Potential Modulation and Control of Redox Reactions at Bipolar Electrodes Using an Ion-Selective Membrane

Potential difference at a bipolar electrode (BPE)/solution interface was controlled by forming a polymeric Na ion-selective membrane (ISM) on one part of the BPE. Using the difference between the potentials at the solution/cathodic pole and solution/anodic pole interfaces along with a predetermined driving voltage, the potential differences at the cathodic/anodic pole interface were independently regulated. For open bipolar systems, distinct changes in the intensity of electrochemiluminescence (ECL) were observed by varying the location of the ISM and/or the concentrations of the primary ions determining the potential of the ISM. Folded BPE structures with ISMs at one or both ends of the BPEs were more effective in changing the potential differences at the cathodic/anodic pole interface over a wider range. Furthermore, the potential control was efficient and changes in the ECL intensity were more significant in closed bipolar systems. The device was used for measuring analyte concentration by optimizing the size of the cathodic pole employed for detection and adjusting the driving voltage. We believe that the technique can be a starting point to achieve bipolar electrochemical devices with better controllabilities than those of previous bipolar electrochemical systems and similar reliabilities as those of three-electrode systems.