Tissue-Adhesive and Stiffness-Adaptive Neural Electrodes Fabricated Through Laser-Based Direct Patterning.

Abstract

Recently, implantable devices for treating peripheral nerve disorders have demonstrated significant potential as neuroprosthetics for diagnostics and electrical stimulation. However, the mechanical mismatch between these devices and nerves frequently results in tissue damage and performance degradation. Although advances are made in stretchable electrodes, challenges, including complex patterning techniques and unstable performance, persist. Herein, an efficient method for developing a tissue-adhesive, stiffness-adaptive peripheral neural interface (TA-SA-PNI) is presented employing mechanically and electrically stable ultrathin conductive micro/nanomembrane bilayer (UC-MNB) electrodes. A direct laser-patterning technique is utilized to anchor the UC-MNB, comprising a conductive Cu micromembrane encapsulated by a biocompatible Au nanomembrane, onto a tough self-healing polymer (T-SHP) substrate using the thermoplastic properties of T-SHP. The UC-MNB with a wavy structure exhibited strain-insensitive performance under strains of up to 60%. Furthermore, its dynamic stress-relaxation properties enable stiffness adaptation, potentially minimizing chronic nerve compression. Finally, the phenylboronic acid-conjugated alginate (Alg-BA) adhesive layer offers stable tissue adhesion and ionic conductivity, optimizing the TA-SA-PNI for seamless integration into neural applications. Leveraging these advantages, in vivo demonstrations of bidirectional neural pathways are successfully conducted, featuring stable measurements of sensory neural signals and feedback electrical stimulation of the sciatic nerves of rats.