Microfabricated elastomeric valve and pump systems

• US 7,601,270 B1
• Filed: 06/27/2000
• Issued: 10/13/2009
• Est. Priority Date: 06/28/1999
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Unger, Marc A., Chou, Hou-Pu, Scherer, Axel, Quake, Stephen R., Thorsen, Todd A.
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/605,520
• Time in Patent Office: 3,395 Days
• Field of Search: 156/242, 156/245, 156/155, 156/307.1
• US Class Current: 216/22
• CPC Class Codes: B01L 2300/0861 Configuration of multiple channels and/or chambers in a single devices
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2300/123 Flexible; Elastomeric
• CPC Class Codes: B01L 2400/046 Chemical or electrochemical formation of bubbles
• CPC Class Codes: B01L 2400/0481 squeezing of channels or chambers
• CPC Class Codes: B01L 2400/0655 pinch valves
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• 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: B29C 51/00 Shaping by thermoforming , i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor blow moulding of tubular preforms B29C49/00, deforming of tubular or hollow preforms B29C67/0014
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: B81B 2201/036 Micropumps
• CPC Class Codes: B81B 2201/054 Microvalves
• CPC Class Codes: B81B 5/00 Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• CPC Class Codes: B81C 1/00119 Arrangement of basic structures like cavities or channels, e.g. suitable for microfluidic systems
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2201/034 Moulding
• CPC Class Codes: C12Q 1/6874 involving nucleic acid arrays, e.g. sequencing by hybridisation
• CPC Class Codes: C12Q 2535/125 Allele specific primer extension
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F04B 43/14 : having plate-like flexible members
• CPC Class Codes: F15C 1/06 : Constructional details; Selection of specified materials ; Constructional realisation of one single element; Canal shapes; Jet nozzles; Assembling an element with other devices, only if the element forms the main part F15C5/00 takes precedence
• CPC Class Codes: F15C 5/00 : Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: F16K 1/20 : with axis of rotation arranged externally of valve member
• CPC Class Codes: F16K 11/20 : operated by separate actuating members with one plug turning in another F16K11/12
• CPC Class Codes: F16K 13/00 : Other constructional types of cut-off apparatus means for plugging pipes or hoses F16L55/10; Arrangements for cutting-off
• CPC Class Codes: F16K 2099/0074 : using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/0076 : using electrical discharge machining [EDM], milling or drilling
• CPC Class Codes: F16K 2099/0078 : using moulding or stamping
• CPC Class Codes: F16K 2099/008 : Multi-layer fabrications
• CPC Class Codes: F16K 2099/0094 : Micropumps
• CPC Class Codes: F16K 31/126 : the fluid acting on a diaphragm, bellows, or the like F16K31/145, F16K31/165, F16K31/365, F16K31/385 take precedence
• 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 99/0015 : Diaphragm or membrane valves
• CPC Class Codes: F16K 99/0046 : using magnets
• CPC Class Codes: F16K 99/0048 : using piezoelectric means
• CPC Class Codes: F16K 99/0051 : using electrostatic means
• CPC Class Codes: F16K 99/0059 : actuated by a pilot fluid
• CPC Class Codes: Y10T 137/0491 : Valve or valve element assembling, disassembling, or replacing
• CPC Class Codes: Y10T 137/0497 : Fluid actuated or retarded
• CPC Class Codes: Y10T 137/2224 : Structure of body of device
• CPC Class Codes: Y10T 137/87249 : Multiple inlet with multiple outlet
• CPC Class Codes: Y10T 137/87981 : Common actuator
• CPC Class Codes: Y10T 156/10 : Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/24479 : including variation in thickness
• CPC Class Codes: Y10T 428/24744 : Longitudinal or transverse tubular cavity or cell

Abstract

A method of fabricating an elastomeric structure, comprising: forming a first elastomeric layer on top of a first micromachined mold, the first micromachined mold having a first raised protrusion which forms a first recess extending along a bottom surface of the first elastomeric layer; forming a second elastomeric layer on top of a second micromachined mold, the second micromachined mold having a second raised protrusion which forms a second recess extending along a bottom surface of the second elastomeric layer; bonding the bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer such that a control channel forms in the second recess between the first and second elastomeric layers; and positioning the first elastomeric layer on top of a planar substrate such that a flow channel forms in the first recess between the first elastomeric layer and the planar substrate.

