Biological Cell Resonators

TL;DR

This thesis advances the understanding of biological cell resonators by developing a comprehensive theoretical and computational framework for whispering gallery modes, demonstrating their potential for non-invasive cell health monitoring.

Contribution

It introduces a unified model for multilayer microspheres, extends Mie scattering theory, and provides evidence that biological cells like bovine embryos can sustain whispering gallery modes.

Findings

Biological cells can sustain whispering gallery modes.

A new computational model for multilayer microspheres is developed.

Bovine embryos are identified as viable resonator candidates.

Abstract

This thesis develops the theory of whispering gallery modes, exploring under what conditions a micro or nanoscale device can sustain these resonances, and for which physical criteria the resonance conditions deteriorate. The study is then extended to consider the biological cell in which modes are definitively sustained without artificial assistance. The properties of resonators and their emitted energy spectra are studied within the general framework of the Finite Difference Time Domain method, requiring supercomputing resources to probe the transient behaviour and interactions among the electromagnetic fields. The formal theory of Mie scattering is also extended to develop a cutting-edge, computationally efficient model for general, multilayer microspheres, which represents a valuable achievement for the scientific community in its own right. The model unifies the approaches in the field of mathematical modelling to express the energy spectrum in a single encompassing equation, which is then applied in a range of contexts. The gulf between modelling and biological resonators is bridged by an in-depth study of the physical characteristics of a range of biological cells, and the selection criteria for viable resonator candidates are developed through a number of detailed feasibility studies. The bovine embryo is consequently selected as the optimal choice for this investigation. Evidence is established for the ability of a bovine embryo to sustain whispering gallery modes. The ability of a cell to sustain modes on its own represents a conceptually elegant paradigm for new technologies involving on-site cell interrogation and reporting of the status and health of a biological cell in the future. The methodological and technological developments contained herein thus become a vital asset for the future realisation of autonomous biological cell sensors.