(a) Micromorphological structure of 2D PMs, where yellow indicates its basic unit cell and green indicates its brick. The deformed PM bricks are obtained by QCT from the regular PM bricks. (b) Acoustic pressure fields for the rigid plane, rigid scatter, latticed PMC and theoretical cloaking at a frequency of 15 kHz incident at 55°. (c) Schematic illustration of the 3D UACC. An enlarged view of a representative unit cell is displayed in the green frame, while the left inset in (c) presents an actual image of the 3D UACC sample. (d) The 10 kHz measurements of the acoustic pressure field in the rectangle frame. The 0 ms value of the incident pressure field, and the 1.8 ms values of the scattered pressure fields from the soft plane, soft target as well as cloaked soft target. Panels (a) and (b) are modified based on the permission from Sun et al., Appl Phys Lett 114, 094101 (2019). Copyright 2019, AIP Publishing. Panels (c) and (d) are modified with permission from Bi et al., Appl Phys Lett 112, 223502 (2018). Copyright 2018, AIP Publishing.