Full-field strain measurements at the nanoscale

A summary of advances in nanomechanical characterization of materials by utilizing high-spatial resolution Atomic Force Microscopy (AFM) for full-field strain measurements is presented along with perspectives for fast and accurate AFM imaging for nanoscale strain mapping. The combination of in situ AFM, and more broadly Scanning Probe Microscopy (SPM), specimen imaging during mechanical testing, with Digital Image Correlation (DIC) based strain calculations has provided full-field nanoscale deformation data in heterogeneous materials, which have enabled the investigation of microstructural effects on local deformation and fracture processes at the nanoscale. However, the inherent line-by-line scanning principle of an AFM requires long image acquisition times, thus prohibiting its application to viscoelastic materials while also increasing the susceptibility of AFM images to noise and thermal drift. Advances in control electronics, photodetectors, and cantilever microfabrication and excitation methods have opened new possibilities to reduce the acquisition time for high-resolution AFM images by 1–2 orders of magnitude, hence making the AFM/DIC experimental methodology an effective tool for nanomechanical studies.