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About this Article
Written by: Kathryn Fink
Written on: March 1st, 2009
Tags: biomedical engineering, material science
Thumbnail by: Autumn/AutumnLab Images
About the Author
In 2009, Kathryn Fink was a senior majoring in Biomedical Engineering with a focus in Mechanical Engineering at the USC Viterbi School of Engineering. After graduation she hopes to pursue an advanced degree in engineering focusing on the intersection of medicine and engineering.
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Volume XI Issue II > Sticking With It
Engineers are increasingly drawing on inspiration from other fields combined with creative problem-solving to construct the products of the future. The ability of the gecko to scale slick vertical surfaces has long been a fascination of biologists and scientists alike, with current engineers looking to harness this power to create new medical products. Three potential methods of engineering artificial gecko-inspired adhesives are examined here, with a focus on their possible medical applications.

Introduction

In the world of academics, creativity is often associated with the liberal arts; the public perception is that those who possess this innate characteristic are most successful as writers, sculptors, or artists. However, the ability to draw inspiration from the world around is a critical skill within the engineering disciplines as well. The biological aspects of the natural world is proving to be a fertile source for creative engineers: the strength of a spider's silk pushes engineers towards improved cables and the evolution of burdock seed fertilization inspired the invention of Velcro [1]. Now the current boundaries of engineering and science are blurring in a push to replicate one of the most unique biological adaptations of all: the gecko’s incredible sticking ability (Fig. 1).
Autumn/AutumnLab Images
Figure 1: A Tokay gecko moves upside down, with an image of its footprint left behind.
While the mind may immediately jump to the thought of climbing walls in special boots, gecko-inspired adhesives could be used in medical applications including “instant” sutures, improved waterproof bandages, and stitches to hold heart tissue together after surgery. In the process of developing these amazing applications, creativity does not end with the inspiration phase but continues through the various stages of design and implementation. Engineers are currently pursuing many different designs to achieve this goal, all inspired by the toe of the gecko.

The Gecko In Nature

The most specialized achievements of the gecko are its abilities to move easily across vertical surfaces and maneuver upside-down along horizontal ones. With the exception of Teflon, it hardly matters what surface a gecko wants to cross: it is able to scale the slickest glass surface with the same ease as a brick wall [2]. The Tokay gecko (Gekko gecko) is the largest of the geckos and can support an average of 20 kg while clinging to a nearly vertical surface. Given that Tokay geckos weigh, on average, only 0.5 kg and that their footpads have a surface area of only 2.5 cm2, this force is astounding [3]. The footprint of a Tokay gecko walking on an inverted surface is visible in Figure 1. The need to suspend such heavy, inverted loads is a challenge that was addressed long ago by structural and mechanical engineers by using everything from cables to well-placed systems of screws.