Brain Implant: Sensors, Stimulation, and Drug Delivery Combined

Researchers from the Technical University of Denmark, the University of Copenhagen, University College London and partner institutions have developed a new type of brain implant that combines neural recording, light stimulation and targeted drug delivery in one ultra-thin implant. The technology is known as microfluidic Axialtrode (mAxialtrode).

The mAxialtrode is a flexible brain electrodeas thin as a needle, which is designed to distribute multiple functional interfaces along its length. This allows researchers to simultaneously record neural signals, stimulate brain tissue with light and administer medication at different depths in the brain. Although the technology is currently focused on basic neuroscience research, the developers see long-term potential for clinical applications, including the treatment of neurological disorders such as epilepsy.

More accurate brain research

According to postdoctoral researcher Kunyang Sui, who led the development together with Associate Professor Christos Markos, the key innovation lies in combining different capabilities in a single, soft implant. “Most current brain implants are made of hard materials such as silicon, which can irritate brain tissue and cause inflammation,” Sui said. “Our implant is made of soft, plastic-like optical fibers and has a special curved tip that reduces damage during implantation.”

Traditional optical fibers used in neuroscience typically only deliver light or record signals at their distal tip, limiting measurements and stimulation to a single layer of the brain. This is a major disadvantage, as many brain functions, such as those involved in epilepsy, memory or decision-making, depend on interactions between multiple layers and regions.

Microfluidics and optics in one fiber

The mAxialtrode overcomes this limitation through its structure. The device is made by heating a polymer rod and drawing it into a thin fiber and contains a central light-guiding core surrounded by eight microscopic channels. These channels can transport fluids for drug delivery and contain ultra-thin metal wires for electrical measurements.

The final fiber is less than half a millimeter thick and flexible enough to move with the brain, reducing long-term tissue stress. The technology is also becoming describedin the journal Advanced Science.

Validated in animal research

The technology has been tested both in the laboratory and in vivo in mice. In these experiments, the implant enabled simultaneous optical stimulation with blue and red light, electrical recording from superficial and deep brain areas such as the cortex and hippocampus, and targeted injection of substances at multiple depths up to three millimeters apart. All functions were performed using a single lightweight fiber, without apparent discomfort to the animals.

The in vivo validation was conducted in collaboration with experts in neural circuits and epilepsy models, including researchers from the University of Copenhagen and University College London.

Towards future clinical use

The research team is now working to patent the underlying technology and explore opportunities for clinical testing. While it still requires extensive development and regulatory approval, the mAxialtrode points to a future where brain implants are softer, more precise, and able to combine sensors and therapy in one minimally invasive device.

Last year, researchers at ETH Zurich developed a magnetically controlled microrobot that can administer medicines into the human body with extreme precision. Designed for minimally invasive therapies, the small robot can navigate blood vessels and deliver drugs precisely to the site of disease, such as a blood clot in the brain or a tumor. The microrobot is made of a soluble gel capsule containing iron oxide nanoparticles and can be controlled remotely using electromagnetic fields. Additional tantalum nanoparticles make it visible on X-ray images, allowing it to be tracked in real time.

Once the robot reaches its target, a high-frequency magnetic field heats the nanoparticles, causing the capsule to dissolve and the medication to be released locally. The research, published in Science, shows an important step towards precision medicine, potentially reducing the side effects of systemic drug delivery, especially in conditions such as stroke, where targeted treatment is critical.