Micromachined fluidic device and method for making same

• US 20040052657A1
• Filed: 03/31/2003
• Published: 03/18/2004
• Est. Priority Date: 05/25/2000
• Status: Active Grant

• Current Assignee: Debiotech S.A.
• Original Assignee: Debiotech S.A.
• Inventors: Maillefer, Didier, Gamper, Stephan, Van Lintel, Harald T.
• Granted Patent: US 7,005,078 B2
• Time in Patent Office: Days
• US Class Current: 417/322
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: F04B 43/043 Micropumps

Abstract

The fluid-flow device (100) of the invention comprises a stack (30) covered by a closure wafer (20), said stack (30) comprising a support wafer (36), a layer of insulating material (34), and a silicon layer (32). The closure wafer (20) and/or said silicon layer (32) are machined so as to define a cavity (38) between said closure wafer (20) and said silicon layer (32), said support wafer (36) has at least one duct (102) passing right through it, said layer of insulating material (34) presenting at least one zone (35) that is entirely free of material placed at least in line with said duct (102) so as to co-operate with said cavity (38) to define a moving member (40) in said silicon layer (32), the moving member being suitable under the pressure of liquid in said cavity (38) for reversibly moving towards said support wafer (36) until contact is made between said moving member (40) and said support wafer (36).

Claims

1. / A method of manufacturing a fluid-flow device, the method being characterized in that it comprises the following steps:

providing a stack (30) comprising a support wafer (36), a single layer of insulating material (34) covering at least part of said support wafer (36), and a layer of single-crystal or polycrystalline silicon (32) covering said layer of insulating material (34) and presenting a free face;

providing at least one closure wafer (20);

using photolithography and chemical etching to machine a cavity (38) from said closure wafer (20) and/or from the free face of said silicon layer (32);

using photolithography and chemical etching to machine at least one duct (102;

412, 412′

) passing right through said support wafer (35);

chemically etching said layer of insulating material (34) at least via said duct (102;

412, 412′

) such that a zone of said silicon layer (32) is freed from said layer of insulating material (34), thereby forming a moving member (40) that is adjacent to said cavity and that responds to liquid pressure in said cavity (38) by moving reversibly towards said support wafer (36); and

using a physicochemical method, preferably by wafer bonding, to connect said closure wafer (20) in leaktight manner to said surface of silicon layer (32) that has not been machined.

3. / A device according to claim 1, characterized in that said moving member (40) moves reversibly towards said support wafer (36) until making contact between said moving member (40) and said support wafer (36).

2. / A fluid-flow device (100;

400;

500) comprising a stack (30) of the silicon-on-insulator (SOI) type covered by a closure wafer (20), said stack (30) comprising a support wafer (36), a single layer of insulating material (34) covering at least part of said support wafer (36), and a layer of single-crystal or polycrystalline silicon (32) covering said layer of insulating material (34) and covered by said closure wafer (20),

said closure wafer (20) and/or said silicon layer (32) being machined so as to define between said closure wafer (20) and said silicon layer (32) a cavity (38) to be filled with liquid,

said support wafer (36) having at least one duct (102;

412, 412′

) passing right through it, and

said layer of insulating material (34) being made of silicon oxide and having at least one zone that is entirely free from material (35) placed at least in line with said duct (102, 412, 412′

) and obtained by structuring by chemical etching via said duct (102;

412, 412′

) so as to co-operate with said cavity (38) to define a moving member (40) in said silicon layer (32) that responds, by virtue of its elasticity, to pressure of the liquid in said cavity (38) by moving reversibly towards said support wafer (36).

4. / A device according to claim 2 or claim 3, characterized in that said closure wafer (20) is made of glass.

5. / A device according to any one of claims 2 to 4, characterized in that said support wafer (36) is made of silicon, of quartz, or of sapphire.

6. / A device according to any one of claims 2 to 5, characterized in that said support wafer (36) is of thickness lying in the range 50 μ

m to 1 mm.

