Wireless, battery-free, and fully implantable electrical neurostimulation in freely moving rodents

Alex Burton,Tucker Stuart,Flavia Vitale,Philipp Gutruf,Andrew G Richardson,John A Rogers,Andrew Gabros,Yoonseok Park,Arian Kolahi Sohrabi,Amir Amirhossein,Jong Uk Kim,Sang Min Won

doi:10.1038/s41378-021-00294-7

Abstract

Implantable deep brain stimulation (DBS) systems are utilized for clinical treatment of diseases such as Parkinson’s disease and chronic pain. However, long-term efficacy of DBS is limited, and chronic neuroplastic changes and associated therapeutic mechanisms are not well understood. Fundamental and mechanistic investigation, typically accomplished in small animal models, is difficult because of the need for chronic stimulators that currently require either frequent handling of test subjects to charge battery-powered systems or specialized setups to manage tethers that restrict experimental paradigms and compromise insight. To overcome these challenges, we demonstrate a fully implantable, wireless, battery-free platform that allows for chronic DBS in rodents with the capability to control stimulation parameters digitally in real time. The devices are able to provide stimulation over a wide range of frequencies with biphasic pulses and constant voltage control via low-impedance, surface-engineered platinum electrodes. The devices utilize off-the-shelf components and feature the ability to customize electrodes to enable broad utility and rapid dissemination. Efficacy of the system is demonstrated with a readout of stimulation-evoked neural activity in vivo and chronic stimulation of the medial forebrain bundle in freely moving rats to evoke characteristic head motion for over 36 days.

Highlights

Wireless battery-free investigative tools for targeted neurostimulation of the brain have become important to expand neuromodulation to freely moving small animal subjects[1,2,3,4,5]
Recent examples include the first demonstration of neuromodulation in freely flying birds[6] and in multiple socially behaving rodents[4], both of which would be difficult or impossible to achieve with standard tethered approaches. These current demonstrations utilize optogenetic stimulation, which is a powerful tool for exploratory research because of cell-type-specific modulation capabilities and minimal electronic hardware requirements, which enable subdermal embodiments that are scalable and feature small footprints
The flexible serpentine structure that connects the device body and the injectable stimulation probe allows for easy manipulation of the probe during surgical procedures and provides an interface that facilitates custom probe designs

Summary

Introduction

Wireless battery-free investigative tools for targeted neurostimulation of the brain have become important to expand neuromodulation to freely moving small animal subjects[1,2,3,4,5]. Continuous wireless power transfer (WPT) to the implants enables ultrathin platforms that are fully subdermally implantable, which reduces infection risk. These current demonstrations utilize optogenetic stimulation, which is a powerful tool for exploratory research because of cell-type-specific modulation capabilities and minimal electronic hardware requirements, which enable subdermal embodiments that are scalable and feature small footprints. Current clinical neuromodulation therapies, such as deep brain stimulation (DBS) for movement disorders, Burton et al Microsystems & Nanoengineering (2021)7:62 a Components Copper b PI Polyimide Copper Probe Pt Au W c Red LED Electrode

Methods

Results

Conclusion