Resonant Waveguide Imaging of Living Systems: From Evanescent to Propagative Light
Résumé
For more than 50 years, resonant waveguides (RWGs) have offered highly sensitive label-free sensing platforms to monitor surface processes such as protein adsorption, affinity binding, monolayer to multilayer build-up, bacteria and more generally adherent or confined living mammalian cells and tissues. Symmetrical planar dielectric RWG sensitivity was improved by metal coating of at least one of their surfaces for surface plasmon resonance undertaking (SPRWG). However, RWG sensitivity was often obtained at the expense of spatial resolution and could not compete with other high resolution fluorescence microscopies. For years, RWGs have only rarely been combined with high-resolution microscopy. Only recently, the improvement of intensity and phase light modulation techniques and the availability of low-cost high numerical aperture lenses have drastically changed the devices and methodologies based on RWGs. We illustrate in this chapter how these different technical and methodological evolutions have offered new, versatile, and powerful imaging tools to the biological community.