Werner Ziegler

Oxygen flux fluorescence lifetime imaging

We describe a device capable of imaging distributions of surface PO2 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 PO2, or alternatively for the oxygen flux through a permeable diffusion barrier. For an illuminated sensor area of 10 cm2 and a spatial resolution of 1 mm at the sensor layer, the oxygen resolution is better than ΔPO2 = 0.3 torr in the absence of oxygen, and better than ΔPO2 = 4 torr at PO2= 160 torr.

Fluorescence Lifetime Imaging of the Skin PO2 Supply

The quality of the local blood microcirculation and the cutaneous “respiration” are important factors in the diagnosis of circulatory disturbances, which may arise as a consequence of a number of clinical diseases. Some of the more important are smokers leg, burns, ulcerations, or tumors of the skin.