Self-cleaning adhesive structure and methods
A method and apparatus for transporting an object from one workstation to another, 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. The movable transfer arm has an end effector including an array of nano-scale projections, where each projection provides one or more distal contact ends. The density of the contact ends is such as to grip a surface of the object with an intermolecular force sufficient to hold the object for movement After moving the gripped object to the workstation, the end effector is manipulated to release the gripped object. Before, during or after transport of the object, the arm's end effector is brought into contact with a cleaning surface.
1. A method for transporting an object from one workstation to another or for manipulating an object within a workstation, said method comprising:
(a) adhesively gripping the object at one workstation with an end effector including an array of nano-scale projections, where each projection provides one or more distal contact ends, the density of the contact ends is such that a surface of the object is gripped with an intermolecular force sufficient to hold the object for movement, and the relative sizes of the object and any unwanted dirt or dust particles that have contaminated the object or a workstation are such that the object makes contact with a greater number of contact ends than contact the unwanted dirt or dust particles,
(b) moving the end effector such that the gripped object is moved within a workstation or transported to another 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 the unwanted dirt or dust particles carried on the end effector that is as great or greater than the surface interaction energy between the unwanted dirt or dust particles and the end effector, thereby to transfer the unwanted dirt or dust particles to the cleaning surface.
2. The method of claim 1 , wherein said cleaning surface provides a greater area of contact with the unwanted dirt or dust particles than does 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 an unwanted dirt or dust particle from the end effector to the cleaning surface.
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 an unwanted dirt or dust particle from the end effector to the cleaning surface.
6. The method of claim 1 , wherein said manipulating includes placing the object on a workstation and rotating the end effector to peel the object away from the gripping surface.