Spontaneous periodic pulsation of contact line in oil/water system - Frequency control with divalent cations and applied voltage

► We found a quasi-periodic pulsation of contact line for an oil/water system. ► The frequency increased with the increase in applied voltage across the interface. ► The frequency depended on cation species, and its order was Ba2+ > Sr2+ > Mg2+ ≫ Ca2+. ► This order agreed with the order of ion concentrations in the oil phase.