Re-programmable Combinatorial Acoustic Metamaterials

In this work, we study a combinatorial metamaterial composed of asymmetric pillars that can manipulate acoustic waves based on their angular orientation. The proposed metamaterial can produce different attenuation frequency regions (i.e., bandgaps) that can be altered in real-time by means of active control. We utilize a combinatorial design approach to characterize our metamaterials numerically and experimentally for different unit cells in both 1 and 2D configurations. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.