Electrochemical detection of droplet content in microfluidic devices: Evidence of internal recirculating convection within droplets

摘要

The electrochemical detection of aqueous droplets carried by an immiscible oil-phase was investigated in a rectangular microchannel. Droplets having large aspect ratio as plugs were generated on demand and their electroactive content was detected amperometrically by a channel microband electrode. Under these conditions, electrode responses showed steady-state currents during the passage of droplets. The influence of electrode width and droplet velocity on faradaic current was studied. Results demonstrated that mass transfer to the electrode was controlled by convective flow regimes. Internal recirculating convection was evidenced in comparison to known operating regimes of microchannel electrodes in continuous pressure-driven flow.