Atomic force microscopy (AFM) has long been recognized as a potent tool for capturing high-resolution topographical data across a wide spectrum of samples. However, this superior spatial imaging capability has traditionally been counterbalanced by its relatively low temporal resolution. This temporal limitation has posed challenges when investigating dynamic biological interactions that occur on timescales shorter than those achievable by conventional AFM techniques.

In recent years, there has been a concerted effort within the AFM research community, particularly in the realm of biological imaging, to push the boundaries of imaging speed. High-speed atomic force microscopy (HS-AFM) has emerged as a valuable tool for studying biological samples. This technique, which operates in amplitude modulation mode, leverages small cantilevers characterized by high resonance frequencies. It offers the unique capability of real-time visualization of molecular processes. However, due to the relatively substantial interaction forces involved, HS-AFM in tapping mode has been primarily suitable for examining tightly bound biological interactions.

An alternative approach, AFM in off-resonance tapping mode (ORT), holds significant promise for imaging weaker interactions occurring in the micromolar range. In this method, the forces exerted by the tip on the sample are notably reduced compared to tapping mode AFM, enabling non-destructive imaging of biological specimens. Nonetheless, ORT is inherently slow, typically operating at a force curve rate of about 1 Hz.

The proposed project aims to revolutionize high-speed AFM imaging by introducing direct cantilever actuation to perform force-distance ramps at speeds faster than current techniques. This will be accomplished through the development of advanced cantilevers designed for photothermal actuation. The fabrication of such small bimorph cantilevers will necessitate expertise in thin film stress engineering, a thorough understanding of thin film optical properties, and the selection of appropriate optical coating materials. The resulting technology will facilitate rapid yet gentle imaging of biological samples.

Our research will focus on investigating complex biological systems. we will conduct a detailed characterization of the development of order in 2D DNA origami lattices assembled on mica surfaces. These endeavors hold significant promise for advancing our understanding of fundamental biological processes through high-speed AFM imaging.