Kirigami‐Design‐Enabled Hydrogel Multimorphs with Application as a Multistate Switch

Abstract

Morphing materials have promising applications in soft robots, intelligent devices, and so forth. Among the various design strategies, kirigami structures are recognized as a powerful tool to obtain sophisticated 3D configurations and unprecedented properties from planar designs on common materials. Here, some kirigami designs are demonstrated for programmable, multistable 3D configurations from composite hydrogel sheets. Via photolithographic polymerization, perforated composite hydrogel sheets are fabricated, in which soft and active hydrogel strips are patterned in stiff and passive hydrogel frames. When immersed in water, the gel strips buckle out of plane due to swelling mismatch. In the kirigami structures, the geometric continuity is disrupted by the introduction of cutouts, and thus the degrees of deformation freedom increases remarkably. Multiple configurations are obtained in a single composite hydrogel by controlling the buckling direction of each strip. Multitier configurations are also obtained by using a hierarchically designed kirigami structure. A multicontact switch of an electric circuit is designed by harnessing the multitier gel configurations. Furthermore, a rotation mode is realized by introducing chirality in the kirigami design. The versatile design of the kirigami structure for programmable deformations should be applicable for other intelligent materials toward promising applications in biomedical devices and flexible electronics.

Multicolor Fluorescent Polymeric Hydrogels

“…To achieve more effective multistage data security, there has been recent research interest in expanding traditional 2D information encryption platforms to their 3D counterparts. In this regard, MFPHs are believed to be perfect candidate materials, because their soft and flexible nature enable them to be facilely programmed into various complex 3D geometries by employing such methods as “Lego” assembly [39] or the origami technique [40] . To this end, a proof‐of‐concept example has been demonstrated by us.…”

Multicolor Fluorescent Polymeric Hydrogels

“…To achieve more effective multistage data security,t here has been recent research interest in expanding traditional 2D information encryption platforms to their 3D counterparts.In this regard, MFPHs are believed to be perfect candidate materials,b ecause their soft and flexible nature enable them to be facilely programmed into various complex 3D geometries by employing such methods as "Lego" assembly [39] or the origami technique. [40] To this end, ap roof-of-concept example has been demonstrated by us.A ss hown in Figure 11 A, the MFPHs were prepared by repeated freezing/ thawing cycles of perylene tetracarboxylic acid grafted gelatin (PTG) and poly(vinyl alcohol) (PVA) solutions,which exhibit ap H-triggered emission color change and typical Fe 3+induced fluorescence quenching. [38c] Theh ydrogels also have astrong shape memory and self-healing properties because of the highly reversible borate bonds between the PVAa nd borax (Figure 11 B).…”

Actuating Supramolecular Shape Memorized Hydrogel Toward Programmable Shape Deformation

“…materials in the rising area of intelligent research, [6,7] have aroused increasing interest and shown promising applications in the fields of soft robotics, [8,9] biomedical engineering, [10][11][12] and biomimetic manufacturing. [13] In the past decade, simple bending, folding, and complex shape deformations have been achieved by inducing anisotropic structure such as gradient, [14,15] bilayer, [16,17] patterned, [18][19][20] or orient structure [21,22] in hydrogel. For example, Wu et al have proposed a novel strategy to achieve planar-to-helical 3D shape deformation by patterning on the surface of hydrogel sheet.…”