Electrochemiluminescence reaction pathways in nanofluidic devices

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

Reducing adsorption in nanochannels: from fundamental understanding to practical application

Electrochemical nanofluidic devices are chip-based sensors consisting of a nanochannel of approximately 100 nm in height. By employing a pair of electrodes positioned at the top and bottom of this channel, the detected current can be greatly amplified, allowing much higher sensitivity and the possibility to investigate systems at the fundamental level. However, a high surface-to-volume ratio means that these channels suffer from adsorption of molecules onto the electrodes causing reduction in current and complication of experiments. By using additives, the absorptivity inside these nanochannels has been investigated with the aim of both understanding and reducing its effects

Electrofluorochromic systems: Molecules and materials exhibiting redox-switchable fluorescence

Electrofluorochromic molecules share the unique property that their fluorescence changes as a function of their oxidation state. This makes them interesting from a fundamental perspective as molecular dyads are designed and synthesized to tune the interplay of electrochemical and luminescent properties of molecules. Electrofluorochromic systems also find applications in sensing because a fluorescent signal can be detected with high sensitivity. Moreover, in the recent years the interest in redox-switchable fluorescent polymers has strongly increased due to their applicability in display devices. Here, we review electrofluorochromic molecules and polymers; we emphasize their structures and functional principles and point to specific applications