Tailoring Stretchable, Biocompatible, and 3D Printable Properties of Carbon-Based Conductive Hydrogel for Bioelectronic Interface Applications

Functional conductive hydrogels with customizable shapes and structures facilitate seamless integration between biological and electronic interfaces. However, the current capacity to adjust the properties of conductive gels is constrained, frequently requiring complex post-processing methods to ensure gel formation and achieve a balance between mechanical and electrical properties. This significantly limits the flexibility in fabricating gel-based sensing interfaces. In this study, a 3D-printable, photo-crosslinked, carbon-based conductive nanocomposite hydrogel (FPCH) comprising poly(ether) F127 diacrylate (F127DA), Single-Walled carbon nanotubes (SWCNT), and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) is developed. By optimizing the proportion of conductive fillers, the hydrogel achieves tunable modulus (as low as 90 kPa), high stretchability (up to 520% strain), conductivity (440 S m⁻¹), and 3D printability. The conductive gel can be rapidly cured on demand via UV-induced crosslinking and demonstrates good biocompatibility. It functions not only as a “skin electronic tattoo” for multimodal applications, such as strain and humidity sensing and thermal compensation but also effectively stimulates the sciatic nerve in vivo at low voltage. Furthermore, electrodes fabricated using 3D printing technology offer conformal contact with brain tissue and enable real-time monitoring of electrophysiological signals, providing a versatile bioelectronic sensing interface for multi-modal applications adaptable for both the in vivo and in vitro environments.