The ability to induce luminescence in a separate cell allows any electrochemical process to be reported on, not just those which can directly or indirectly change the redox state of a local luminophore. The first example of remote reporting used a closed bipolar microelectrode array to monitor the oxidation of ferrocenemethanol in one cell, referred to as the detection cell, through the change in quantum efficiency that accompanied the reduction of resazurin to resorufin in another cell, referred to as the reporting cell. This was used to image the heterogeneity of a Pt catalyst deposited on the detection cell side of the array, but could only be used to report on oxidation reactions. Continued work led to the same system being used to report on the reduction of hexacyanoferrate(III) through the oxidation of dihydroresorufin to resorufin. This method of remote reporting has since been used to detect µM concentrations of hydrogen peroxide and glucose, map the diffusion field of hexacyanoferrate at a microelectrode, and report on the hydrogen evolution occurring at a Pt nanoparticle. Similar systems using the electrochemiluminescence of [Ru(bpy) 3 ] 2+