479 BrainPacer: Wireless Battery-Free Neuromodulator Embedded in a Dural Graft

Abstract

INTRODUCTION: Neuromodulation represents an emerging realm of disruptive technologies for brain/spine disorders with potential applications across disease states, including neurodegenerative, neoplastic, epilepsy, trauma and vascular disorders. However, current implants have limitations inherent to the use of wires, batteries that need replacement, infection, and implant failure that have hindered wider adoption. METHODS: A 100 µm-thick, biocompatible, flexible, and transparent Parylene/PDMS substrate was used. In vivo validation (120 stimulation bursts, 10 pulses, 4 rats and 4 implants) was pursued using motor cortex stimulation after identification of the hindlimb representation via direct cortical stimulation. Hindlimb motion and reliability of stimulation and movement were detected via a video analysis software. A comparison of efficiency was conducted between the proposed dura substitute method and conventional direct stimulation method. RESULTS: Benchtop testing demonstrates reliable monophasic voltage pulses with an amplitude of 20V that can be subsequently regulated. Stimulation through the dura substitute results in reduced efficiency by 60% due to current loss but it offers the same reliability, triggering a motor response at each stimulation onset with an average limb deflection of 5.2 ± 2.986 mm with 99% confidence level. At least 30 seconds of recordings were obtained in each animal at a stimulation frequency of 1 Hz. CONCLUSIONS: We designed, validated and tested both a novel wireless and battery-free implant and a novel embodiment for placement with revolutionary potential. The implant triggers motor response through an FDA-approved dura substitute, without contacting the cortical surface. Studies in free-moving animals for chronic response studies are ongoing.