Nanoengineering conductive soft interfaces for electrogenic cell interactions: a review of materials, fabrication and functionalisation strategies

Conductive soft materials are emerging as critical platforms for interfacing with electrogenic cells, such as neurons and cardiomyocytes. Unlike rigid metal electrodes, these materials offer tuneable conductivity for reliable electrical communication, tissue-like softness for mechanical compliance, and chemical or bioactive functionalities for effective integration with biological systems. However, achieving an optimal balance between conductivity, mechanical properties, and biocompatibility remains a significant challenge that is strongly dependent on the fabrication pathway selected. The array of advanced biofabrication methodologies continues to expand rapidly, enabling "top down" approaches that start with bulk materials or "bottom up" approaches that enable more precise formation of structures from molecular building blocks. To equip researchers with a practical toolkit for selecting application-specific materials and designing effective bio-interfaces in areas such as neuroengineering and cardiac modelling, here we provide a comprehensive review of fabrication and functionalisation strategies for these materials. We first introduce some key classes of conductive soft materials, highlighting their unique properties when interacting with electrogenic cells. Fabrication techniques, including spin-coating, electrospinning, moulding, lithography, and 3D printing, are then examined, with a focus on identifying their strengths and limitations in the context of specific bioelectronic applications. Finally, strategies for tailoring post-fabrication surface chemistry to enhance cell interaction and growth are discussed. In the final section, emerging opportunities and future directions for conductive soft interfaces are highlighted.