Figure 9.

Demonstration of respiratory monitoring using optical fiber humidity sensors coated with nanomaterials. (a) Schematic of experimental setup for humidity measurement with an enlarged illustration of an MoS₂-coated etched single-mode fiber (ESMF). The humidity responses from human breathing of the MoS₂-coated ESMF sensor and a comparison to a bare ESMF sensor are shown in the middle and right panels, respectively [86]. Courtesy: Adapted with permission from ref. [86]. Copyright 2017 Elsevier. (b) Schematic of a large-angle tilted fiber grating (TFG) with graphene oxide deposited on the fiber surface. The bottom panel shows the humidity responses from normal (Test 1) and rapid (Test 2) breathing measurements [87]. Courtesy: Adapted with permission from ref. [87]. Copyright 2019 Elsevier.