Jun 18, 2010 video
Polymer microbristles, each one-hundredth the diameter of a human hair, are embedded in an 'artificial muscle' made of hydrogel -- the same material used in diapers. This hydrogel is printed in a honeycomb pattern. When the humidity level changes, the hydrogel swells or contracts, which in turn bends the microbristle, forming a strikingly different pattern. In this particular example, because of an accidentally formed defect in the center, the microbristles reconfigure into honeycomb pattern and then into a chiral pattern with color change. This procedure is reversible and can be operated for many cycles.