Electrophotonics: multimodal sensors for bacteria identification and phenotyping

Abstract

A comprehensive understanding of bacteria phenotypes requires tools that are able to characterise structure and function across multiple length scales, from communities and individual cells down to single molecules. Multimodal sensing combines multiple transduction technologies in parallel to probe different properties simultaneously, and thereby increase the range of measurable interactions, the amount of information that can be extracted, and improve detection accuracy. Electrophotonics is a multimodal sensing approach that combines electrochemical and photonic techniques in a single, integrated device that provides enhanced quantitative measurements of chemical reactions. We present a new electrophotonic device based on a Si3N4 guided mode resonant (GMR) structure with an integrated indium tin oxide (ITO) electrode. The GMR structure is sensitive to refractive index changes at the sensor surface, enabling label free, real time detection of biomolecules, microorganisms and imaging of molecular interactions with micrometre-scale resolution to provide spatial information about surface binding interactions. The ITO electrode has been shown to be compatible with voltammetry-based techniques for interrogating redox behaviour along with electrochemical impedance spectroscopy. We demonstrate the wide range of microbiological applications of electrophotonic technology including the characterisation of redox active protein electron transfer and surface adsorption, bacterial adherence and growth on chemically functionalised surfaces, and label free parallel detection of clinically relevant biomarkers. We believe that the multimodal measurements with this novel technology can provide new approaches to investigate and understand microbial biology.