Microfluidic system including a bubble valve for regulating fluid flow through a microchannel

• US 7,069,943 B2
• Filed: 12/21/2004
• Issued: 07/04/2006
• Est. Priority Date: 04/17/2002
• Status: Expired due to Term

• Current Assignee: Cytonome Inc.
• Original Assignee: Cytonome Inc.
• Inventors: Deshpande, Manish, Gilbert, John R., Böhm, Sebastian
• Primary Examiner(s): CHAMBERS, A MICHAEL
• Application Number:
  US11/021,251
• Publication Number:
  US 20050109410A1
• Time in Patent Office: 560 Days
• Field of Search: 137/827, 137/833, 137/830, 137/831, 137/806, 137/807, 204/601
• US Class Current: 137/14
• CPC Class Codes: B01L 2200/0636 Focussing flows, e.g. to laminate flows
• CPC Class Codes: B01L 2200/0647 Handling flowable solids, e.g. microscopic beads, cells, particles
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/089 Virtual walls for guiding liquids
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/06 Valves, specific forms thereof
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 2400/082 Active control of flow resistance, e.g. flow controllers
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: B01L 3/502776 specially adapted for focusing or laminating flows
• CPC Class Codes: B07C 5/34 Sorting according to other particular properties material testing per se G01N; quality control G07C3/14
• CPC Class Codes: F16K 2099/0074 using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/008 Multi-layer fabrications
• CPC Class Codes: F16K 2099/0084 Chemistry or biology, e.g. "lab-on-a-chip" technology
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0017 Capillary or surface tension valves, e.g. using electro-wetting or electro-capillarity effects
• CPC Class Codes: F16K 99/0019 Valves using a microdroplet or microbubble as the valve member
• CPC Class Codes: F16K 99/0034 Operating means specially adapted for microvalves
• CPC Class Codes: F16K 99/0036 : operated by temperature variations
• CPC Class Codes: F16K 99/004 : using radiation
• CPC Class Codes: F16K 99/0046 : using magnets
• CPC Class Codes: F16K 99/0048 : using piezoelectric means
• CPC Class Codes: G01N 15/149 : specially adapted for sorting particles, e.g. by their size or optical properties
• CPC Class Codes: Y10T 137/0318 : Processes
• CPC Class Codes: Y10T 137/0396 : Involving pressure control
• CPC Class Codes: Y10T 137/0497 : Fluid actuated or retarded
• CPC Class Codes: Y10T 137/2076 : Utilizing diverse fluids
• CPC Class Codes: Y10T 137/2082 : Utilizing particular fluid
• CPC Class Codes: Y10T 137/2191 : By non-fluid energy field affecting input [e.g., transducer]
• CPC Class Codes: Y10T 137/2196 : Acoustical or thermal energy
• CPC Class Codes: Y10T 137/2202 : By movable element
• CPC Class Codes: Y10T 137/2207 : Operating at timed intervals [e.g., to produce pulses]
• CPC Class Codes: Y10T 137/2213 : Electrically-actuated element [e.g., electro-mechanical transducer]
• CPC Class Codes: Y10T 137/2224 : Structure of body of device
• CPC Class Codes: Y10T 29/49405 : Valve or choke making
• CPC Class Codes: Y10T 436/143333 : Saccharide [e.g., DNA, etc.]
• CPC Class Codes: Y10T 436/25375 : Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Abstract

A microfluidic system includes a bubble valve for regulating fluid flow through a microchannel. The bubble valve includes a fluid meniscus interfacing the microchannel interior and an actuator for deflecting the membrane into the microchannel interior to regulate fluid flow. The actuator generates a gas bubble in a liquid in the microchannel when a sufficient pressure is generated on the membrane.

Claims

1. A method of making a bubble valve, comprising:

providing a microchannel having an interior bounded by a side wall, an aperture formed in the side wall and a valve chamber adjacent to the aperture in communication with the interior;

filling the microchannel with a liquid to form a meniscus of the liquid in the aperture, whereby the step of filling traps a gas in the valve chamber;

providing an actuator for increasing the pressure in the valve chamber to deflect the meniscus into the interior.

2. The method of claim 1, wherein the step of providing an actuator comprises

applying and sealing an actuator comprising a chamber to a top surface of the microchannel to form a gas-filled chamber adjacent to the meniscus, wherein the actuator varies the pressure in the gas-filled chamber to deflect the meniscus into the interior, thereby regulating fluid flow.

6. The microfluidic device of claim 1, wherein the actuator deflects the meniscus into the microchannel interior to regulate the flow of fluid through the microchannel.

7. The microfluidic device of claim 1, wherein the meniscus comprises a virtual wall formed in an aperture in the side wall of the microchannel when the microchannel is filled with a liquid.

8. The microfluidic device of claim 1, wherein the actuator generates a gas bubble in the microchannel.

9. The microfluidic device of claim 8, further comprising a hydrophobic patch attached to an inner wall of the microchannel for anchoring the gas bubble.

10. The microfluidic device of claim 8, wherein the microchannel defines a cavity for retaining the gas bubble.

11. The microfluidic device of claim 1, wherein the gas filled reservoir comprises a movable membrane.

12. The microfluidic device of claim 11, wherein the actuator deflects the movable membrane to create a bubble in the microchannel interior.

3. A method of varying an electrical resistance in a microchannel, comprising the steps of:

generating a bubble by applying a pressure to a meniscus formed in a side wall of the microchannel, wherein the meniscus is formed by the liquid in the microchannel filling an aperture in the side wall;

injecting the bubble into a liquid in the microchannel, whereby the bubble varies the electrical resistance of the microchannel.

4. The method of claim 3, wherein the step of applying a pressure comprises increasing the pressure within a sealed reservoir formed adjacent to the aperture.

5. A microfluidic device, comprising:

a microchannel having an interior bounded by a side wall;

a valve for regulating the flow of fluid through the microchannel, the valve comprising a gas-filled reservoir external to and in communication with the microchannel interior, a fluid meniscus interfacing the reservoir and the interior and an actuator for varying the volume of the reservoir to increase an internal pressure of the reservoir to vary the flow of liquid through the channel.

13. A microfluidic device comprising:

a first plate having a groove formed therein defining a microchannel;

a second plate for enclosing the microchannel bonded to the first plate having an aperture adjacent to the groove sized and dimensioned to form a meniscus when the microchannel is filled with a liquid, the aperture defining a reservoir adjacent to the microchannel, wherein the meniscus forms an interface between the microchannel and the reservoir; and

a flexible membrane bonded to the second plate to seal the reservoir and defining a movable wall of the reservoir.

14. The microfluidic device of claim 13, further comprising an actuator for deflecting the flexible membrane, wherein the deflection of the membrane increases the pressure in the reservoir and deflects the meniscus into the microchannel to regulate liquid flow therethrough.

15. The microfluidic device of claim 13, further comprising a hydrophobic patch attached to the groove.

16. The microfluidic device of claim 13, wherein the meniscus forms a bubble in the microchannel to block liquid flow.

17. An electrophoretic system, comprising

a first electrokinetically operated microchannel;

a sample well for providing a sample to the first electrokinetically operated microchannel microchannel;

a voltage source;

a bubble valve for injecting a bubble into the microchannel to vary the electrical resistance of the microchannel.

18. The electrophoretic system of claim 17, further comprising:

a second electrokinetically operated microchannel in communication with the first electrokinetically operated microchannel, wherein the

a bubble valve selectively blocks flow from the first electrokinetically operated microchannel to the second electrokinetically operated microchannel by selectively injecting a bubble into a microchannel.