The Nanoscale World

PF QNM and FV on same cells

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jimmy05 posted on Wed, Mar 12 2014 6:29 AM

Dear all

I was wondering when I do same analysis on force curves from FV mode and PFQNM mode, the value of Young Modulus is about 10 times and more different. From FV are softer than from PFQNM. What could be the cause?

It was measured in same day, few minutes appart themselves (switching between modes).

Thanks for suggestions.


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Ang Li replied on Wed, Mar 19 2014 4:03 AM

Hi, Jimmy,

Your results could be explained from science point of view that your cells are viscoelastic instead of elastic materials. The major difference between FV mode and QNM mode is the indentation rate, that FV mode is usually 100-1000 time slower. Simply speaking, same force but slower indentation generally gives rise to larger deformation on viscoelastic material (you can think about a simple spring-dash model and do some simple calculation).

Technically speaking, you can also take note of the fitting range between the two modes, a more accurate way is to export the force curves from QNM by peakforce capture function and run the same analysis on the two set of results using the same set of parameters.

Ang Li    

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