Flow control systems

• US 7,597,790 B2
• Filed: 06/13/2002
• Issued: 10/06/2009
• Est. Priority Date: 06/13/2001
• Status: Active Grant

• Current Assignee: AB Sciex LLC (Danaher Corporation)
• Original Assignee: Eksigent Technologies LLC
• Inventors: Paul, Phillip H., Neyer, David W., Bailey, Christopher G., Arnold, Don Wesley
• Primary Examiner(s): Phasge; Arun S
• Application Number:
  US10/480,691
• Publication Number:
  US 20040163957A1
• Time in Patent Office: 2,672 Days
• Field of Search: 204/450, 204/451, 204/454, 204/600, 204/601
• US Class Current: 204/450
• 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

A flow controller which uses a combination of hydrostatic pressure and electroosmotic flow to control the flow of a fluid. A driving fluid (1204) whose flow rate is dependent on both hydrostatic pressures and electroosmotic flow can be used (a) directly as a working fluid in an operable device, for example a chromatograph, or (b) to displace a working fluid (1203) from a storage container (625) into an operable device (1301), or both (a) and (b). The driving fluid (1204) can be composed of one or more fluids. Part or all the driving fluid (1204) is passed through an electroosmotic device (100) so as to increase or decrease the flow rate induced by hydrostatic pressure.

Claims

1. An apparatus suitable for use in causing a working fluid to flow from a first point to a second point through a channel by applying a driving pressure to the working fluid at the first point, wherein (a) at least part of the driving pressure is provided by a driving fluid different from the working fluid, (b) the rate of flow of the driving fluid comprises a hydrostatic component and an electroosmotic component, and (c) the driving fluid does not mix with any working fluid reaching the second point, comprising:

(1) a channel which includes an inlet and an outlet, and through which a fluid under pressure can flow from the inlet to the outlet;

(2) a porous solid dielectric material which is positioned within the channel between the inlet and the outlet; and

(3) electrodes which are positioned so that, when an electrokinetic fluid under pressure is flowing through the channel between the inlet and the outlet, the rate at which the fluid flows can be changed by changing an electric potential connected to the electrodes;

said apparatus having at least one of the following characteristics;

(a) it comprises a flow control element through which a fluid under pressure can flow before reaching the inlet;

(b) it comprises a flow control element through which a fluid under pressure can flow after leaving the outlet;

(c) it comprises an operable device which;

(i) employs a pressurized fluid in its operation; and

(ii) is connected to;

(a) the outlet, so that when pressurized fluid flows from the outlet, it passes through the device, or

(b) a first outlet of a conduit having a second outlet connected to the channel and an inlet which can be connected to a source of pressurized fluid;

(d) it comprises a first source for a first fluid and a second source for a second fluid, both the first source and the second source being connected to the inlet so that pressurized fluid from the sources can pass through the inlet into the channel;

(e) it comprises a variable power supply connected to the electrodes;

(f) it comprises at least one sensor for monitoring a control signal, and a feedback control mechanism operatively connected to the sensor, whereby, when the apparatus includes a power supply connected to the electrodes, the feedback control mechanism modulates the electric potential supplied by the power supply;

(g) it comprises a conduit having (i) a first conduit outlet which is connected to the inlet, (ii) a second conduit outlet which can be connected to an operable device or a plurality of operable devices, and (iii) a conduit inlet which can be connected to a source of pressurized fluid, whereby, when pressurized fluid enters the conduit, a part of the pressurized fluid flows through the channel and the remainder of pressurized fluid flows through the device or devices;

(h) it comprises two or more said channels and a conduit having (i) a plurality of conduit inlets connected to an inlet or an outlet of each of said channels, and (ii) a conduit outlet which can be connected to an operable device or a plurality of operable devices; and

(i) it comprises two or more said channels, the dielectric materials in the channels being different from each other.

2. The apparatus according to claim 1, wherein the porous dielectric material comprises a fused silica capillary, silica particles, an organic polymer, or a product made by lithographic patterning, lithographic etching, direct injection molding, sol-gel processing, or electroforming.

3. The apparatus according to claim 1, comprising a power supply connected to the electrodes, the power supply having one or both of the following characteristics:

(i) it is a variable power supply, and

(ii) it is connected to the electrodes through a bridge.

4. The apparatus according to claim 1, comprising at least one sensor for monitoring a control signal, and a feedback control mechanism operatively connected to the sensor, whereby, when the apparatus includes a power supply connected to the electrodes, the feedback control mechanism maintains the control signal within a predetermined range by modulating the electric potential supplied by the power supply, the sensor being one or more 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.

5. The apparatus of claim 1, wherein the driving fluid has a characteristic selected from the group consisting of:

(a) it comprises a liquid having an ionic strength of least 25 millimolar;

(b) it comprises a liquid having an ionic strength less than 0.5 millimolar;

(c) it comprises a liquid having a dynamic viscosity greater than 5 centipoise;

(d) it comprises a substantially pure organic liquid;

(e) it comprises a liquid having a dielectric constant less than 20;

(f) it comprises a liquid containing polyvalent ions;

(g) it comprises a liquid having a pH value less than 7; and

(h) it comprises a liquid having a pH value less than 4.

6. The apparatus of claim 1, wherein the 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.

7. The apparatus of claim 1, wherein the driving fluid has a characteristic selected from the group consisting of:

(a) it comprises a liquid having an ionic strength of least 25 millimolar;

(b) it comprises a liquid having an ionic strength less than 0.5 millimolar;

(c) it comprises a liquid having a dynamic viscosity greater than 5 centipoise;

(d) it comprises a substantially pure organic liquid;

(e) it comprises a liquid having a dielectric constant less than 20;

(f) it comprises a liquid containing polyvalent ions;

(g) it comprises a liquid having a pH value less than 7; and

(h) it comprises a liquid having a pH value less than 4.

8. An apparatus suitable for use in a method of causing a working fluid to flow from a first point to a second point through a channel, which comprises applying a driving pressure to the working fluid at the first point, wherein (a) at least part of the driving pressure is provided by a driving fluid;

and (b) the rate of flow of the driving fluid comprises (i) a hydrostatic component, and (ii) an electroosmotic component, the apparatus comprising;

(a) a first channel through which a working fluid under pressure can flow;

(b) a second channel through which a driving fluid under pressure can flow;

(c) a third channel which includes an outlet and an inlet, the inlet for receiving working fluid from the first channel and for receiving the driving fluid from the second channel, wherein a mixture of the working fluid and driving fluid under pressure can flow from the inlet to the outlet;

(d) a porous solid dielectric material positioned within the third channel between the inlet and the outlet; and

(e) electrodes which are positioned so that, when the mixture is flowing through the channel between the inlet and the outlet, the rate at which the mixture flows can be changed by changing an electric potential connected to the electrodes.