Theoretical And Experimental Studies Of Biological Wet Adhesion

Biological wet adhesion is one of the frontiers of the interdisciplinary research fields of mechanics, materials science and biology. In this thesis, the roles of the triple-phase contact line in the contact angle hysteresis were first studied. Software Surface Evolver was adopted for calculating the contact angle hysteresis of surfaces of different surface pattern and the results were consistent with the predictions of our previously developed theoretical model as well as our experiments. We then studied mechanisms of the wet adhesion of adhesion systems of gecko by developing a two-dimensional theoretical model in which the surface structures of gecko were modeled by surfaces with multiple fibers. The difference in the adhesion force between surface with single fiber and that with multiple fibers on the condition of same surface size and same liquid volume was calculated. The theoretical model was validated by numerical simulation using Surface Evolver. We also compare our model resuts with other researcher's rusult, and validated our model again. We showed that the adhesion force of surface with multiple fibers increases with the increase of fiber number, and it is larger than that of surface with single fiber when the fiber number is larger than a critical value. In addition, the adhesion force is more robust and less sensitive to the distance between surface and substrate, and have large adhesion on the rough surface. We found that the splitted structure has advantages in achieving high adhesion at different moisture environment and various contact angle. In addition, the adhesion force is less sensitive to the distance. The adhesion force of surface with multiple fibers of which the total size of the fibers is equal to the un-splitted single fiber was also studied. Our results showed that the larger the fiber number, the larger the adhesion force. The adhesion force of the foot of gecko estimated by our model is consistent with the experiment results. At last, the anti-biofouling coating was synthesized by mimicking the biological superhydrophobic surfaces. First we get traditional coating with sole structure and then we produce dual structure on the coating surface which can make it superhydrophobic.The biomimicking superhydrophobic surfaces were produced on different materials, such as steel and rubber etc. The mechanical properties and anti-erosion properties of the coatings were tested.