Digital microfluidic liquid-liquid extraction device and method of use thereof

A closed digital microfluidic device for the separation of a non-polar species from a substantial polar droplet to a substantially non-polar liquid, said device comprising:

• a first substrate;
• at least one input digital microfluidic electrode formed on said first substrate;
• a separation array in flow communication with said input digital microfluidic electrode, said separation array comprising at least two digital microfluidic electrodes formed on said first substrate;
• at least one output digital microfluidic electrode in flow communication with said separation array, said output digital microfluidic electrode formed on said first substrate;
• a second substrate provided in a spaced relationship with said first substrate such that a gap is formed therebetween, wherein said first substrate and said second substrate enclose a volume including said input digital microfluidic electrode, said separation array, and said output digital microfluidic electrode, and wherein said second substrate comprises at least one electrode, such that the substantially polar droplet is transportable among said input digital microfluidic electrode, said separation array, and said output digital microfluidic electrode while contacting said second substrate under the application of voltages between respective electrodes of said first substrate and said second substrate;
• and
• a retaining wall for retaining a substantially non-polar liquid over said separation array, wherein said retaining wall is provided such that the substantially non-polar liquid is retained over said separation array without filling the entire volume enclosed by said first substrate and said second substrate, wherein said retaining wall encloses said separation array with a first opening for an inlet into the separation array and a second opening for an outlet out of the separation array.