Abstract

CORDOBA, Carlos; MERA, Jenny; PAREDES, Omar  and  BENAVIDES, Javier. Sensor óptico para mediciones de PH obtenido por el método sol-gel con moléculas orgánicas dopadas en matriz vítrea. Rev. Soc. Quím. Méx [online]. 2004, vol.48, n.3, pp.203-207. ISSN 0583-7693.

A sensor for optical response to measure the environmental acidity was prepared with four- organic molecules mixture: p-dimethylaminazobenzene (dimethyl yellow), (o-[[p-(dimethylamin)phenyl]azo]benzoic) acid (methyl red), α,α Bis (6 bromo 5 hydroxycarvacryl) a hidroxi -o- toluene g sulphone (bromothymol blue), and α-hidroxi-α , α-bis (5 hydroxycarvacryl)-p-toluensulphonic acid (timol blue), which were incorporated to the vitreous network through a sol-gel process using tetraethylortosilicate (TEOS) and methyltrietoxide of silicon (ME₃S) as precursors; the pH ranged from 1 to 10. The films were deposited over a small pieces of soda lime glass, and the optical characterization of films was carried out by absorption spectrometry using a Perkin Elmer Lambda 11. The Photostability surveys of the samples were performed with an ultraviolet lamp of 10W at different exposure times, after that they were immersed in different acid, aqueous and alkaline environments (NaOH 0.5M, Na₂CO₃ 0,1M) to probe adherence and chemical resistance properties. The Sensor obtained is sensitive to pH variations both in liquids as in moist gases, in addition, it is a reversible and stable sensor to chemical changes.

Keywords : Optical sensor; sol-gel method; absorption.