Dual-Color Electrogenerated Chemiluminescence from Dispersions of Conductive Microbeads Addressed by Bipolar Electrochemistry

Bipolar electrochemistry (BPE) is exploited here to address simultaneously thousands of carbon microbeads dispersed in solution. The suspension is placed in a capillary between two feeder electrodes generating an electric field insitu. The simultaneous occurrence of electrogenerated chemiluminescence (ECL) at each bead leads to a global 3D luminescent phenomenon, remotely driven by BPE. This concept, demonstrated previously as a proof-of-principle, is extended here to luminol in order to tune the emission wavelength. Determinant analytical parameters such as the applied voltage and the number of emitters were studied for the optimization of the system. The linearity of the ECL intensity in the bulk as a function of the luminophore concentration is successfully demonstrated for both ECL systems [luminol and Ru(bpy)₃²⁺]. Finally, we show that both luminophores can be combined in the same capillary and addressed by BPE, thus leading to simultaneous ECL emissions at distinct wavelengths.