On-chip organic synthesis enabled by engine-and-cargo in an electrowetting-on-dielectric digital microfluidic device

1. A method of moving a solvent that is not movable by electro-wetting-on-dielectric (EWOD) actuation on an EWOD microfluidic device, the method comprising:

disposing a first droplet of a first fluid that is movable by EWOD actuation on a surface of the EWOD microfluidic device, the first fluid comprising an ionic liquid;

disposing a second droplet of a second fluid that is not movable by EWOD actuation on the surface;

applying a first voltage to the surface to move the first droplet towards the second droplet;

contacting the first droplet with the second droplet to form an encapsulated droplet, where the second droplet encapsulates the first droplet.

2. The method of claim 1 , further comprising transporting the encapsulated droplet across the surface by applying a second voltage to the surface, the second voltage being the same or different from the first voltage.

3. The method of claim 1 , wherein the ionic liquid comprises an organic cation that is imidazolium-based, pyridinium-based, pyrrolidinium-based, phosphonium-based, ammonium based, sulfonium-based, or any combination thereof.

4. The method of claim 3 , wherein the ionic liquid comprises an anion that is an alkylsulfate, tosylate, methansulfonate, trifluoromethanesulfonate (triflate), bis(trifluoromethylsulfonyl)imide, tetrafluoroborate, hexafluorophosphate, a halide, or any combination thereof.

5. The method of claim 1 , wherein the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6).

6. The method of claim 1 , wherein the second fluid has a lower surface tension than water.

7. The method of claim 1 , wherein the second fluid is an organic solvent.

8. The method of claim 1 , wherein the first fluid has a higher surface tension than the second fluid.

9. The method of claim 1 , further comprising forming two or more encapsulated droplets on the surface, each of the two or more encapsulated droplets comprising the second droplet encapsulating the first droplet.

10. The method of claim 9 , wherein the second fluid of each encapsulated droplet comprises one or more reactants.

11. The method of claim 9 , further comprising applying a second voltage to the surface to move the two or more encapsulated droplets together, the second voltage being the same or different from the first voltage.

12. The method of claim 11 , further comprising merging the two or more encapsulated droplets together.

13. The method of claim 12 , wherein merging the two or more encapsulated droplets comprises mixing the second fluid from each encapsulated droplet together.

14. The method of claim 12 , wherein merging the two or more encapsulated droplets together initiates a chemical reaction between one or more reactants present in the two or more encapsulated droplets.

15. The method of claim 9 , wherein the second fluid in each encapsulated droplet is the same.

16. The method of claim 9 , wherein the second fluid in each encapsulated droplet is different.

17. The method of claim 9 , wherein the first fluid in each encapsulated droplet is the same or different.

18. The method of claim 9 , wherein the first fluid and the second fluid are immiscible.

19. A method of moving a solvent that is not movable by electro-wetting-on-dielectric (EWOD) actuation on an EWOD microfluidic device comprising:

combining a first fluid with an immiscible second fluid in an EWOD reservoir puddle, the first fluid being an ionic liquid movable through EWOD actuation and the second fluid being unmovable through EWOD actuation;

moving a first droplet of the first fluid out of the reservoir puddle by applying a voltage to a surface of the EWOD device; and

encapsulating the first droplet with a second droplet of the second fluid as the first droplet is moved out of the reservoir puddle to form an encapsulated droplet.