Fabrication of Long Range Surface Plasmon Polariton Biosensors incorporating Optical Waveguides and Encapsulated Microfluidic Channels via Wafer Bonding"

A microfabricated structure incorporating optical waveguides and closed microfluidic channels is an essential component in realizing a practical long range surface plasmon polariton (LRSPP) biosensor. This has been achieved through advances in fabrication processes to realize reliable optical waveguides, and by development of a reliable wafer bonding process to create closed fluid channels. An existing process for fabrication of gold waveguides was modified by introducing ultra-shallow trenches to recess waveguides and present a planar surface for bonding. An improved fluidic channel etching process was characterized and successfully employed, yielding very smooth channel surfaces free from curtaining and grass issues. Optical performance of the complete bonded chips was demonstrated and verified using a cutback measurement method, producing an attenuation loss of 4.92 dB/mm. An alternative hot embossing process for formation of microfluidic channels on a TOPAS substrate was investigated.