Customized ultra-flexible and adhesive spinal cord stimulation electrode for chronic pain management

Epidural spinal cord stimulation (SCS) has emerged as an effective therapy for chronic pain. However, its long-term efficacy is limited by the poor biocompatibility and instability at the electrode-tissue interface. Herein, we developed an innovative electrode fabrication strategy to address these limitations and validated it in mouse chronic pain models. We designed and synthesized a modified polydimethylsiloxane substrate carrying hydroxyl groups and sulfur anchor points. The hydroxyl groups enhance interfacial adhesion with surrounding tissue, improving mechanical stability and preventing electrode displacement, while the thiol groups form strong chemical bonds with the metal circuit layer, effectively avoiding delamination. The fabricated electrode with this innovative material demonstrated exceptional stability and maintained functional integrity for over 6 weeks with minimal inflammatory responses. SCS with our electrode showed robust analgesic effects in spinal cord injury, sciatic nerve injury, and diabetic neuropathic pain models. Specifically, the analgesic effects persisted for over 1.5 h after stimulation, unveiling its sustained efficacy. Stable spinal local field potential recordings further confirmed reliable neural interfacing of the electrode. Our research introduces a promising electrode revealing long-term stability, exceptional biocompatibility, and validated efficacy across diverse pain models, which paves the foundation of electrode fabrication for advanced neuromodulation technologies in treating chronic pain management.