Quantitative electrolysis of droplet contents in microfluidic channels. Concept and experimental validation

Abstract

A cross-channel geometry was studied to perform quantitative electrolysis of circulating droplets without influence of the counter electrode reaction on the droplet content. In the microdevices, the counter electrode is located in a secondary microchannel to prevent any contact with the droplets during detection. The electrochemical performance was assessed both theoretically and experimentally based on the droplet properties and mass transport above the working electrode. The results showed that under optimal conditions, quantitative electrolysis of droplet contents can be achieved when the working electrode operates in thin-layer regime. These results pave the way for new strategies allowing the implementation of electrochemical detections in droplet microfluidics without the need to perform calibration or to determine both the size and velocity of droplets prior to detection.