Phantom head for electrophysiology

"Electroencephalography (EEG) system validation faces a fundamental challenge: the absence of ground truth when measuring human subjects. Physical head phantoms provide controlled testing environments with known signals; however, existing commercial solutions are typically reported in the $400–640 range per unit and are often proprietary, limiting accessibility in research and educational contexts. This work presents a practical and accessible tool for systematic EEG hardware validation, algorithm development, and research, with all design files, software, and numerical models documented for community adoption. A bilayer phantom head is defined through a parametric CAD model, comprising an anthropomorphic shell fabricated from 3D-printed conductive PLA and an internal network of wire guides to ensure reproducible and controlled signal injection. The gelatine-based electrolyte filling medium, selected for availability and cost-effectiveness, was experimentally characterized. Tunable electrical properties are achieved through adjustable ionic concentration, demonstrating reproducible impedance behavior with inter-batch variability below 8% and confirming suitability for controlled EEG signal transmission. Material costs for a complete phantom realization are approximately $160, substantially below commercial alternatives. The electrical behavior of the phantom head was characterized through finite element modeling and conditioned to obtain a bidirectional transfer model between eight internal actuation points and surface measurement locations corresponding to the international 10–20 system. This characterization enables prediction of surface potentials for given excitation patterns, as well as conditioned inverse computation of the required inputs to achieve desired measurement profiles. Benchmark validation confirmed numerical accuracy suitable for experimental planning and calibration workflows. The desktop application provides a user-friendly interface for deterministic multi-channel signal synthesis across physiologically relevant EEG frequency bands, real-time waveform visualization, and integration with OpenBCI acquisition hardware. The software supports both native signal generation and EDF file import, offers dual operational modes for generation and measurement, and enables session recording with export to standard formats. In combination, the proposed phantom head, numerical transfer characterization, and software interface provide a controlled and reproducible environment for systematic EEG system evaluation".