Meeting Abstract
Live remora can generate anisotropic friction force while attaching to a diversity of biological and non-biological surfaces by using spinule-covered lamellar plates in their disc interior. In this study, we used μCT, ESEM and DMA (dynamic thermomechanical analysis) to investigate the morphological and mechanical properties of the preserved remora adhesive disc. The kinematic motion of the disc lamellae when live remoras slide on the glass surface was analyzed through synchronized ventral and lateral high-speed images. Remoras push both the soft-tissue surrounding the lamellae and the rigid spinules against or away from the glass during attachment. To understand the effect of the rigid spinules and lamellae soft tissue on the frictional force during remora attachment, we extracted spinules from a remora specimen and glued them on the rotatable, synthetic lamellae in a bio-robotic remora adhesive disc. We then investigated the influence of the lamellae pitch angle and surface roughness on the frictional forces of the bio-robotic prototype both with and without the biological spinules. The results show that on surface of roughness less than 20µm, the soft tissues rather than the spinules play a dominant role in regulating the friction while changing the lamellae pitching angle. However, on biological shark skin and surface with a roughness of 200µm, the spinules play a more significant role than the soft tissues. Our findings suggest that the rigid spinules and the soft tissues enveloping the rigid skeletons of lamellae work in concert to tune friction during remora attachment on different surfaces.
