Multimaterial additive manufacturing of GelMA hydrogel-based structures with tuneable compositional and mechanical properties

Abstract

Multimaterial additive manufacturing is an emerging field that could underpin innovation across various industries. Stereolithography based processes offer high resolution and compatibility with materials, such as hydrogels, which are in strong demand, particularly for healthcare. Here, we present a methodology to achieve high resolution multimaterial fabrication of GelMA- and PEG-based hydrogels using vat-photopolymerisation processes, including projection micro-stereolithography, and two-photon polymerisation. By optimising resin formulations, printing strategies, and post-printing process, we produce high-fidelity 3D multimaterial hydrogel structures with either defined material interfaces or with compositional gradients, which provides a tool for tuning of their compositional properties, alongside tunable mechanical properties (in the range 2–12 kPa). Using Rhodamine B and acrylated Rhodamine B, as exemplar guest molecules, we demonstrate reversible impregnation of hydrogels for sustained release and permanent compositional gradient formation. These capabilities, combined with the inherent biocompatibility of hydrogels, are relevant for applications in drug delivery, wound healing, and environmental sensing, among others. As an illustration, we evaluate the performance of printed hydrogels as sensing layers on interdigitated devices for monitoring salt-rich environments. Together, these findings establish a versatile platform for high-resolution multi-material hydrogel manufacturing, offering new opportunities for engineered bio-architectures, gradient scaffolds, healthcare devices and other sensing applications.