Challenges in imaging of soft layers and structures at solid surfaces using atomic force microscopy

Abstract

Imaging of soft, deformable fluid layers and structures, such as submicron droplets and bubbles or two-dimensional fluid patches, at solid interfaces with an atomic force microscopy (AFM) is a very challenging task. In this article, the authors describe the most common imaging AFM modes and advances in tapping mode AFM imaging of soft systems, as well as discuss the most common artifacts occurring in such experiments during imaging of soft and deformable features at solid interfaces. In general, for rigid and deformable systems, images recorded with the AFM are always a convolution of the tip geometry and the shape of the features being imaged. With deformable samples, the size and shape of the imaged features can additionally be affected by the imaging parameters such as set-point or gains. In addition, AFM images can be easily misprocessed with image enhancement software, resulting in an image that does not represent real features at the surface is created. This review will highlight the necessary procedures to ensure successful and accurate image acquisition in soft features in AFM.