Oblique Indented or Machined Micro Wedges
Due to the difficulties and limitations inherent to the double-exposure lithographic method of producing molds, other mold production methods were investigated. One such method involved using a very sharp indenting tool, currently a microtome blade, to make serial indentations in to a soft, malleable material to produce the desired negative shape. Once the mold was indented in to the material, currently a flat sheet of wax, liquid polymers could be cast in it and left to cure. Using such a method allows much tighter control over feature body angle, internal angle, spacing, and depth.
For an explanation of the micro-wedge machining process see:
Suresh, S. Arul, Christensen, David L., Elliot W. Hawkes, and Mark Cutkosky. "Surface and Shape Deposition Manufacturing for the Fabrication of a Curved Surface Gripper." JMR 14, no. 1212 (2015)
Hawkes, E.W., Eason, E.V., Asbeck, A.T., and Cutkosky, M.R., "The Gecko’s Toe: Scaling directional adhesives for climbing applications," IEEE/ASME Transactions on Mechatronics, vol. 18, no. 2, pp. 518-526, April 2013. DOI:10.1109/TMECH.2012.2209672
Day, P., Eason, E. V., Esparza, N., Christensen, D., and Cutkosky, M., "Microwedge Machining for the Manufacture of Directional Dry Adhesives," ASME Journal of Micro and Nano-Manufacturing, vol. 1, no. 1, 011001, March 2013. DOI:10.1115/1.4023161
older notes: Private Indenting Page