We describe a device capable of imaging distributions of surface PO 2 as well as oxygen flux (e.g., into the human skin). Oxygen is monitored by a phase-angle-sensitive imaging technique using the effect of luminescence lifetime quenching of ruthenium complexes incorporated into a polymer layer system. The dyes are excited by modulated radiation of blue light-emitting diodes. The phase-shifted luminescence is detected by an intensified CCD camera. Several modulation techniques have been comparatively investigated. The obtained images correspond pixel-by-pixel to the local luminescence lifetimes, which are a direct measure for the distribution of surface PO 2 , or alternatively for the oxygen flux through a permeable diffusion barrier. For an illuminated sensor area of 10 cm 2 and a spatial resolution of 1 mm at the sensor layer, the oxygen resolution is better than ΔPO 2 = 0.3 torr in the absence of oxygen, and better than ΔPO 2 = 4 torr at PO 2 = 160 torr.