Two-Photon Lithography of Platinum-Porphyrin Oxygen Sensors

Oxygen sensing structures were generated by two-photon microfabrication. By copolymerizing metalloporphyrins with a two-photon (2P) photo-initiated polymer, oxygen sensors were patterned into complex 3-D shapes. The sensors were generated on the interior walls of small bore capillaries to allow for controlled concentrations of oxygenated water and cell-rich media to be pumped through their local environment. Phosphorescence lifetime of the patterns were acquired at known levels of O₂ as a standard for measuring the respiration rate of a tiny population of bacterial cells. In addition, we report that the inclusion of the Pt-Porphyrin significantly reduces the 2P polymerization threshold. Fabricating near the inferred polymerization threshold, 3-D structures as small as 50 nm were observed in both the Pt-Porphyrin enhanced and the pure photopolymerizable monomers