Millimeter-sized battery-free epidural cortical stimulators

Abstract

Refractory neurological and psychiatric disorders are increasingly treated with brain stimulation therapies using implanted neuromodulation devices. Current commercially available stimulation systems, however, are limited by the need for implantable pulse generators and wired power; the complexity of this architecture creates multiple failure points including lead fractures, migration, and infection. Enabling less invasive approaches could increase access to these therapies. Here we demonstrate the first millimeter-sized leadless brain stimulator in large animal and human subjects. This Digitally programmable Over-brain Therapeutic (or DOT) is approximately 1 cm in width yet can produce sufficient energy to stimulate cortical activity on-demand through the dura. This extreme miniaturization is possible using recently developed magnetoelectric wireless power transfer that allows us to reach power levels required to stimulate the surface of the brain without direct contact to the cortical surface. This externally powered cortical stimulation (XCS) opens the possibility of simple minimally invasive surgical procedures to enable precise, long-lasting, and at-home neuromodulation with tiny implants that never contact the surface of the brain.

Endocisternal interfaces for minimally invasive neural stimulation and recording of the brain and spinal cord

“…Using a millimeter-sized battery-free implantable stimulator we demonstrate multi-site electrical stimulation and recording through the ECI. We take advantage of recent developments in magnetoelectric materials, which are thin films that convert magnetic fields to electric fields, to engineer miniaturized battery-free bioelectronics to serve as the implantable pulse generator 35 . By using a magnetic field, we can not only send power and data into the implant to have programmable stimulus pulses with varying amplitudes up to 14.5 V, pulse widths, and duty cycles, but we are also able to take advantage of recently developed magnetoelectric backscatter to also wirelessly record physiologically relevant signals through this endocisternal neural interface 36 (Fig.…”

“…The data '0' and data '1' are encoded by changing the applied electric load to the magnetoelectric films (Supplementary Fig. 4B, see methods) 35 . We implanted two catheter electrodes in the body, one in the brain over the motor cortex connected to a ME stimulator, and the second in the spinal cord connected to a separate ME recording implant.…”

“…The implantable pulse generator used in this study is described in detail in Millimeter-sized battery-free epidural cortical stimulators 35 . In brief, the implantable pulse generator is composed of a custom printed circuit board (PCB), two 7.5x3mm magnetoelectric films (resonant frequency 218kHz), and a glass enclosure.…”