Design of a passive controllable negative modulus metamaterial with a split hollow sphere of multiple holes

We present a passive controllable negative modulus metamaterial based on a split hollow sphere (SHS) with multiple holes. The metamaterial is obtained by changing the number of split holes. The experimental results show that the position of one split hole does not affect the transmission dip, whereas the resonance frequency depends on the relative position of two holes. Furthermore, when the number of split holes is increased, the resonance frequency undergoes a blueshift. Simulation results via the finite element method (FEM) are in accord with experimental data. The design of a negative modulus metamaterial at an expected frequency is simple, and the proposed method is expected to provide a basis for the simultaneous control of acoustic metamaterials (AMs) through a variety of methods.