Planar optical waveguide-based dimethylamine sensor with cresol red/TiO₂ composite thin film

Abstract

A planar optical glass-slide-based dimethylamine (DMA) sensor was fabricated with composite thin film of cresol red and titanium dioxide as the sensing layer and tin-diffused planar glass slide as the substrate. The UV-visible spectrum before and after analyte exposure was investigated to detect the color transformation of sensing layer and to select a laser light source wavelength (532 nm). DMA detection response along with time were performed on an optical waveguide system at room temperature. Experimental results show that this sensing film had not only fast response (6 s) but also rapid recovery (21 s) ( 0.004 m g / m 3 ). Besides, detection is available for DMA solution as low as 0.0008 m g / m 3 concentration with signal-to-noise ratio (S/N) 5.29. The sensing film is stable for one month at ambient temperature, and the response reaction is reversible.