Simple planar waveguides are well established components for the optical
interrogation of chemical processes at surfaces, with total internal reflection
fluorescence (TIRF) elements having a long pedigree and surface plasmon
resonance (SPR) sensors finding widespread use in biomolecular research, for
example. Key attributes of these devices are that the optical fields are confined to a
submicrometer region above the solid surface of the transducer and that the light is
delivered to the surface in a well-controlled way without passing through the bulk
of the sample. Microfabricated integrated optical waveguides provide a strong and
well-controlled evanescent interaction of light with chemical species at a surface
over a long interaction length and in a very small sample volume, allow integration
of reference sensors and arrays of sensors measuring different parameters on the
same chip, can integrate metallic or transparent electrodes for electrochemical
monitoring or reaction control, may probe a wide range of optical phenomena, and
are compatible with microfluidics systems for sample delivery and with optical
fibre for “solid-state” connection to instrumentation. Optical forces on particles in
the evanescent field also provide the opportunity for manipulation and sorting at
the waveguide surface. In this talk, the potential for planar lightwave circuits as
versatile platforms for constructing advanced biosensors and chemical sensors by
application of suitable surface chemistry will be discussed.