Abstract
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•SiO2, TiO2, and SiO2-TiO2 are synthesized and encapsulated by a mixture of four organic dyes by sol-gel method at (60 °C–80 °C).•Crack-free morphology, surface roughness, and thermal stability is attributed to the effect of dyes immobilization on the host matrices.•The sensitivity ∼ 16.34 a.u./pH for d-SNPs, 133.06 a.u./pH for d-TNPs, and 45.14 a.u./pH for d-STNPs matrix is reported.•The fast time response is estimated as 0.35 s, 0.33 s, and 0.31 s in pH 12 for d-SNPs, d-TNPs, and d-STNPs matrices, respectively.
Owing to opto-chemical sensing, three matrices i.e., SiO2, TiO2, and SiO2-TiO2 are synthesized and a mixture of four different organic dyes encapsulated in them through the sol-gel method. Thermally stable, large surface area 434 m2/gm, 197 m2/gm, 332 m2/g, and refractive index 1.49, 1.8, 1.5 at 632 nm are observed for d-SNPs (dyes encapsulated silica nanoparticles), d-TNPs (dyes encapsulated titania nanoparticles), and d-STNPs (dyes encapsulated silica-titania nanoparticles), respectively. When the evanescent field interacts with the fiber optic coating, absorption varied due to pH change and the output intensity is recorded as a sensor response in terms of transmission. The prepared sensors exhibited linear response, non-leachability, and stability towards high pH 12. The fast time response is estimated ∼ 0.35 s, 0.33 s, and 0.31 s in pH 12 for d-SNPs, d-TNPs, and d-STNPs, respectively. Therefore, these prepared optical fiber sensing devices have the potential for practical pH sensing applications.