Top-Down Approach to the Fabrication of GaN-based Photonic Crystal Biosensor

Abstract

Combining optics and microfluidics to create a portable optofluidic photonic crystal (PhC) biosensor is an approach with promising applications in the fields of counter-terrorism, agricultural sciences, and health sciences. Presented here are fabrication processes of a gallium nitride (GaN)-based PhC biosensor with a resonance-enhanced fluorescence detection mechanism that shows potential for meeting the single molecule detection requirements of these application areas. GaN is being targeted as the photonic crystal slab material for two main reasons: its transparency in the visible spectral range, within which the excitation and emission wavelengths of the commercial fluorescent-labeling dyes fall, and its intrinsic thermal stability which provides an increased flexibility of operating in different environments. Optical modeling efforts indicate a 25-fold enhancement of the fluorescent emission in this portable fluorescentbased PhC biosensor.

Fluorescence enhancement in a polymer-based photonic-crystal biosensor

“…In the active modality, the adsorption of target molecules to the PhC surface causes a refractive index change that is translated into reflectance or transmission peak shifts [1][2][3][4][5]. The passive modality demonstrated by our group utilizes the PhC structure to observe enhanced fluorescent emission within resonant defect cavities in a 2D PhC lattice [6][7][8]. Integrating these semiconductor-based PhC structures with biocompatible microfluidic channels is a challenging task that can significantly increase the final cost of the sensor system.…”