Dual Fabry–Pérot interferometric carbon monoxide sensor based on the PaNI/CoO sensitive membrane-coated fibre tip

A novel dual Fabry–Pérot (F-P) interferometric carbon monoxide gas sensor based on polyaniline/CoO (PANI/CoO) sensing film coated on the optical fibre end face is proposed and fabricated. Its structure is composed of standard single-mode-fibre (SMF), endlessly photonic crystal fibre (EPCF), and PANI/CoO sensing membrane (PCSM). Therefore, they form three FP reflectors, the reflector between SMF and EPCF, that between EPCF and PCSM, and interface between PCSM and air. So, the dual F-P interferometer is achieved. The results show that in the range of 0–70 ppm, the interference spectra appear red shift with the increasing carbon monoxide concentration. In addition, the high sensitivity of 21.61 pm/ppm, the excellent linear relationship (R = 0.98476), and high selectivity for carbon monoxide are achieved. The response and recovery time are 35 and 84 s, respectively. The sensor has the advantages of high sensitivity, strong selectivity, low cost, and simple structure and is suitable for sensitive detection of trace carbon monoxide gas.