Microprobe array structure and method for manufacturing the same

• US 20080009763A1
• Filed: 11/15/2006
• Published: 01/10/2008
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: National Chiao Tung University (Government of The Republic of China)
• Original Assignee: National Chiao Tung University (Government of The Republic of China)
• Inventors: Hung, Chen-Chun, Chang, Chih-Wei, Chiou, Jin-Chern
• Granted Patent: US 7,941,201 B2
• Time in Patent Office: Days
• US Class Current: 600/544
• CPC Class Codes: A61B 5/14514 using means for aiding extraction of interstitial fluid, e.g. microneedles or suction
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/257 using adhesive means, e.g. adhesive pads or tapes
• CPC Class Codes: A61B 5/262 Needle electrodes
• CPC Class Codes: A61B 5/266 containing electrolytes, conductive gels or pastes
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/685 Microneedles

Abstract

A microprobe array structure with self-stabilization capability and a method for manufacturing the same are proposed. The microprobe array structure is used to sense various biopotential signals, and is characterized in that the etching parameters are controlled during etching to manufacture a microprobe structure with a reduced bottom cross section so that the microprobe can be firmly stabilized in the skin tissue. Moreover, a conducting layer is formed on the microprobe to sense signals. A design of electric isolation between microprobes is also proposed. The microprobe array can therefore be used for the measurement of various biopotential signals, and can also be used as a stimulus.

Claims

1. A microprobe structure used to measure biopotential signals, said microprobe structure comprising:

a tip portion;

a needle with a top connected to said tip portion, the cross-sectional area of said top being larger than that of a bottom of said needle; and

a conducting layer covering on said tip portion and said needle.

2. The microprobe structure as claimed in claim 1, wherein said tip portion is conical.

3. The microprobe structure as claimed in claim 1, wherein said tip portion can puncture the Stratum Corneum and Stratum Germinativum to allow said microprobe to get into said Stratum Germinativum and measure said biopotential signals.

4. The microprobe structure as claimed in claim 1, wherein said biopotential signals include electroencephalographic (EEG) signals, electrocardiographic (ECG) signals and electromyographic (EMG) signals.

5. The microprobe structure as claimed in claim 1, wherein the total length of said tip portion and said needle is 250˜

450 micrometers.

6. The microprobe structure as claimed in claim 1, wherein the connection between said tip portion and said needle can have edges and corners to enhance the stabilization capability of said microprobe.

7. The microprobe structure as claimed in claim 1, wherein the ratio of the cross-sectional areas of said top and said bottom is larger than 1.

8. The microprobe structure as claimed in claim 1, wherein the material of said conducting layer can be polymer, thin film material or metal.

9. The microprobe structure as claimed in claim 1, wherein said bottom of said needle is connected to a substrate and used as a sensing electrode that is connected to an external circuit and used to receive said measured biopotential signals.

10. The microprobe structure as claimed in claim 9, wherein the material of said substrate is silicon.

11. The microprobe structure as claimed in claim 9, wherein a plurality of said microprobes can be disposed on said substrate to form a microprobe array.

12. The microprobe structure as claimed in claim 11, wherein said conducting layers of said microprobes can be connected together to measure one of said biopotential signals.

13. The microprobe structure as claimed in claim 11, wherein said conducting layers of said microprobes can be mutually isolated, and said microprobe array can be used to measure a plurality of said biopotential signals.

14. The microprobe structure as claimed in claim 13, wherein each of said microprobes with mutually isolated conducting layers can be used as a stimulus.

15. The microprobe structure as claimed in claim 14, wherein when said microprobe is used as a stimulus, a voltage or a current is conducted into said microprobe to electrify said microprobe or render pressure to the punctured location.

16. The microprobe structure as claimed in claim 11, wherein the shape of said microprobe array can be a square, a circle, or an irregular shape.

17. The microprobe structure as claimed in claim 1, wherein the tip portion and the needle can be hollow.

18. A microprobe array structure used to measure biopotential signals, said microprobe array structure comprising:

a substrate; and

a plurality of microprobes each having a tip portion, a needle and a conducting layer, a top of said needle being connected to said tip portion and a bottom of said needle being connected to said substrate, the cross-sectional area of said top being larger than that of said bottom, said conducting layer covering on said tip portion and said needle.

19. The microprobe array structure as claimed in claim 18, wherein said tip portion is conical.

20. The microprobe array structure as claimed in claim 18, wherein said tip portion can puncture the Stratum Corneum and Stratum Germinativum to allow said microprobe to get into said Stratum Germinativum and measure said biopotential signals.

21. The microprobe array structure as claimed in claim 18, wherein said biopotential signals include electroencephalographic (EEG) signals, electrocardiographic (ECG) signals and electromyographic (EMG) signals.

