A dual luminescent sensor material for simultaneous imaging of pressure and temperature on surfaces

A novel kind of composite material for simultaneous luminescent determination of air pressure and temperature is presented. The dual sensor consists of a fluorinated platinum porphyrin complex (PtTFPP) as an oxygen-sensitive probe, and of the highly temperature-sensitive europium complex Eu(tta)(3)(dpbt) as temperature probe. Both are incorporated into different polymer microparticles to control response characteristics and to avoid interferences. Encapsulation of PtTFPP in poly(styrene-co-acrylonitrile) (PSAN) results in a broad dynamic range from 0.05 to 2.00 bar for pressure measurements. The europium complex was incorporated into poly(vinyl chloride) to reduce the cross sensitivity towards oxygen. This system represents a new class of luminescent sensor system, where the signals are separated via the different luminescence lifetimes of the indicators. It is possible to monitor the emission of the temperature-sensitive probe by means of time-resolved fluorescence imaging without interferences, because the luminescence lifetime of the temperature indicator is tenfold longer than that of the oxygen indicator. The temperature image can then be used to compensate cross sensitivity of the pressure indicator towards temperature. In combination with an appropriate time-resolved measurement technique, this material enables simultaneous imaging of pressure (or oxygen partial pressure) and temperature distributions on surfaces. It is distinguished from other approaches of dual pressure and temperature sensitive paints because it avoids the need of signal separation by application of different cameras or by use of different optical filters or light sources.