Information security with the artificial structural colors
(A) Illustration of the relationship between the displayed color with the information code.
(B) The pre-built congruent relationship between the optical stopband and digital signal.
(C) Septenary PC coding system formed by encoding the PC dots with more distinguishable stopbands. Reprinted with permission from Li et al. (2017). Copyright 2017, Royal Society of Chemistry.
(D) Illustration of the presentation of the hidden information after blowing.
(E) Optical images of the prepared sample before and after a breath. Insets are the microscopic images of the droplet (2 μL) deposited on the sample surface of unetched (Left) and etched (Right) regions, showing the contrast wettability. Reprinted with permission from Zhong et al. (2018). Copyright 2018, John Wiley & Sons, Inc.
(F) Optical and SEM images of the transparent SiO2-NP/PDMS composite device in the normal state.
(G) Optical and SEM images of the same device with colorful information when the patterned side is bent. Reprinted with permission from Zhou et al. (2020). Copyright 2020, John Wiley & Sons, Inc.