Fig. 1. Schematic of experimental setup

Fig. 2. Diagram of fused optical fiber

Fig. 3. XPS image. (a) CuO/PANI; (b) C 1s; (c) N 1s

Fig. 4. SEM images. (a) Cross section of fiber after coating; (b) thickness of cross section

Fig. 5. Spectra response of sensor in various volume fractions of carbon monoxide and fitting line of wavelength shift

Fig. 6. Performance of carbon monoxide gas sensor. (a) Selectivity for gases; (b) response-recovery curve