Plastic optical fiber sensor for gastric pH detection

An optical fiber sensor for gastric pH detection is described, making use of plastic fibers 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 glass (CPG) fixed at the end of plastic optical fibers following a proprietary process. The realized optrode, satisfying clinical requirements, was tested `in vitro.' A precision of <= 0.04 pH units and a response time of (<= 15 seconds) were reached.