Gastric pH sensing with controlled pore glasses (CPGs) fixed at the distal end of plastic optical fibers

An optical fibre sensor for gastric pH detection is here described, making use of plastic optical fibres (POF) as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), are immobilized on controlled pore glasses (CPGs) fixed at the end of POFs following a proprietary process. The optrode, satisfying clinical requirements, was tested in vitro and in vivo. Precision 0.05 pH units and response time ( 25 seconds) were reached.