Session: 06-05-01: Biomedical Devices, Sensors, and Actuators

Paper Number: 150872

150872 - High-Performance Neural Stimulation Based on 3d Porous Graphene-Based Electrodes 

Developing effective treatments for chronic pain, neurological disorders, and recovery post-injury is essential. Neural electrodes are promising for precise neural modulation, as they can selectively activate or inhibit specific neural pathways. High-performance electrodes that possess significant charge storage and injection capacities (CSC and CIC) are crucial for effective neural stimulation. Traditional metal-based electrodes, particularly platinum (Pt), face limitations in CIC due to their relatively small surface area, which can reduce their effectiveness. The use of higher voltages necessary for Pt electrodes can also lead to harmful electrochemical reactions and potential damage to neural tissues, including oxidative stress and inflammation. To enhance the charge capacities of Pt electrodes, strategies involve using composite materials like Pt–TiN, Pt–IrOx, Pt-PEDOT, and Pt–PEDOT, which offer improved capacities and a larger surface area for charge storage and enhanced conductivity. Approaches like creating porous metal structures, including nanoporous Pt and nanofibrous Pt (Pt-grass), as well as metal oxides/nitrides, significantly increase the electrochemically active surface area, boosting both CSC and CIC. Although metal-based electrodes have limitations in terms of flexibility and biocompatibility, the demand for materials that minimize tissue damage in neural electrodes is increasing. Carbon-based materials, including nanotubes, fibers, glassy carbons, and graphene, outperform metal-based electrodes in terms of biocompatibility, flexibility, and electrical impedance. However, non-structured graphene has low interfacial capacitance, which can hinder neural stimulation. Researchers are exploring nanostructured graphene-based electrodes that provide high specific surface area, conductivity, and low impedance. Laser-induced micro-scale porous graphene electrodes, derived from polyimide films, demonstrate improved charge capacities due to their enhanced electrochemically active surface area and interconnected porous structure. Current research focuses on advancing the specific surface area and porous structure of neural electrodes to achieve higher capacities, aiming to improve neural tissue stimulation in applications such as deep brain stimulation, spinal cord stimulation, and cochlear implants. We introduce high-performance 3D micro-/nano-scale porous graphene-based (3DPG) neural electrodes for efficient neural stimulation, manufactured using a scalable, rapid, and cost-effective direct laser scribing method from a fluorinated polyimide (fPI) precursor. The fPI allows for the creation of highly microporous graphene structures with micro-/nano-scale pores, which significantly enhances the specific surface area and thus increases charge storage at the electrode interface, improving CSC and overall electrode performance with reduced impedance. The structural properties of fPI-3DPG contribute to an eightfold increase in CSC and a doubling of CIC compared to PI-3DPG. With their increased specific surface area and unique electrical properties like high electron mobility, fPI-3DPG neural electrodes exhibit superior electrochemical performance with high CIC and low impedance. The microporous structures in fPI-3DPG provide more active sites on the electrode surface, facilitating charge transfer between the electrode and surrounding tissue, reducing the ion travel distance within the interconnected graphene pores and the tissue. These 3D highly microporous graphenes, with their enhanced charge transfer efficiency and substantial increase in CSC compared to PI-3DPG, hold great promise as a neural interface, enabling more effective and efficient stimulation of neural tissue.

Presenting Author: Byoung Gak Kim Korea Research Institute of Chemical Technology (KRICT)

Presenting Author Biography: Since joining Mason in 2017 as a principal investigator, Pilgyu Kang, PhD, has focused on overcoming core challenges in advanced materials and manufacturing technologies. An Assistant Professor in the Department of Mechanical Engineering at the Quantum Science and Engineering Center, Dr. Kang specializes in the synthesis, structural modification, and application of innovative nanomaterials, particularly laser-induced graphene (LIG). His research aims to improve synthesis techniques, structural configurations, and performance of graphene-based composites, thereby transforming their applications in advanced materials.

Dr. Kang explores the intricate relationships between processing, structure, properties, and performance, developing composites that integrate LIG with various materials to enhance functionalities across multiple applications, such as wearable technology, energy storage, and biomedical devices. Furthermore, his work extends to enhancing sensor technologies through the development of highly sensitive photodetectors and hydrogen sensors utilizing laser-induced graphene, contributing to advances in micro-supercapacitors and solar steam generation. These efforts have broad implications in enhancing high-performance applications, including membrane technology for nanofiltration, advanced neural electrodes, and energy storage technologies, thereby pushing the boundaries of technology and expanding the applications of advanced materials.

Dr. Kang's key interests include nanomaterials, atomically-thin 2D materials, micro/nano mechanics, micro/nano manufacturing, nano-photonics, opto-fluidics, optoelectronics, and plasmonics. He holds a PhD in Mechanical Engineering from Cornell University. His innovative work continues to drive significant advancements in the fields of materials science and engineering.

Authors:

Byoung Gak Kim Korea Research Institute of Chemical Technology (KRICT)
Pilgyu Kang George Mason University