Programmable Closed Bipolar Electrochemical Platforms with Ion-Selective Electrode for Electrochemiluminescence Sensing

Abstract Precise and independent control of the interfacial potential of bipolar electrodes (BPEs) is essential for controllable and programmable bipolar electrochemical systems but remains challenging because BPE polarization is inherently coupled to the applied driving voltage and electrode geometry. We report a closed bipolar electrochemical platform in which the interfacial potential of an individual closed bipolar electrode (cBPE) is programmed by integrating an ion-selective electrode (ISE) into a closed electrical loop that represents a fundamental advance in the development of BPE technology. By coupling an ISE to either the anodic or the cathodic pole of a cBPE through Ag/AgCl electrodes and using Kirchhoff’s voltage law, the local potential at the electrode−solution interface can be fixed without introducing a potential-determining opening, drawing a measurable current, or altering the global driving voltage. Electrochemiluminescence (ECL) imaging provides an optical readout of the resulting potential modulation, revealing either selective enhancement or suppression of anodic ECL emission under constant driving conditions. Systematic modulation of the NaCl concentration in the ISE chamber enabled reproducible modulation of cBPE polarization, converting corresponding changes into pronounced optical responses. This closed bipolar ISE-mediated strategy enables signal amplification and sensitivity modulation for cathodic analyte detection and can be readily extended to other ISEs, including pH-selective electrodes. By decoupling the electrode potential from both device geometry and external voltage, this study establishes a general framework for programmable closed bipolar electrochemical sensing and provides a potential basis for future miniaturized and multiplexed sensing platforms.