We report on the development of a novel optical oxygen sensor for breath monitoring applications using the technique of phase fluorometry. The principal design criteria are that the system be compact, lightweight, and employ a disposable sensing element (while performing competitively with current commercial analyzers). The oxygen-sensitive, luminescent ruthenium complex Ru[dpp] is encapsulated in a sol-gel matrix and deposited onto a custom-designed, polymer sensor chip that provides significantly improved luminescence capture efficiency. The performance of the sensor module is characterized using a commercially available lung simulator. A resolution of 0.03% O2 is achieved, which compares well with commercial breath monitoring systems and, when combined with its immunity to humidity and ability to respond effectively across a broad range of breathing rates, makes this device an extremely promising candidate for the development of a practical, low-cost biodiagnostic tool.
The development of polymer waveguide chips as platforms for optimized absorption-based optical chemical sensors is reported here. The chips were designed in accordance with theoretical predictions published elsewhere relating to the optimization of the sensitivity of optical absorption-based sensors. The waveguides were fabricated by micro-injection moulding and coated with a colourimetric, sol-gel-derived sensing layer. They were then incorporated into a compact, LED-based sensing device for the detection of gaseous NH3. Results presented here demonstrate comparable sensitivity to more complex systems reported to date.