The application of photonic crystals in biosensor applications has lead to the development of highly sensitive and selective sensor elements. The research efforts undertaken by this group have led to the development of a photonic crystal transducer that acts as a waveguide, nanofluidic flow channel, and resonant defect cavity. This sensor architecture shows promise for greatly enhancing the emission of naturally fluorescent or fluorescently-labeled biomolecules. Due to its transparency in the visible regime, GaN is a viable candidate for this photonic crystal biosensor application. This paper provides an overview of the sensor architecture as well as a discussion of one particular bottom-up approach to its fabrication. Molecular Beam Epitaxy (MBE) growth of heavily Mg doped GaN can result in inversion of the surface polarity from Ga-polar to N-polar GaN. This bottom-up approach includes patterning and etching of the Mg inversion layer, followed by re-growth of the opposite polarity to produce periodically poled GaN. Subsequent wet etching of N-polar regions then produces a GaN based photonic crystal structure. This process shows promise for achieving high aspect ratio, highly anisotropic nanostructures.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.