Self-cleaning adhesive structure and methods

• US 20050151385A1
• Filed: 01/05/2005
• Published: 07/14/2005
• Est. Priority Date: 01/05/2004
• Status: Active Grant

• Current Assignee: Lewis & Clark College
• Original Assignee: Lewis & Clark College
• Inventors: Hansen, Wendy R., Autumn, Kellar
• Granted Patent: US 7,785,422 B2
• Time in Patent Office: Days
• US Class Current: 294/86.400
• CPC Class Codes: B08B 17/06 by giving articles subject to fouling a special shape or arrangement
• CPC Class Codes: B08B 7/0028 by adhesive surfaces
• CPC Class Codes: B25J 7/00 Micromanipulators specimen supports for investigating or analysing materials G01N23/2204; associated with microscopes G02B21/32; means for supporting or positioning the objects or the material in discharge tubes H01J37/20
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: B81C 99/002 Apparatus for assembling MEMS, e.g. micromanipulators micromanipulators per se B25J7/00

Abstract

A method and apparatus for transporting an object from one workstation to another, or for manipulating an object within a workstation, where the object or workstations may be contaminated with unwanted dirt or dust particles, are disclosed. The object is gripped at one work station with a movable transfer arm a movable transfer arm having an end effector composed of an array of nano-scale projections, where each projection provides one or more distal contact ends, the density of contact ends is such as to grip a surface of the object with an intermolecular force sufficient to hold the object for movement, where the relative sizes of the object and particles are such that the object makes contact with severalfold times of the number of contact ends than contacted by such particles. After moving the gripped object to the other workstation, the end effector is manipulated to release the gripped object at the other workstation. Before, during or after transport of the object, the arm'"'"'s end effector is brought into contact with a cleaning surface having a surface energy interaction with particles carried on said effector as great or greater than the surface energy interaction between particles and effector, thereby to transfer such particles to the cleaning surface. Also disclosed is an apparatus for transporting small elements or objects in a nano- or micro-fabrication assembly or in printing, and a self-cleaning adhesive tape.

Claims

1. A method for transporting an object from one workstation to another, or for manipulating an object within a workstation, where the object or workstations may be contaminated with unwanted dirt or dust particles, said method comprising:

(a) gripping the object at one workstation with an end effector composed of an array of nano-scale projections, where each projection provides one or more distal contact ends, the density of contact ends is such as to grip a surface of the object with an intermolecular force sufficient to hold the object for movement, and the relative sizes of the object and particles are such that the object makes contact with severalfold times of the number of contact ends than contact such particles,

(b) moving the gripped object within the workstation or to the other workstation,

(c) manipulating the end effector to release the gripped object, and

(d) before or after any of steps (a)-(c), contacting the end effector with a cleaning surface having a surface energy interaction with particles carried on said effector that is as great or greater than the surface interaction energy between particles and effector, thereby to transfer such particles to the cleaning surface.

2. The method of claim 1, wherein said cleaning surface provides a greater area of contact with the unwanted particles than the end effector.

3. The method of claim 2, wherein the cleaning surface has a surface roughness of less than about 100 nm R_RMS.

4. The method of claim 1, wherein said contacting includes bringing the end effector into and out of contact with the cleaning surface N times, where N is calculated to effect transfer of a particle from the end effector to the cleaning surface with high probability.

5. The method of claim 4, wherein said contacting includes vibrating the end effector into and out of contact with the cleaning surface for a selected time which is calculated to effect transfer of a particle from the end effector to the cleaning surface with high probability.

6. The method of claim 1, wherein said manipulating includes placing the object on said other workstation and rotating the end effector to peel the object away from the arm'"'"'s gripping surface.

7. Apparatus for transporting an object from one workstation to another, or for manipulating an object within a workstation, where the object or workstations may be contaminated with unwanted dirt or dust particles, said device comprising:

(a) a movable transfer arm having an end effector composed of an array of nano-scale projections, where each projection provides one or more distal contact ends, the density of contact ends is such as to grip a surface of the object with an intermolecular force sufficient to hold the object for movement, and the relative sizes of the object and particles are such that the object makes contact with severalfold times of the number of contact ends than contacts such particles,

(b) a cleaning surface disposed within the area of movement of the transfer arm, said surface having a surface energy interaction with particles carried on said effector as great or greater than the surface energy interaction between particles and effector, and

(c) a control unit operatively connected to said arm for;

(i) placing the arm'"'"'s end effector in contact with such an object at one workstation;

thereby to grip the object

(ii) moving the arm and gripped object within the workstation or to the other workstation;

(iii) manipulating the arm'"'"'s end effector to release the gripped object, and

(iv) bringing the arm'"'"'s end effector into contact with the cleaning surface one or more times, to transfer unwanted dust particles on the gripping surface to the cleaning surface.

