Figure 3.

Schematic and implementation of U-shape fiber biosensors: schematic of a U-bent fiber section with light propagation within the curved portion of the fiber (a) with inset showing the surface-penetrating meridional rays providing RI sensitivity, and functionalization of the biosensor for glucose detection (b) (ARS—Alizarin Red S) (images reproduced from [27]); (c) U-bent LSPR sensor proposed by Yang et al. with the respective production steps, namely, U-shape production and photographs, and formation of ITO coating for plasmonic-based sensing, with results of the change in transmission spectrum for three different values of RI (d) and the response of the sensor, measuring the wavelength shift over time, for different DNA concentrations (e) (images adapted from [28]).