New mechanical metamaterials can block symmetry of motion, findings suggest
(PHYSorg.com Physics)

Engineers and scientists at The University of Texas at Austin and the AMOLF institute in the Netherlands have invented the first mechanical metamaterials that easily transfer motion effortlessly in one direction while blocking it in the other, as described in a paper published on Feb. 13 in Nature. The material can be thought of as a mechanical one-way shield that blocks energy from coming in but easily transmits it going out the other side.