Underwater Atomic Force Microscope: Development and In situ Testing in Deep Sea

We describe the development and in situ testing results of an underwater atomic force microscope (UAFM) system. The UAFM system is compact, mobile, and mountable on underwater vehicles or submersible seafloor platforms, and intended for in situ observation of microorganisms and microparticulates with a nanometer-scale spatial resolution, especially near deep-sea hydrothermal features. First, we tested the UAFM system in shallow water and achieved AFM imaging in sea water by operating the AFM head remotely from a pier. We then mounted the UAFM on a remotely operated vehicle, and operated the approach and imaging procedures at a water depth of 1600 m. As a result, we successfully achieved in situ imaging of underwater samples with nanometer-scale resolution. This system can provide significant information regarding oceanic ecosystems and material circulation by monitoring and analyzing the spatial distribution of these micrometer-scale particles and their interactions with other parameters (e.g., seawater temperature and dissolved components).