Probing shapes of microbes using liquid crystal textures

TL;DR

This paper introduces a new optical microscopy technique using liquid crystal textures to determine the shape and asymmetry of microbes embedded in nematic liquid crystals, even at nanometer scales.

Contribution

It presents a novel method combining optical microscopy and numerical simulations to infer microbe shapes from liquid crystal textures, revealing asymmetries at small scales.

Findings

Brush patterns reflect microbe shape asymmetry

Method can detect nanometer-scale microbes

Brush geometry correlates with microbe aspect ratio

Abstract

We propose a novel technique to probe shape of a single microbe embedded in a nematic liquid crystal (NLC) sample by observing geometry of dark brushes with optical microscope using a cross-polarizer set up. Assuming certain anchoring conditions for the NLC director at the surface of the microbe, we determine the resulting shapes of brushes using numerical simulations. Our results suggest that for asymmetrical microbes (such as cylindrical shaped bacteria/viruses), resulting brushes may carry the imprints of this asymmetry (e.g. the aspect ratio of cylindrical shape) at relatively large distances to be able to be seen using simple optical microscopy even for microbe sizes in few tens to few hundred nanometer range.