Rigid Probes to Adaptive Interfaces: Overcoming the Mechanical Mismatch in High-Density Neural Electrodes

Abstract Brain-computer interfaces (BCIs) are important for neural circuit analysis, neurological disease diagnosis and treatment, and functional restoration. Compared with non-invasive techniques, invasive intracranial electrodes provide a higher signal-to-noise ratio and spatial resolution by directly interfacing with brain tissue. This review summarizes the development and current progress of invasive neural recording electrodes and proposes a unified evaluation framework based on seven key metrics: channel count/density, spatial resolution, recording depth, signal-to-noise ratio, biocompatibility, adhesion, and long-term stability. According to their structural characteristics, planar electrodes, probe-type electrodes, and high-density electrode arrays are compared in terms of operating principles, fabrication methods, advantages, and limitations. Their applications in epilepsy evaluation, deep brain stimulation, and BCI-based neural prostheses are also reviewed. Finally, major challenges and future trends in electrode materials, device integration, and long-term neural interfacing are discussed, providing guidance for developing next-generation invasive neural interfaces with improved performance, safety, and reliability.