AFM enabled the observation of a greater number of smaller GO flakes, which adhered better to the mica substrates coated with positively charged poly-L-lysine. Despite a clear size difference visually observable on AFM scans, the boxplots did however not reveal a dramatic change in terms of lateral dimensions between s-GO and us-GO (Figure ). The boxplots suggest that the sonication time affected preferentially the remaining larger GO flakes in s-GO and induced their break down into smaller pieces during the production of us-GO, thus narrowing the overall size distribution of us-GO in comparison to s-GO. However, we cannot exclude other possible explanations for the lack of statistical significance, such as the limitations of the segmentation algorithm used to discriminate the GO flakes on AFM scans, which may include pixel artefacts or unsatisfying segmentation of nearby flakes which led to the fusion of several sheets all together.