Combined electroosmotic and pressure driven flow system

• US 20020195344A1
• Filed: 05/24/2002
• Published: 12/26/2002
• Est. Priority Date: 06/13/2001
• Status: Abandoned Application

• Current Assignee: Eksigent Technologies LLC
• Original Assignee: Eksigent Technologies LLC
• Inventors: Paul, Phillip H., Neyer, David W., Bailey, Christopher G.
• Application Number:
  US10/155,474
• Publication Number:
  US 20020195344A1
• Time in Patent Office: Days
• US Class Current: 204/600
• CPC Class Codes: B01D 61/56 Electro-osmotic dewatering
• CPC Class Codes: G01N 2030/285 electrically driven carrier
• CPC Class Codes: G01N 2030/324 speed, flow rate
• CPC Class Codes: G01N 2030/326 pumps
• CPC Class Codes: G01N 30/32 of pressure or speed G01N30/36 takes precedence
• CPC Class Codes: G01N 30/34 of fluid composition, e.g. gradient G01N30/36 takes precedence
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence
• CPC Class Codes: G05D 7/0694 by action on throttling means or flow sources of very small size, e.g. microfluidics microvalves F16K99/0001; microstructural devices per se B81B
• CPC Class Codes: Y10T 137/85978 With pump
• CPC Class Codes: Y10T 137/85986 Pumped fluid control
• CPC Class Codes: Y10T 137/86027 Electric

Abstract

Electroosmotic flow controllers that may be used in conjunction with multiple fluids and methods of fluid flow control are described. The invention uses an electroosmotically generated flow component in combination with a pressure driven flow component to modulate fluid flow. A working fluid and a second fluid that supports electroosmotic function may be used in conjunction with embodiments of the invention. Embodiments of the invention may include salt bridges for making electrical connections between a power supply and a channel filled with a porous dielectric material and a fluid.

Claims

1. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication with a first fluid source at pressure P₁, and a second fluid source at pressure P₂;

(ii) a fluid outlet in fluid communication with the fluid inlet and at pressure P₃, with a first fluid terminus, wherein P₃<

P₁ and P₃<

P₂; and

(iii) a porous dielectric material disposed in the channel; and

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the electrodes, the electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes;

whereby the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₃ pressure differential and the P₂−

P₃ pressure differential.

2. The system of claim 1, wherein the power supply is a variable power supply.

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

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

5. The system of claim 1, wherein the electrical communication is through a bridge.

6. The system of claim 1, wherein the first fluid terminus is a chromatograph.

7. The system of claim 1, wherein the channel comprises a fused silica capillary.

8. 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.

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

10. The system of claim 1, wherein one of the fluid sources supplies a fluid having an ionic strength of at least 25 millimolar to the system.

11. The system of claim 1, wherein one of the fluid sources supplies a fluid having an ionic strength less than 0.5 millimolar to the system.

12. The system of claim 1, wherein one of the fluid sources supplies a fluid having a dynamic viscosity greater than 5 centipoise.

13. The system of claim 1, wherein one of the fluid sources supplies a substantially pure organic fluid to the system.

14. The system of claim 1, wherein one of the fluid sources supplies a fluid having dielectric constant less than 20 to the system.

15. The system of claim 1, wherein one of the fluid sources supplies a fluid bearing polyvalent ions to the system.

16. The system of claim 1, wherein the porous dielectric material includes silica particles.

17. The system of claim 16, wherein one of the fluid sources supplies a fluid having a pH value <

7 to the system.

18. The system of claim 16, wherein one of the fluid sources supplies a fluid having a pH value <

4 to the system.

19. The system of claim 1, further comprising at least one sensor for monitoring at least one control signal, and a feedback control mechanism operatively connected to the sensor and the power supply, wherein 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.

