We report the development of oxygen sensors using polymer photonic bandgap structure and CMOS chips. These integrated sensors provide a new platform for the development of low cost, low (battery) powered, light weight, robust, fast and small sensors. We demonstrate an approach to encapsulation of chemical and biological recognition elements within the porous structures. This sensing platform is built on our recently demonstrated nanofabrication technique using holographic interferometry of a photo-activated mixture that includes a volatile solvent as well as monomers, photoinitiators, and co-initiators. Resulting structure is nanoporous polymer 1D photonic bandgap structures that has reflection grating property and can be directly integrated into optical sensor systems that we have previously developed. For optical sensor system, CMOS (Complementary Metal Oxide Semiconductor) detectors that include phototransistors, trans impedance amplifier, and other signal processing units are used. Combining CMOS chip and nano-porous polymer reflection grating, we demonstrate an oxygen sensor as a prototype by encapsulating the fluorophore (tris(4,7-diphenyl-1,10-phenathroline)ruthenium(II) using fluorescence intensity.