A peanut-shaped optical fiber sensor coated with electrospinning polyvinyl alcohol/nano-ZnO film

A peanut-shaped optical fiber sensor cascaded with a fiber Bragg grating (FBG) was designed to measure temperature and humidity. A mixed polyvinyl alcohol/nano-zinc oxide (PVA/nano-ZnO) solution was electrospinning into nanofibers, and these nanofibers were then attached to the peanut-shaped structure surface to form a nanofiber film. Humidity changes caused changes in both the refractive index and the thickness of the PVA/nano-ZnO composite nanofiber film that subsequently caused changes in the transmitted light loss. Temperature changes caused a shift in the center wavelength of the FBG. Experimental results showed that the humidity and temperature sensitivities of the proposed sensor coated with the PVA/nano-ZnO composite film were −0.02539 dB/%RH and 11.14 pm/℃, respectively. Compared with an optical fiber sensor using a PVA film alone, the humidity sensitivity of the proposed sensor was increased by nearly four times after the addition of nano-ZnO.