Magnetically actuated fluid handling devices for microfluidic applications

• US 6,408,884 B1
• Filed: 12/15/1999
• Issued: 06/25/2002
• Est. Priority Date: 12/15/1999
• Status: Expired due to Term

• Current Assignee: University of Washington, Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Böhringer, Karl, Weigl, Berhard, Yager, Paul, Hatch, Anson, Kamholz, Andrew
• Primary Examiner(s): RIVELL, JOHN A
• Application Number:
  US09/464,379
• Time in Patent Office: 923 Days
• Field of Search: 137/827, 137/251.1, 417/92
• US Class Current: 137/827
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0861 Configuration of multiple channels and/or chambers in a single devices
• CPC Class Codes: B01L 2300/088 Channel loops
• CPC Class Codes: B01L 2400/043 magnetic forces
• CPC Class Codes: B01L 2400/0694 vents used to stop and induce flow, backpressure valves
• 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: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: B01L 3/502784 specially adapted for droplet or plug flow, e.g. digital microfluidics automatic analysis using a stream of discrete samples in a tube system G01N35/08
• CPC Class Codes: F04B 17/044 using solenoids directly actuating the piston
• CPC Class Codes: F04B 43/046 with piezoelectric drive
• CPC Class Codes: F04B 43/14 having plate-like flexible members
• CPC Class Codes: F04F 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: F16K 13/10 by means of liquid or granular medium
• CPC Class Codes: F16K 2099/0084 Chemistry or biology, e.g. "lab-on-a-chip" technology
• CPC Class Codes: F16K 2099/0094 Micropumps
• CPC Class Codes: F16K 31/08 using a permanent magnet
• CPC Class Codes: F16K 99/0019 Valves using a microdroplet or microbubble as the valve member
• CPC Class Codes: F16K 99/0046 using magnets
• CPC Class Codes: Y10T 137/0318 Processes
• CPC Class Codes: Y10T 137/2191 : By non-fluid energy field affecting input [e.g., transducer]
• CPC Class Codes: Y10T 137/4643 : Liquid valves

Abstract

Magnetically actuated fluid handling devices using magnetic fluid to move one or more fluids (gases or liquids or both) through microsized flow channels are provided. Fluid handling devices include micropumps and microvalves. Magnetically actuated slugs of magnetic fluid are moved within microchannels of a microfluidic device to facilitate valving and/or pumping of fluids and no separate pump is required. The magnets used to control fluid movement can be either individual magnets moved along the flow channels or one or more arrays of magnets whose elements can be individually controlled to hold or move a magnetic slug. Fluid handling devices include those having an array of electromagnets positioned along a flow channel which are turned on and off in a predetermined pattern to move magnetic fluid slugs in desired paths in the flow channel. The fluid handling devices of the present invention can handle gases and liquids simultaneously and thus can be made to be self-priming. These devices are more resistant to fluctuations in fluid input than other types of micropumps which need to be tuned to pump either liquid or gas. In a particular embodiment, a micropump having a loop channel containing a stationary magnetic slug and one or more moving slugs is provided.

Claims

1. A fluid handling device comprising:

at least one microsized flow channel in fluid communication with at least one fluid inlet and at least one fluid outlet; and

one or more slugs of magnetic fluid located within the flow channel, wherein a slug can be held stationary or moved in the channel by at least one magnet and wherein a slug blocks fluid flow through the channel when it is stationary and a slug pulls or pushes fluid through the channel when it is moved;

said device also comprising at least one slug inlet in fluid communication with the flow channel for conducting the slug into the flow channel.

2. The fluid handling device of claim 1, wherein the slug inlet comprises a flow channel containing at least one vent.

3. The fluid handling device of claim 1, further comprising at least one slug outlet in fluid communication with the flow channel for conducting the slug out of the flow channel.

4. The fluid handling device of claim 1, further comprising at least one slug outlet in fluid communication with the flow channel for conducting the slug out of the flow channel.

5. The fluid handling device of claim 1, wherein an array of magnets is used to move one or more slugs through the flow channel.

6. The fluid handling device of claim 5 wherein the array of magnets is an array of electromagnets.

7. The fluid handling device of claim 1 wherein the magnetic fluid is a ferrofluid.

8. The fluid handling device of claim 1 for use with liquid fluids.

9. The fluid handling device of claim 1 for use with aqueous media.

10. The fluid handling device of claim 1 for use with fluids that are gases.

11. A microfluidic device comprising at least one of the fluid handling device of claim 1.

12. A method for moving fluid in a fluid handling device having at least one fluid inlet and at least one fluid outlet comprising the, steps of;

providing at least one microsized flow channel in fluid communication with the fluid inlet and the fluid outlet;

providing one or more slugs of magnetic fluid located within the flow channel, a slug being either held stationary or moved by at least one magnet;

providing at least one slug inlet in fluid communication with the flow channel wherein the slug inlet is distinct from the fluid inlet and the fluid outlet; and

using at least one magnet to move a slug through the flow channel causing a net flow of fluid into the fluid inlet and a net outflow of fluid out of the fluid outlet.

13. A method for moving fluid in a fluid handling device having at least one fluid inlet and at least one fluid outlet comprising the steps of:

providing a plurality of microsized flow channels, each channel being in fluid communication with at least one fluid inlet and at least one fluid outlet, wherein at least one channel branches off from another channel;

providing one or more slugs of magnetic fluid located within at least one of the flow channels, a slug being either held stationary or moved by at least one magnet; and

using at least one magnet to move a slug through the flow channel causing a net flow of fluid into the fluid inlet and a net outflow of fluid out of the fluid outlet.