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Hi,
My sample is a microspherical membrane made of PLGA (diameter 5-8 micron, thickness: in the range of 100-500 nm). I want to apply large deformation to the sample and get the nonlinear viscoelastic properties. For now, I want to use Peak Force QNM, but I am wondering whether this mode can be used to produce large deformation depth and help me to get the nonlinear viscoelastic information using the force curves and the disspation channel or not? Should I use tapping mode or contact mode instead of PF QNM?
Thanks
Nhung,It depends on how large of a deformation you want to make. In QNM the max deformation you would want to try is about 25% of the PFT z range (or about 125nm for a 500nm oscillation). If you need to do more than this, I would recommend Force Volume. As always, you will need to pick the cantilever with the right spring constant for your experiment. Likewise, in either QNM or FV you will have to apply your own analysis and model to get the nonlinear viscoelastic properties you desire.Good luck,Steve