3D-printed metallogels

Three-dimensional (3D) printed metallic soft gels have emerged as a flexible platform in advanced manufacturing and polymer chemistry. Hydrogels and ferrogels (magnetic gels) offer special opportunities for functionally active and mechanically adaptable materials. Hydrogels are widely used in tissue engineering, drug delivery, and soft robotics due to their high water content, elasticity, swelling capacity, and biocompatibility. Metal ions, such as iron (Fe 3+ ), calcium (Ca 2+ ), and zinc (Zn 2+ ), increase the stability, mechanical strength, self-healing capacity, and stimuli-responsive behaviour of networks by introducing additional crosslinking pathways. The architecture of gels and the distribution of metals can be precisely controlled in space because of recent advances in 3D printing techniques, including extrusion-based deposition, inkjet, light-assisted printing, and magnetic-field-assisted manufacturing. These techniques aid in the logical design of structure-function interactions, in which printability and performance are highly dependent on polymer-to-metal ratios, gelation mechanisms, rheological characteristics, and particle dispersion. This paper discusses the design principles of printed metal-based gels alongside their applications in bioelectronics, drug delivery, tissue engineering, soft robotics, sensors, and innovative microfluidic and transient devices. The main problems, like metal toxicity, the trade-off between printability and functionality, and scalability, are discussed in detail. Future opportunities of metal-driven design in 3D-printed soft gel technologies are highlighted by future prospects of multi-metal systems, intelligent responsive structures, and integrated functional devices.