Imaging material properties of biological samples with a Force Feedback Microscope

TL;DR

This paper presents a Force Feedback Microscope technique that quantitatively images the mechanical properties of biological samples with high resolution, using minimal vibrational energy and allowing frequency-dependent biomechanical studies.

Contribution

It introduces a robust method for quantitative high-resolution force measurements in biological samples using a Force Feedback Microscope with simultaneous force, gradient, and dissipation measurements.

Findings

Quantitative high-resolution force measurements achieved.

Mechanical properties depend on tip force and sample indentation.

Frequency of excitation can be arbitrarily chosen for spectroscopic studies.

Abstract

Mechanical properties of biological samples have been imaged with a \textit{Force Feedback Microscope}. Force, force gradient and dissipation are measured simultaneously and quantitatively, merely knowing the AFM cantilever spring constant. Our first results demonstrate that this robust method provides quantitative high resolution force measurements of the interaction The little oscillation imposed to the cantilever and the small value of its stiffness result in a vibrational energy much smaller than the thermal energy, reducing the interaction with the sample to a minimum. We show that the observed mechanical properties of the sample depend on the force applied by the tip and consequently on the sample indentation. Moreover, the frequency of the excitation imposed to the cantilever can be chosen arbitrarily, opening the way to frequency-dependent studies in biomechanics, sort of spectroscopic AFM investigations.