Electrochemiluminescence reaction pathways in nanofluidic devices

Abstract

Nanofluidic electrochemical devices confine the volume of chemical reactions to femtoliters. When employed for light generation by electrochemiluminescence (ECL), nanofluidic confinement yields enhanced intensity and robust luminescence. Here, we investigate different ECL pathways, namely coreactant and annihilation ECL in a single nanochannel and compare light emission profiles. By high-resolution imaging of electrode areas, we show that different reaction schemes produce very different emission profiles in the unique confined geometry of a nanochannel. The confrontation of experimental results with finite element simulation gives further insight into the exact reaction ECL pathways. We find that emission strongly depends on depletion, geometric exclusion, and recycling of reactants in the nanofluidic device.

Wireless Enhanced Electrochemiluminescence at a Bipolar Microelectrode in a Solid-State Micropore

“…The fact that we were not able to resolve better the size and the shape of the rhombus surface by ECL imaging is most probably due to the low optical resolution resulting from the transmission through the 2.5millimeter thick PDMS layer covering the microchip. In previous works, 22,23 we investigated also ECL in confined environments. The ECL patterns were different because light was generated either in the nanochannel at or the level of the access hole areas depending on the annihilation or coreactant modes, respectively.…”

“…[15][16][17][18][19][20][21] ECL was also investigated in various confined configurations. 7,10,11,[22][23][24] In the last decade, ECL was successfully combined with bipolar electrochemistry (BE) because it is a wireless electrochemical technique. [25][26][27][28][29][30][31][32][33] Indeed, due to this contactless nature, classical BE setups do not allow to measure directly an electrochemical signal reflecting the reactivity of the investigated conductive object in a straightforward way.…”

A Guide Inside Electrochemiluminescent Microscopy Mechanisms for Analytical Performance Improvement

“…The reagents lifetime limits the ECL vertical resolution, and mechanistic insights were successfully investigated by Voci et al exploiting the reduced volume of a nanochannel device. 34 ECL was generated applying 2 V at the electrode at the bottom of the nanochannel and 0 V potential at the top electrode to avoid the reduction of luminophore [Ru(bpy) 3 ] 2+ and consequently the annihilation pathway. 2 Luminescence was observed only at the level of access holes of the nanochannel, and this limitation is due to the diffusion of oxidized [Ru(bpy) 3 ] 3+ and the lifetime of the coreactant TPrA, as previously anticipated.…”

“…The reagents lifetime limits the ECL vertical resolution, and mechanistic insights were successfully investigated by Voci et al exploiting the reduced volume of a nanochannel device . ECL was generated applying 2 V at the electrode at the bottom of the nanochannel and 0 V potential at the top electrode to avoid the reduction of luminophore [Ru­(bpy) 3 ] 2+ and consequently the annihilation pathway .…”

Deciphering the Mechanisms of Electrochemiluminescence by Spatially Resolved Measurements

“…Moreover, the light emission was distributed homogeneously along the nanochannel. Interestingly, ECL intensity decreased remarkably upon adding TPrA to the nanochannel [65] . Under this circumstance, annihilation and coreactant ECL coexisted, whereas byproduct of side‐reactions during oxidation of TPrA induced the decline of ECL intensity.…”