Claims

1. A method of microfabricating an elastomeric structure, comprising:

microfabricating a first elastomeric layer having a recess formed therein that forms a flow channel, and a deflectable membrane formed integral with the first elastomeric layer, wherein the flow channel and deflectable membrane are formed from a single piece of elastomeric material;

microfabricating a second elastomeric layer having a recess formed therein, wherein the deflectable membrane is deflected to close the flow channel in response to an actuation force from the recess in the second elastomeric layer;

positioning the second elastomeric layer on top of the first elastomeric layer; and

,

bonding a bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer.

2. The method of claim 1 wherein the first and second elastomeric layers are microfabricated by replication molding.

3. The method of claim 1 wherein the first and second elastomeric layers are microfabricated by laser cutting.

4. The method of claim 1 wherein the first and second elastomeric layers are microfabricated by chemical etching.

5. The method of claim 1 wherein the first and second elastomeric layers are microfabricated by sacrificial layer methods.

6. The method of claim 1 wherein the first and second elastomeric layers are microfabricated by injection molding.

7. The method of claim 1 further comprising:

microfabricating an nth elastomeric layer; and

bonding the bottom surface of the (n−

1)th elastomeric layer onto a top surface of the nth elastomeric layer.

8. The method of claim 1 further comprising:

sequential addition of further elastomeric layers, whereby each layer is added by;

microfabricating a successive elastomeric layer; and

bonding the bottom surface of the successive elastomeric layer onto a top surface of the elastomeric structure.

9. The method of claim 1 wherein at least one of the first elastomeric layer and the second elastomeric layer are fabricated from a material selected from the group consisting of:

poly(bis(fluoroalkoxy)phosphazene), poly(carborane-siloxanes), poly(acrylonitrile-butadiene) (nitrile rubber), poly(1-butene), poly(chlorotrifluoroethylene-vinylidene fluoride) copolymers, poly(ethyl vinyl ether), poly(vinylidene fluoride), and poly(vinylidene fluoride-hexafluoropropylene) copolymer.

10. The method of claim 1 wherein at least one of the first elastomeric layer and the second elastomeric layer are fabricated from a composition selected from the group consisting of:

polyvinylchloride (PVC), polysulfone, polycarbonate, polymethylmethacrylate (PMMA), and polytertrafluoroethylene.

11. The method of claim 1 wherein at least one of the first elastomeric layer and the second elastomeric layer are fabricated from a material selected from the group consisting of:

elastomeric compositions of polyisoprene, polybutadiene, polychloroprene, polyisobutylene, poly(styrene-butadiene-styrene), the polyurethanes, and silicones.

12. The method of claim 11 wherein at least one of the first elastomeric layer and the second elastomeric layer are fabricated from a material selected from the group consisting of polydimethylsiloxane (PDMS), and aliphatic urethane diacrylates.

13. The method of claim 1 wherein the first and second elastomeric layers are made of the same material.

14. The method of claim 13 wherein at least one of the first and second elastomeric layers are incompletely cured.

15. The method of claim 13 wherein the elastomeric layers comprise thermoset elastomers which are bonded together by heating above an elastic/plastic transition temperature of at least one of the first and second elastomeric layers.

16. The method of claim 13 wherein both the first and second elastomeric layers comprise a crosslinking agent.

17. The method of claim 16 wherein the crosslinking agent is activated by light.

18. The method of claim 16 wherein the crosslinking agent is activated by heat.

19. The method of claim 16 wherein the crosslinking agent is activated by an additional chemical species.

20. The method of claim 1 wherein the first and second layers are bonded by a layer of adhesive.

21. The method of claim 20 wherein the adhesive comprises an uncured elastomer which is cured to bond the first and second elastomeric layers together.

22. The method of claim 21 wherein the adhesive comprises the same material as at least one of the first or second elastomeric layers.

