Characterization of diatom silica exoskeletons using atomic force microscopy: Topography and mechanical properties

Abstract

Hierarchically structured natural objects provide a promising base for developing advanced hybrid materials and devices for a wide range of applications. Particularly high level of interest has recently been placed on diatom algae, eukaryotic unicellular microorganisms that represent a potential solution to the fundamental problems of bionics, specifically, the effective application of exoskeleton building principles to high efficiency engineering device fabrication. Developing hull engineering structures, in particular, requires a thorough understanding of the structural and mechanical characteristics of diatom frustules. The present study investigated the morphology, topography and mechanical properties of Coscinodiscus oculus-iridis diatom frustules using atomic force microscopy and scanning electron microscopy. The Young’s modulus showed a decrease from the side to the center of the frustule, with the variance up to fivefold, demonstrating the deformation of the structure. Nanostructured siliceous exoskeletons (frustules) offer unique guidance for developing a new generation of nano- and microdevices for electronic, electromechanical, photonic, and other uses by revealing the underlying relationship in the structure-properties-function chain.