20. The system of claim 19, wherein the 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.

21. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication with a first fluid source at pressure P₁, and a second fluid source at pressure P₂;

(ii) a fluid outlet in fluid communication with the fluid inlet and a first fluid terminus at pressure P₃, wherein P₃<

P₁ and P₃<

P₂; and

(iii) a porous dielectric material disposed in the channel; and

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the electrodes, the electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes and;

(c) a first flow element interposed between the first fluid source and a first node, the first flow element having a first flow element inlet in fluid communication with the first fluid source, the first flow element also having a first flow element outlet in fluid communication with the first flow element inlet and, at the first node at pressure P_N1, with the fluid inlet, wherein P₃<

P_N1;

whereby the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₃ pressure differential and the P₂−

P₃ pressure differential.

22. The system of claim 21, further comprising:

(d) a second flow element interposed between the second fluid source and the first node, the second flow element having a second flow element inlet in fluid communication with the second fluid source, the second flow element also having a second flow element outlet in fluid communication with the second flow element inlet and, at the first node, with the fluid inlet;

wherein the channel is also a third flow element.

23. The system of claim 22 wherein the first flow element has a conductance k₁, the second flow element has a conductance k₂, the third flow element has a conductance k₃ and 1+k₃/k₁>

P₁/P₂ and 1+k₃/k₂>

P₂/P₁.

24. The system of claim 22, further comprising:

(e) a fourth flow element interposed between the first node and the third element, the fourth flow element having a fourth flow element inlet in fluid communication at the first node with the first flow element outlet and the second flow element outlet, the fourth flow element having a fourth flow element outlet in fluid communication with the fourth flow element inlet and the third flow element inlet.

26. The system of claim 22 further comprising:

(e) a second fluid terminus at pressure P₄, wherein P₄<

P₁, the second fluid terminus being in fluid communication at a second node at pressure P_N2, wherein P₃<

P_N2, and P₄<

P_N2 with the first fluid source and the first flow element inlet;

(f) a fourth flow element interposed between the first fluid source and the second node, the fourth flow element having a fourth flow element inlet in fluid communication with the first fluid source, the fourth flow element also having a fourth flow element outlet in fluid communication with the fourth flow element inlet and, at the second node at pressure P_N2, with the first flow element inlet and the second fluid terminus; and

(g) a fifth flow element interposed between the second node and the second fluid terminus, the fifth flow element having a fifth flow element inlet in fluid communication at the second node with the fourth flow element outlet, the fifth flow element also having a fifth flow element outlet in fluid communication with the fifth flow element inlet and the second fluid terminus.

27. The system of claim 26 wherein one of the fluid terminuses is a chromatograph.

28. The system of claim 26 further comprising an accumulator located in the second flow element inlet.

29. The system of claim 26, further comprising an accumulator at the first node.

30. The system of claim 26, further comprising an accumulator between the first fluid source and the inlet to the first flow element.

33. The system of claim 26, wherein the second flow element has a conductance k₂, the third flow element has a conductance k₃, the fourth flow element has a conductance k₄, the fifth flow element has a conductance k₅, and k₂k₄+k₃k₄+(k₂k₅+k₃k₅)P₄/P₁>

(k₂k₄+k₂k₅)P₂/P₁.

34. The system of claim 26, wherein the first flow element has a conductance k₁, and k₁>

k₂, k₃, k₄, and k₅.

35. The system of claim 34, wherein k₁ is more than 100 times greater than each of k₂, k₃, k₄, and k₅.

36. The system of claim 26, further comprising:

(h) a sixth flow element interposed between a third node at pressure P_N3, wherein P₃<

P_N3 and the first node, the sixth flow element having a sixth flow element inlet in fluid communication at the first node with the second flow element outlet and the first flow element outlet, the sixth flow element also having a sixth flow element outlet in fluid communication with the sixth flow element inlet and, at the third node, with the third element inlet.

37. The system of claim 36, wherein the first flow element has a conductance of k₁ the second flow element has a conductance of k₂, the third flow element has a conductance of k₃, the fourth flow element has a conductance of k₄, the fifth flow element has a conductance of k₅ and the sixth flow element has a conductance of k₆, and wherein k₁+k₆>

each of k₂, k₃, k₄ and k₅.

