A systematic approach to quantitative nanoscale mass spectrometry using atomic force microscopy

Atomic force microscopy (AFM) enables mass sensing through resonance-frequency changes of microcantilevers, but quantitative measurements can be affected by calibration and environmental factors. Here, we investigated whether a calibrated AFM cantilever and controlled mass loading could provide nanogram-scale mass estimation. Cantilevers were cleaned and calibrated by force-distance measurements, and resonance acquisition parameters were optimized under ambient conditions. UV-curable resin droplets were locally deposited on the cantilever to generate mass loading, and resonance-frequency shifts were measured and analyzed using a mass-spring model and finite-element simulations. Increasing resin mass produced progressive decreases in resonance frequency, demonstrating a consistent relationship between mass loading and cantilever resonance behavior. Finite-element simulations reproduced the resonance responses and supported the mass estimates obtained from the experimental measurements. These findings establish a calibration and modeling framework for resonance-based mass quantification using conventional AFM cantilevers and provide a basis for extending quantitative mass analysis to microstructures and biological assemblies.