Atomic force microscopy as a tool for mechanical characterization at the nanometer scale

Abstract

The design, optimization and realization of innovative nanocomposite materials for advanced applications in a broad range of fields, from energy, automotives and photonics to biology and nanomedicine, require the capability to characterize their physical properties (e.g. mechanical, electric and magnetic) from a multiscale perspective, in particular not only at the macroscopic scale but also at the nanometer one. In particular, methods are needed to characterize mechanical properties at a nanometer lateral resolution, in order to understand the contribution of the nanosized features of the materials and related phenomena. Atomic force microscopy (AFM) has evolved from a tool for the morphological analysis of the sample surface to an integrated platform for the physicochemical characterization of samples. Current AFM systems host several advanced techniques for the mechanical characterization of materials at a high speed and a high lateral resolution in a broad range of mechanical moduli – for example, from stiff samples (e.g. coatings and crystals) to soft materials (e.g. polymers and biological samples) – in different environments (e.g. air, vacuum and liquid) and conditions (controlled humidity and controlled temperature). Here, a short review of AFM-based methods for the nanomechanical characterization of materials, in particular, force spectroscopy, is reported with the emphasis on materials that can be analyzed.