Characterization of planar phosphorescence based oxygen sensors on a TCSPC-PLIM macro-imager

Abstract A set of phosphorescent materials were evaluated using a new macro-imager based on fast time-stamping Tpx3Cam camera with phosphorescent lifetime imaging (PLIM) capabilities. The near-infrared emitting O2-sensitive dye PtBP was embedded in several polymers having different permeability for O2 and applied as solid-state coatings on polyester film support. These sensor materials were placed on a temperature-controlled stage of the imager and imaged under pulsed excitation with a 627 nm LED. The resulting PLIM images showed good uniformity, accuracy and contrast of measured lifetime values for the different phosphorescent materials, and the anticipated lifetime changes with altered temperature or oxygenation conditions, proving the dynamic mechanism of quenching by O2. By imaging the coatings with decreasing dye concentration, stability and limits of sensitivity of the PLIM mode were determined and compared with intensity-based imaging. Several commercial O2 sensors were also imaged and compared with the hand-made sensors, while lifetime measurements on the new imager were compared with those performed on the confocal TCSPC-PLIM microscope.