Enhancing higher-order modal responses in atomic force microscopy with a segmented constraint methodology

Bimodal atomic force microscopy (bimodal-AFM) has emerged as a powerful tool for nanoscale material characterization, but its performance in atmospheric environments is often limited by the weak response of higher eigenmodes. Here, we address this challenge by introducing a segmented fixture design, which adjusts the excitation boundary conditions of the atomic force microscope probe. This approach significantly enhances the second eigenmode's vibrational amplitude while maintaining base-mode sensitivity. Experimental results demonstrate a 2.8-fold increase in higher eigenmode response compared to conventional bimodal-AFM, enabling improved material property mapping on polymer surfaces under ambient conditions. This work presents a practical and hardware-based solution that can enhance the performance of bimodal-AFM, without requiring complex micro-nano processing techniques, thereby expanding its application scope.