Prevention of surface adsorption in microchannels by application of electric current during pressure-induced flow

• US 6,458,259 B1
• Filed: 05/11/1999
• Issued: 10/01/2002
• Est. Priority Date: 05/11/1999
• Status: Active Grant

• Current Assignee: Caliper Holdings Incorporated
• Original Assignee: Caliper Holdings Incorporated
• Inventors: Chow, Andrea W., Parce, J. Wallace
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): STARSIAK, JOHN S
• Application Number:
  US09/310,027
• Time in Patent Office: 1,239 Days
• Field of Search: 204/450, 204/451, 204/452, 204/453, 204/454, 204/455, 204/600, 204/601, 204/602, 204/603, 204/604, 204/605
• US Class Current: 204/454
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/1833 using electrical currents in the sample itself
• CPC Class Codes: B01L 2400/0409 centrifugal forces
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B08B 17/00 Methods preventing fouling preventing accumulation of deposits in pneumatic conveyors B65G53/521
• CPC Class Codes: G01N 27/44704 Details; Accessories
• CPC Class Codes: G01N 27/44752 Controlling the zeta potential, e.g. by wall coatings

Abstract

Methods and apparatus for reducing adsorption in microscale devices are provided. In the methods and apparatus, an electrical current such as an alternating current is applied to materials under pressure-induced flow. Integrated systems for simultaneous control of current and pressure in a channel are also provided.

Claims

1. A method of regulating surface adsorption in a channel of a microfluidic device, the method comprising;

flowing a fluid through the channel by applying pressure to the fluid in the channel, wherein the fluid comprises a material which adheres to walls of the channel during pressure-based flow; and

,

continuously or periodically applying an electric field to the fluid in the channel, wherein the electric field is an alternating electrical field.

2. The method of claim 1, wherein the alternating electric field is a square wave field.

3. The method of claim 1, wherein the alternating electric field is a sine wave field.

4. The method of claim 2, wherein applying the electric field heats at least a portion of the fluid in the channel.

5. The method of claim 1, wherein application of the electric field modulates adherence of the material to the walls of the channel.

6. The method of claim 1, wherein the electric field causes negligible movement of the material in a direction of flow of the material.

7. The method of claim 1, wherein the material comprises one or more of:

a protein, a cell, a carbohydrate, a nucleic acid, and a lipid.

8. The method of claim 1, wherein the material is larger than about 10 Å

in average diameter.

9. The method of claim 1, wherein the electric field is applied during pressure induced flow of the fluid in the channel.

10. The method of claim 2, wherein the channel is a microchannel.

11. The method of claim 2, wherein fluid pressure is applied by one or more of:

a vacuum source, a hydraulic pressure source, a pneumatic pressure source, fluidic contact with an absorbent material, an electroosmotic pressure pump, an electroosmotic pressure pump comprising an electroosmotic flow enhancer, and a plurality of fluidly coupled capillary channels.

12. The method of claim 2, wherein continuously or periodically applying an electric field to the fluid in the channel causes less than 0.1×

of total forward movement of the fluid in the channel, or less than 0.1×

of total forward movement of a charged species present in the fluid.

13. The method of claim 2, wherein continuously or periodically applying the electric field causes about 0.5×

or less of the total forward movement of the fluid in the channel, or less than 0.5×

of total forward movement of a charged species present in the fluid.

14. The method of claim 2, wherein continuously or periodically applying the electric field causes about 0.9×

or less of the total forward movement of the fluid in the channel, or less than 0.9×

of total forward movement of a charged species present in the fluid.

16. The method of claim 2, wherein the coating modulates electrokinetic flow of the material in the channel.

15. A method of regulating surface adsorption of a material in a microfluidic channel of a microfluidic device, the method comprising:

applying a surface coating to the microfluidic channel to modulate adsorption of the material in the channel;

flowing a fluid through the channel by applying pressure to the fluid in the channel; and

,

continuously or periodically applying an electric field to the fluid in the channel, wherein the electric field is an alternating electrical field.

17. A method of regulating surface adsorption of a material in a microfluidic channel of a microfluidic device, the method comprising:

flowing a fluid through the channel by applying pressure to the fluid in the channel, wherein the fluid comprises one or more adsorption inhibition agents; and

,

continuously or periodically applying an electric field to the fluid in the channel, wherein the electric field is an alternating electrical field.

18. The method of claim 17, wherein the one or more adsorption inhibition agents is NDSB or BSA.

19. The method of claim 17, wherein the one or more adsorption inhibition agents comprises both NDSB and BSA.

20. The method of claim 19, wherein the fluid comprises NDSB at a concentration of at least about 0.1M and BSA at a concentration of at least about 1 mg/ml.