Interfacing with a digital microfluidic device

1. A method of analyzing a droplet comprising:

forming one or more droplets of a sample on a surface of a digital microfluidic device;

manipulating said one or more droplets of the sample to perform processing using said one or more droplets of the sample generating one or more resulting droplets; and

transferring said one or more resulting droplets from said digital microfluidic device to another device for analysis, wherein said another device performs mass spectrometry, wherein said digital microfluidic device interfaces with said another device using a tube coupled to the digital microfluidic device, wherein the tube is perpendicular to a plane containing said digital microfluidic device and wherein the digital microfluidic device includes a hole formed through a bottom portion of the digital microfluidic device and the tube is connected to the hole in the bottom portion, wherein said tube is electrically conductive providing electrical contact between a control electrode in said bottom portion of said microfluidic device and a tip of said tube, wherein the tip of the tube is formed at a tapered end that extends in a direction substantially perpendicular to the plane containing the digital microfluidic device, and wherein the method further includes:

creating an electrical field by applying a voltage to said control electrode in said bottom portion of said digital microfluidic device, said electrical field being sufficient to cause formation of a Taylor cone at said tip of said tube and electrospray.

2. The method of claim 1 , wherein the bottom portion includes a plurality of control electrodes and said manipulating is performed by controlling voltages associated with the plurality of control electrodes located in the bottom portion of said digital microfluidic device and said one or more droplets of the sample are located on a surface of said bottom portion over said plurality of control electrodes.

3. The method of claim 1 , wherein said digital microfluidic device includes a top portion, said one or more droplets of the sample are positioned on a surface of said bottom portion and between said top portion and said bottom portion.

4. The method of claim 3 , wherein the top portion includes a substrate layer with a reference electrode embedded therein or formed thereon.

5. The method of claim 4 , wherein the top portion includes a hydrophobic insulation layer covering the reference electrode.

6. The method of claim 4 , wherein the bottom portion includes a plurality of control electrodes including said control electrode and wherein said plurality of control electrodes are covered by a hydrophobic insulation layer.

7. The method of claim 1 , wherein applying said voltage at said control electrode in said bottom portion causes a first droplet of said one or more resulting droplets to move to a location over said control electrode at which said tube is connected, said first droplet moving from said location on said digital microfluidic device through the hole in said bottom portion at said location, said first droplet flowing through said tube to said tip of said tube containing an opening therein.

8. The method of claim 7 , wherein said tube is made of an electrically conductive material.

9. The method of claim 1 , wherein said tube has an inner hydrophilic surface.

10. The method of claim 1 , wherein said manipulating includes processing to perform a chemical reaction.

11. The method of claim 1 , further comprising:

providing said one or more droplets of the sample used on the surface of a digital microfluidic device from an analysis instrument.

12. The method of claim 11 , wherein said analysis instrument is a liquid chromatographic instrument.

13. The method of claim 1 , wherein inside surfaces of said tube are hydrophilic.