The Dark Side of the Spine—Using Flexible Bioelectronics to Interface with the Spinal Cord

Implantable bioelectronic devices for diagnosing and treating disease are emerging as a prominent component of modern healthcare. Within this field of medicine, the spinal cord offers an interesting target as the primary bi-directional information highway between the brain and the rest of the body. However, there remains several technical and clinical barriers within the development of new tools to interface with the central nervous system (CNS). Overcoming these barriers could improve the lives of people suffering from conditions such as Parkinson's(1), chronic pain(2), and paralysis(3) as well enabling better neuroscientific research, diagnostics, and prognostics.<br/>In this work, we present thin, flexible, and shape adaptive implants based on the conductive polymer PEDOT:PSS which can be used to interface with the CNS. The devices are fabricated from biocompatible materials such as parylene-C/silicone and use conductive metals and polymers to stimulate and sense the tracks of the spinal cord. These devices are fabricated using scalable manufacturing techniques to create conformable interfaces up to 100 times thinner than commercially available spinal cord implants. This allows larger coverage than previously possible, whilst minimising surgical risk during implantation. To validate the surgical implantation of these devices they have been tested within a human cadaver model, with utility-based studies explored <i>in vivo.</i><br/>After showing our technology can be used as a minimally invasive interface for conventional spinal cord stimulation(4), we are now aiming to elucidate the ‘dark’ side of the spinal cord, where the majority of motor information lies. Taking these recording devices 360° around the spinal cord, has proven to be a fascinating tool in describing the spatial and temporal arrangements of spinal networks and may offer therapeutic benefits in both prognostics and SCI therapy.<br/>1. Samotus O, Parrent A, Jog M. Spinal Cord Stimulation Therapy for Gait Dysfunction in Advanced Parkinson’s Disease Patients. Mov Disord. 2018;33(5):783–92.<br/>2. Dones I, Levi V. Spinal Cord Stimulation for Neuropathic Pain: Current Trends and Future Applications. Brain Sci. 2018 Jul 24;8(8).<br/>3. Wagner FB, Mignardot J-B, Goff-Mignardot CGL, Demesmaeker R, Komi S, Capogrosso M, et al. Targeted neurotechnology restores walking in humans with spinal cord injury. Nature. 2018 Nov;563(7729):65.<br/>4. Woodington BJ, Curto VF, Yu Y-L, Martínez-Domínguez H, Coles L, Malliaras GG, et al. Electronics with shape actuation for minimally invasive spinal cord stimulation. Sci Adv. 7(26):eabg7833.