Investigation of Light Manipulation by the Ultrastructure of Marine Diatoms

Abstract

Abstract : This report results from a contract tasking University of Exeter as follows: Our investigation will comprise five principle sections: 1. Determination of the ranges and geometries of the most common forms of diatom structures. This will enable selection of representative species for optical characterisation and will be accomplished thorough literature searches and short visits to two eminent diatom biology specialists (in Germany and in Belgium). 2. Measurement of absolute spectral transmittance of diatom valve structures Experimental analysis will be challenging due to the microscopic sizes of individual diatoms and the difficulty with which conventional optical experiments may be applied to the study of constituent parts of isolated individual diatoms. To this end, we aim to refine the process that was originally developed to characterise optically the isolated single photonic scales of butterflies, applying it in turn both to single whole diatoms and also to individual separated valves. 3. Rigourous SEM and TEM analysis of diatom valve ultrastructures. This will yield ultrastructure symmetry geometries and periodicity-dimensions with which light interaction may be modeled. The resulting theoretical band diagrams and calculated diffraction efficiencies will be compared and contrasted to experimental data. 4. Finite-element based computer modelling. Comsol (formerly Femlab) will be used to recreate virtual 3D diatom structures and model light interaction. 5. Measurement of the spatial symmetry of diffractive interaction of incident light with diatom ultrastructures. This will offer insight into the key assumed potential advantages associated with diatom ultrastructure evolution. Additionally, it will offer strong indication of the feasibility of incorporating natural and also cell-cultured and mineral- or metal-infused diatoms into electro-optical devices.