22. The microprobe array structure as claimed in claim 18, wherein the total length of said tip portion and said needle is 250˜

450 micrometers.

23. The microprobe array structure as claimed in claim 18, wherein the connection between said tip portion and said needle can have edges and corners to enhance the stabilization capability of said microprobe.

24. The microprobe array structure as claimed in claim 18, wherein the ratio of the cross-sectional areas of said top and said bottom is larger than 1.

25. The microprobe array structure as claimed in claim 18, wherein the material of said conducting layer can be polymer, thin film material or metal.

26. The microprobe array structure as claimed in claim 18, wherein said substrate is used as a sensing electrode that is connected to an external circuit and used to receive said measured biopotential signals.

27. The microprobe array structure as claimed in claim 18, wherein the material of said substrate is silicon.

28. The microprobe array structure as claimed in claim 18, wherein said conducting layers of said plurality of microprobes can be connected together to measure one of said biopotential signals.

29. The microprobe array structure as claimed in claim 18, wherein said conducting layers of said plurality of microprobes can be mutually isolated, and said microprobe array can be used to measure a plurality of said biopotential signals.

30. The microprobe array structure as claimed in claim 29, wherein each of said microprobes with mutually isolated conducting layers can be used as a stimulus.

31. The microprobe array structure as claimed in claim 30, wherein when said microprobe is used as a stimulus, a voltage or a current is conducted into said microprobe to electrify said microprobe or render pressure to the punctured location.

32. The microprobe array structure as claimed in claim 18, wherein the shape of said plurality of microprobe can be a square, a circle, or an irregular shape.

33. The microprobe array structure as claimed in claim 18, wherein the microprobe can be hollow.

34. A method for manufacturing microprobes, said method comprising the steps of:

providing a substrate and forming a patterned masking layer thereon;

isotropically etching a plurality of tip portions with said masking layer as the mask;

anisotropically etching downwards a plurality of needles and controlling etching parameters to let the cross-sectional area of the connection between said needle and said tip portion be larger than that of the other end of said needle;

removing said masking layer to get said microprobe structure; and

forming a conducting layer on said microprobe structure.

35. The method for manufacturing microprobes as claimed in claim 34, wherein said patterned masking layer is defined out by means of photo lithography.

36. The method for manufacturing microprobes as claimed in claim 34, wherein the material of said masking layer is photoresist or thin film material.

37. The method for manufacturing microprobes as claimed in claim 34, wherein said isotropic etching is dry etching or wet etching.

38. The method for manufacturing microprobes as claimed in claim 34, wherein said tip portion etched by said isotropic etching is conical.

39. The method for manufacturing microprobes as claimed in claim 34, wherein said anisotropic etching is dry etching or wet etching.

40. The method for manufacturing microprobes as claimed in claim 34, wherein during said anisotropic etching, said etching parameters can be controlled to let the connection between said tip portion and said needle have edges and corners to enhance the stabilization capability of said microprobe.

41. The method for manufacturing microprobes as claimed in claim 34, wherein the total length of said tip portion and said needle is 250˜

450 micrometers.

42. The method for manufacturing microprobes as claimed in claim 34, wherein the removal of said masking layer is carried out by means of dry etching or wet etching.

43. The method for manufacturing microprobes as claimed in claim 34, wherein the material of said conducting layer is polymer, thin film material or metal.

44. The method for manufacturing microprobes as claimed in claim 34, wherein the material of said substrate is silicon.

45. The method for manufacturing microprobes as claimed in claim 34, further comprising a step of removing said conducting layer on said substrate to electrically isolate said plurality of microprobes on said substrate.

46. The method for manufacturing microprobes as claimed in claim 45, wherein said step removing said conducting layer on said substrate further comprising the steps of:

forming a photoresist layer on said plurality of microprobes;

forming a mask and defining out a routing by means of exposure;

removing said conducting layer on said plurality of microprobes and said routing; and

removing said mask and said photoresist layer.

47. The method for manufacturing microprobes as claimed in claim 45, wherein each of said plurality of microprobes can be used as a stimulus.

48. The method for manufacturing microprobes as claimed in claim 47, wherein when said microprobe is used as a stimulus, a voltage or a current is conducted into said microprobe to electrify said microprobe or render pressure to the punctured location.

49. A method for manufacturing microprobes, said method comprising the steps of:

forming a mold with a imprint or negative image of the desired surface features which may include microprobes and substrates;

filling the mold to produce the microprobes; and

forming a conducting layer on said microprobe.

50. The method for manufacturing microprobes as claimed in claim 49, wherein the filling of the mold comprises injection molding, casting, and deposition.