Researchers have engineered an octopus-like soft robot that can expand inside the skull, offering a potentially less invasive method for placing brain electrodes. This breakthrough could pave the way for improved brain-computer interfaces, better monitoring after traumatic brain injuries, and more effective treatment for conditions such as epilepsy.
A New Approach to Brain Electrode Deployment
Traditionally, doctors place electrocorticography grids on the brain by making large openings in the skull—sometimes as extensive as 100 square centimeters—to lay grids of electrodes directly on the brain’s surface. Although these grids provide higher-quality signals than external methods, the invasive nature of the procedure often leads to complications like inflammation and scarring.
The new technique employs a soft robotic device that fits through a minuscule opening in the skull. In tests conducted on a mini pig, the device was inserted through a tiny hole and then unfurled inside the skull. Using a watery solution, the robot’s six spiral arms gradually turned inside out over 30 to 40 seconds, expanding to form an electrocorticography grid approximately 4 centimeters in diameter. This unfolding mechanism allows the grid to navigate the narrow space between the skull and the brain with minimal disruption.
Engineering Details and Testing
The grid is created by depositing ultra-thin, flexible gold electrodes—less than 400 micrometers thick—onto a soft, medical-grade silicone substrate. The design, with its six spiral arms, maximizes the surface area available for brain contact, thereby increasing the number of electrodes that can record neural signals.
During experiments, the device’s integrated sensors monitored fluid pressure in real time, ensuring that the expanding arms did not exert excessive force on the brain tissue. When the researchers electrically stimulated the mini pig’s snout, the array successfully captured the corresponding brain activity. Future iterations of this technology may include capabilities for both detecting brain waves and stimulating the brain.
Advantages and Future Prospects
Earlier attempts involved rolling up the electrode arms, but this method caused the arms to thicken as they lengthened, complicating their deployment. The eversion technique used in the current design avoids this issue, potentially allowing for grids that could cover the entire brain surface.
A start-up spun off from the Federal Polytechnic School of Lausanne, Neurosoft Bioelectronics, is now working to transition this proof-of-concept into a clinical tool. With recent funding of 2.5 million Swiss francs from the Swiss innovation agency Innosuisse, the team is focused on adapting and scaling the technology to meet stringent medical standards.
While further work is needed before clinical application, this innovative soft robot represents a promising advance in the field of brain-computer interfaces and minimally invasive neurosurgery.
