Solvent-assisted titania nanoparticles based fiber optic pH sensor: structural, optical, and sensing characteristics

Owing to pH sensing applications, titania nanoparticles (TNPs) are synthesized at low temperatures 90 °C by sol-gel method and exposed to different solvents i.e., methanol, ethanol, propanol, and butanol. The solvents formed the pores in the TNPs matrices which effectively host phenol red (PR) dye species and enhanced the sensitivity of the fiber optic sensor. Atomic force microscopy exhibited the crack-free, dense porous morphology of butanol-assisted TNPs with average roughness 2.5 and film thickness of ~13 nm. The refractive index 1.7 with 64% porosity is observed for B-TNPs. The sensitivity of PR-immobilized B-TNPs is observed 5.47 counts/pH. The experimental findings suggested that the synthesized B/TNPs have practical usage in different fields such as food science, environmental monitoring, and agriculture research. Graphical abstract