A method, comprising: providing a system, the system comprising a substrate that defines microfluidic channels including: a main channel having a main input in fluid communication with a main output, the main channel defining an intersection site along a path of fluid flow from the main input to the main output; a first side channel having a first side input in fluid communication with a first side output, the first side output being in fluid communication with the main channel at the intersection site; a second side channel having a second side input in fluid communication a second side output, the second side output being in fluid communication with the main channel at the intersection site; a first electrode comprising an electrochemical half-cell with the first side channel fluid when the first side channel has been charged with the first side channel fluid; and a second electrode comprising an electrochemical half-cell with the second side channel fluid when the second side channel has been charged with the second side channel fluid; charging the main channel with a main channel fluid from the main input; cha rging the first side channel with a first side channel fluid from the first side input, the first side channel fluid being immiscible with at least a first component of the main channel fluid, wherein said first component is an oil; charging the second side channel with a second side channel fluid from the second side input such that the first and second side channels are separated from one another by the main channel fluid, the second side channel fluid being immiscible with at least the first component of the main channel fluid; flowing the main channel fluid from the main channel input to the main channel output and through the intersection point; allowing electrical current to flow through the intersection; connecting the first and second side channel fluids with a fluid bridge at the intersection point; and disconnecting the fluid bridge from at least one of either the first or the second side channel fluids so that the first and second side channel fluids are separated by the first component of the main channel fluid, wherein the first and second side channel fluids are miscible with each other, and the fluid bridge is miscible with both the first and second side channel fluids. providing a system, the system comprising a substrate that defines microfluidic channels including: a main channel having a main input in fluid communication with a main output, the main channel defining an intersection site along a path of fluid flow from the main input to the main output; a first side channel having a first side input in fluid communication with a first side output, the first side output being in fluid communication with the main channel at the intersection site; a second side channel having a second side input in fluid communication a second side output, the second side output being in fluid communication with the main channel at the intersection site; a first electrode comprising an electrochemical half-cell with the first side channel fluid when the first side channel has been charged with the first side channel fluid; and a second electrode comprising an electrochemical half-cell with the second side channel fluid when the second side channel has been charged with the second side channel fluid; a main channel having a main input in fluid communication with a main output, the main channel defining an intersection site along a path of fluid flow from the main input to the main output; a first side channel having a first side input in fluid communication with a first side output, the first side output being in fluid communication with the main channel at the intersection site; a second side channel having a second side input in fluid communication a second side output, the second side output being in fluid communication with the main channel at the intersection site; a first electrode comprising an electrochemical half-cell with the first side channel fluid when the first side channel has been charged with the first side channel fluid; and a second electrode comprising an electrochemical half-cell with the second side channel fluid when the second side channel has been charged with the second side channel fluid; charging the main channel with a main channel fluid from the main input; cha rging the first side channel with a first side channel fluid from the first side input, the first side channel fluid being immiscible with at least a first component of the main channel fluid, wherein said first component is an oil; charging the second side channel with a second side channel fluid from the second side input such that the first and second side channels are separated from one another by the main channel fluid, the second side channel fluid being immiscible with at least the first component of the main channel fluid; flowing the main channel fluid from the main channel input to the main channel output and through the intersection point; allowing electrical current to flow through the intersection; connecting the first and second side channel fluids with a fluid bridge at the intersection point; and disconnecting the fluid bridge from at least one of either the first or the second side channel fluids so that the first and second side channel fluids are separated by the first component of the main channel fluid, wherein the first and second side channel fluids are miscible with each other, and the fluid bridge is miscible with both the first and second side channel fluids.