Intracortical Flexible Microneedle Neural Electrode (f-μNeurode) Based on Projection-Micro-Stereolithography (PμSL) Technology for Chronic In-Vivo Electrophysiological Recording

This paper reports a novel intracortical neural interface device, called f-μNeurode, for chronic in-vivo electrophysiological recording. The device achieved excellent electrical properties and has been implanted for 28 days, successfully recorded single-cell spikes and local-field potentials (LFPs). The f-μNeurode consists of a high-aspect-ratio polymer microneedle array electrode, which is bottom-up additively manufactured on a flexible substrate by Projection-Micro-Stereolithography (PμSL) technology. Compared to the conventional Utah Electrode Array (UEA), the f-μNeurode is more flexible and thinner, overcoming the limitation of brittleness and fragility of silicon material, reducing the mechanical stimulation to the brain as well as bringing higher biosafety. Owing to the flexibility and compatibility of the PμSL, which is utilized to fabricate the intracortical neural interface for the first time, microneedle arrays with different channel numbers, different layouts, different lengths and diameters can be easily customized and mass-produced with relatively low cost.