SUMMARY

Temporary biological attachment systems have long intrigued scientists and engineers because the animals that possess these systems are capable of climbing walls and even walking on ceilings irrespective of their surface properties. However, unlike prototype biological spatulate contact elements, which show a non-sticky default state, strong shear-induced attachment, and insensitivity to surface conditions, the current biomimetic microstructured adhesives are deficient in these abilities. As an alternative to existing bio-inspired dry adhesives, a wall-shaped hierarchical microstructure has been suggested but it is still unclear how loading and surface conditions, as well as material and geometrical properties affect the adhesive and frictional performance of the microstructure. It is also evident that its current mold-based manufacture can be considered impractical. To this end, the attachment performance of the wall-shaped adhesive microstructures in various conditions along with a new manufacturing technique was examined, focusing on the following. 1) Architecting a novel cost-effective method for fabricating shear-activated biomimetic adhesives. 2) Finding the effects of loading condition (pre-load, pulling angle, and preliminary displacement) with the goal to gain insight into how to use the adhesive microstructures. 3) Understanding the effects of the counterface surface conditions (topography and chemistry) with the goal to gain insight into where to use the adhesive microstructures. 4) Investigating the effects of the microstructure shape and material properties with the goal to gain insight into what path to take to improve their attachment/detachment performance.