Asymptotical Correction to Bottom Substrate Effect Arising in AFM Indentation of Thin Samples and Adherent Cells Using Conical Tips

Abstract

The bottom substrate effect is one of the major sources of error in force map studies of adherent cells and thin soft samples in an atomic force microscope (AFM)-based force spectroscopy. Because of this, samples appear stiffer than the natural. The popular Sneddon’s contact model, which assumes the sample as infinitely thick, fails to correct this error. In the present work, a simple asymptotically correct analytical correction to the bottom substrate effect is derived through contact mechanics approach and later the model is experimentally validated on a wide range of thickness of soft polyacrylamide gel and on adherent cells.