Bioinspired Surface for Surgical Graspers Based on the Strong Wet Friction of Tree Frog Toe Pads

Soft tissue damage is often at risk
during the use of a surgical grasper, because of the strong holding
force required to prevent slipping of the soft tissue in wet surgical
environments. Improvement of wet friction properties at the interface
between the surgical grasper and soft tissue can greatly reduce the
holding force required and, thus, the soft tissue damage. To design
and fabricate a biomimetic microscale surface with strong wet friction,
the wet attachment mechanism of tree frog toe pads was investigated
by observing their epithelial cell structure and the directionally
dependent friction on their toe pads. Using these observations as
inspiration, novel surface micropatterns were proposed for the surface
of surgical graspers. The wet friction of biomimetic surfaces with
various types of polygon pillar patterns involving quadrangular pillars,
triangular pillars, rhomboid pillars, and varied hexagonal pillars
were tested. The hexagonal pillar pattern exhibited improved wet frictional
performance over the modern surgical grasper jaw pattern, which has
conventional macroscale teeth. Moreover, the deformation of soft tissue
in the bioinspired surgical grasper with a hexagonal pillar pattern
is decreased, compared with the conventional surgical grasper.