Electric fields enable tunable surfactant transport to microscale fluid interfaces.

The transport dynamics of oil-soluble surfactants to oil-water interfaces are quantified using a custom-built electrified capillary microtensiometer platform. Dynamic interfacial tension measurements reveal that surfactant transport is enhanced under a dc electric field, due to electro-migration of charge carriers in the oil toward the interface. Notably, this enhancement can be precisely tuned by altering the field strength and temporal scheduling. We demonstrate electric fields as a new parameter to manipulate surfactant transport to microscale fluid-fluid interfaces.