Fig. 2: Mechanical, acoustic, bacteria-repairing properties of the BC meta-skin.

a Illustration of BC meta-skin paper-cutting, via which we can realize the ultrathin meta-lenses with different functionalities. The inset shows that the BC meta-skin has a surprising bacteria-repairing property. b Three stages (I, II, III) in the bacteria repairing of a broken meta-skin. c Complex pattern comprising ‘building’, ‘flag’, ‘HUST’, and other elements. d Laser-cut BC meta-skin with the narrowest line width of ~200 µm, showing excellent processability. e Optical image of the patterned meta-skin immersed in water, where the silvery surface indicates the existence of a very stable air-filled interface (or the Cassie-Baxter states) on the meta-skin. f Illustration of perfect mirror reflection for ultrasound on the nanosurface due to the stark acoustic impedance mismatch. g The time-domain measurement in reflection (with \(\pi\)-phase compensation) and transmission for a short ultrasound pulse incident on the meta-skin. h Spectral analyses of incident, transmitted, and reflected signals, indicating broadband ultrasound reflection.