7. / A device according to claim 6, characterized in that said support wafer (36) is of thickness lying in the range 300 μ

m to 500 μ

m.

8. / A device according to any one of claims 2 to 7, characterized in that said layer of insulating material (34) is of thickness lying in the range 100 nm to 2 μ

m.

9. / A device according to claim 8, characterized in that said layer of insulating material (34) presents thickness lying in the range 0.5 μ

m to 1 μ

m.

10. / A device according to any one of claims 2 to 9, characterized in that said silicon layer (32) presents a thickness lying in the range 1 μ

m to 100 μ

m.

11. / A device according to claim 10, characterized in that said silicon layer (32) presents a thickness lying in the range 10 μ

m to 50 μ

m.

12. / A fluid-flow device according to any one of claims 2 to 11, characterized in that it constitutes a liquid inlet control member (100;

100′

;

100″

;

100″

′

) forming a non-return check valve, said cavity (38) presenting at least one gap (104;

104₁;

104₂) machined in the entire thickness of the silicon layer (32),

said duct formed in said support wafer (36) constituting a liquid inlet duct (102) situated at least in register with said cavity (38), and

said zone (35) entirely free of material extending at least in line with said gap (104;

104₁;

104₂), said moving member (40) forming a flap for said valve, a portion of said silicon layer (32) surrounding said moving member (40) presenting elasticity making it possible in the event of a difference in liquid pressure between said liquid inlet duct (102) and said cavity (38) to allow said moving member (40) to move reversibly towards said support wafer (36).

13. / A fluid-flow device (100;

100′

) according to claim 12, characterized in that said liquid inlet duct (102) is situated close to but not in register with said gap (104), and in that said moving member (40) moves between a closed position in which the moving member (40) is in leaktight contact against said support wafer (36) which forms a seat for said valve at least around said duct (102), liquid flow being prevented between said liquid inlet duct (102) and the cavity (38), and an open position of the valve in which the moving member (40) is no longer in leaktight contact against the support wafer (36) around said duct (102), in which the moving member (40) allows liquid flow from said liquid inlet duct (102) towards said gap (104).

14. / A fluid-flow device (100′

) according to claim 13, characterized in that it further comprises bearing means (106, 110) between said closure wafer (20) and said moving member (40), said bearing means (106, 110) placing said moving member (40) in said closed position while it is in its rest position.

15. / A fluid-flow device (100″

) according to claim 12, characterized in that said closure wafer (20) is a first closure wafer (20), in that it further comprises a second closure wafer (20′

) fixed on the face of the support wafer (36) facing away from said first closure wafer (20) and provided with a duct (102″

a) passing right through it, in that a moving portion (361) is made in the support wafer (36) in register with and extending said cavity (38), said moving member (40), and said duct (102″

a), said moving portion (361) being situated close to but not in register with said gap (104₂), an annular volume free from material (102″

) being machined through the entire thickness of the support wafer (36) in register with said zone (35) that is entirely free from material in the layer of insulating material (34), thereby separating said moving portion (361) from the remainder of the support wafer (36) and forming said liquid inlet duct (102″

) which communicates with said gap (104₂), in that said layer of insulating material (34) presents a connection zone (321) securely connecting said moving portion (361) to said moving member (40), and in that it further comprises an annular valve element (370) made in an anti-adhesion material, said valve element (370) being situated either on the face of the second closure wafer (20′

) placed facing said moving portion (361) so that when said moving member (40) is as close as possible to the support wafer (36), the face of the moving portion (361) facing towards the second closure wafer (20′

) and the face of the valve element (370) facing towards the support wafer (36) are in leaktight contact thus putting the liquid inlet control member (100″

) in its closed position, or else on the face of said moving portion (361) placed facing the second closure wafer (20) such that when said moving member (40) is as close as possible to the support wafer (36), the face of the valve element (370) facing towards said second closure wafer (20′

) and the face of the second closure wafer (20′

) facing towards the support wafer (36) are in leaktight contact, thus putting the liquid inlet control member (100″

) into the closed position, in which closed position flow of liquid from the duct (102″

a) of the second closure wafer (20′

) towards said liquid inlet duct (102″

) of the support wafer (36) is prevented.

