from Emerging Technology Trends -
Nanotechnology-based self-cleaning fabrics
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Another application of the self-cleaning technology that is based on the application of a thin coating of titanium dioxide, which breaks down organic materials in the presence of ultra-violet radiation.

Also see earlier posts:
"Self-Cleaning Tiles"
"Cleaning walls? No sweat - just add sunlight and rain"
"Eco glass cleans itself with Sun"
.