Miniaturised, Flexible Deep Brain Probes

Microfabricated brain electrodes offer a distinctive method for directly interfacing with individual neurons in vivo. However, their long-term reliability is compromised by the formation of scarring tissue around them. A primary factor contributing to this issue is the mechanical disparity between the electrode and the surrounding biological tissue, prompting the exploration of more adaptable neuroelectronic interfaces. Advances in soft coatings that mirror the brain's elasticity, along with the introduction of compact, flexible designs, are paving the way for enhanced compatibility and durability of these implants. In our research, we fine-tuned a micrometric zwitterionic hydrogel coating for neural implants, leveraging its softness and minimal fouling characteristics while minimizing the implant size. This specialized coating was incorporated into microfabricated polyimide neural probes. These were chronically implanted into deeper brain regions prone to micromotion. Consistent weekly recordings from freely moving rats demonstrated an enduring capability to record for a minimum of 8 weeks, showcasing a high signal-to-noise ratio.