Figure 9.

The strategies for improving sensor recovery time and continuous measurement. a) Self‐recovering gas sensors by using CNTs as both the sensing element and heater, significantly improving baseline drift and response time. Reproduced with permission.^{[ 221 ]} Copyright 2018, Royal Society of Chemistry. b) Paper‐based microfluidic skin patches where channels are patterned and radially arranged with different lengths to realize the discrete real‐time measurement of sweat secretion. Reproduced with permission.^{[ 226 ]} Copyright 2019, Springer Nature. c) Sweat collection through microchannels where the passive valves were used for chronometric collection of sweat, resulting in time‐dynamic analysis of sweat analysis using galvanic stopwatches. Reproduced with permission.^{[ 227 ]} Copyright 2019, Wiley‐VCH.