Fig. 2From: Colorimetric Humidity Sensors Based on Electrospun Polyamide/CoCl2 Nanofibrous Membranes a The photographs of PA66/CoCl2·6H2O NFMs containing different concentrations of CoCl2·6H2O: 0, 10, 30, and 50 wt% in different RH. b Humidity dependence of visible absorption spectra (380–780 nm) of PA66/CoCl2·6H2O (50 wt%)Back to article page