Geckos are famous for their ability to walk up walls and scamper across ceilings. The dry-adhesive surface of geckos’ toes has inspired many attempts to copy this ability in an artificial material. Isabel Rodríguez at the A*STAR Institute of Materials Research and Engineering and co-workers at Nanyang Technological University in Singapore1 have now made one of the closest mimics to gecko toes yet, and shown that it has the properties to match.
Artificial hairs just a few hundred nanometers in diameter mimic the adhesive surface of a gecko’s toe-pads. Copyright : Agency for Science, Technology and Research
The geckos’ ability to cling to surfaces is not due to glue but to the millions of microscopic hairs that coat the surface of their toes. Each hair has a branched, hierarchical structure—toward its tip, each fiber breaks into multiple sub-fibers, which in turn break into hundreds of fibrils 100–200 nanometers in diameter. This structure ensures a high surface area, which helps the gecko to cling to the wall. In addition, the hairs become more flexible as they become thinner, which helps to maximize the number of fibrils in contact with the wall.
Rodríguez and her co-workers have successfully mimicked this hierarchical structure through the use of an anodization technique that allows branched nanopores to be etched controllably into sheets of aluminium foil—a process they used to form templates with which to create the dry adhesive surface. These templates were stamped into sheets of polycarbonate plastic using a process known as capillary force-assisted nanoimprinting, forming a hairy polycarbonate surface.
To evaluate the qualities of the hierarchical hair structure, the researchers created two separate surfaces: one with simple, unbranched hairs; and one in which the hairs branched at their tips to form nanoscopic fibrils (pictured) closely resembling those found on gecko toe-pads. They found that the sheer adhesion force of the branched material was 150% greater than that of the linear material.
“One of the most important findings from the study is the insight of how the fibrils can be made using a simple process,” says Rodríguez. “There have been reports of other hierarchical structures fabricated in polymers, but the fabrication methods they use are rather costly and complicated and not suitable for large scale.” The relatively high cost of previous attempts is due to the way the template is made—a problem that the team have now overcome using their porous alumina template technology. “Our branched, porous template fabrication is straightforward and allows large areas of gecko-like structures to be fabricated at low cost,” she adds.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering
Engineers develop smart material that changes stiffness when twisted or bent
15.02.2018 | Iowa State University
Breaking local symmetry: Why water freezes but silica forms a glass
14.02.2018 | Institute of Industrial Science, The University of Tokyo
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy