MICROFLUIDIC VALVE HAVING FREE-FLOATING MEMBER AND METHOD OF FABRICATION

• US 20100025613A1
• Filed: 09/23/2009
• Published: 02/04/2010
• Est. Priority Date: 08/10/2006
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Tai, Yu-Chong, Rodger, Damien C., Chen, Po-Jui, Humayun, Mark S.
• Granted Patent: US 8,141,573 B2
• Time in Patent Office: Days
• US Class Current: 251/318
• CPC Class Codes: F16K 15/144 the closure elements being fixed along all or a part of their periphery
• CPC Class Codes: F16K 99/0005 Lift valves
• CPC Class Codes: F16K 99/0015 Diaphragm or membrane valves
• CPC Class Codes: F16K 99/0057 the fluid being the circulating fluid itself, e.g. check valves
• CPC Class Codes: Y10T 137/0497 Fluid actuated or retarded
• CPC Class Codes: Y10T 137/7866 Plural seating
• CPC Class Codes: Y10T 137/7904 Reciprocating valves
• CPC Class Codes: Y10T 137/7914 Cage
• CPC Class Codes: Y10T 29/49409 Valve seat forming

Abstract

Micro check valves having a free-floating member for controlling flow of fluid in microfluidic and biomedical applications and methods of fabrication. A micro check valve includes a valve seat, a valve cap that contacts the valve seat and an untethered floating member that can move between the valve seat and the valve cap. Certain micro check valves have zero cracking pressure and no reverse leakage. Certain other valves may be configured to permit flow of fluid within a pressure range. The floating member can be solid or define an orifice, and the valve seat can have one or two levels. Valves can be configured to allow fluid to flow when the floating member is pushed by fluid against the valve cap or against the valve seat. The valve seat may be silicon or another material that is compatible with micromachining processes, and the valve cap and the floating member may be a polymer such as Parylene.

Claims

1. A micro check valve for controlling flow of a liquid, comprising:

a valve seat comprised of a substrate material;

a valve cap disposed on the valve seat, a space being defined between the valve seat and the valve cap; and

a floating member movable in the space between the valve seat and the valve cap by application of pressure on the floating member by the liquid to passively control flow of the liquid through the valve seat and the valve cap.

2. The micro check valve of claim 1, wherein the valve seat defines a port and the valve cap defines at least one orifice, the port and the at least one orifice being in fluid communication with each other.

3. The micro check valve of claim 2, wherein the floating member defines an orifice.

4. The micro check valve of claim 3, wherein the liquid can flow through the at least one orifice of the valve cap, through the orifice of the floating member and through the port when the floating member is pushed by the liquid against the valve seat.

5. The micro check valve of claim 3, wherein the liquid cannot flow through the at least one orifice of the valve cap when the floating member is pushed by the liquid against the valve cap.

6. The micro check valve of claim 3, wherein the port is defined through a center of the valve seat, the orifice of the floating member is defined through a center of the floating member, and the valve cap defines a plurality of orifices that are positioned radially outwardly relative to the port and the orifice of the floating member.

7. The micro check valve of claim 2, wherein the floating member is solid.

8. The micro check valve of claim 7, wherein the liquid can flow through the port, over the floating member, and through the at least one orifice when the floating member is pushed by the liquid against the valve cap.

9. The micro check valve of claim 7, wherein the liquid cannot flow through the port when the floating member is pushed by the liquid against the valve seat.

10. The micro check valve of claim 1, the valve seat comprising a multi-level valve seat having a first surface at a first level and a second surface at a second level below the first level, the valve cap being disposed on the first surface.

11. The micro check valve of claim 1, wherein the substrate material is silicon and the valve cap and the floating member are a polymer material.

12. The micro check valve of claim 1, wherein the valve seat, the valve cap and the floating member are configured for continuous flow of the liquid, zero cracking pressure and zero reverse leakage.

13. The micro check valve of claim 1, wherein the valve seat, the valve cap and the floating member are configured to control the flow of a bodily fluid, water, a solution, or a drug or medication.

14. The micro check valve of claim 1, wherein the floating member is bendable.

15. A micro check valve for controlling flow of a fluid, comprising:

a multi-level valve seat comprised of a substrate material, the multi-level valve seat having a first surface at a first level and a second surface at a second, lower level;

a valve cap disposed on the first surface, a space being defined between the valve seat and the valve cap; and

a floating member movable in the space between the multi-level valve seat and the valve cap by application of pressure on the floating member by a fluid to passively control flow of the fluid through the multi-level valve seat and the valve cap.

16. The micro check valve of claim 15, wherein the multi-level valve seat, the valve cap and the floating member are configured to permit flow of the fluid when the fluid pressure is between a threshold pressure and a cut-off pressure.

17. The micro check valve of claim 15, wherein the floating member is bendable.

18. The micro check valve of claim 17, wherein the floating member is bendable between a flat configuration and an arcuate configuration in which a portion of the floating member can contact the second surface by application of pressure on the floating member by a fluid.

19. The micro check valve of claim 15, wherein the floating member is movable between the first surface of the valve seat and the valve cap

20. A method of fabricating a micro check valve having a floating member for controlling flow of fluid, the method comprising:

depositing a plurality of polymer layers and a plurality of sacrificial layers on a substrate in an alternating manner, the substrate comprising a valve seat, the plurality of polymer layers including a first polymer layer comprising the floating member, a second polymer layer comprising a valve cap, and a third polymer layer comprising an outer wall defining a fluid channel; and

removing the plurality of sacrificial layers, thereby forming an in-channel microfluidic valve having a floating polymer member that is movable between the valve seat and the polymer valve cap.