Microfabricated two-pin liquid sample dispensing system

• US 20030059345A1
• Filed: 12/21/2001
• Published: 03/27/2003
• Est. Priority Date: 09/25/2001
• Status: Active Grant

• Current Assignee: Cytonome/St, Llc (Cytonome Inc.)
• Original Assignee: Coventor, Inc. (Lam Research Corporation)
• Inventors: Gilbert, John, Harley, John
• Granted Patent: US 7,041,257 B2
• Time in Patent Office: Days
• US Class Current: 422/100
• CPC Class Codes: B01L 2200/143 Quality control, feedback systems
• CPC Class Codes: B01L 2200/147 Employing temperature sensors
• CPC Class Codes: B01L 2400/0439 ultrasonic vibrations, vibrating piezo elements
• CPC Class Codes: B01L 3/0244 using pins
• CPC Class Codes: B01L 3/0248 Prongs, quill pen type dispenser
• CPC Class Codes: G01N 2035/1037 Using surface tension, e.g. pins or wires
• CPC Class Codes: Y10T 436/119163 with aspirator of claimed structure
• CPC Class Codes: Y10T 436/25625 Dilution
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

A two-pin liquid sample dispensing system is provided. The two-pin dispensing system comprises a pair of separately movable pins for holding a droplet of liquid therebetween. Each pin includes a tip spaced predetermined distance from the other pin to define a sample acquisition region. The pins acquire and hold a droplet of the liquid sample in the sample acquisition region formed in the space between the tips and apply the droplet to a selected sample handing system. The distance between the tips is variable to accommodate different liquid samples having varying physical properties and to vary the volume of the acquired droplet.

Claims

1. A liquid sample dispensing system, comprising:

a holder;

a first pin coupled to the holder and having a first tip; and

a second pin coupled to the holder and having a second tip spaced a predetermined separation distance D from the first tip, wherein the first and second pins are movable relative to each other.

2. The liquid sample dispensing system of claim 1, further comprising a first actuator for moving the first tip to vary the initial separation distance.

3. The liquid sample dispensing system of claim 1, further comprising a second actuator for moving the second tip to vary the initial separation distance.

4. The liquid sample dispensing system of claim 1, further comprising a sensor for sensing the separation distance between the first tip and the second tip.

5. The liquid sample dispensing system of claim 1, further comprising a sensor for measuring the physical properties of the liquid sample.

6. The liquid sample dispensing system of claim 5, further comprising an actuator for varying the separation distance in response to the measurement of the physical properties.

7. The liquid sample dispensing system of claim 1, wherein the first pin and the second pin are fabricated from a silicon wafer.

8. A method of applying a liquid sample to a substrate, comprising:

providing a dispensing system comprising two pins for holding a droplet of the liquid sample and having a first tip and a second tip separated from the first tip by a variable separation distance;

acquiring a droplet of the liquid sample between the first tip and the second tip having a drop volume defined by the separation distance; and

contacting the substrate to deposit a spot of the liquid sample on the substrate.

9. The method of claim 8, wherein the spot has having a spot volume less than the drop volume.

10. The method of claim 8, wherein the step of acquiring the droplet comprises immersing the first tip and the second tip in a reservoir containing a supply of the liquid sample

11. The method of claim 8, wherein the substrate comprises a solid surface.

12. The method of claim 8, further comprising the step of varying the separation distance between the tips.

13. A method of diluting a first liquid sample in a second liquid sample, comprising:

providing a dispensing system comprising two pins for holding a droplet of the liquid sample and having a first tip and a second tip separated from the first tip by a variable separation distance;

acquiring a droplet of the first liquid sample between the first tip and the second tip; and

immersing the pin tips containing the droplet of the first liquid sample in the second liquid sample, whereby the droplet of the first liquid sample is diffused into the second liquid.

14. The method of claim 13, wherein the step of acquiring the droplet comprises immersing the pin tips in a first reservoir containing a supply of the first liquid sample to produce and hold the droplet between the first tip and the second tip.

15. The method of claim 13, further comprising the step of varying the separation distance of the tips to accelerate diffusion of the first liquid sample into the second liquid sample.

16. The method of claim 13, further comprising the step of removing the pin tips from the second liquid sample.

17. A liquid sample dispensing system, comprising:

a holder;

a first pin connected to the holder and having a first tip;

a second pin connected to the holder and having a movable tip spaced a predetermined separation distance from the first tip to form a sample acquisition region for holding a predetermined volume of liquid sample; and

a driver for effecting movement of the movable pin with respect to the first pin to adjust the predetermined separation distance.

18. The liquid sample dispensing system of claim 17, wherein the second pin is attached to the holder at a fixed pivot point.

19. The liquid sample dispensing system of claim 18, wherein the driver rotates the second pin about the fixed pivot point to adjust the predetermined separation distance.

20. The liquid sample dispensing system of claim 19, wherein the driver applies one of a predetermined force and a predetermined displacement to the second pin to rotate the second pin a predetermined amount.

21. The liquid sample dispensing system of claim 20, wherein the driver comprises a silicon bar.

22. The liquid sample dispensing system of claim 21, wherein the silicon bar expands a predetermined distance to apply the predetermined force to the second pin.

23. The liquid sample dispensing system of claim 17, wherein the driver comprises a piezoelectric assembly for moving the second pin.

24. The liquid sample dispensing system of claim 17, wherein the driver comprises an electromechanical assembly for moving the second pin.

25. The liquid sample dispensing system of claim 17, wherein the driver comprises a thermoelectric assembly for moving the second pin.

26. The liquid sample dispensing system of claim 20, further comprising a bending sensor for detecting the rotation of the second pin about the fixed pivot point.

