Method for modifying the concentration of reactants in a microfluidic device

1. A method of modifying the concentration of reactants and carrying out a chemical reaction on a microfluidic device, the method comprising:

delivering a first reactant into a reaction channel;

subjecting the first reactant to a stacking process, thereby producing a first stacked reactant;

exposing the first stacked reactant to a second reactant that is not stacked so that the first stacked reactant and the second reactant undergo a chemical reaction, thereby producing a first product; and

subjecting the first product to the stacking process, thereby producing a first stacked product.

2. The method of claim 1 , wherein the steps of subjecting the first reactant and the first product to the stacking process comprise subjecting the first reactant and the first product to isotachophoresis.

3. The method of claim 1 , wherein the steps of subjecting the first reactant and the first product to the stacking process comprise subjecting the first reactant and the first product to field amplified stacking.

4. The method of claim 1 , wherein the steps of subjecting the first reactant and the first product to the stacking process comprise subjecting the first reactant and the first product to isoelectric focusing.

5. The method of claim 1 , wherein the steps of subjecting the first reactant and the first product to the stacking process comprise subjecting the first reactant and the first product to temperature gradient focusing, viscosity gradient focusing, or pH induced focusing.

6. The method of claim 1 , wherein exposing the first stacked reactant to the second reactant so that the first stacked reactant and the second reactant undergo a chemical reaction comprises subjecting the first stacked reactant and the second reactants to an electrophoretically mediated micro-analysis method.

7. The method of claim 1 , further comprising:

exposing the first stacked product to a third reactant that is not stacked so that the first stacked product and the third reactant undergo a chemical reaction, thereby producing a second product; and

subjecting the second product to the stacking process, thereby producing a second stacked product.

8. The method of claim 1 , wherein exposing the first stacked reactant to the second reactant so that the first stacked reactant and the second reactant undergo a chemical reaction comprises subjecting the first stacked reactant and the second reactants to a capillary electrophoresis process.

9. The method of claim 8 , wherein exposing the first stacked reactant to the second reactant so that the first stacked reactant and the second reactant undergo a chemical reaction comprises subjecting the first stacked reactant and the second stacked reactants to a band-crossing method.

10. The method of claim 8 , wherein exposing the first stacked reactant to the second reactant so that the first stacked reactant and the second reactant undergo a chemical reaction comprises mixing the first stacked reactant and the second reactants in the reaction channel to enhance the reaction between the first stacked reactant and second reactants.

11. The method of claim 10 , wherein the microfluidic device includes one or more of bends and a ridge to promote mixing.

12. The method of claim 10 , wherein the mixing is tuned by controlling a loading pressure and a current in the reaction channel.

13. The method of claim 12 , wherein tuning the mixing controls a degree of the chemical reaction.

14. The method of claim 10 , further comprising:

subjecting the first stacked reactant and the second reactant to a pressure-driven flow to promote mixing.

15. The method of claim 14 , wherein the pressure-driven flow is directed toward a direction of motion caused by the isotachophoresis.

16. The method of claim 14 , wherein the pressure-driven flow is directed against a direction of motion caused by the isotachophoresis.