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Portable, Low-Cost, Solid-State Luminescence-Based O2 Sensor

Volume 52, Number 5 (May 1998) Page 750-754

Watkins, A. Neal; Wenner, Brett R.; Jordan, Jeffrey D.; Xu, Wenying; Demas, James N.; Bright, Frank V.

A novel sensor for quantifying molecular O2 based entirely on solidstate electronics is presented. The sensor is based on the luminescence quenching of tris(4,7-diphenyl-1, 10-phenanthroline)ruthenium(II) ([Ru(dpp)3]2+) by molecular O2. The sensor involves immobilizing the ruthenium complex within a porous sol-gel-processed glass film and casting this film directly onto the surface of a blue quantumwell light-emitting diode (LED). The ruthenium complex is excited by the LED, the [Ru(dpp)3]2+ emission is filtered from the excitation with a low-cost acrylic color filter, and the emission is detected with an inexpensive silicon photodiode. The sensor response to gaseous O2 and dissolved O2 in water is presented. The sensor exhibits fast response times and good reversibility, and detection limits are 0.5% , 0.02% , and 110 ppb, respectively, for O2 in the gaseous (linear Stern-Volmer and multi-site Stern-Volmer analysis) and aqueous phase. This sensor provides a cost-effective alternative to traditional electrochemical-based O2 sensing and also provides a platform for other optically based sensors.