Two optical sensor platforms based on evanescent wave interactions for detection of biomolecules are presented. The first, a sol-gel derived planar waveguide, employs a grating coupler to couple light into a guided mode. The evanescent field of the mode interrogates the sensing layer. The platform employing mono-mode waveguides is described and applied to the imaging of fluorescently labelled antibodies which are immobilised on the waveguide surface. The antibodies, immunoglobulin G, are immobilised via an avidin-biotin bridge. First avidin is coated onto a silanized waveguide via a crosslinker. Then the surface is incubated with biotinylated fluorescently labelled antibodies. Compact optics image the evanescently excited fluorescence onto a large area, cooled CCD array. The image data is processed and corrected for local background levels. The second, a Surface Plasmon Resonance (SPR) refractive index sensor comprises of an integrated miniature SPR device interfaced to a computer. The sensor combines all of the necessary electro-optical components to excite a surface plasmon wave and quantify the resonance condition, within a single platform. This sensor is applied to liquid refractive index sensing and the monitoring of biomolecular interactions. Finally, work leading to the development of disposable sensor chips for use on the TI SPR sensor is presented.