27. The liquid sample dispensing system of claim 28, wherein the bending sensor communicates with the driver to form a closed loop control circuit for controlling the amount of rotation of the second pin.

28. The liquid sample dispensing system of claim 21, wherein the silicon bar includes heating resistors for applying a controlled amount of heat to the silicon bar to effect expansion of the silicon bar.

29. The liquid sample dispensing system of claim 28, wherein the silicon bar further includes at least one cooling fin for cooling the silicon bar.

30. The liquid sample dispensing system of claim 29, wherein the silicon bar further includes a temperature sensor for detecting the temperature of the silicon bar

31. The liquid sample dispensing system of claim 17, wherein one of the first tip and the movable tip includes a chemical coating to enhance control over a liquid sample held in the sample acquisition region.

32. The liquid sample dispensing system of claim 17, wherein the first tip includes a first contact surface and the movable tip includes a second contact surface defining the sample acquisition region.

33. The liquid sample dispensing system of claim 32, wherein the first contact surface and the second contact surface are tapered.

34. The liquid sample dispensing system of claim 32, wherein the first contact surface and the second contact surface are parallel.

35. The liquid sample dispensing system of claim 32, wherein one of said first contact surface and said second contact surface is curved.

36. The liquid sample dispensing system of claim 17, further comprising a relaxation region for absorbing an impact on the tips.

37. The liquid sample dispensing system of claim 36, wherein the relaxation region comprises a spring connecting the first tip and the holder.

38. The liquid sample dispensing system of claim 36, wherein the relaxation region comprises a spring connecting the movable tip and the holder.

39. The liquid sample dispensing system of claim 38, wherein the relaxation region includes a sensor for measuring the force on the tips.

40. A pin assembly for use in a system for dispensing droplets, comprising:

a first pin having a first tip; and

a second pin having a second tip spaced a predetermined separation distance from the first tip, wherein one of said first pin and said second pin includes a fulcrum region comprising a fixed pivot point to permit movement of the pin about the fixed pivot point.

41. The pin assembly of claim 40, further comprising an actuator for moving the pin that includes the fulcrum region about the fixed pivot point.

42. The pin assembly of claim 40, wherein one of said first pin and said second pin further includes a spring portion for absorbing an impact on the tip.

43. The pin assembly of claim 40, further comprising a chemical coating applied to one of the first tip and the second tip for enhancing control over a liquid sample.

44. A liquid sample dispensing system, comprising:

a holder;

a first pin connected to the holder and having a first tip; and

a second pin connected to the holder and having a second tip spaced an initial separation distance from the first tip to form a sample acquisition region for holding a predetermined volume of liquid sample, wherein the initial separation distance is variable.

45. A liquid sample dispensing system, comprising

a holder;

a first pin connected to the holder and having a first tip;

a second pin connected to a holder and having a second tip spaced from the first tip defining a sample acquisition region for holding a volume of liquid sample; and

a chemical coating applied to one of said first tip and said second tip to enhance control over a volume of liquid sample held in the sample acquisition region.

46. The liquid sample dispensing system of claim 45, wherein the chemical coating comprises a hydrophobic material.

47. The liquid sample dispensing system of claim 45, wherein the chemical coating comprises a hydrophilic material

48. The liquid sample dispensing system of claim 45, wherein the chemical coating is applied in a predetermined pattern.

49. The liquid sample dispensing system of claim 48, wherein the predetermined pattern is determined by a mask used in applying the chemical coating to the tip.

50. A liquid sample dispensing system, comprising:

a first pin having a shaft and a tip for holding a liquid sample; and

a chemical coating applied to the pin for enhancing control over the liquid sample.

51. The liquid sample dispensing system of claim 50, wherein the chemical coating comprises a hydrophobic material applied to the shaft.

52. The liquid sample dispensing system of claim 50, wherein the chemical coating comprises a hydrophilic material applied to the tip.

53. The liquid sample dispensing system of claim 50, wherein the chemical coating is applied in a predetermined pattern to the pin using a mask.

54. A liquid sample dispensing system, comprising

a holder;

a first pin tip connected to the holder;

a second pin tip connected to a holder and spaced from the first tip to define a sample acquisition region for holding a volume of liquid sample; and

a chemical coating applied to one of said first tip and said second tip to enhance control over a volume of liquid sample held in the sample acquisition region

55. A method of fabricating a liquid sample dispensing system, comprising:

providing a substrate;

applying a pattern to the substrate to define a holder, a first pin having a first tip and a second pin having a second tip spaced from the first tip to define a sample acquisition region; and

etching the substrate to remove excess portions of the substrate, thereby fabricating the liquid sample dispensing system.

56. The method of claim 55, wherein the substrate comprises a silicon wafer.

57. The method of claim 55, wherein the substrate comprises a glass plate.

58. A liquid sample dispensing system, comprising:

a holder;

a first pin having a first tip; and

a relaxation region for absorbing an impact on the tip.

59. The liquid sample dispensing system of claim 58, wherein the relaxation region comprises a spring connecting the first tip and the holder.

60. The liquid sample dispensing system of claim 58, further comprising a second pin having a second tip and spaced from the first tip to define a sample acquisition region between said first and second tips.

61. The liquid sample dispensing system of claim 60, wherein the second pin includes a relaxation region for absorbing an impact.

62. The liquid sample dispensing system of claim 61, wherein the relaxation region on the second pin comprises a spring connecting the second tip and the holder.

63. The liquid sample dispensing system of claim 60, wherein the second tip is movable relative to the first tip.

64. The liquid sample dispensing system of claim 60, wherein the first tip is movable relative to the second tip.