Unmasking imaging forces on soft biological samples in liquids when using dynamic atomic force microscopy: a case study on viral capsids.

Dynamic atomic force microscopy is widely used for the imaging of soft biological materials in liquid environments; yet very little is known about the peak forces exerted by the oscillating probe tapping on the sample in liquid environments. In this article, we combine theory and experiments in liquid on virus capsids to propose scaling laws for peak interaction forces exerted on soft samples in liquid environments. We demonstrate how these laws can be used to choose probes and operating conditions to minimize imaging forces and thereby robustly image fragile biological samples.