38. The system of claim 26, wherein α

₁=θ

₁V₁, where V₁ is the internal volume of the first node and θ

₁ is the sum of apparent compressibilities within V₁, α

₂=θ

₂V₂ where V₂ is the internal volume of the second node and θ

₂ is the sum of apparent compressibilities within V₂, and wherein α

₁/k₂>

α

₂/k₄.

39. The system of claim 36, wherein D represents the diffusion coefficient of the second fluid into the first fluid and the sixth element has a flowrate Q₆ and a length L and L>

Q₆/2π

D.

40. The system of claim 36, further comprising a fluid mixer located in the sixth flow element.

41. The system of claim 26, further comprising at least one sensor for monitoring at least one control signal, and a feedback control mechanism operatively connected to the sensor and the power supply, wherein 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.

42. The system of claim 41, wherein the at least one sensor is a pair of pressure transducers arranged to determine the flowrate through the fifth flow element.

43. The system of claim 41, wherein a pressure transducer is located at the first node.

44. The system of claim 41, wherein a pressure transducer is located at the second node, further comprising an accumulator located at the first node.

45. The system at claim 41, wherein a pressure transducer is located at the second node, further comprising a check valve located between the first and second nodes.

25. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication with a first fluid source at pressure P₁, and a second fluid source at pressure P₂;

(ii) a fluid outlet in fluid communication with the fluid inlet and, at pressure P₃, with a first fluid terminus, wherein P₃<

P₁ and P₃<

P₂; and

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

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the electrodes, the electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes;

(c) a first flow element interposed between the first fluid source and a first node, the first flow element having a first flow element inlet in fluid communication with the first fluid source, the first flow element also having a first flow element outlet in fluid communication with the first flow element inlet and, at the first node at pressure P_N1, with the fluid inlet, wherein P₃<

P_N1;

(d) a second flow element interposed between the second fluid source and the first node, the second flow element having a second flow element inlet in fluid communication with the second fluid source, the second flow element also having a second flow element outlet in fluid communication with the second flow element inlet and, at the first node, with the fluid inlet;

wherein the channel is also a third flow element;

(e) a fourth flow element interposed between the first node and the third element, the fourth flow element having a fourth flow element inlet in fluid communication at the first node with the first flow element outlet and the second flow element outlet, the fourth flow element also having a fourth flow element outlet in fluid communication with the fourth flow element inlet and the third flow element inlet; and

(f) a fluid mixer located in the fourth flow element;

whereby the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₃ pressure differential and the P₂−

P₃ pressure differential.

31. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication with a first fluid source at pressure P₁, and a second fluid source at pressure P₂;

(ii) a fluid outlet in fluid communication with the fluid inlet and, at pressure P₃, with a first fluid terminus wherein P₃<

P₁ and P₃<

P₂; and

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

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the electrodes, the electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes;

(c) a first flow element interposed between the first fluid source and a first node, the first flow element having a first flow element inlet in fluid communication with the first fluid source, the first flow element also having a first flow element outlet in fluid communication with the first flow element inlet and, at the first node at pressure P_N1, with the fluid inlet, wherein P₃<

P_N1;

(d) a second flow element interposed between the second fluid source and the first node, the second flow element having a second flow element inlet in fluid communication with the second fluid source, the second flow element also having a second flow element outlet in fluid communication with the second flow element inlet and, at the first node, with the fluid inlet;

(e) a second fluid terminus at pressure P₄, wherein P₄<

P₁, the second fluid terminus being in fluid communication at a second node at pressure P_N2, wherein P₃<

P_N2, and P₄<

P_N2 with the first fluid source and the first flow element inlet;

wherein the channel is also a third flow element;

(f) a fourth flow element interposed between the first fluid source and the second node, the fourth flow element having a fourth flow element inlet in fluid communication with the first fluid source, the fourth flow element also having a fourth flow element outlet in fluid communication with the fourth flow element inlet and, at the second node at pressure P_N2, with the first flow element inlet and the second fluid terminus;

