Revealing the static and dynamic nanomechanical properties of diatom frustules-Nature's glass lace

Diatoms are single cell microalgae enclosed in silica exoskeletons (frustules) that provide inspiration for advanced hybrid nanostructure designs mimicking multi-scale porosity to achieve outstanding mechanical and optical properties. Interrogating the structure and properties of diatoms down to nanometer scale leads to breakthrough advances reported here in the nanomechanical characterization of Coscinodiscus oculus-iridis diatom pure silica frustules, as well as of air-dried and wet cells with organic content. Static and dynamic mode Atomic Force Microscopy (AFM) and in-SEM nanoindentation revealed the peculiarities of diatom response with separate contributions from material nanoscale behavior and membrane deformation of the entire valve. Significant differences in the nanomechanical properties of the different frustule layers were observed. Furthermore, the deformation response depends strongly on silica hydration and on the support from the internal organic content. The cyclic loading revealed that the average compliance of the silica frustule is 0.019 m/N and increases with increasing number of cycles. The structure-mechanical properties relationship has a direct impact on the vibrational properties of the frustule as a complex micrometer-sized mechanical system. Lessons from Nature's nanostructuring of diatoms open up pathways to new generations of nano- and microdevices for electronic, electromechanical, photonic, liquid, energy storage, and other applications.

Automated summary

Diatoms, with their unique silica exoskeletons, provide inspiration for the design of advanced nanostructures with outstanding mechanical and optical properties. Through nanomechanical characterization, it is found that diatoms exhibit peculiar responses at the nanoscale due to material behavior and membrane deformation. The nanomechanical properties of different layers of the exoskeleton differ significantly, and the deformation response is influenced by silica hydration and organic content. The relationship between structure and mechanical properties has implications for the vibrational properties of diatoms as mechanical systems. Lessons from diatom nanostructuring have the potential to advance various applications in electronics, electromechanics, photonics, liquid systems, and energy storage.