3D Printable Electrically Conductive Hydrogel Scaffolds for Biomedical Applications: A Review

Electrically conductive hydrogels (ECHs), an emerging class of biomaterials, have garnered tremendous attention due to their potential for a wide variety of biomedical applications, from tissue-engineered scaffolds to smart bioelectronics. Along with the development of new hydrogel systems, 3D printing of such ECHs is one of the most advanced approaches towards rapid fabrication of future biomedical implants and devices with versatile designs and tuneable functionalities. In this review, an overview of the state-of-the-art 3D printed ECHs comprising conductive polymers (polythiophene, polyaniline and polypyrrole) and/or conductive fillers (graphene, MXenes and liquid metals) is provided, with an insight into mechanisms of electrical conductivity and design considerations for tuneable physiochemical properties and biocompatibility. Recent advances in the formulation of 3D printable bioinks and their practical applications are discussed; current challenges and limitations of 3D printing of ECHs are identified; new 3D printing-based hybrid methods for selective deposition and fabrication of controlled nanostructures are highlighted; and finally, future directions are proposed.

Automated summary

Electrically conductive hydrogels (ECHs) are a promising class of biomaterials for a wide range of biomedical applications, with 3D printing being an advanced technique for rapid fabrication of future biomedical implants and devices with versatile designs and adjustable functionalities. This review provides an overview of state-of-the-art 3D printed ECHs, discussing mechanisms of electrical conductivity, design considerations, and recent advances in formulation of 3D printable bioinks. Challenges and limitations of 3D printing of ECHs are identified, along with highlighting new 3D printing-based hybrid methods for selective deposition and controlled nanostructure fabrication.