(g) a fifth flow element interposed between the second node and the second fluid terminus, the fifth flow element having a fifth flow element inlet in fluid communication at the second node with the fourth flow element outlet, the fifth flow element also having a fifth flow element outlet in fluid communication with the fifth flow element inlet and the second fluid terminus;

(h) a third fluid terminus at pressure P₅, wherein and P₅<

P₂, the third fluid terminus being in fluid communication at a third node with the second fluid source and the second flow element inlet;

(i) a sixth flow element interposed between the third fluid terminus and the third node, the sixth flow element having a sixth flow element inlet in fluid communication at the third node with the second fluid source, the sixth flow element also having a sixth flow element outlet in fluid communication with the sixth flow element inlet and the third fluid terminus; and

(j) a seventh flow element interposed between the second fluid source and the third node, the seventh flow element having a seventh flow element inlet in fluid communication with the second fluid source, the seventh flow element also having a seventh flow element outlet in fluid communication with the seventh flow element inlet and, at the third node, with the sixth flow element inlet and the second flow element inlet;

whereby the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₃ pressure differential and the P₂−

P₃ pressure differential.

32. The system of claim 31, further comprising:

(k) a porous dielectric material disposed in the sixth flow element;

(l) a second power supply in electrical communication with the second set of spaced electrodes for applying an electric potential to the second set of spaced electrodes, the second set of spaced electrodes being positioned so that the sixth flow element is electrokinetically active when the second power supply applies an electric potential to the second set of spaced electrodes.

46. A flow controller system, comprising:

(a) a first conduit having;

(i) a first fluid inlet in fluid communication with a first fluid source at pressure P₁;

(ii) a first fluid outlet at pressure P₃ in fluid communication with the first fluid inlet, wherein P₃<

P₁; and

(iii) a first flow element disposed between the first fluid inlet and a first node; and

(b) a second conduit having;

(i) a second fluid inlet in fluid communication with a second fluid source at pressure P₂, wherein P₃<

P₂;

(ii) a second fluid outlet in fluid communication with the second fluid inlet and, at the first node, with the first conduit;

(iii) a second flow element disposed between the second fluid inlet and the second fluid outlet; and

(iv) a third fluid outlet at pressure P₄, wherein P₄<

P₁ and P₄<

P₂, the third fluid outlet being in fluid communication at a second node with the second flow element outlet;

wherein α

₁=θ

₁V₁, where V₁ is the internal volume of the first node and θ

₁ is the sum of apparent compressibilities within V₁, α

₂=θ

₂V₂ where V₂ is the internal volume of the second node and θ

₂ is the sum of apparent compressibilities within V₂, the first flow element has a conductance of k₁, the second flow element has a conductance of k₂, and wherein α

₁/k₁>

α

₂/k₂.

47. A flow controller system, comprising:

(a) a first conduit having;

(i) a first fluid inlet in fluid communication with a first fluid source at pressure P₁;

(ii) a first fluid outlet at pressure P₃ in fluid communication with the first fluid inlet, wherein P₃<

P₁; and

(iii) a first flow element disposed between the first fluid inlet and a first node; and

(b) a second conduit having;

(i) a second fluid inlet in fluid communication with a second fluid source at pressure P₂, wherein P₃<

P₂;

(ii) a second fluid outlet in fluid communication with the second fluid inlet and, at the first node, with the first conduit;

(iii) a second flow element disposed between the second fluid inlet and the second fluid outlet; and

(iv) a third fluid outlet at pressure P₄, wherein P₄<

P₁ and P₄<

P₂, the third fluid outlet being in fluid communication at a second node at pressure P_N2, with the second flow element outlet;

(c) a pressure transducer located at either the first or the second node; and

(d) an accumulator located at the opposite node as the pressure transducer;

wherein α

₁=θ

₁V₁, where V₁ is the internal volume of the first node and θ

₁ is the sum of apparent compressibilities within V₁, α

₂=θ

₂V₂ where V₂ is the internal volume of the second node and θ

₂ is the sum of apparent compressibilities within V₂, the first flow element has a conductance of k₁, the second flow element has a conductance of k₂, and wherein α

₁/k₁>

α

₂/k₂.

