Entrapment of phenol red pH indicator into polyaniline sol-gel / N. Othman, U. M. Noor and Herman, S. H.

Optical pH sensors offer a promising alternative
method over the existence pH electrochemical sensor and other.
Due to ability to achieve high performance, electrical passive
operation, simplicity and price effectiveness. Recently, significant
research efforts have been devoted to pH sensors for the
detection of pH variation in high resolution short range changes.
It becomes important to consider ways to heighten the sensitivity
of the indicator by improving combination of the material and
simple method of sensor fabrication. Effort has been put in
studying the fabrication and the sensitivity of film towards pH
range in physiological application. Most optical sensors consist of
an indicator which is immobilized in a polymer matrix. In this
research, polyaniline act as a sol - gel matrix to support pH
sensitive indicator molecules which is phenol red. Polyaniline has
been found to be versatile functional material which is the most
suitable organic material to act as a matrix in aqueous medium
and capability to sense on pH changes. The sensing capabilities of
the device in term its optical absorption intensity with different
pH values were explored. Besides that, simpler and low cost
methods was prepared and developed. Through the final
investigations, it was found that the phenol red immobilized in a
polyaniline film on a portion of fiber optic developed by
deposited for 4 layers at thickness is 88.46 nm, withdrawal speed
with 15 mm/s and re-cladded length is 0.5 cm is the best
optimized parameters.