Brain Implant Records Neural Signals and Delivers Precise Medication

Most existing brain electrodes are made from rigid materials that may irritate tissue and trigger inflammatory responses over time. Conventional optical fibers also limit stimulation and measurement to their distal tip, restricting access to deeper and interconnected brain regions. Now, a newly developed needle-thin brain implant integrates multiple functions along its length, enabling neural signal recording and precisely targeted drug delivery across different brain areas with reduced tissue damage.

The implant, known as the microfluidic Axialtrode (mAxialtrode), was constructed by researchers from the Technical University of Denmark (DTU, Lyngby, Denmark), along with collaborators, using soft, plastic-like optical fibers and is designed to move with brain tissue rather than cut through it. The fiber is manufactured by heating and drawing a polymer rod into a thin strand, like producing fine sugar threads, but with high precision. It contains a central light-conducting core surrounded by eight microscopic channels that transport fluids and house ultra-thin metal wires for electrical recordings.

The angled tip design minimizes insertion damage while allowing distributed functional interfaces along the implant’s length. The researchers validated the technology both in laboratory settings and in vivo in mice. The implant was connected to light sources, electrical recording systems, and micro-pumps for fluid delivery. Experiments demonstrated that the device could stimulate neurons with blue and red light, record electrical activity from superficial and deeper layers such as the cerebral cortex and hippocampus, and inject substances at depths separated by up to three millimeters.

All functions were achieved using a single lightweight fiber without visible discomfort to the animals. The findings, published in Advanced Science, show that the mAxialtrode can integrate stimulation, recording, and targeted delivery within one minimally invasive platform. The technology was initially designed for fundamental brain research, enabling scientists to better study signal transmission across layers involved in epilepsy, memory, and decision-making.

By overcoming the limitations of single-point stimulation, it offers a more comprehensive understanding of neural circuit dynamics. In the long term, the implant could support clinical applications such as targeted drug delivery combined with electrical or light-based stimulation for neurological disorders. Researchers are currently pursuing patent protection and exploring pathways for further development, safety validation, and potential clinical testing.

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