandwidth. Its physical origins and limitations are determined by Mie scattering analysis. This enables a dramatic miniaturization of detectable cantilevers, with attendant reductions to the fundamental minimum force noise in highly damping environments. We measure the force noise of an 81±9 nm radius Ag₂Ga nanowire cantilever in water at 6±3 fN/√Hz.