What can a gecko’s foot teach us about adhesives? After noticing the gecko’s unique ability to run up vertical surfaces and hold onto glass with just one toe, scientists at UC Berkeley’s Biomimetic Milisystems Lab are questioning the ways we think about superglue and duct tape.
Animals have developed a plethora of ways to adhere to surfaces in their environment. Scientists once believed that this “stickiness” was accomplished by natural glues composed of sugars and oils in combination with hooked claws and light body weights. However, a closer look with a high-powered imaging and microscopic force sensors revealed that the gecko foot is covered with tiny hair-like structures called setae. These hairs split even further into tips with surfaces as small as 200 nanometers in diameter. The hairs adhere independently of surface polarity using van der Waals forces. They work on hard or soft textures and on dry or wet surfaces, can hold on under water, in a vacuum, and can support the entire weight of the gecko with just one toe pad. The gecko manually un-sticks itself with a toe curling motion, which can happen quite quickly as it runs up walls or tree trunks.
By discovering that gecko adhesion is due to geometry and surface area, scientists at Berkeley were able to begin considering practical applications. Gecko inspired adhesive would be strong, but reusable and self cleaning and unaffected by environmental conditions like dampness or rough surfaces. The Biomimetic Lab is looking at its application to robotics, where locomotion is necessary in difficult environments. Without relying on mechanical wheels or sticky glues for adhesion, robots could become much more efficient in data collection and rescue missions.
Though gecko feet have been a topic interest and research for decades, recent work at Berkeley came to light as the greater scientific community became more aware of a concept called biomimicry. This approach looks closely at nature’s solutions and applies them to more complex design issues. It can include anything from building using thermal regulation inspired by termites to designing a garden to mimic natural ecosystems to designing new adhesives based on gecko feet. Look at many human inventions and you’ll see it’s not such a new idea to be inspired by the natural world, but many scientists think that the last few decades have been dominated by more synthetic solutions and that many of our design problems, as well as environmental issues, can be faced by taking a look at natural solutions that have had thousands of years to evolve around us. These alternatives are typically nontoxic, reuseable, and adaptable to a variety or conditions and environments. To learn more, check out Biomimicry, Janine Beynus’ popular book that helped form an entire new movement in engineering and design, as well as the Biomimicry Institute.