Ultra-flexible wireless endovascular stimulator for cortical simulation.

Abstract

Endovascular neural stimulation (ENS) offers a minimally invasive alternative to conventional intra-cranial implants. However, present ENS devices rely on long transvascular leads, which are prone to foreign body responses, breakage, higher impedance, and noisy input. In this study, we aimed to demonstrate the feasibility of fully wireless cortical stimulation using an ultra-flexible, leadless endovascular stimulator that can be delivered with standard neurointerventional techniques.

Approach. We designed an ENS implant integrating a miniaturized receiver coil, passive rectification circuitry, and an electrode pair on a flexible substrate that can be rolled into a catheter and self-expand against the vessel wall. Wireless power transfer was modeled and validated in vitro using sheep tissue to characterize inductive coupling, power transfer efficiency, and stimulation output over a range of coil separations (5-30 mm), vessel diameters (3-5 mm), and load impedances. In acute in vivo sheep experiments (n = 4), the device was placed either subdurally over motor cortex or endovascularly in the superior sagittal sinus, while an external transmitter (Tx) coil on the skull drove pulse-modulated bursts to control stimulation intensity and duration. 

Main Results. The ENS implant generated 3-11 V monophasic pulses across 1-4.7 kΩ loads at 20 mm separation and evoked neural responses in sheep. In vivo, controlled increases in Tx current produced corresponding changes in stimulation amplitude, and clear N1/N2 evoked potentials were observed for both subdural and endovascular stimulations at higher drive currents, whereas no responses were detected at low input levels or post-mortem.

Significance. This study provides the first in vivo demonstration of a fully wireless, catheter-deliverable endovascular cortical stimulator, capable of generating electrically evoked neural responses. This approach outlines a scalable path toward multi-site, leadless endovascular neuromodulation, potentially leads to fewer catastrophic failures, lower the risk of transvascular infection, and reduce crosstalk and noise in the stimulation waveforms.&#xD.