Direct Printing of Soft Intraspinal Electronics for Durable Restoration of Locomotor Function

Spinal cord injury (SCI), particularly in the lumbar region, often results in irreversible lower limb motor impairment. While spinal cord stimulation (SCS) shows promise for restoring motor function, conventional epidural and intraspinal approaches are limited by rigid materials that cannot adapt to spinal cord movement. Herein, we present a bio-integrated, customized intraspinal interface that accommodates dynamic spinal cord movements through tissue-adaptable direct printing of liquid metals, forming soft electronic neural interfaces. This system comprises soft intraspinal liquid-metal electrodes and interconnections printed directly onto the spinal cord surface. The intraspinal electrodes of liquid metals are printed with tailored lengths and diameters to target specific motor neurons within the gray matter. Liquid-metal interconnections adapt seamlessly to spinal cord movements, reducing mechanical stress on electrodes and interfaces. Utilizing Support Vector Machine (SVM) algorithms, our electronic neural interface optimizes stimulation parameters to elicit biomimetic locomotor patterns in rats with complete SCI. Extensive in vivo studies demonstrate the safety, biocompatibility, and long-term functionality of our system.