Biosensing with optical waveguides

Abstract

The chapter gives an overview on modern technologies utilizing optical waveguides for biological, medical and environmental sensing. Section 28.2 presents state-of-the-art transduction mechanisms used in extrinsic sensor schemes as well as the potential and setup of the corresponding biooptrodes. The emphasis of Sect. 28.3 is on intrinsic methods, where the optical waveguide works as a bio-optical transducer itself. High precision techniques to evaluate the resulting changes of the waveguide's properties will be discussed as well as the impact of the waveguide's geometry on functionality and sensitivity of the sensor. In order to illustrate the variety of possible implementations, two novel biosensors will be presented in detail. The first one deploys a planar-optical waveguide to form a microring resonator, while the second uses grating structures inscribed in an optical fiber for the excitation of surface plasmon waves. Section 28.4 gives an introduction to the necessary biofunctionalization of the optical waveguide surface. Section 28.5 discusses the assembly of the sensor with focus on coupling and alignment of the light source.