Princeton Researchers Grow Artificial Hairs With Clever Physics Trick

Princeton researchers found they could spin liquid elastic polymers on a disc to form the kinds of intricate hair-like shapes needed to create biomimetic surfaces. Credit: Image courtesy P.-T. Brun

Things just got hairy at Princeton.

Researchers found they could coat a liquid elastic on the outside of a disc and spin it to form useful, complex patterns. When spun just right, tiny spindles rise from the material as it cures. The spindles grow as the disc accelerates, forming a soft solid that resembles hairs.

Inspired by biological designs and rationalized with mathematical precision, the new method could be used at an industrial scale for production with plastics, glasses, metals and smart materials.

The researchers published their findings on February 22, 2021, in the Proceedings of the National Academy of Sciences.

Princeton researchers found they could coat a liquid elastic on the outside of a disc and spin it to form useful, complex patterns. When spun just right, tiny spindles rise from the material as it cures. The spindles grow as the disc accelerates, forming a soft solid that resembles hairs. Inspired by biological designs and rationalized with mathematical precision, the new method could be used at an industrial scale for production with plastics, glasses, metals, and smart materials. Credit: Princeton School of Engineering and Applied Science

Their technique draws on fairly simple physics but turns an old set of engineering problems into a new manufacturing solution. The method’s simplicity, cheaper and more sophisticated than conventional molds, comes as part of a major shift toward additive manufacturing.

It also promises to play a key role in developing robotic sensing capabilities and in surfaces that mimic biological patterns — the hairs on a spider leg or on a lotus leaf — deceptively simple structures that provide essential life functions.

“Such patterns are ubiquitous in nature,” said Pierre-Thomas Brun, an assistant professor of chemical and biological engineering at Princeton and the study’s principal investigator. “Our approach leverages the way these structures form naturally.”

Reference: “Elastic amplification of the Rayleigh–Taylor instability in solidifying melts” by Etienne Jambon-Puillet, Matthieu Royer Piéchaud and P.-T. Brun, 22 February 2021, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2020701118