Design of conformal planar penetrating multi-electrode arrays for recording multiple brain regions

Simultaneous recording of neural activity across multiple interacting brain regions is a central objective in systems neuroscience and neural engineering. Penetrating multi-electrode arrays (MEAs) are essential for this purpose, yet their performance is fundamentally constrained by the complex three-dimensional anatomy of the brain and by substantial variability across species and brain regions. As a result, fixed or generic MEA designs, with periodic electrode distribution, often provide limited spatial coverage and suboptimal recording efficiency. In this work, we present a systematic design framework for conformal planar penetrating MEAs that explicitly links neuroanatomical constraints to key engineering decisions, including probe geometry, shank arrangement, electrode distribution, and implantation strategy. The framework integrates anatomical analysis, surgical considerations, device prototyping, electrophysiological validation, and histological verification within an iterative workflow, enabling progressive refinement from initial concept to final design. We illustrate this approach through representative case studies with an initial emphasis on hippocampal arrays, where highly curved and layered cytoarchitecture presents stringent design challenges, and subsequent extensions to other brain regions and animal models. These examples demonstrate how anatomy-aware, conformal designs can improve access to targeted neural structures and enable multi-region recordings. Overall, this work provides a practical, generalizable methodology for designing conformal planar penetrating MEAs. The proposed framework complements existing high-density and/or flexible probes, offering a unifying perspective for developing anatomically tailored neural recording technologies for basic neuroscience research and future translational applications.