A compact optical instrument with artificial neural network for pH determination.
The aim of this work was the determination of pH with a sensor array-based optical portable instrument. This sensor array consists of eleven membranes with selective colour changes at different pH intervals. The method for the pH calculation is based on the implementation of artificial neural networks that use the responses of the membranes to generate a final pH value. A multi-objective algorithm was used to select the minimum number of sensing elements required to achieve an accurate pH determination from the neural network, and also to minimise the network size. This helps to minimise instrument and array development costs and save on microprocessor energy consumption. A set of artificial neural networks that fulfils these requirements is proposed using different combinations of the membranes in the sensor array, and is evaluated in terms of accuracy and reliability. In the end, the network including the response of the eleven membranes in the sensor was selected for validation in the instrument prototype because of its high accuracy. The performance of the instrument was evaluated by measuring the pH of a large set of real samples, showing that high precision can be obtained in the full range.
Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, E-18071 Granada, Spain. scapel@ugr.es
Sonia
S
Capel-Cuevas
Nuria
N
López-Ruiz
Antonio
A
Martinez-Olmos
Manuel P
MP
Cuéllar
Maria del Carmen
Mdel C
Pegalajar
Alberto José
AJ
Palma
Ignacio
I
de Orbe-Payá
Luis Fermin
LF
Capitán-Vallvey