Wireless Iridium Oxide-Based pH Sensing Systems

Monitoring of pH level plays an important role in various processes. Commercial devices can provide precise and reproducible readings; however the drawbacks in size as well as spatial and temporal resolution limit their use in a number of applications. In this paper, we present complete systems of pH measurement incorporated with wireless communication. The pH sensors were developed by electrodeposition onto polymer-based gold electrodes to form the iridium oxide sensing film. The wireless schemes were achieved by using an active method via Bluetooth-low-energy (BLE) communication and a passive method via load modulation-based (LM) inductive coupling. Both approaches were validated against probe calibrations for comparisons, showing promising results. Thus, our proof-of-concept systems hold promise to be applied in numerous practical scenarios, supporting research as well as process and environmental monitoring.