Recently, a novel integrated optical waveguide 50/50 splitter was developed. It is fabricated using standard lithographic
methods, a pair of etching steps and a laser reflow step. However, unlike other integrated waveguide splitters, the
waveguide is elevated off of the silicon substrate, improving its interaction with biomolecules in solution and in a flow
field. Additionally, because it is fabricated from silica, it has very low optical loss, resulting in a high signal-to-noise
ratio, making it ideal for biosensing.
By functionalizing the device using an epoxy-silane method using small samples and confining the protein solutions to
the device, we enable highly efficient detection of CREB with only 1 μL of solution. Therefore, the waveguide coupler
sensor is representative of the next generation of ultra-sensitive optical biosensors, and, when combined with
microfluidic capabilities, it will be an ideal candidate for a more fully-realized lab-on-a-chip device.