8. The apparatus of claim 7, wherein said projections individual or groups of setae, each seta composed of a setal stalk terminating at a distal tip, and said setae are sufficiently flexible to adapt said array for non-planar contact with said object.

9. The apparatus of claim 8 wherein said setal stalks have a Young'"'"'s modulus of 1 megaPascal or greater, and said distal tips have a hydrophobicity, as measured by surface energy, of between 10-40 mJ/m².

10. The apparatus of claim 9, wherein said setae terminate at enlarged, rounded contact ends.

11. The apparatus of claim 7, wherein each of said projections includes individual or groups of spatular arrays, where each spatula is composed of a spatular stalk terminating at a distal contact ends, and said spatulae are sufficiently flexible to adapt said array for non-planar contact with said object.

12. The apparatus of claim 11, wherein said spatular stalks have a Young'"'"'s modulus of 1 megaPascal or greater, and said distal tips have a hydrophobicity, as measured by a surface energy, of between 10-40 mJ/m².

13. The apparatus of claim 12, wherein said spatulae terminate at enlarged, rounded ends.

14. The apparatus of claim 7, wherein said cleaning surface provides a greater area of contact with the unwanted particles than the end effector.

15. The apparatus of claim 14, wherein the cleaning surface has a surface roughness of less than about 100 nm R_RMS.

16. The apparatus of claim 15, for use in transporting an object having a contact area A_o which is in a defined size range greater than about 5,000 nm², and for self-cleaning unwanted particles having a contact area A_p in a defined size range between about 100 and 6400 nm², and less than about 0.1A_o, wherein said projections terminate at a hemispherical distal tip having a selected radial dimension R between about 5 and 2,000 nm, and where:

(i) A_p≧

2π

nm×

R,

(ii) the spacing between adjacent projections is such that an unwanted particle makes contact on average several fold times fewer projections than does the object; and

(iii) the projections are formed of a material having a surface energy of between about 10-40 mJ/m².

17. The apparatus of claim 16, wherein the radial dimension R and corresponding areal dimensions A_o and A_p are selected from the group consisting of:

(i) when R≧

5 nm, A_p≧

80 nm², and A_o≧

800 nm²;

(ii) when R≧

25 nm, A_p≧

200 nm², and A_o≧

2,000 nm²;

(iii) when R≧

50 nm, A_p≧

400 nm², and A_o≧

4,000 nm²;

(iv) when R≧

100 nm, A_p≧

650 nm², and A_o≧

6,500 nm²;

(v) when R≧

250 nm, A_p≧

1,600 nm², and A_o≧

16,000 nm2;

(vi) when R≧

500 nm, A_p≧

3,200 nm², and A_o≧

32,000 nm2;

(vii) when R≧

1,000 nm, A_p≧

6,300 nm², and A_o≧

63,000 nm2;

(viii) when R≧

1,500 nm, A_p≧

9,500 nm², and A_o≧

95,000 nm2;

(ix) when R≧

2,000 nm, A_p≧

12,600 nm², and A_o≧

126,000 nm2;

18. The apparatus of claim 17, wherein the peak to peak spacing between adjacent projections is greater than R.

19. The apparatus of claim 7, wherein said control unit operates to carry out step (iv) by bringing the arm'"'"'s gripping surface into and out of contact with the cleaning surface N times, where N is calculated to effect transfer of a particle from the arm'"'"'s gripping surface to the cleaning surface with high probability.

20. The apparatus of claim 19, wherein said control unit operates to carry out step (iv) by vibrating the arm'"'"'s gripping surface into and out of contact with the cleaning surface for a selected time which is calculated to effect transfer of a particle from the arm'"'"'s gripping surface to the cleaning surface with high probability.

21. The apparatus of claim 7, wherein said control unit operates to carry out step (iii) by (iiia) placing the object on said other workstation and (iiib) rotating the end effector to peel the object away from the arm'"'"'s gripping surface.