Luminescence lifetime-based carbon dioxide optical sensor for clinical applications Original Research Article

The development of both an optical planar and capillary based carbon dioxide sensor, which final aim is pCO2 monitoring in adipose tissue of critically ill patients, is reported. The sensor is based on the measuring principle of phase fluorometry using a dual luminophore referencing scheme (DLR) to convert the CO2 dependent intensity signal into phase domain. The CO2 sensors have been prepared by incorporating two appropriate luminophores and a phase transfer agent in a same hydrophobic polymer as matrix. The short-lifetime luminophore used as pH indicator is 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS). The second inert luminophore is the long-lifetime dye Ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) (Ru(dpp)32+), which has been made insensitive to oxygen by immobilising in a suitable oxygen impermeable polymer. As phase transfer agent, tetraoctylammonium hydroxide (TOA-OH) has been chosen.