16. / A fluid-flow device (100″

) according to claim 12, characterized in that said closure wafer (20) is a first closure wafer (20), in that it further comprises a second closure wafer (20′

) fixed on the face of the support wafer (36) facing away from said first closure wafer (20) and provided with a duct (102″

a) passing right through it, in that the annular moving portion (361) is made in the support wafer (36) in register and in line with said cavity (38) and said moving member (40), a first annular volume (102″

′

a) free form material being machined through the entire thickness of the support wafer (36) in register with said cavity (38) and said zone (35) entirely free of material in the layer of insulating material (34), thereby separating said moving portion (361) from the remainder of the support wafer (36), a second cylindrical volume free from material (102″

′

) being machined throughout the entire thickness of the support wafer (36) at the location of the moving portion, thereby forming said liquid inlet duct (102) which communicates with said gap (104), in that said layer of insulating material (34) presents a connection zone (321) securely connecting said moving portion (361) to said moving member (40) around said liquid inlet duct (102) and said gap (104₁), and in that it further comprises an annular valve element (370) surrounding said liquid inlet duct (102″

′

), and made of an anti-adhesion material, said valve element (370) being situated either on the face of the second closure wafer (20′

) placed facing said moving portion (361) so that when said moving member (40) is as close as possible to the support wafer (36) the face of the moving portion (361) facing towards the second closure wafer (20′

) and the face of the valve element (370) facing towards the support wafer (36) are in leaktight contact thus putting the liquid inlet control member (100″

′

) into its closed position, or else on the face of said moving portion (361) placed facing the second glass closure wafer (20′

) such that when said moving member (40) is as close as possible to the support wafer (36), the face of the valve element (370) facing towards the second closure wafer (20′

) and the face of the second closure wafer (20′

) facing towards the support wafer (36) are in leaktight contact thus putting the liquid inlet control member (100″

′

) in its closed position, in which closed position liquid arriving in said first annular volume (102″

′

a) from the duct (102″

a) in the second closure wafer (20′

) is prevented from penetrating into said liquid inlet duct (102″

′

) in the support wafer (36).

17. / A fluid-flow device according to any one of claims 2 to 11, characterized in that it constitutes a liquid pressure detection member (400),

said duct formed in said support wafer (36) being situated in register with said cavity (38), and

said silicon support wafer (36) presenting a portion (414) in register with the moving member (40) forming an island that is separated from the remainder of the support wafer (36) by said duct (412′

).

18. / A fluid-flow device (400) according to claim 17, characterized in that said moving member (40) is capable of going from an open position to a closed position in which the moving member (40) is in physical contact with said portion (414) situated facing the moving member (40) forming an island that is separated from the remainder of the support wafer (36) by said duct (412′

) and which forms a bearing portion (414) of the silicon wafer, said physical contact being electrically detectable.

19. / A fluid-flow device (400) according to claim 18, characterized in that it further comprises connection means (416) between the bearing portion (414) and said silicon layer (32).

20. / A fluid-flow device (400″

′

) according to claim 17, characterized in that said closure wafer (20) is a first closure wafer (20), in that it further comprises a second closure wafer (20′

) fixed on the face of the support wafer (36) facing away from said first closure wafer (20), in that said portion which forms an island separated from the remainder of the support wafer (36) constitutes a moving portion (461), and in that said layer of insulating material (34) presents a connection zone (321) connecting said moving portion (461) securely to said moving member (40).