23. The method of claim 1 wherein:

the first elastomeric layer is fabricated on a first micromachined mold having at least one raised protrusion which forms at least one recess in the bottom of the first elastomeric layer; and

the second elastomeric layer is fabricated on a second micromachined mold having at least one raised protrusion which forms at least one recess in the bottom of the first elastomeric layer.

24. The method of claim 23 wherein the first micromachined mold has at least one first raised protrusion which forms at least one first channel in the bottom surface of the first elastomeric layer.

25. The method of claim 24 wherein the second micromachined mold has at least one second raised protrusion which forms at least one second channel in the bottom surface of the second elastomeric layer.

26. The method of claim 25 wherein a bottom surface of the second elastomeric layer is bonded onto a top surface of the first elastomeric layer such that the at least one second channel is enclosed between the first and second elastomeric layers.

27. The method of claim 24 further comprising positioning the first elastomeric layer on top of a planar substrate such that the at least one first channel is enclosed between the first elastomeric layer and the planar substrate.

28. The method of claim 27 wherein a hermetic seal is formed between the bottom of the first layer and the top of the planar substrate.

29. The method of claim 1 wherein at least one of the elastomeric layers further comprises a conductive portion.

30. The method of claim 29 wherein the conductive portion is made by:

patterning a thin layer of metal on a flat substrate;

adhering the elastomeric layer onto the flat substrate; and

peeling the elastomeric layer off the flat substrate, such that the metal sticks to the elastomeric layer and comes off the flat substrate.

31. The method of claim 30 wherein the adhesion of the metal to the flat substrate is weaker than the adhesion of the metal to the elastomer.

32. The method of claim 29 further comprising sealing the microfabricated elastomeric structure onto a flat substrate, wherein the flat substrate comprises at least one conductive portion.

33. The method of claim 32 wherein the flat substrate is covered by an insulating layer.

34. The method of claim 29 wherein the conductive portion is produced by doping the elastomer with a conductive material.

35. The method of claim 34 wherein the conductive material comprises a metal.

36. The method of claim 34 wherein the conductive material comprises carbon.

37. The method of claim 34 wherein the conductive material comprises a conductive polymer.

38. The method of claim 34 wherein the elastomer used is inherently conductive.

39. The method of claim 29 wherein the conductive portion is made by metal deposition.

40. The method of claim 39 wherein the conductive portion is made by sputtering.

41. The method of claim 39 wherein the conductive portion is made by evaporation.

42. The method of claim 39 wherein the conductive portion is made by electroplating.

43. The method of claim 39 wherein the conductive portion is made by electroless plating.

44. The method of claim 39 wherein the conductive portion is made by chemical epitaxy.

45. The method of claim 29 wherein the conductive portion is made by made by carbon deposition.

46. The method of claim 45 wherein the conductive portion is made by mechanically rubbing material directly onto the elastomeric layer.

47. The method of claim 45 wherein the conductive portion is made by electrostatic deposition.

48. The method of claim 45 wherein the conductive portion is made by a chemical reaction producing carbon.

49. The method of claim 45 wherein the conductive portion is made by exposing the elastomer to a solution of carbon particles in solvent.

50. The method of claim 49 wherein the solvent causes swelling of the elastomer.

51. The method of claim 49 wherein the elastomer comprises silicone and the solvent comprises a chlorinated solvent. elastomer.

52. Method of claim 29 wherein the conductive portion is patterned.

53. The method of claim 52 wherein the conductive portion is patterned by masking a surface of the conductive portion with a patterned sacrificial material.

54. The method of claim 52 wherein the conductive portion is patterned by:

depositing a sacrificial material on one of the elastomeric layers,

patterning the sacrificial material,

depositing a thin coat of conductive material thereover, and

removing the sacrificial material.

55. The method of claim 52 wherein the conductive portion is patterned by masking the surface with a shadow mask.

56. The method of claim 55 wherein the conductive portion is patterned by:

positioning a shadow mask adjacent to an elastomeric layer;

depositing a thin coat of conductive material through apertures in the shadow mask; and

removing the shadow mask.

