Evolutionary Biomaterials Group
Max-Planck Inst for Metals Research, Stuttgart

Structure and properties of biological hairy attachment devices for

Stanislav N. Gorb

Abstract: Many animals bear leg attachment pads with an excellent ability to adhere
to a smooth surface as well as to a variety of natural surfaces with rough
profiles. There are two alternative designs of such systems: smooth and
hairy. The smooth systems consist of soft deformable structures with a
relatively smooth surface. Pads of geckos, flies, beetles, and spiders are
covered by relatively long, deformable setae which, due to individual
bending, increase the number of contacting points with the surface. Most
recent data on hairy systems demonstrated their excellent adhesion and
high defect tolerance of contact. The size of single points gets smaller
and their density higher as the body mass increases. We provided the first
experimental evidence of adhesion enhancement by division of contact area.
A patterned surface, made out of polyvinylsiloxane (PVS), has
significantly higher tenacity on a glass surface than a smooth sample made
out of the same material. This effect is even more pronounced on curved
substrata. An additional advantage of patterned surfaces is the
reliability of contact on various surface profiles and the increased
tolerance to defects of individual contacts.