Meeting Abstract
The North American river otter must traverse slippery, bio-fouled rocks in rivers and streams as it travels and hunts for food. Many aquatic organisms have developed grip mechanisms to combat these slippery bio-fouled surfaces, such as hooks, hairs, and adhesives. Qualitative observations have shown unique callous-like pads on the rear paws of the river otter. In this experimental study, we investigate the use of these pads and surrounding soft tissue for enhancing underwater grip. The composition and material properties of the paw pad tissue were determined using histology and nanoindentation, while the paw surface texture was characterized using microscopy and profilometry. The friction between the paw pad and various wet and dry surfaces was measured using a rheometer with tribological attachment. Field experiments were conducted concurrently with a live river otter. Field experiments included a locomotion analysis, friction testing with a custom adjustable ramp, and testing of an original paw scanning device using frustrated total internal reflection. Preliminary results indicate that the paw pad maximizes contact area between substrate and tissue through highly deformable tissue and tire-tread-like patterns on the epidermis. The results of this project may provide unique grip solutions for multi-terrain robots, tires, or even human apparel like boots or gloves.
