Microfabricated adhesive mimicking gecko foot-hair

Abstract

The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force approximately 10(-7) N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of approximately 10 N x cm(-2): sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved.

Biomimetics: lessons from nature–an overview

“…Geim et al 2003;Bhushan 2007bBhushan , 2008Bhushan & Sayer 2007;Gorb et al 2007). (It should be noted that common man-made adhesives, such as tape or glue, involve the use of wet adhesives that permanently attach two surfaces.)…”

Strength statistics of adhesive contact between a fibrillar structure and a rough substrate

“…Several researchers, motivated by these biological systems, have recently attempted to mimic the fibrillar architecture to attain enhanced adhesion (Geim et al 2003;Sitti & Fearing 2003;Glassmaker et al 2004;Gorb et al 2006). Fabrication of synthetic structures with a high degree of hierarchy is still technologically challenging and most of the fibrillar adhesives fabricated so far are either one-or two-level structures.…”

Toward Self‐Powered Wearable Adhesive Skin Patch with Bendable Microneedle Array for Transdermal Drug Delivery

“…In such case, the bendable microneedle will be dragged out of the skin instead of leaving a broken needle in the skin when lateral movement occurs. The sharp tips assembled onto the soft bases can be either non bio‐dissolvable, i.e., made of SU‐8,43 or biodissolvable, i.e., made of maltose 44. For the configuration with SU‐8 sharp tips, the outlets of the microneedles, connecting with the drug reservoirs, are always exposed to air.…”

“…However, there are increasing demands on less‐irritating, biocompatible medical bondages, as aging skin is more sensitive and vulnerable to a prolonged exposure, e.g., insulin delivery, as in the case of conventional medical patches. Dry adhesive, which is inspired by the hierarchical structure on Gecko foot hair,43, 44 possesses several advantages compared with conventional acrylic medical bandages: First, it shows repeatable and restorable adhesion with surface cleaning after each usage. Second, the physical structure to generate adhesive force is less affected by surface contamination, oxidation and other environmental stimuli.…”