Abstract:We introduce a new class of neural implants with the topology and compliance of dura mater, the protective membrane of the brain and spinal cord. These neural interfaces, which we called e-dura, achieve chronic bio-integration within the subdural space where they conform to the statics and dynamics of neural tissue. e-dura embeds interconnects, electrodes and chemotrodes that sustain millions of mechanical stretch cycles, electrical stimulation pulses, and chemical injections. These integrated modalities enable multiple neuroprosthetic applications. e-dura extracted cortical states in freely behaving animals for brain machine interface, and delivered electrochemical spinal neuromodulation that restored locomotion after paralyzing spinal cord injury. e-dura offers a novel platform for chronic multimodal neural interfaces in basic research and neuroprosthetics.3 Neuroprosthetic medicine is improving the lives of countless individuals. Cochlear implants restore hearing in deaf children, deep brain stimulation alleviates Parkinsonian symptoms, and spinal cord neuromodulation attenuates chronic neuropathic pain (1). These interventions rely on implants developed in the 1980s (2, 3). Since then, advances in electroceutical, pharmaceutical, and more recently optogenetic treatments triggered development of myriad neural interfaces that combine multiple modalities (4-9). However, the conversion of these sophisticated technologies into chronic implants mediating long-lasting functional benefits has yet to be achieved. A recurring challenge restricting chronic bio-integration is the substantial biomechanical mismatch between implants and neural tissues (10-13). Here, we introduce a new class of soft multimodal neural interfaces that achieve chronic bio-integration, and we demonstrate their long-term efficacy in clinically relevant applications. e-dura fabrication. We designed and engineered soft interfaces that mimic the topology and mechanical behavior of the dura mater (Fig. 1A-B). The implant, which we called electronic dura mater or e-dura, integrates a transparent silicone substrate (120µm in thickness), stretchable gold interconnects (35nm in thickness), soft electrodes coated with a novel platinum-silicone composite (300µm in diameter), and a compliant fluidic microchannel (100µm x 50µm in crosssection) (Fig. 1C-D, fig. S1-S2-S3). The interconnects and electrodes transmit electrical excitation and transfer electrophysiological signals.The microfluidic channel, termed chemotrode (14), delivers drugs locally (Fig. 1C, fig. S3). Microcracks in the gold interconnects (15) and the newly developed soft platinum-silicone composite electrodes confer exceptional stretchability to the entire implant (Fig. 1B, Movie S1). The patterning techniques of metallization and microfluidics support rapid manufacturing of customized neuroprostheses.4 e-dura implantation. Most implants used experimentally or clinically to assess and treat neurological disorders are placed above the dura mater (3,(16)(17)(18). The compliance of e-...

Hand loss is a highly disabling event that markedly affects the quality of life. To achieve a close to natural replacement for the lost hand, the user should be provided with the rich sensations that we naturally perceive when grasping or manipulating an object. Ideal bidirectional hand prostheses should involve both a reliable decoding of the user's intentions and the delivery of nearly "natural" sensory feedback through remnant afferent pathways, simultaneously and in real time. However, current hand prostheses fail to achieve these requirements, particularly because they lack any sensory feedback. We show that by stimulating the median and ulnar nerve fascicles using transversal multichannel intrafascicular electrodes, according to the information provided by the artificial sensors from a hand prosthesis, physiologically appropriate (near-natural) sensory information can be provided to an amputee during the real-time decoding of different grasping tasks to control a dexterous hand prosthesis. This feedback enabled the participant to effectively modulate the grasping force of the prosthesis with no visual or auditory feedback. Three different force levels were distinguished and consistently used by the subject. The results also demonstrate that a high complexity of perception can be obtained, allowing the subject to identify the stiffness and shape of three different objects by exploiting different characteristics of the elicited sensations. This approach could improve the efficacy and "life-like" quality of hand prostheses, resulting in a keystone strategy for the near-natural replacement of missing hands.