Octopus-inspired smart skin uses 4D printing to encrypt data, change shape on demand

Researchers at Penn State have developed a novel "smart synthetic skin" made from hydrogel that can dynamically change its appearance, texture, and shape while encrypting or revealing information on demand. Utilizing a 4D printing technique called halftone-encoded printing, digital image and texture data are embedded as binary patterns directly into the hydrogel. These patterns serve as programmed instructions dictating how different regions of the material respond to external stimuli such as heat, solvents, or mechanical stress. This allows the material to perform multiple functions simultaneously, including adaptive camouflage, information encryption/decryption, and shape morphing—capabilities inspired by cephalopods like octopuses, which can rapidly alter their skin for communication and blending into environments. One key demonstration involved encoding an image of the Mona Lisa into the hydrogel, which could be hidden or revealed by changing environmental conditions like immersion in ethanol or ice water. Beyond visual changes, the smart skin also reveals hidden information through mechanical deformation, as stretching the material exposes