Novel optical oxygen and carbon dioxide sensors for monitoring biological systems

Optical sensing methods are particularly attractive for such applications due to their high sensitivity, low cost, non-consumptive nature, and suitability for sealed and miniaturised measurement systems. This thesis investigates the development and application of optical oxygen (O₂) and carbon dioxide (CO₂) sensors for use in micro-respirometry systems, with a focus on rapid microbiological analysis and the monitoring of small gaseous changes in biological systems.<br><br>The Introduction chapter outlines the principles of micro-respirometry and optical gas sensing, including the photophysical basis of luminescent oxygen sensing and colourimetric carbon dioxide sensing.

Existing applications of optical O₂ and CO₂ sensors in microbiology, environmental monitoring, and biological<br>analysis are also discussed.<br><br>The Experimental chapter describes the principal instrumentation and methodologies employed throughout the thesis, including luminescence lifetime measurements, digital photography and digital colour analysis (DCA), UV-Vis spectroscopy, microbiological techniques, gas blending, and the preparation of optical sensor<br>systems.<br><br>Chapter 3 investigates inexpensive ink-based phosphorescent O₂ sensors for measuring total viable count (TVC) using micro-respirometry.