Electrogenerated Chemiluminescence Reporting on Closed Bipolar Microelectrodes and the Influence of Electrode Size

We report a fundamental study on the use of Ru(bpy)(3)(2+)-based electrogenerated chemiluminescence (ECL) as an optical reporting system for the detection of redox-active analytes on closed bipolar microelectrodes, focused on gaining an in-depth understanding of the correlation between the ECL emission intensity and the electrochemical current. We demonstrate the significant effect that the size of the anodic and cathodic poles has on the resulting ECL signal and show how this influences the quantitative detection of an analyte on a closed bipolar electrode. By carefully designing the geometry of the bipolar electrode, the detection performance of the system can be tuned to different analyte concentration ranges. We show that, through a simple voltammetric study of the individual reactions, one can understand the coupled bipolar behavior and accurately predict the ECL signal response to a range of analyte concentrations, enabling the accurate prediction of calibration curves.