Figure 3.

Applications of flexible humidity sensors: (a) the current signal profiles of human nose breathing and mouth breathing (reproduced with permission from [65]); (b) image of the application of the humidity sensor for monitoring human breath (reproduced with permission from [66]); (c) photos of a SAS diagnosing–treating system with an integrated CEH sensor (reproduced with permission from [67]); (d) a TiO₂/CNC humidity sensor used in a moisturization experiment, in which a commercial skin moisture detector was used as a reference (marked as “C”) (reproduced with permission from [68]); (e) schematic illustration of MPHS for detecting exhaled air during speaking (reproduced with permission from [69]); (f) proof-of-concept of non-contact fingertip interfaces (reproduced with permission from [33]).