An international collaboration led by Brown researchers recently discovered a new method to produce "nanopipes" — tiny fluid channels with potential applications in biology and energy. The pipes are constructed using the wrinkling characteristics of thin metal films, the researchers reported last week in Proceedings of the Royal Society A, a scientific journal.
"Previously, people studied wrinkles extensively, but nobody worked on folding to make a pipe," said Professor of Engineering Kyung-Suk Kim PhD'80 P'11, the corresponding author of the paper.
While studying the natural phenomenon of wrinkling, the team of scientists unintentionally discovered the nanopipe fabrication method.
During a sabbatical at the Korea Institute of Science and Technology, Kim initiated a collaboration between the nanoscale manufacturing facilities in Seoul and his lab at Brown.
"Our interest was to make a general theory of folding," Kim said. His team hoped to describe wrinkly surfaces like the human brain, which has evolved to maximize the processing-intensive surface area of the cortex within the confines of a primate skull.
Other examples of natural folding, such as geological formations and the wrinkling of human skin, were included in this vision of a general theory. Wrinkled surfaces also have potential engineering applications, such as increasing the reactive area of a catalytic converter in a car.
Surprisingly, the wrinkled surfaces produced in the fabrication process appeared to have lost surface area. The team realized secondary-mode folds — wrinkles formed when wrinkles fold into one another — existed below the apparent surface. The enclosed spaces surrounded by the "lost" surface formed thousands of nanoscale channels in parallel to one another. This accidental discovery became a significant finding in its own right.
"In this nanoworld, whoever can make a new structure can provide a new tool," Kim said.
Possible applications of nanopipe technology include cancer-selective biopsy needles, controlled self-cleaning adhesive surfaces and transport channels to improve the lifespan of a lithium battery, he said.