48. A flow controller system, comprising:

(a) a first conduit having;

(i) a first fluid inlet in fluid communication with a first fluid source at pressure P₁;

(ii) a first fluid outlet at pressure P₃ in fluid communication with the first fluid inlet, wherein P₃<

P₁; and

(iii) a first flow element disposed between the first fluid inlet and a first node; and

(b) a second conduit having;

(i) a second fluid inlet in fluid communication with a second fluid source at pressured P₂, wherein P₃<

P₂;

(ii) a second fluid outlet in fluid communication with the second fluid inlet and, at the first node, with the first conduit;

(iii) a second flow element disposed between the second fluid inlet and a second fluid outlet; and

(iv) a third fluid outlet at pressure P₄, wherein P₄<

P₁ and P₄<

P₂, the third fluid outlet being in fluid communication at a second node with the second flow element outlet;

(c) a pressure transducer located at either the first or the second node; and

(d) a check valve between the first and second nodes;

wherein α

₁=θ

₁V₁, where V₁ is the internal volume of the first node and θ

₁ is the sum of apparent compressibilities within V₁, α

₂−

θ

₂V₂ where V₂ is the internal volume of the second node and θ

₂ is the sum of apparent compressibilities within V₂, the first flow element has a conductance of k₁, the second flow element has a conductance of k₂, and wherein α

₁/k₂>

α

₂/k₂.

49. A flow controller system, comprising:

(a) a first channel having;

(i) a first channel fluid inlet in fluid communication at a node with a first fluid source at pressure P₁ and a second fluid source at pressure P₂;

(ii) a first channel fluid outlet in fluid communication with the first channel fluid inlet and, at pressure P₃, with a fluid terminus, wherein P₃<

P₁ and P₃<

P₂; and

(iii) a porous dielectric material disposed in the first channel;

(b) a second channel having;

(i) a second channel fluid inlet in fluid communication with the second fluid source;

(ii) a second channel fluid outlet in fluid communication with the second channel fluid inlet and, at the first node, with the first channel inlet; and

(iii) a porous dielectric material disposed in the second channel; and

(c) a power supply in electrical communication with spaced electrodes for applying an electrical potential to the electrodes, the electrodes being positioned so that the channels are electrokinetically active when the power supply applies an electric potential to the electrodes;

wherein the electric potential generates an electroosmotically-driven flow component through at least one of the first and the second channels, wherein the electroosmotically-driven flow component modulates at least one pressure-driven flow component resulting from the P₁−

P₃ and the P₂−

P₃ pressure differentials.

50. A flow controller system, comprising:

(a) a first channel having;

(i) a first channel fluid inlet in fluid communication at a first node with a first fluid source at pressure P₁ and a second fluid source at pressure P₂;

(ii) a first channel fluid outlet in fluid communication with the first channel fluid inlet and, at pressure P₃, with a fluid terminus, wherein P₃<

P₁ and P₃<

P₂; and

(iii) a porous dielectric material disposed in the first channel;

(b) a second channel having;

(i) a second channel fluid inlet in fluid communication with the second fluid source;

(ii) a second channel fluid outlet in fluid communication with the second channel fluid inlet and, at the first node, with the first channel; and

(iii) a porous dielectric material disposed in the second channel;

(c) a first power supply in electrical communication with a first set of spaced electrodes for applying a first electric potential to the first set of spaced electrodes, the first set of spaced electrodes being positioned so that the first channel is electrokinetically active when the first power supply applies an electric potential to the first set of spaced electrodes;

(d) a second power supply in electrical communication with a second set of spaced electrodes for applying a second electric potential to the second set of spaced electrodes, the second set of spaced electrodes being positioned so that the second channel is electrokinetically active when the second power supply applies an electric potential to the second set of spaced electrodes;

wherein the first electric potential generates a first electroosmotically-driven flow component through the first channel, the first electroosmotically-driven flow component modulating at least one pressure-driven flow component resulting from the P₁−

P₃ and the P₂−

P₃ pressure differentials and the second electric potential generates a second electroosmotically-driven flow component through the second channel, the second electroosmotically-driven flow component modulating at least one pressure-driven flow components resulting from the P₁−

P₃ and the P₂−

P₃ pressure differentials.

51. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication at a node with a fluid source at pressure P₁;

(ii) a fluid outlet in fluid communication with the fluid inlet and, at pressure P₂, with a first fluid terminus, wherein P₂<

P₁; and

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

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the spaced electrodes, the spaced electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes; and

(c) a first fluid storage element being disposed between the node and a second fluid terminus at pressure P₃, wherein P₃<

P₁, wherein the first fluid storage element has a first fluid storage element inlet in fluid communication at the node with the fluid source, and wherein the first fluid storage element also has a first fluid storage element outlet in fluid communication with the first fluid storage element inlet and the second fluid terminus;

wherein the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₂ and the P₁−

P₃ pressure differentials.

52. The system of claim 51, further comprising:

(d) a first flow element disposed between the fluid source and the node, the first flow element having a first flow element inlet in fluid communication with the fluid source, the first flow element also having a first flow element outlet in fluid communication with the first flow element inlet and, at the first node, with the first fluid storage element inlet and the fluid inlet;

wherein the channel is also a second flow element;

(e) a third flow element disposed between the node and the first fluid storage element, the third flow element having a third flow element inlet in fluid communication at the first node with the first flow element outlet, the third flow element also having a third flow element outlet in fluid communication with the third flow element inlet and the first fluid storage element inlet; and

(f) a fourth flow element disposed between the first fluid storage element and the second fluid terminus, the fourth flow element having a fourth flow element inlet in fluid communication with the first fluid storage element outlet, the fourth flow element also having a fourth flow element outlet in fluid communication with the fourth flow element inlet and the second fluid terminus;

wherein the fluid storage element is also a flow element.

53. The system of claim 51, further comprising:

(d) a second fluid storage element; and

(e) a valve for switching the first fluid storage element with the second fluid storage element.

54. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in fluid communication at a node with a fluid source at pressure P₁;

(ii) a fluid outlet in fluid communication with the fluid inlet and, at pressure P₂, with a first fluid terminus, wherein P₂<

P₁; and

(iii) a porous dielectric material disposed within the first channel;

(b) a power supply in electrical communication with the spaced electrodes for applying an electrical potential to the spaced electrodes, the spaced electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes;

(c) a first fluid storage element disposed between the node and the fluid inlet, the first fluid storage element having a first fluid storage element inlet in fluid communication at the node with the fluid source, the first fluid storage element also having a first fluid storage element outlet in fluid communication with the first fluid storage element inlet and the fluid inlet; and

(d) a second fluid terminus at pressure P₃, wherein P₃<

P₁, in fluid communication at the node with the fluid source,

wherein the electric potential generates an electroosmotically-driven flow component through the first channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₂ and the P₁−

P₃ pressure differentials.

55. The system of claim 54, further comprising:

(e) a first flow element disposed in the first channel between the first fluid source and the node, the first flow element having a first flow element inlet in fluid communication with the fluid source, the first flow element also having a first flow element outlet in fluid communication at the node with the first flow element inlet, the fluid storage element inlet, and the second fluid terminus;

wherein the channel is also a second flow element; and

(f) a third flow element disposed between the node and the second fluid terminus, the third flow element having a third flow element inlet in fluid communication at the node with the first flow element outlet, the third flow element also having a third flow element outlet in fluid communication with the third flow element inlet and the second fluid terminus.

56. The system of claim 54, further comprising:

(e) a second fluid storage element; and

(f) a valve for switching the first fluid storage element with the second fluid storage element.

57. A flow controller system, comprising:

(a) a channel having;

(i) a fluid inlet in liquid communication with a fluid source at pressure P₁;

(ii) a fluid outlet in liquid communication with a first fluid terminus at pressure P₂, wherein P₂<

P₁; and

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

(b) a power supply in electrical communication with spaced electrodes for applying an electric potential to the spaced electrodes, the spaced electrodes being positioned so that the channel is electrokinetically active when the power supply applies an electric potential to the electrodes; and

(c) a fluid storage element fluid disposed between the fluid source and the channel, the fluid storage element having a fluid storage element inlet in fluid communication with a fluid source, the fluid storage element also having a fluid storage element outlet in fluid communication with the fluid storage element inlet and the fluid inlet;

whereby the electric potential generates an electroosmotically-driven flow component through the channel that modulates a pressure-drive flow component resulting from the P₁−

P₂ pressure differential.

58. A method for controlling a flow of a fluid, comprising:

applying an electric potential to spaced electrodes in electrical communication with a channel, the channel having a porous dielectric material disposed therein, the channel also having a fluid inlet in fluid communication with a first fluid source at pressure P₁ and a second fluid source at pressure P₂, the channel also having a fluid outlet in fluid communication with the fluid inlet and, at pressure P₃, with a terminus, wherein P₃<

P₁ and P₃<

P₂, wherein the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₃ and the P₂−

P₃ pressure differentials.

59. A method of controlling the flow of a fluid comprising:

(a) placing a first accumulator at a first node, wherein the first node is in a first conduit having;

a first fluid inlet in fluid communication with a first fluid source at pressure P₁, a first fluid outlet at pressure P₃, wherein P₃<

P₁, and a first flow element disposed between the first fluid inlet and the first fluid outlet;

(b) placing a second accumulator at a second node;

wherein, the second node is in a second conduit having;

a second fluid inlet in fluid communication with a second fluid source at pressure P₂, wherein P₃<

P₂, a second fluid outlet in fluid communication with the first conduit at the first node, a second flow element disposed between the second fluid inlet and the second fluid outlet, and a third fluid outlet at pressure P₄, wherein P₄<

P₁ and P₄<

P₂, the third fluid outlet being in fluid communication at the second node with the second fluid inlet.

60. A method of controlling a flow of a fluid, comprising:

applying an electric potential to spaced electrodes in electrical communication with a channel, the channel having a porous dielectric material disposed therein, the channel also having a fluid inlet in fluid communication at a node with a fluid source at pressure P₁, the channel also having a fluid outlet in fluid communication with the fluid inlet and, at pressure P₂, with a first fluid terminus, wherein P₂<

P₁, and wherein a fluid storage element is disposed between the node and a second fluid terminus at pressure P₃, wherein P₃<

P₁, the fluid storage element having a fluid storage element inlet in fluid communication at the node with the fluid source, the fluid storage element also having a fluid storage element outlet in fluid communication with the fluid storage element inlet and the second fluid terminus, wherein the electric potential generates an electroosmotically-driven flow component through the channel that modulates at least one pressure-driven flow component resulting from the P₁−

P₂ and the P₁−

P₃ pressure differentials.

61. A method for controlling a flow of fluid, comprising:

applying an electric potential to spaced electrodes in electrical communication with a channel, the channel having a porous dielectric material disposed therein, the channel also having a fluid inlet in fluid communication at a node with a fluid source at pressure P₁, the channel also having a fluid outlet in fluid communication with the fluid inlet and, at pressure P₂, with a first fluid terminus, wherein P₂<

P₁, and wherein a fluid storage element is disposed between the node and the fluid inlet, the fluid storage element having a fluid storage element inlet in fluid communication at the node with the fluid source, the fluid storage element also having a fluid storage element outlet in fluid communication with the fluid storage element inlet and the fluid inlet, wherein the electric potential generates an electroosmotically driven flow component through the channel that modulates a pressure-driven flow component resulting from the P₁−

P₂ pressure differential.