Novel optical pH sensor for high and low pH values

The development of an optical pH sensor based on immobilization of mixture of two dyes on a triacetylcellulose membrane is described. The sensor has a useful pH range at low and high pH values, where glass electrodes show acidic and alkaline errors, respectively. Application of a back-propagation artificial neural network (ANN) model extends the measuring range of the proposed optode to the whole pH range. The results show very good agreement between true and predicted pH values. The response of the sensor is reversible and reproducible (R.S.D. less than 2%).