Functional inks for 3D printing: a review of materials, rheology and industrial applications

Purpose This review aims to explore recent developments in functional ink formulations for 3D printing, emphasizing their role in expanding the functionality, precision and sustainability of additive manufacturing across sectors such as electronics, biomedicine and energy. Design/methodology/approach The paper synthesizes findings from contemporary research on polymeric, conductive, ceramic, bio-based and hybrid inks. It focuses on their chemical composition, rheological behavior, curing mechanisms and printability across various 3D printing platforms, including inkjet, extrusion and photopolymerization systems. Findings The review highlights how advanced ink formulations contribute to print fidelity, structural performance and functional behavior in printed products. It also discusses key challenges such as nozzle clogging, interlayer adhesion and sustainability. Practical implications Insights from this review can assist materials scientists and industrial developers in optimizing ink formulations to enhance scalability, reduce environmental impact and improve functional integration in 3D-printed components. Originality/value This work provides a multidisciplinary perspective, linking materials science, chemistry and advanced manufacturing. It offers a roadmap for future innovation in sustainable and high-performance functional inks.