g. However, preparing patterned bub

g. However, preparing patterned bubble crystals in water remainsa challenge because of the instability of bubbly liquids. Here, inspired bybiological superhydrophobic systems, we report a simple and rapidapproach to prepare patterned bubble arrays in water and theirapplications in low-frequency acoustic blocking. Patterned bubbleswith the desired size, shape, and position can be prepared. Single-layerbubble arrays can block the sounds at low frequencies because of localresonance. By varying the size and distance of the bubbles withoutchanging the thickness, the operating frequency can change from 9 to1756 kHz. Besides, by preparing multilayer bubbles, broad and low-frequency acoustic band gaps can be achieved, with thegeneralized width of γ (ratio of the bandgap width to its start frequency) reaching 1.26. This method provides a feasible strategyto control acoustic waves at low frequencies for applications such as acoustic blocking, focusing, imaging, and detecting