US 12,263,621 B2
Indirect metal mold for directional dry adhesives
Capella F. Kerst, Los Gatos, CA (US); and Mark R. Cutkosky, Palo Alto, CA (US)
Assigned to The Board of Trustees of the Leland Stanford Junior University, Stanford, CA (US)
Appl. No. 17/769,832
Filed by The Board of Trustees of the Leland Stanford Junior University, Stanford, CA (US)
PCT Filed Nov. 13, 2020, PCT No. PCT/US2020/060570
§ 371(c)(1), (2) Date Apr. 18, 2022,
PCT Pub. No. WO2021/097334, PCT Pub. Date May 20, 2021.
Claims priority of provisional application 62/936,325, filed on Nov. 15, 2019.
Prior Publication US 2022/0371230 A1, Nov. 24, 2022
Int. Cl. B29C 33/42 (2006.01); B29C 33/38 (2006.01); B29K 105/00 (2006.01)
CPC B29C 33/42 (2013.01) [B29C 33/3842 (2013.01); B29K 2105/0097 (2013.01); B29K 2905/00 (2013.01)] 1 Claim
OG exemplary drawing
 
1. A method of making a metal mold for casting an array of directional dry adhesive wedges, comprising:
(a) casting a silicone layer onto a micromachined mold,
wherein the micromachined mold comprises an array of wedges at a surface of the micromachined mold,
wherein the casting casts the array of wedges from the micromachined mold into one surface of the silicone layer,
wherein the casting comprises using a stainless-steel wafer at another side of the silicone layer,
wherein on one side of the stainless-steel wafer, the stainless-steel wafer has a UV tape as a backing material,
wherein on another side of the stainless-steel wafer, the stainless-steel wafer is treated with a primer to promote adhesion of the silicone layer to the stainless-steel wafer;
(b) demolding and degassing the cast silicone layer and stainless-steel wafer from the micromachined mold;
(c) sputtering in a vacuum environment a film of titanium and platinum onto the cast silicone layer and stainless-steel wafer, whereby the sputtering includes sputtering the array of wedges of the silicone layer;
(d) electroplating the sputtered cast silicone layer with a layer of copper, wherein the layer of copper has a thickness of about a double height of the array of wedges of the silicone layer;
(e) soldering a copper base block to a surface of the copper layer, wherein the soldering uses an indium solder; and
(f) pulling off the cast silicone layer and stainless-steel wafer thereby leaving the electroplated copper layer soldered to the copper base block, wherein the electroplated copper layer has now on one surface an array of wedges which is a mirror-image of the array of wedges of the silicone layer.