Abstract
Transient concentration gradients generated and detected electrochemically in continuous flow microchannels were investigated by numerical simulations and amperometric measurements. Operating conditions including device geometry and hydrodynamic regime were theoretically delineated for producing gradients of various profiles with tunable characteristics. Experiments were carried out with microfluidic devices incorporating a dual-channel-electrode configuration. Under these conditions, high electrochemical performance was achieved both to generate concentration gradients and to monitor their dynamics along linear microchannels. Good agreement was observed between simulated and experimental data validating predictions between gradient properties and generation conditions. These results demonstrated the capability of electrochemical microdevices to produce in situ tunable concentration gradients with real-time monitoring. This approach is versatile for the active control in microfluidics of microenvironments or chemical gradients with high spatiotemporal resolution.
Highlights
In recent years, microfluidic devices have been used in biomolecular and chemical gradient generation with special interest
The pseudoreference electrode is located upstream to ensure its potential stability during the electrochemical cell operation
The two working electrodes are separated by a given gap distance and operate in generator-collector mode
Summary
Microfluidic devices have been used in biomolecular and chemical gradient generation with special interest. We investigated through a conceptual approach the electrochemical generation and/or monitoring of transient concentration gradients within microchannels (Graphical Abstract). This concept relies on a dual-channelelectrode configuration operating in generator-collector mode under potentiostatic conditions (Figure 1A). Such systems have been exploited to study homogeneous reaction kinetics (Unwin and Compton, 1989; Fisher and Compton, 1991; Unwin, 1991; Bitziou et al, 2013), catalysis (Dumitrescu et al, 2012), corrosion (Itagaki et al, 1997; Sasaki and Maeda, 2010), and reaction products (Wang et al, 2010). Comparisons between theoretical and experimental data were established to assess the validity of the predictions
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