We investigate wave propagation in meta-structures. We have developed a magneto-elastic system for demonstrating unidirectional wave propagation through experiments. Achieving unidirectional wave propagation could pave the way for developing mechanical diodes and transistors. We have also looked at origami structures as periodic structures and have shown that, similar to meta-structures, they exhibit band gaps. This suggests a new structural health monitoring technique, where the changes in the bandgap of origami structures indicates a damage.