fig5

Figure 5. Overview of sensing principles based on optical loss. (A) Schematic diagram of two bending deformations of the optical fiber^[126]. Copyright 2023, Elsevier. (a) Micro-bending. (b) U-shaped macro-bending; (B) Stress changes lead to optical loss changes through changes in sawtooth bending of the optical fiber^[119]. Copyright 2016, Elsevier; (C) Three different macro-bending^[130]. Copyright 2024, Elsevier. (a) Droplet-shaped. (b) Knot shape. (c) Figure-of-eight shape; (D) Schematic of the sensing principle of a stretchable optical fiber sensor doped with dye molecules^[131]. Copyright 2022, Elsevier.