Fig. 4.

(A) A functional soft mechanical diode can be realized by creating a heterogeneous chain composed of a region with soft connectors and a small energy barrier (on the left) and a region with stiff connectors and a large energy barrier (on the right). A pulse initiated in the soft region (from the left) cannot pass into the stiff region due to the large energy barrier, causing the pulse to freeze indefinitely at the interface (A, iv–vi, and B). In contrast (A, vii–ix, and C), when the pulse is initiated in the stiff region, the propagation continues into the soft region and through the whole chain without interruption.