Electroosmotic flow controller

1. A flow controller, comprising:

(a) a channel having

(i) a fluid inlet in liquid communication with a fluid source at pressure P 1 ,

(ii) a fluid outlet at pressure P 2 , wherein P 2 <P 1 , and

(iii) a porous dielectric material disposed in said channel;

(b) a fluid contained within said channel;

(c) spaced electrodes in electrical communication with said fluid;

(d) a power supply in electrical communication with said electrodes for applying an electric potential to said spaced electrodes;

(e) a first node between the fluid inlet and the porous dielectric material;

(f) a first flow element having a first flow element inlet in liquid communication at the first node at pressure PN with said fluid inlet and said fluid source, wherein P 2 <PN, and a first flow element outlet at pressure P 3 ;

(g) at least one sensor for monitoring at least one control signal; and

(h) a feedback control mechanism operatively connected to the sensor and the power supply;

whereby said electric potential generates an electroosmotically-driven flow component through said channel that modulates a pressure-driven flow component resulting from the P 1 −P 2 pressure differential;

whereby the electroosmotically driven flow component affects the proportion of fluid flowing through said channel and said first flow element; and

whereby the feedback control mechanism maintains the at least one control signal within a predetermined range by modulating the electric potential applied by the power supply.

2. The flow controller of claim 1 , further comprising:

(f) a second flow element interposed between said fluid source and said first node, said second flow element having a second flow element inlet in liquid communication with said fluid source, and a second flow element outlet in liquid communication at said first node with said fluid inlet and said first flow element inlet.

3. The flow controller of claim 1 , wherein said power supply is a variable power supply.

4. The flow controller of claim 1 , wherein said pressure-driven and said electroosmotically-driven flow components through said channel are in the same direction.

5. The flow controller of claim 1 , wherein said pressure-driven and said electroosmotically-driven flow components through said channel are in the opposite direction and the pressure-driven fluid flux is greater than or equal to the electroosmotically driven fluid flux.

6. The flow controller of claim 1 , wherein said electrical communication is through a bridge.

7. The flow controller of claim 1 , wherein said channel has a circular cross-section.

8. The flow controller of claim 1 , wherein said channel comprises a fused silica capillary.

9. The flow controller of claim 1 , wherein the porous dielectric material includes silica particles.

10. The flow controller of claim 9 , wherein the silica particles have a diameter of between about 100 nm and 5 μm.

11. The flow controller of claim 1 , wherein the porous dielectric material includes porous dielectric materials fabricated by processes selected from the group consisting of lithographic patterning and etching, direct injection molding, sol-gel processing, and electroforming.

12. The flow controller of claim 1 , wherein the porous dielectric material includes organic polymer materials.

13. The flow controller of claim 1 , wherein said at least one sensor is selected from the group consisting of a pressure transducer, a flowmeter, a temperature sensor, a heat flux sensor, a displacement sensor, a load cell, a strain gauge, a conductivity sensor, a selective ion sensor, a pH sensor, a flow spectrophotometer, and a turbidity sensor.

14. The flow controller of claim 13 , wherein said at least one sensor is a pressure transducer.

15. The flow controller of claim 14 , wherein said pressure transducer is a differential pressure transducer.

16. The flow controller of claim 13 , wherein said at least one sensor is a flowmeter.