Electrical Writing Induced Covalent Cross-Linking on Hydrogel for Multidimensional Structural Information Storage

Abstract

The storage of dynamic information in hydrogel is extremely interesting due to the reprogrammable and responsive features of hydrogel. Here, we report that structural information can be stored in polysaccharide hydrogel by electrically induced covalent cross-linking, and the imbedded information can be retrieved by different means (dye adsorption, protonation of chitosan, and acid dissolution). Taking the advantage of diffusible feature of hydrogel, OH– was generated from the contacting area of the electrode and controllably diffused by electrical writing, thus the high pH domain (pH ∼ 10) triggered covalent cross-linking of the hydrogel. The written area exhibits different micromorphology, chemical properties, and pH sensitivity, allowing dynamic 2D and 3D information to be stored and read when necessary. This work demonstrates the use of stable electrical inputs to store dynamic structural information in a biopolymer-based hydrogel and how the chemical and physical varies allow eye recognition to the embedded information.

Patterning meets gels: Advances in engineering functional gels at micro/nanoscales for soft devices

“…Consequently, large‐scale dynamic patterning was achieved, in which the patterns could be erased and rewritten through repeated freezing and photopatterning procedures (Figure 10C). 103 A similar information encryption and decryption system was also demonstrated by utilizing the electric field to crosslink chitosan hydrogels locally, in which the patterns could disappear in water and emerge again in acetic acid 104 …”

“…103 A similar information encryption and decryption system was also demonstrated by utilizing the electric field to crosslink chitosan hydrogels locally, in which the patterns could disappear in water and emerge again in acetic acid. 104 The patterned inhomogeneity also enabled programed mechanical properties and shape morphing. Since a wide range of hydrogels can be crosslinked and stiffened by ions, selective addition of ions into hydrogels allowed facile surface patterning with programmable bulk mechanical properties and surface functionalities.…”

Paper‐Structure Inspired Multiresponsive Hydrogels with Solvent‐Induced Reversible Information Recording, Self‐Encryption, and Multidecryption

“…[8] Over the last few decades, various approaches have emerged for information encryption and decryption/protection, such as holographic anti-counterfeiting, multidimensional security codes, stimulus-response, and fluorescence recognition. [8][9][10][11] For example, Tang et al [12] designed an aggregation-induced emission (AIE) supramolecular hydrogel which exhibited adhesiveness and multiple fluorescent colors. The storage capacity of this system for large amounts of information was demonstrated based on the code methods under UV light irradiation, showing 1D, 2D, and 3D information recording capabilities.…”

“…Over the last few decades, various approaches have emerged for information encryption and decryption/protection, such as holographic anti‐counterfeiting, multidimensional security codes, stimulus‐response, and fluorescence recognition. [ 8–11 ] For example, Tang et al. [ 12 ] designed an aggregation‐induced emission (AIE) supramolecular hydrogel which exhibited adhesiveness and multiple fluorescent colors.…”

Enhanced Macroporous Cationic Chitosan Hydrogel by Freezing and Thawing Method with Superadsorption Capacity for Anionic Dyes

“…Moreover, it has been found that chitosan hydrogel has a better adsorption capacity than that chitosan polymer with non-crosslinking specially in acidic medium due to chitosan can be dissolved in acidic environment [26]. Chitosan hydrogels designed via either chemical or physical cross-linking using different crosslinker agents such as glutaraldehyde, glyoxal, formaldehyde, ethylene glycol diglycidyl ether, epichlorohydrin and oxalic acid were reported [27][28][29][30]. The mechanical properties and the chemical stability of chitosan are improved after cross-linking process [31].…”