'Zipping' mechanism that keeps feathers unruffled could lead to aerospace materials

A 'zipping' mechanism that keeps feathers unruffled could provide a model for new aerospace materials and adhesives, a researcher has claimed.

The mechanism, which allows segments of birds’ feathers to be ‘unzipped’ before they pull themselves together again, was investigated by materials scientist Tarah Sullivan from the Jacobs School of Engineering at the University of California in San Diego.

Sullivan 3D printed feathers’ vanes, barbs and barbules to better understand their properties, such as how the underside of a feather can capture air for lift while the topside can block out air when descending. Her work, billed as the first in two decades to study the general structure of bird feathers, found that barbules – small, hook-like structures that connect feather barbs – are spaced within eight to 16 micrometres in all birds, from hummingbirds to condors.

“The first time I saw feather barbules under the microscope I was in awe of their design – intricate, beautiful and functional,” she said. “As we studied feathers across many species it was amazing to find that despite the enormous differences in size of birds, barbules spacing was constant.”

Further study of vane-barb-barbule structure could lead to the development of materials for aerospace structures and to new, Velcro-like adhesives, said Sullivan. She built prototypes using similar structures, and hopes to prove their applicability in a follow-up paper. “We believe that these structures could serve as inspiration for an interlocking one-directional adhesive or a material with directionally tailored permeability,” she said.

The research, which also studied bones in birds’ wings, was published in Science Advances.