Patent ID: 7294397

Claim:
A dry fibrillar microstructure that adheres to and is reapplicable to a surface, and that comprises (a) a substrate, and (b) a plurality of fibrils attached to the substrate, wherein a fibril is attached to the substrate at a plane of attachment of the substrate; wherein a first fibril (c) is characterized by a value of P as defined by Equation III in the range of about 10 2 to about 10 6 Pa, (d) has a neutral axis, passing through the centroid of the cross-sectional area of the fibril, that has an orientation with the plane of the substrate, at the point of intersection of the neutral axis with the plane of the substrate, in the range of greater than 75° to about 90°, and (e) has a cross-sectional shape and area that is constant along the length of the fibril; wherein Equation III is P=c*E *( a/L ) 2 ; wherein E is the Young's modulus of the material of the first fibril as determined by ASTM D412-87, a is one-half of the characteristic width of the fibril, L is the length of the fibril, c is a dimensionless constant having a value in the range of about 0.1 to about 1.0, and * indicates multiplication; wherein the distance between the surface of the first fibril and the surface of a second adjacent fibril, at the plane of attachment of the fibrils to the substrate, is at least a distance of 2w where w is determined from Equation IV; wherein Equation IV is w> ( g 2 *L 2 /4 a )*(2γ/3 Ea ) 1/2 ; and wherein γ is the surface energy of the material of the first fibril as determined by ASTM D724-99, g is a dimensionless constant having a value in the range of about 0.05 to about 5.0, and E, a, L and * are as defined above.