MRI-compatible 3D Soft Carbon Neural Interface Enabled by Versatile Depth-tunable Laser Drawing

Abstract

Soft neural interfaces are designed to minimize mechanical mismatch with the brain. However, planar and recessed electrode sites remain locally decoupled from the curved and pulsating cortical surface, degrading the fidelity of neural sensing. Here, we report a 3D soft carbon electrode array, enabled by a depth-tunable laser drawing strategy. This laser-driven workflow achieves versatile fabrication of customizable 3D soft carbon neural interfaces, eliminating the reliance on conventional thin-film microfabrication processes. The fully silicone-based electrode structure realize device-scale conformality, and the 3D soft carbon sites promote a non-penetrating, intimate neural-electrode interface. The CNT-3D array combined superior in-vitro electrochemical and in-vivo recording performance compared with Au-2D and CNT-2D controls. Furthermore, in bilateral rabbit cortex implantation, CNT-3D array retained 80.4% of electrocorticography power after 4 months, versus 11.7% for CNT-2D control. Moreover, the 3D sensing sites significantly suppressed line-frequency harmonics and background noise interference. Subsequently, during magnetic resonance imaging, the CNT-3D array exhibits negligible implant-induced artifacts compared to the conventional Pt-Ir metal array. Overall, this work establishes a laser drawing strategy that extends neural interfaces from macro device-scale conformality to micro site-scale coupling, providing a technological pathway for practical and translational soft neurotechnology.