In this paper, we present our results from process development and characterization of optical oxygen sensors that are patterned by traditional UV lithography. An oxygen sensitive luminescent probe, platinum octaethylporphyrin (PtOEP), was encapsulated in commercially purchased photoresist (AZ5214) to form uniform thin sensor films on fused silica substrates. Plasticizer ethoxylated trimethylolpropane triacrylate (SR454) was added to the dye-photoresist sensor mixtures to improve the oxygen sensitivity. The optimum sensor mixture composition that can be patterned with maximum sensitivity was identified. The microfabrication process conditions, cell adherence and oxygen sensitivity results from patterned structures were characterized in detail. Down to 3 µm features have been fabricated on fused silica substrates using the developed techniques. The result implies the developed methods can provide a feasible way to miniaturize the optical sensor system for single cell analysis with precise control of sensor volume and response.