57. The method of claim 52 wherein the conductive portion is patterned by etching.

58. The method of claim 57 wherein the conductive portion is patterned by:

depositing a mask layer onto one of the elastomeric layers;

patterning the mask layer;

etching the conductive portion through holes in the mask layer; and

removing the mask layer.

59. The method of claim 1 wherein the first elastomeric layer has an excess of a first chemical species and the second elastomeric layer has an excess of a second chemical species.

60. The method of claim 59 wherein the elastomeric layers comprise thermoset elastomers which are bonded together by heating above an elastic/plastic transition temperature of at least one of the first and second elastomeric layers.

61. The method of claim 59 wherein the first and second chemical species comprise different molecules.

62. The method of claim 59 wherein the first and second chemical species comprise different polymer chains.

63. The method of claim 59 wherein the first and second chemical species comprise different side groups on the same type of polymer chains.

64. The method of claim 59 wherein the first and second elastomeric layers are formed of different elastomeric materials.

65. The method of claim 59 wherein the first and second elastomeric layers are initially composed of the same elastomeric material, and an additional elastomeric material is added to one of the first and second layers.

66. The method of claim 59 wherein each of the elastomeric layers are made of polyurethane.

67. The method of claim 66 wherein the polyurethane comprises an aliphatic urethane diacrylate.

68. The method of claim 59 wherein the first chemical species forms bonds with the second chemical species when at least one chemical species is activated.

69. The method of claim 68 wherein the at least one chemical species is activated by light.

70. The method of claim 68 wherein the at least one chemical species is activated by heat.

71. The method of claim 68 wherein the at least one chemical species is activated by the addition of a third chemical species.

72. The method of claim 71 wherein the at least one chemical species diffuses through the elastomer structure.

73. The method of claim 59 wherein the first and second elastomeric layers are composed of the same component materials, but differ in the ratio in which the component materials are mixed together.

74. The method of claim 73 wherein each of the elastomeric layers is made of two-part silicone.

75. The method of claim 74 wherein each elastomeric layer comprises an addition cure elastomer system.

76. The method of claim 74 wherein the silicone comprises two different reactive groups and a catalyst.

77. The method of claim 76 wherein the first reactive group comprises silicon hydride moieties, the second reactive group comprises vinyl moieties, and the catalyst comprises platinum.

78. The method of claim 77 wherein each elastomeric layer comprises a two-part addition-cure silicone rubber having a part A that contains vinyl groups and a catalyst and a part B that contains silicon hydride (Si-H) groups.

79. The method of claim 78 wherein the first elastomeric layer is mixed with a ratio of less than 10A:

1B (excess Si-H groups) and the second elastomeric layer is mixed with a ratio of more than 10A;

B (excess vinyl groups).

80. The method of claim 79 wherein the first elastomeric layer has a ratio of 3A:

1B (excess Si-H groups) and the second elastomeric layer has a ratio of 30A;

1B (excess vinyl groups).

81. A method of microfabricating an elastomeric structure, comprising:

microfabricating a first elastomeric layer having a recess formed therein that forms a flow channel, and a deflectable membrane formed integral with the first elastomeric layer, wherein the flow channel and deflectable membrane are formed from a single piece of elastomeric material;

microfabricating a second elastomeric layer having a recess formed therein that forms a control channel, wherein a long axis in the control channel is substantially parallel to a bottom surface of the second elastomeric layer, and wherein the deflectable membrane is deflectable in response to an actuation force in the control channel;

positioning the second elastomeric layer on top of the first elastomeric layer; and

,

bonding the bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer.

82. A method of microfabricating an elastomeric structure, comprising:

microfabricating a first elastomeric layer having a plurality of recesses formed therein that form a plurality of flow channels, and a plurality of deflectable membranes formed integral with the first elastomeric layer, wherein the flow channels and deflectable membranes are formed from a single piece of elastomeric material;

microfabricating a second elastomeric layer having a recess formed therein that forms a control channel, wherein the plurality of deflectable membranes are deflected in response to an actuation force from the control channel;

positioning the second elastomeric layer on top of the first elastomeric layer; and

,

bonding a bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer.