Dry adhesives and methods of making dry adhesives

Abstract

Dry adhesives and methods of making dry adhesives including a method of making a dry adhesive including applying a liquid polymer to the second end of the stem, molding the liquid polymer on the stem in a mold, wherein the mold includes a recess having a cross-sectional area that is less than a cross-sectional area of the second end of the stem, curing the liquid polymer in the mold to form a tip at the second end of the stem, wherein the tip includes a second layer stem; corresponding to the recess in the mold, and removing the tip from the mold after the liquid polymer cures.

1 . A dry adhesive, comprising:
 a backing layer;   a stem having first and second ends on opposite ends of the stem, wherein the first end of the stem is connected to the backing layer, and wherein the stem is not perpendicular to the backing layer; and   a tip connected to the second end of the stem, wherein the tip includes an expanded surface, wherein the expanded surface is planar, wherein the expanded surface is not parallel to the backing layer, and wherein the expanded surface has an area that is greater than a cross-sectional area of the second end of the stem in a plane parallel to the expanded surface.   
     
     
         2 . The dry adhesive of  claim 1 , including:
 a plurality of stems, each stem having first and second ends at opposite ends of the stem, wherein the first end of each of the stems is connected to the backing layer, and wherein each of the stems is not perpendicular with the backing layer; and   each of the stems includes a tip connected to the second end of a corresponding stem, wherein each tip includes an expanded surface, wherein each expanded surface is planar, and wherein each expanded surface is not parallel to the backing layer.   
     
     
         3 . The dry adhesive of  claim 2 , wherein:
 the stem forms an angle θ relative to a line perpendicular to the backing layer, wherein θ is greater than zero degrees and less than ninety degrees; and   the expanded surface of the tip forms an angle β−θ relative to a plane parallel to the backing layer, wherein β is greater than θ and less than ninety degrees.   
     
     
         4 . A dry adhesive structure comprising:
 a backing layer; and   a non-perpendicular stem,
 wherein the stem includes first and second ends on opposite sides of the stem, 
 wherein the first end of the stem is connected to the backing layer, 
 wherein the stem forms an angle θ relative to an imaginary line perpendicular to the backing layer, wherein the angle θ is greater than zero and less than ninety degrees, 
 wherein the stem forms an angle β relative to the imaginary line perpendicular to the backing layer, wherein the angle β is greater than the angle θ and less than ninety degrees, 
 wherein the tip of the second end of the stem comprises a cured polymer having an expanded surface, and 
 wherein the expanded surface of the tip forms an angle β−θ relative to an imaginary plane parallel to the backing layer. 
   
     
     
         5 . The dry adhesive structure according to  claim 4 , wherein the expanded surface of the tip has an area that is greater than a cross-sectional area of the second end of the stem in a plane parallel to the expanded surface of the tip. 
     
     
         6 . The dry adhesive structure according to  claim 4 , wherein
 the expanded surface of the tip is planar; and   the expended surface of the tip is not parallel to the backing layer after removing the tip from the tip shaping surface.   
     
     
         7 . The dry adhesive structure according to  claim 4 , further comprising a plurality of non-perpendicular stems, wherein each non-perpendicular stem of the plurality of non-perpendicular stems comprises first and second ends on opposite sides of the stem, and wherein the first end of the each non-perpendicular stem is connected to the backing layer. 
     
     
         8 . The dry adhesive structure according to  claim 7 , wherein the each non-perpendicular stem of the plurality of non-perpendicular stems further comprises an expanded surface on the second end. 
     
     
         9 . The dry adhesive structure according to  claim 8 , wherein the each non-perpendicular stem of the plurality of non-perpendicular stems further comprises:
 an angle θ relative to an imaginary line perpendicular to the backing layer, wherein the angle θ is greater than zero and less than ninety degrees; and   an angle β relative to the imaginary line perpendicular to the backing layer, wherein the angle β is greater than the angle θ and less than ninety degrees.   
     
     
         10 . The dry adhesive structure according to  claim 8 , wherein the expanded surface comprises a cured polymer. 
     
     
         11 . The dry adhesive structure according to  claim 8 , wherein the expanded surface comprises an angle β−θ relative to the imaginary plane parallel to the backing layer.