Luminescence-based optical sensors towards in vivo analysis

Abstract

Continuous monitoring of physiological parameters such as pH and oxygen (O₂) are of great importance in determining the health status of a patient. Arterial blood gas analysis is a current clinical method used to measure pH, PCO₂, PO₂, and the concentration of variety of ions, typically with blood withdrawn from an artery. The need for robust, and a rapidly responding technology to enable bed-side monitoring has driven considerable efforts to produce better sensor devices. Optical sensing systems have experienced rapid growth, with drivers including low-cost optical fibres, and the availability of miniature optical set-ups (light sources, detectors, etc.).

Herein, polymer-based optical fibre sensors for pH and O₂ sensing were developed. The pH and/or oxygen reporters were immobilised at the end of an optical fibre by photo-polymerisation, and their performance in measuring pH and O₂ concentration investigated. pH sensing was based on fluorescence detection using single excitation/single emission (Chapter 2), and single excitation/dual emission (Chapter 3). O₂ sensing was based on the luminescence quenching of metalloporphyrins by oxygen (Chapter 4). In the last chapter, the in vivo applicability of an O₂ sensor was investigated by measuring O₂ level changes inside an ex vivo lung.