Industrial-scale production of a self-cleaning film covering for windows may soon be possible thanks to an invention that borrows the microscopic surface patterns of a butterfly wing.
Butterfly wings and lotus-leaves share an unusual surface property that makes them self-cleaning: a complex microstructure comprised of miniscule bumps. This surface is effectively self-cleaning since it prevents waterdroplets from properly wetting the wing, instead causing them to remain as droplets and roll-off, taking dirt with them. Previous attempts to copy this natural architecture have involved using lithographic technology used in silicon chip-fabbing, a process too complex and costly for high speed or large area treatments.
Now a team at the French National Centre for Scientific Research has created a technique that actually copies the wing surface directly, by pouring a silicon-based polymer actually onto a butterfly wing, and peeling it off to act as a mold. The mold is used to cast 900-nanometer thick copies in methyltriethoxysilane--an agent already used in glass-making. By combining multiple copies of the casts, a whole-window film could be produced.
Self-cleaning windows with this efficient technology would be an boon to many a householder, and the cost-saving implications for businesses owning millions of square-feet of glass windows across tens of vertical floors that currently need manual cleaning are undoubtable.
[via New Scientist]