Measurement of the Poisson's ratio and Young's modulus of an isotropic material with T-shape contact resonance atomic force microscopy

The Poisson's ratio and the Young's modulus play an important role in the characterization of nanomaterial mechanical properties. They are the vital parameters of understanding nanoscale material behavior. Here we report a method of quantitatively determining the values of the Poisson's ratio and the Young's modulus with a T-shape contact resonance atomic force microscopy. Unlike the cantilever of a traditional atomic force microscopy, the flexural and torsional modes of the T-shape cantilever are simultaneously excited and coupled in the contact mode. Through the analysis, the bifurcation of the coupled contact resonance frequencies is found in higher modes with the increasing contact stiffness. More importantly, the frequency bifurcation point can be used to decouple the Poisson's ratio and the Young's modulus, which leads to the determination of their separate values. In contrast to the previous methods, in which the Poisson's ratio and the Young's modulus are intrinsically coupled and there is no effective way of decoupling, the method presented in this study offers a new way of decoupling and determining these two parameters. This efficient and accurate method can be of significant help to the characterization of various nanomaterials.