Liquid film with switchable properties
Dynamic natural processes are inspiring a new generation of adaptive material technologies. The tears that coat human eyes, for example, are fascinating for their ability to maintain optical clarity, provide protection from foreign particles, and flush out wastes. Taking inspiration from tears, scientists at Harvard’s Wyss Institute for Biologically Inspired Engineering and the university’s John A. Paulson School of Engineering and Applied Sciences have developed a continuous liquid coating with highly controllable capabilities.
The new material consists of an elastic substrate embedded with micropores, coated with a liquid film. When the substrate is stretched or bent, the pore sizes change, causing deformations in the liquid coating. Variations in the film exhibit precise controllability over two characteristics: transparency and wettability. When the material is at rest, it is smooth, light transmitting, and hydrophobic. In tension, it becomes rough, opaque, and hydrophilic. The coating may also be used to adjust adhesion or antifouling characteristics.
Future applications of the highly tunable film include responsive building envelopes, plumbing that regulates liquid flow rate automatically, and fabrics that can adjust their opacity and hydrophobicity based on weather conditions.
Contact: Wyss Institute, Harvard University, Boston, MA, USA.
For more information, see Transmaterial Next: A Catalog of Materials that Redefine Our Future