Self-Assembled Nanoparticle Surface Patterning for Improved Digital Image Correlation in a Scanning Electron Microscope

A self-assembled gold nanoparticle surface patterning technique is presented that enables nanometer spatial resolution for digital image correlation (DIC) experiments in a scanning electron microscope. This technique, originally developed for surface-enhanced Raman scattering substrates, results in the assembly of individual 15–136 nm diameter gold nanoparticles over the surface of the test sample. The resulting dense, randomly isotropic, and high contrast pattern enables DIC down to an unprecedented image resolution of approximately 4 nm/pixel. The technique is inexpensive, fast, results in even coverage over the entire surface of the test sample, and can be applied to metallic and non-metallic substrates as well as curved or delicate specimens. In addition, the pattern is appropriate for multi-scale experimental investigations through the utilization of nanoparticle aggregates that collect on the surface in combination with the pattern formed by individual nanoparticles.