ETH Zurich’s Flexible Brain Probes: A Safer Twist in the BCI Journey
Neuralink recently captured the public's attention with the implantation of its brain chip in a second patient, allowing the person to command digital devices with mere thoughts. This achievement represents a significant stride in the realm of brain-computer interfaces (BCIs), but it also underscores the deeply invasive nature of the technology—requiring the surgical insertion of rigid electrodes directly into brain tissue. Such interventions entail risks of tissue damage, infection, and the challenges of complex surgical procedures.
In the pursuit of safer, more adaptive solutions, researchers at ETH Zurich have introduced Ultra-Flexible Tentacle Electrodes (UFTEs), designed to dramatically minimize these inherent risks, offering a gentler and more responsive interface between mind and machine.
Ultra-Flexible Tentacle Electrodes: A Technical Overview
The UFTEs developed by ETH Zurich are designed to record brain activity with minimal tissue damage and high signal fidelity. These electrodes consist of ultra-thin fibers made from gold and polymers, with each fiber being just 7 µm wide and 2.4 µm thick. The UFTEs are mechanically coupled to a tungsten shuttle for precise insertion into the brain, and the use of a biodegradable silk coating temporarily holds the fibers together during the insertion process. This approach allows the UFTEs to be inserted into deep brain regions without causing detectable damage to surrounding tissues, even after several months of implantation.
"Drawn-to-scale comparison of the geometries of a rigid silicon probe, flexible planar shank probe, neural mesh, and UFTE (from left to right) with reference to the soma and dendrites of surrounding neurons. Zoomed insets (bottom) show the impact of different probe geometries on neuronal processes after insertion into the brain." (Yasar TB et al. Nature Communications 2024, modified)
One of the key advantages of UFTEs is their ability to achieve high signal-to-noise ratios (SNRs), with mean spike SNRs ranging from 1.5 to 3 times higher than current state-of-the-art flexible electrode arrays. Some electrodes within the UFTEs have recorded SNRs as high as 89, which is significantly higher than other available technologies. These electrodes are capable of tracking the same neurons across multiple sessions over extended periods, with the longest tested duration being 10 months. This stability is particularly advantageous for long-term studies of brain dynamics and could have implications for both research and clinical applications.
The UFTEs have been tested in animal models, where they were implanted in multiple brain areas, including the hippocampus, retrosplenial cortex, and medial prefrontal cortex. The electrodes successfully recorded neuronal activity from these regions, providing insights into the coordinated dynamics of brain networks involved in functions such as memory and decision-making. The ability to record from multiple brain areas simultaneously and maintain stable recordings over long periods makes UFTEs a valuable tool for studying complex brain functions and disorders.
Full paper in Nature Communications available here.
Expanding the BCI Landscape
Beyond Neuralink and ETH Zurich, the BCI landscape is rich with a variety of approaches and innovations. Companies like Blackrock Neurotech and Synchron are also developing invasive BCI technologies, each with distinct focuses and technical specifications. Blackrock Neurotech, for example, uses its Utah Array technology to achieve high-resolution neural recordings that have enabled applications such as restoring speech in ALS patients. Synchron, on the other hand, has integrated generative AI into its BCI system, allowing non-verbal individuals to generate text and audio outputs using thought alone.
Non-invasive BCI technologies are also making significant strides. Companies such as Kernel and Neurable are leveraging non-invasive methods like EEG and functional near-infrared spectroscopy (fNIRS) to capture neural signals without the need for surgical implantation. While these non-invasive systems typically offer lower signal resolution compared to invasive approaches, they provide safer, more accessible alternatives for applications ranging from neurorehabilitation to enhanced human-computer interactions in virtual reality environments.
The broader BCI sector continues to evolve rapidly, driven by advancements in materials science, signal processing, and artificial intelligence. The diversity of approaches within the field reflects a growing understanding that no single technology will meet all needs. Invasive BCIs, like those developed by Neuralink and ETH Zurich, offer high precision and are suitable for applications requiring fine control and detailed neural recording. Non-invasive BCIs, while less precise, are easier to deploy and pose fewer risks, making them suitable for a broader range of applications.
Future Directions and Challenges
As BCI technology progresses, researchers and companies face ongoing challenges related to the biocompatibility, stability, and long-term functionality of implants. ETH Zurich’s UFTEs demonstrate that it is possible to achieve stable, high-quality recordings with minimal tissue disruption. However, the field must continue to innovate in areas such as electrode design, signal processing algorithms, and data interpretation to fully realize the potential of BCI technology.
The BCI market is expected to reach $3.7 billion by 2027, driven by the need for better communication, rehabilitation, and augmented cognitive capabilities. From restoring lost functions in patients with neurological disorders to enabling new forms of human-computer interaction, BCIs hold the promise of fundamentally changing how we interact with technology and understand the human brain. As the field expands, it will be crucial to navigate the ethical and societal implications of these technologies, ensuring that they are developed and deployed in ways that maximize their benefits while minimizing potential risks.
See also: Beyond Neuralink: The Diverse Landscape of Brain-Computer Interfaces
Moreover, the broader BCI landscape includes innovative contributions from various players. For instance, Dr. Brian Jamieson, an ex-NASA scientist and founder of Diagnostic Biochips, discusses the evolving landscape of BCIs and the potential of hybrid systems that combine MEMS silicon electrodes with advanced CMOS electronics. These systems are aimed at enhancing brain interfacing for neurological studies and advancing drug discovery processes. Jamieson emphasizes that while Neuralink has brought significant attention to the field, it is critical to recognize the diverse and rapidly advancing technologies developed by other companies and research institutions, which continue to push the boundaries of what BCIs can achieve.
Topics: NeuroTech
