Dispensing Single Drops as Electrochemical Reactors.

A strategy is proposed to generate single microdrops with femtoliter to microliter volumes as a liquid reactor and to guide them towards a reactive surface within a viscous carrier liquid. Reactions of the drop content with the surface are exemplified by exhaustive electrolysis of the reactor content, making use of an ion‐conducting pathway through the carrier liquid. The mechanisms by which the redox‐active species from the aqueous drop reach the electrode surface were established by a combination of time‐lapse microscopy of the drop shape, chronoamperometric recording of the single drop electrolysis, and modelling of the reaction‐transport problem, showing that partitioning over the liquid‐liquid interface must be a key step in this mechanism. The possibilities of reagent delivery and external triggering of a reaction are expanded by the possibility for controlled addition of further dissolved reactants to the liquid microreactor. [ABSTRACT FROM AUTHOR]