21. / A fluid-flow device according to any one of claims 2 to 11, characterized in that it constitutes a micropump,

said cavity (38) including a pump chamber (504),

said duct formed in said support wafer (36) constituting a first duct (102, 508, 412, 412′

, 204) situated in register with said cavity (38),

said zone that is entirely free of material constituting a first zone (35₁) that is entirely free of material, said moving member (40) constituting a first moving member (40) that is suitable under pressure of liquid in said pump chamber (504) for moving reversibly towards said support wafer (36), said first moving member (40) forming part of the flap of a liquid inlet control member (100), and

said fluid-flow device further comprising a pumping portion (502) comprising control means fitted with a pump diaphragm (506) to cause the volume of the pump chamber (504) to vary periodically, and liquid outlet control means (100).

22. / A fluid-flow device according to claim 21, characterized in that said first moving member (40) is suitable for coming into leaktight contact against said support wafer (36), said first moving member (40) constituting the flap of said liquid inlet control member (100).

23. / A fluid-flow device according to claim 22, characterized in that said layer of insulating material (34) further presents a second zone (35₄) that is entirely free of material which co-operates with said cavity (38) to define a second moving member (40) in said silicon layer (32), the second moving member being suitable under the pressure of liquid in said pump chamber for moving towards said support wafer (36), said second moving member (40) constituting the flap of a liquid outlet control member (200).

24. / A fluid-flow device according to any one of claims 21 to 23, characterized in that said liquid inlet control member (100) is in accordance with any one of claims 12 to 16.

25. / A fluid-flow device according to any one of claims 21 to 24, characterized in that it further comprises at least one liquid pressure detection member (400) in accordance with any one of claims 17 to 20.

26. / A fluid-flow device according to any one of claims 21 to 25, characterized in that said closure wafer (20) is a first closure wafer (20) made of glass.

27. / A fluid-flow device according to claim 26, characterized in that it further comprises a second closure wafer (20′

) made of glass fixed on the face of the support wafer (36) facing away from said first closure wafer (20) made of glass.

28. / A fluid-flow device according to claim 27, characterized in that said micropump control means are situated facing the pump chamber (504) and are integrated directly in the micropump by being fixed to the face of the second closure wafer (20′

) facing away from the stack (30).

29. / A fluid-flow device according to any one of claims 21 to 27, characterized in that said micropump control means are external to the micropump and are connected indirectly to said pump diaphragm (506).

30. / A fluid-flow device according to any one of claims 21 to 29, characterized in that said control means operate in piezoelectric, electromagnetic, or pneumatic manner.

31. / A fluid-flow device according to any one of claims 21 to 28, characterized in that a moving pumping portion (514;

514′

) is made in said support wafer (36) in register with the pump chamber (504), an annular volume free of material (508) machined in said support wafer (36) separating the moving pump portion (514;

514′

) from the remainder of the support wafer (36), and in that said micropump control means are situated in register with the pump chamber (504) and directly integrated in the micropump by being fixed to said moving pump portion (514;

514′

).

32. / A fluid-flow device according to claim 31, characterized in that the silicon layer (32) forms said pump diaphragm (506) in register with the pump chamber (504), and in that said moving pump portion (514′

) is pierced right through by a passage (540) which is suitable for receiving a control rod having one end fixed to the diaphragm (506) and having its opposite end forming a handle.

33. / A fluid-flow device according to claim 31, characterized in that said moving portion (514;

514′

) includes at least one liquid pressure detection member.

34. / A fluid-flow device according to claim 33, characterized in that said pumping portion (502′

) is provided with at least two liquid pressure detectors (400′

) each forming a liquid pressure detection member, said members being regularly spaced apart angularly in said moving pumping portion (514′

) which is pieced right through by at least two series of ducts (512′

).

35. / A fluid-flow device according to claim 33, characterized in that said pumping portion (502″

) is provided with an annular liquid pressure detector (400″

) presenting ducts (512′

) passing right through said moving portion (514′

) in an annular zone.

36. / The use of a fluid-flow device according to any one of claims 21 to 35, as a medical pump of the “

implantable”

type.

37. / The use of a fluid-flow device according to any one of claims 21 to 35, as a medical pump of the “

external”

type.