  Nanometer-scale structures with high aspect ratio such as nanowires and
nanotubes combine low mechanical dissipation with high resonance frequencies,
making them ideal force transducers and scanning probes in applications
requiring the highest sensitivity. Such structures promise record force
sensitivities combined with ease of use in scanning probe microscopes. A wide
variety of possible material compositions and functionalizations is available,
allowing for the sensing of various kinds of forces with optimized sensitivity.
In addition, nanowires possess quasi-degenerate mechanical mode doublets, which
has allowed the demonstration of sensitive vectorial force and mass detection.
These developments have driven researchers to use nanowire cantilevers in
various force sensing applications, which include imaging of sample surface
topography, detection of optomechanical, electrical, and magnetic forces, and
magnetic resonance force microscopy. In this review, we discuss the motivation
behind using nanowires as force transducers, explain the methods of force
sensing with nanowire cantilevers, and give an overview of the experimental
progress and future prospects of the field.
