Robust Reconstruction of Atomic Force Microscopy Tip Shape From Force-Indentation Curves

A robust method, termed Piecewise Inverse Force Curve Analysis (PIFCA), is introduced for reconstructing the shape of atomic force microscopy (AFM) tips. The approach relies on piecewise linear axisymmetric approximation of the tip shape based on the analysis of force versus indentation depth curves acquired on a soft reference sample. PIFCA was validated using force curves collected on polydimethylsiloxane samples and was able to reconstruct nearly axisymmetric tip shapes with high goodness-of-fit (R² ≥ 0.98). PIFCA does not require any additional measurements such as electron microscopy or blind tip reconstruction (BTR). Thus, it simplifies the workflow and minimizes the risks of altering the tip shape and mechanical properties associated with those methods. Unlike other methods, PIFCA is robust for both deep and shallow indentations, which makes it particularly appealing for applications involving soft materials and deep indentations.