Development of pH sensor with enhanced sensitivity using volume of bubbles generated by electrolysis

We have demonstrated a novel and simple pH sensor using electrolysis process. The pH sensor is composed of actuating and sensing electrodes sets, micro-channel and micro-reservoir embedded PDMS part. The electrodes on silicon substrate are formed by a single-step lift-off, and the channel and reservoir are molded on PDMS. The volume of hydrogen bubbles generated by electrolysis is dependent on the pH value, and the bubbles push the pH buffer solution in the reservoir into the micro-channel. The pushed distance results in the current changes between the sensing electrodes. The experimental results show that the developed pH sensor gives enhanced sensing response at strong acid, and the sensing resolution can be enhanced as the electrolysis time increases.