Breath-by-breath measurement of oxygen using a compact optical sensor.

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](3)(2+) 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% O(2) 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.

Development of an integrated optic oxygen sensor using a novel, generic platform.

This paper describes the development of a generic platform for enhanced, integrated optic sensors based on fluorescence detection. The platform employs a novel optical configuration in order to achieve enhanced performance and has inherent multianalyte detection capability. The sensor element comprises a multimode ridge waveguide that has been patterned with an analyte-sensitive fluorescent spot, which is excited directly using a LED. The platform was applied to the detection of gaseous oxygen as a proof of principle. The sol-gel-derived sensor spots were doped with an oxygen-sensitive fluorescent dichlororuthenium dye complex and intensity-based calibration data were generated from the oxygen-dependent waveguide output. The sensor achieved a LOD of 0.62% and a resolution of less than 0.96% gaseous oxygen, which compares favourably with a similar, recently reported system. This device highlights the combination of inexpensive rapid prototyping techniques and a dedicated sensor enhancement strategy that together facilitate the production of an effective prototype sensor platform.

Sol-gel based optical carbon dioxide sensor employing dual luminophore referencing for application in food packaging technology.

An optical sensor for the measurement of carbon dioxide in Modified Atmosphere Packaging (MAP) applications has been developed. It is based on the fluorescent pH indicator 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) immobilised in a hydrophobic organically modified silica (ormosil) matrix. Cetyltrimethylammonium hydroxide was used as an internal buffer system. Fluorescence is measured in the phase domain by means of the Dual Luminophore Referencing (DLR) sensing scheme which provides many of the advantages of lifetime-based fluorometric sensors and makes it compatible with established optical oxygen sensor technology. The long-term stability of the sensor membranes has been investigated. The sensor displays 13.5 degrees phase shift between 0 and 100% CO2 with a resolution of better than 1% and a limit of detection of 0.08%. Oxygen cross-sensitivity is minimised (0.6% quenching in air) by immobilising the reference luminophore in polymer nano-beads. Cross-sensitivity towards chloride and pH was found to be negligible. Temperature effects were studied, and a linear Arrhenius correlation between ln k and 1/T was found. The sensor is stable over a period of at least seven months and its output is in excellent agreement with a standard reference method for carbon dioxide analysis.