Optimization of Carbon Nanotube Morphology in Self-Supporting Buckypapers for Bioelectronic Interfaces

Bioelectronics requires advanced conducting materials to interface with biological systems without triggering inflammatory responses. Conventional metal electrodes often suffer from mechanical and chemical mismatches with living tissue, a challenge that can be addressed using flexible, self-supporting carbon nanotube (CNT) films known as buckypapers (BPs). This study focuses on the optimization of CNT morphology, specifically length and thickness, to enhance the electrochemical performance and porosity of these interfaces.

The fabrication process involved the vacuum filtration of various multi-walled CNT types dispersed in DMF through sonication, followed by overnight drying to produce mechanically stable, self-supporting films. The electrochemical properties were evaluated using cyclic voltammetry and electrochemical impedance spectroscopy, comparing different nanotube morphologies against commercial references. The results demonstrate that nanotube dimensions dictate electrode efficiency. Short and thin nanotubes provided the highest current density and capacitance due to their superior accessible surface area, while maintaining the lowest total impedance and nearly zero charge transfer resistance. In contrast, longer and wider nanotubes exhibited high stability but lower energy storage capacity. Furthermore, long nanotubes with medium thickness created continuous electrical pathways that minimized ion entry barriers. Optimized in-house samples consistently exhibited better kinetic efficiency and lower series resistance compared to standard commercial BPs.

In conclusion, precise control over nanotube morphology is essential for creating efficient bio-derived interfaces. These optimized BPs provide a robust platform for further modification with bioactive hydrogel layers designed to mimic natural tissue structures. Subsequent research will evaluate these materials in vitro with human-derived cell lines (SH-SY5Y, U87) and ex vivo with embryonic co-cultures to confirm their biocompatibility and ability to stimulate neural activity.

The Authors would like to thank the National Science Centre, Poland [mERA NET 2024/06/Y/ST5/00217].