This research focuses on the design of chemically functionalized optical waveguide sensors. The waveguide is an optically transparent sol-gel coated onto a glass substrate chip. By having a higher refractive index than the substrate, the waveguide internally reflects a laser beam to photodetectors at both ends of the chip. The adsorption of any species onto the waveguide surface changes the light propagation, and therefore its effective refractive index, N. The change in N is dependent upon the amount of analyte present. By covalently bonding specific chemical receptors onto its surface, it can be designed to target a particular analyte. This research involves functionalizing the surface of the waveguide with ED3A in order to complex out of solution Ni2+. The change in N and the thickness of the adlayer will allow the concentration to be determined.