CMOS-based colour-change pH measurement system

A real-time pH detection and monitoring sensor system using a novel design neuromorphic CMOS optical sensor chip is presented. The system uses Bogen´s universal indicator solution combined with a white light source and the CMOS optical sensor chip to measure pH as a function of colour change in a sample. Bogen´s universal indicator solution causes a colour change in a sample according to the pH of the sample. The output voltage from the colour-sensitive CMOS photodetector circuit on the chip is proportional to the pH of the sample. Experimental results show that this sensor system can determine the pH of a sample from pH 1 to 9 in real-time. The sensor chip is implemented in AMI 1.5 mum CMOS technology available through MOSIS.