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Conventional lifetime imaging requires rather complex and expensive instrumentation, like lasers and intensified CCD−cameras. We demonstrate that an array of light-emitting diodes and a directly gatable CCD−camera can be alternatively used for special applications as, for example, imaging of oxygen concentrations on a surface covered by an optical sensor. The suitability of low-cost devices is in this case favored by the microsecond decay times and the spectral properties of highly luminescent ruthenium(II) complexes. For an illuminated sensor area of 5 cm2 and an aimed spatial resolution of 1 mm, oxygen resolution was better than ΔPO2 = 0.4 Torr in the absence of oxygen and ΔPO2 = 2.5 Torr at PO2 = 100 Torr.

The capability of fiber-optic light guides to transmit a variety of optical signals simultaneously has been exploited to construct an optical fiber sensor for measurement of both oxygen and carbon dioxide. The oxygen-sensitive material (a Kieselgel-adsorbed fluorescent metal-organic complex) and the CO/sub 2/-sensitive material (an immobilized pH indicator in a buffer solution) are entrapped in a gas-permeable polymer matrix that is attached to the distal end of the fiber. Both indicators have the same excitation wavelength (in order to avoid energy transfer) but quite different emission maxima. The two emission bands can easily be separated with the help of interference filters and give independent signals. Oxygen can continuously be determined in the 0-200 Torr (0-26.6 kPa) range with +/- 1 Torr accuracy and CO/sub 2/ in the 0-150 Torr (0-20 kPa) range with +/- 1 Torr. The accuracy is higher at low partial pressure, so that the detection limits are at approx. 0.5 Torr in both cases.