Soft matter analysis via atomic force microscopy (AFM): A review

Soft materials or soft condensed matter are being globally developed for various technological applications for chemical, consumer goods, pharmaceutical, agri-business, and petroleum industries. As such, there is a growing research interest in understanding the dynamics, structure, and morphology of soft materials, particularly in soft interfacial materials. While atomic force microscopy (AFM) is conventionally used for solid matter research studies, this review focuses on the emerging application of AFM as an effective analytical tool for investigating soft materials. By harnessing the capabilities of AFM, researchers can explore soft condensed matter in novel ways. Specifically, this review discusses the three AFM modes; contact, non-contact, and tapping modes, highlighting their working principles and recent applications in soft matter analysis. Moreover, derivatives of each principal AFM mode, such as Lateral Force Microscopy (LFM), nanolithography, force spectroscopy, Conductive AFM (CAFM), Scanning Polarization Force Microscopy (SPFM), and PeakForce Tapping (PFT) are included and discussed in detail. Critical analysis and comparison of these imaging modes are presented, shedding light on their advantages and disadvantages in soft matter analysis. This review aims to provide researchers with valuable insights for further advancements in the field by presenting a comprehensive overview of AFM modes in soft matter research.