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selecting the appropriate cantilever stiffness, tip size and indentation settings. For example, when
working with samples that have a porous surface, selecting a tip diameter that is either much
smaller or larger than the average pore size avoids having the tip trapped in the sample.
Sample immobilization
Next to a stable sample, it is important to immobilize the sample to eliminate lateral and height drift
during and between indentations. Indenting a drifting or floating sample results in unreliable
indentation measurements. Especially when performing automated matrix scans make sure the
sample is immobilized correctly.
Figure 28: Piuma camera view of a living immersed micro-tissue on a microscope slide. Extra care should be taken when
measuring samples that cannot be glued or weighed down.
4.3 Probe stability
The probe may be subject to instability if subjected to sudden temperature changes or if an air
bubble is trapped near or on the cantilever upon immersion in a liquid.
Solution temperature
When immersing the probe in a liquid of a different temperature, such as refrigerated liquids or
liquids obtained from the incubator, wait a few minutes upon immersion to let the probe adjust to
the new temperature and equilibrium is reached. This can be observed by the interferometer signal:
if the voltage is changing a lot when the probe is immersed, this is a sign the probe is still adjusting
to its new environment.