Electrochemical Approach for In Situ pH Control and Monitoring in Hydrodynamic Environments

While electrochemically driven pH control sensing under quiescent conditions is emerging as a viable electroanalytical method, application of this approach under hydrodynamic conditions is less well documented. In this work, we report the finite element modeling of electrochemical pH control under both quiescent and hydrodynamic conditions, with subsequent experimental validation. A reusable microfluidic platform enabled controlled electrochemical pH control under hydrodynamic conditions. The effect of different flow conditions on proton generation was elucidated both theoretically and experimentally. This dual approach allowed iterative optimization of both the simulation and the experimental setup. Once optimized, this approach was applied to the pH sensitive detection of hypochlorous acid in water under various flow rates. Sensor sensitivity was enhanced from both the localized electrochemical pH control and the signal-boosting effects associated with hydrodynamic forces. This approach demonstrates the potential for future use of these sensors with pH control for in-line measurement such as that in water quality measurement.