Surface area independent response of closed bipolar electrodes

Here, we demonstrated the application of a closed bipolar electrode to measure the change in open circuit po-tential (OCP) of Prussian blue/white as a function of [Cl-] concentration independently of electrode surface area. In this bipolar scheme, a potentiostat holds a constant voltage across two separate cells linked by a shared electrode that is sensitive to [Cl- ] on one end and electrodeposited by Prussian blue on the other. As [Cl- ] is added to the sample compartment, the ion associates with Ag+ to produce Ag/AgCl, altering the junction po-tential. This change is balanced electrochemically by a shift in the ratio of Prussian blue/Prussian white. A second potentiostat is used to monitor these changes over the Prussian blue electrode, yielding a for the quan-tification of chloride. We measured a range of 1.0 mM - 55 mM [Cl-] over various electrode surface areas, demonstrating that the signal response is independent of electrode area. Additionally, the system had the capability to translate signal across a single bipolar electrode while using differently sized electrodes in each compartment, a property that could be beneficial for microarrays or signal amplification.

Automated summary

In this study, we presented the application of a closed bipolar electrode for measuring the change in open circuit potential (OCP) of Prussian blue/white as a function of chloride ion concentration. The bipolar scheme consisted of two separate cells connected by a shared electrode, with one end sensitive to chloride ions and the other electrodeposited with Prussian blue. By monitoring the changes in the ratio of Prussian blue/Prussian white over the Prussian blue electrode, we demonstrated the capability of quantifying chloride ions independently of electrode surface area.