Optical Fibre Sensor For Measuring pH In Physiological Range

The principle of fibre optic pH sensor operation is given in this paper. PH measurement in 7.0-7.5 range is based on changing of optical property of a indicator. The indicator is sensitive to the hydrogen ion concentration in the water solution. Microspheres of the polymer XAD-2 (a styrene-divinylbenzene copolymer) containing bound phenol red were used as a indicator. Such prepared indicator was inserted in optrode. The optrode was connected with transmitter and receiver by a bundle of glass fibres (multicomponent glass). Transmitter was done by using green LED while receiver construction was based on pin photodiode.