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Updated: May 2, 2026

Preparation of Hydroxy-PAAm Hydrogels for Decoupling the Effects of Mechanotransduction Cues
Published on: August 28, 2014
Spatiotemporal toughness modulation in hydrogels through on-demand cross-linking
Jihun Lee1, Rogerio M Castilho2,3, Sungmin Nam1,3,4
1Department of Mechanical Engineering, School of Engineering, University of Michigan, Ann Arbor, MI, USA.
Abstract:
Tough hydrogels are promising for soft robotics, bioelectronics, and tissue adhesives due to their exceptional resilience and biocompatibility, yet precise spatiotemporal control of their mechanics remains challenging. Here, we present a hydrogel platform that enables spatiotemporal modulation of toughness through a latent ionic cross-linking mechanism. By embedding calcium carbonate (CaCO3) microparticles in alginate/polyacrylamide double-network hydrogels, we create a system where localized calcium release and thus ionic cross-linking can be programmed in both space and time. Spatial control is achieved by direct ink writing of CaCO3, while temporal activation is triggered by glucono-δ-lactone, a biocompatible acidifier that releases calcium on demand. This strategy allows user-defined tuning of stiffness and toughness, enabling fabrication of three-dimensional (3D) hydrogels with tailored mechanical profiles. The resulting materials offer a versatile platform for anisotropic impact shielding, directional strain sensing, and 3D-printed tissue adhesives, representing a paradigm shift for adaptive, reconfigurable, and multifunctional soft materials.
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