  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.
