Flexible Neural Probe with an Optimized Electrode Density for Neural Network Investigations

Neural probes are essential tools for the study of neural networks and brain function. While silicon-based probes offer high-electrode density and precise recordings, their high fabrication cost and complex packaging requirements limit scalability and accessibility. Flexible neural probes utilizing flexible printed circuit board (FPCB) technology have emerged as a cost-effective alternative, but their low electrode density, attributed to process limitations, remains a challenge. Herein, we present a fabrication-optimized, flexible neural probe with enhanced electrode density. By optimizing line width and spacing, we considerably increased electrode density while maintaining compatibility with standard FPCB processes. A stiffener layer was incorporated to improve substrate planarity, and a 20% overetching technique was applied to enhance pattern fidelity and reliability. These optimizations tripled the recordable neural signals while maintaining high-signal quality, with a fabrication yield of 73% (200 samples). The fabricated probe demonstrated electrical and mechanical stability and successful in vivo neural recordings. This cost-effective, scalable probe improves accessibility for neuroscience research, particularly in resource-limited settings. This optimized neural probe will contribute to broader and more efficient neural network investigations.