Polyacrylonitrile/CoCl2 Nanofibers Based Humidity Sensor for Human Breath and Ambient Humidity Monitoring

Abstract A novel humidity sensor was constructed using the hybrid nanofibers of polyacrylonitrile/CoCl2 (PAN/CoCl2), which were fabricated by electrospinning. Scanning electron microscopy (SEM) image demonstrated that the diameter of PAN/CoCl2 nanofibers ranged from 100 - 500 nm. Energy-dispersive X-ray spectrometer (EDS) analysis confirmed that Co and Cl elements were homogeneously dispersed on the PAN nanofibers. CoCl2 on the surface of PAN nanofibers play a dual function in humidity sensing performances. First, CoCl2 serves as an indicator, which can change the color of nanofibers from blue to white-pink as the relative humidity changed from 11 to 98 %, to realize the colorimetric sensing. Second, CoCl2 could remarkably improve the electric sensing performance. As a result, the PAN/CoCl2 nanofibers offered much enhanced response currents compared to the pristine PAN nanofibers, as the humidity changed from RH 11 to 98 %. In addition, the PAN/CoCl2 nanofibers based humidity sensor was employed to monitor human breath and the ambient humidity, which demonstrated the excellent sensitivity of this humidity sensor. Therefore, we believe that the highly sensitive and simply designed PAN/CoCl2 humidity sensor is a promising candidate for various applications in the field of humidity monitoring.