The pad mimics the staggering ability that geckos (and some insects) have to adhere to surfaces carrying more than ten times their own weight. The evolutionary trait has long confounded scientists, yet a chance collaboration between polymer scientist Al Crosby and biologist Duncan Irschick enabled the interdisciplinary approach necessary to make sense of the mystery. Early on while experimenting with applying the structure and function of biological processes to engineer adhesive materials, or biomimetic adhesion, Crosby and his research team came across Irschick’s work on functional morphology and the gecko’s adhesive properties. Only after Crosby decided to contact him directly did he realize Irschick was also on campus and just a stone’s throw away. After discovering each other, the pair of scientists joined forces and began thinking of adhesion in an entirely new way.
“Adhesion is much more than just what brings things into contact right at the interface. It’s really a whole system problem,” Crosby says.
Previous research was directed at replicating setae, the many microscopic hairs that cover geckos’ toe pads and feet. This allowed researchers to create adhesive devices that could hold on a small scale, but could not accomplish the heavy lifting the UMass Amherst team was shooting for. That’s why Crosby, who has studied adhesion for about 16 years, focused on more gecko related research to accomplish his goal. With Irschick, a 20-year veteran in the evolutionary properties of the gecko, on board and with help from Crosby’s doctoral candidates Michael Bartlett and Dan King, and postdoctoral researcher Andrew Croll, the group started connecting the dots and coined the term “draping adhesion.”
“Our contribution is that we’re able to bring two materials close enough, but also keep them very, very stiff. That is usually really hard to do,” Crosby explains.
The draping quality is what lets the gecko adhere to surfaces with such success. Their skin, which is thin and stiff, enables the clinging setae to drape over a surface and conform without relying upon fatty tissues, which would ultimately diminish the adhesive strength, according to the researchers’ theory. Even more remarkable is that their tendons are directly stitched into their skin, connecting skin to skeleton, allowing the whole gecko system to maintain rigidity and maximize adhesive strength.
By infusing existing knowledge of the setae with the draping and rigid properties they discovered, the team created the first Geckskin™ pad in September 2009 using a common polymer, found in things like bathroom caulking, and inexpensive fabric. Crosby procured a sewing machine and hired undergraduate student Beth Paret to bring some sewing and stitching knowledge to the table. “I learned a lot about fabric,” says Bartlett.
Over the past three years, Geckskin™ has been perfected, pending patent and prepared for commercialization. The result is a robust pad the size of an index card that is generating a lot of industry interest for its capacity to hold and adhere, and then to be removed and reused as desired. The material is smooth and non-tacky to the touch and when pressed to a surface is easily removed with no leftover residue. What Scotch™ tape accomplishes with a gluey quality, Geckskin™ accomplishes by activating “van der Waals forces” between the molecules on the two surfaces with its inherent draping ability.
The product is shown mounting flat screen televisions to walls and other such practical applications, yet that is just scratching the surface of its imaginable uses. Geckskin™ can be used anywhere adhesive products are used in everyday life—and also in places where they were previously unable to be used.
“It’s definitely an exciting time. All possibilities are open,” says Irschick.
Geckskin™ research was partially supported by the U.S. Defense Advanced Research Projects Agency through a subcontract to Draper Laboratories. Interest in the product is attracting further funding to campus. The team recently received a $900,000 grant from the Human Frontier Science Program to further explore the unique qualities of the 800 species of gecko. The team also received a 2012 UMass President’s office CVIP Technology Development award to support integration of Geckskin™ into new or existing commercial markets.
Crosby and Irschick may have answered this question, yet there is more work to be done. They are confident that with further testing, they can create larger pads to hold heavier objects and aim to elaborate on the already groundbreaking innovation. They explain that for them, the science is worth much more than the saleable product—they’ve opened a new door to more questions and endless opportunity. “It goes well beyond the commercialization,” Crosby says.
Amanda Drane '12
CNN Money names super adhesive Geckskin™ among their 5 Science Breakthroughs of 2012 and Bloomberg News names it one of14 Inventions Inspired by Nature:Biomimicry in 2013.