Thursday, December 30, 2010
Geckos Inspire Stronger Adhesives
This small lizard has the remarkable ability to grip to any surface, repeatedly, and under all conditions, including dirt, moisture or excessive dryness. Its sticking power comes from millions of microscopic dry hairs on its footpads, each with a mushroom-shaped tip that makes contact with the surface, and adheres to it.
Metin Sitti, an associate professor of mechanical engineering at Carnegie Mellon University, has developed a polymer fiber material based on the gecko’s natural fibers that can duplicate its unusual repetitive adhesive properties, an advance that likely will have broad commercial applications in sports, medicine, robotics, and the military.
“Gecko-like adhesives have already shown promise as new gripping materials for sports and safety applications,” Sitti said. “I think the gecko’s special ability could also hold the key to creating reliable climbing robots for reconnaissance missions and space exploration, as well as for the military.”
The National Science Foundation has funded his research with $150,000 as part of the American Recovery and Reinvestment Act of 2009.
In 2009, Sitti established a new company, called nanoGriptech, a spinoff of the university, to develop and mass produce his microscopic polymer fiber adhesives for use in a number of products, starting with sports clothing. A major sports company has expressed an interest in developing new gloves, shoes and clothing using the material, and has signed on as an industrial partner, Sitti said.
The first products could be on the market within two years. “We want to make them in a large volume at a low cost,” Sitti said. “Right now, we have all the programs in place to do this; we have a good performance, at a relatively low cost.”
So far, the material works best on smooth surfaces, which is one of the reasons the company initially plans to use it only in sports clothing and equipment. But the researchers are fine-tuning the material to make it more adaptable to surfaces that may be rougher.
“On smooth surfaces, we have sticking as good as the animal,” Sitti said. “On rough surfaces, we have some good performance, but not yet as good as the animal. Their hairs branch into smaller hairs, like a brush, and what we’ve made, at first, are simple hairs. We are in the process of developing the fibers for more complicated surfaces.”
Sports equipment is a logical first application because “the market places a high value on performance enhancement, and we have a marketing partner with sales distribution channels,” Sitti said. “Success there will provide significant market visibility that can be leveraged for entry into other product applications.”
Sitti expects the first products to be closures for clothing that could improve upon currently used Velcro and zippers. Velcro can be rigid and requires a second side in order to stick. Zippers can break, or otherwise fail. The new material does not require a ‘mating site’, and is very durable over repeated uses. “Our product is designed to be used many times,” Sitti said. “After tens of thousands of cycles, it still works with a similar performance.”
Later, it likely will be used to make gloves for football receivers, possibly or soccer goalies, and shoes that need a gripping non-slip surface, such as those worn by climbers.
“Our material gives a better performance than any current receiver gloves on the market,” Sitti said. “When you put it on the tips of the fingers, it helps you grip the ball. It’s good for receivers—although maybe not so good for quarterbacks.”
Ultimately, Sitti hopes that its most advanced uses will include medical applications, such as bandages for the skin, or for attaching medical devices inside or outside tissues of the body non-invasively, or in developing more secure face masks for industry and the military. “We have some promising results in those areas, but they are still ongoing projects for us,” he said.
“In the future, we hope to develop face masks that won’t move around, as they do now,” he added. “The sealing of the face mask is a big issue. You can have leakage. The military uses straps on the back of the head to keep the mask in place, which is a big discomfort. Our goal is to have them stick to the skin with a strong attachment to the face. You still need some harnessing, as a safety backup, but we would like to see much less than they use now. That is a very important field for us.”
The company has five employees, and continues to grow. “We really believe that once the first fiber adhesive product appears in the market it will have a big impact on many applications,” he said.
Article Courtesy of US News and World Report