AFM cantilever

A compliant beam whose deflection senses tip–sample force in atomic force microscopy. In its calibrated linear range, normal force is $F=k_c{\delta }_c$.

The normal restoring-force coefficient of an AFM cantilever, $k_c=F/{\delta }_c$, with units $\mathrm{N}{\mathrm{m}}^{-1}$. A quantitative force measurement requires both this stiffness and the optical deflection sensitivity.