In a groundbreaking advance poised to revolutionize neural interfaces, researchers at Seoul National University of Science and Technology (SeoulTech) and the Korea Institute of Science and Technology (KIST) have developed ultra-flexible, high-performance microelectrode arrays incorporating carbon nanotubes (CNTs) embedded within a polymer matrix. These innovative devices promise to overcome long-standing challenges in brain–computer interface (BCI) technology, combining exceptional electrical conductivity with unprecedented mechanical softness, enabling stable, high-resolution neural recording while minimizing tissue damage and immune responses.
Brain–computer interfaces depend critically on microelectrodes implanted within neural tissue to detect or stimulate electrical activity with high fidelity. Conventionally, metal and silicon-based microelectrodes have been widely used due to their robust electrical properties. However, their intrinsic rigidity leads to persistent mechanical mismatch with the brain’s delicate soft tissue, provoking chronic inflammation, gliosis, and neuronal loss, all of which undermine device longevity and signal quality. On the other hand, polymer-based electrodes offer improved biocompatibility and mechanical compliance but fall short in conductivity and signal stability, limiting their practical utility in long-term implants.
The research team, led by Associate Professor Jong G. Ok and Dr. Maesoon Im, tackled this dichotomy by engineering three-dimensional CNT “forests” precisely grown and vertically aligned, then embedded seamlessly within an elastic polymer substrate. This CNT-polymer hybrid achieves a remarkable synergy: the CNT structures confer highly efficient electrical conduction that rivals metals, while the polymer matrix imparts extreme mechanical flexibility, with a softness approximately 4,000 times greater than silicon and 100 times that of polyimide. This combination drastically reduces mechanical mismatch with brain tissue, fostering a more harmonious and less inflammatory interface.
Fabrication of the microelectrode arrays employed a meticulously refined multi-step process. Firstly, CNTs are vertically grown through chemical vapor deposition techniques to form dense, forest-like architectures with nanoscale precision. Subsequently, a proprietary polymerization and hybridization technique embeds these CNT forests within a flexible polymer, ensuring robust adhesion and structural integrity without compromising electrical pathways. This multi-material strategy preserves the electrical advantage of CNTs while addressing mechanical compliance, a feat rarely achieved in neural interface engineering.
The arrays demonstrated remarkable stability and functionality upon implantation in mouse models. They enabled precise recording of visual-evoked neural signals from the visual cortex, confirming their efficacy in capturing dynamic brain activity. Notably, the arrays exhibited significantly reduced inflammatory responses compared to traditional tungsten microwires, as evidenced by diminished activation of astrocytes and microglial cells responsible for immune reactions. This reduction points to a more biocompatible long-term implant capable of enduring weeks or potentially months without eliciting adverse tissue remodeling.
The implications of this technology extend far beyond fundamental neuroscience research. Visual prosthetic applications stand to benefit enormously, particularly for patients suffering from retinal degeneration or optic nerve damage who currently have limited therapeutic options. The capability to record stable neural signals from brain regions processing vision underpins potential brain-machine interfaces that could restore or augment visual perception by bypassing damaged ocular pathways.
Moreover, the intrinsic flexibility and biointegration of these arrays make them promising candidates for incorporation into increasingly sophisticated neuroprosthetic devices. By scaling down the arrays to subcellular dimensions, the researchers envision achieving neural signal recording at unprecedented spatial resolution, enabling richer decoding of brain states. This could catalyze new frontiers in brain-assisted communication technologies, such as systems that read and interpret visual attention in real time, creating immersive augmented or virtual reality experiences controlled directly by brain activity.
Dr. Jong G. Ok emphasizes the dual functionality of the CNT-polymer hybrid: “By combining vertically aligned carbon nanotubes with a flexible polymer, we have realized a neural interface device that maintains both high electrical performance and mechanical compliance. This dual capability enables long-term, stable neural recordings without damaging surrounding brain tissues.” This balance addresses the two most critical and often conflicting design requirements for implanted neural electrodes.
In the in-vivo experiments, light stimuli triggered measurable responses in visual cortex neurons recorded through the CNT-based arrays, confirming that the device can faithfully capture physiologically relevant sensory information. Furthermore, the one-month implantation study highlighted the device’s minimal immune activation compared to more conventional electrodes, suggesting a reduced risk of gliotic encapsulation and signal degradation over time.
These findings open new avenues not only for therapeutic interventions but also for basic neuroscience, providing researchers novel tools to study neural processing with greater resolution and less interference. The envisioned subcellular-scale electrodes could help unravel complexities of neural circuits by reading out signals from individual neurons or even synaptic connections, advancing understanding of brain function and dysfunction.
Looking forward, the research team seeks to refine fabrication methods to produce even smaller and denser electrode arrays capable of chronic implantation. Such progress may fulfill long-held aspirations for seamless brain-computer interfaces with high data throughput, opening possibilities for restoring sensory modalities, enhancing cognitive functions, and developing neuroprostheses that respond naturally to brain intentions.
In summary, this CNT-polymer hybrid microelectrode technology marks a significant milestone in neural engineering. By resolving the long-standing trade-off between electrical performance and mechanical compatibility, it lays a foundation for safer, more effective, and longer-lasting brain implants. Its potential to transform visual prosthetics and other neurotechnologies heralds a promising chapter in the quest to harness brain signals for therapeutic and augmentative applications, blending nanomaterials science, biomedical engineering, and neuroscience into a single visionary platform.
Subject of Research: Animals
Article Title: Polymer-Incorporated Mechanically Compliant Carbon Nanotube Microelectrode Arrays for Multichannel Neural Signal Recording
News Publication Date: 27-Jun-2025
Web References:
https://doi.org/10.1002/adfm.202509630
https://en.seoultech.ac.kr/
References:
DOI: 10.1002/adfm.202509630
Image Credits:
Seoul National University of Science and Technology
Keywords:
Health and medicine, Neuroscience, Nanotechnology, Biomedical engineering, Carbon nanotubes, Medical technology, Prosthetics, Vision disorders, Bionics, Nanomaterials
