A patient-specific, 3D printed neurostimulator enabling focal transcranial electrical stimulation and EEG at home.

BACKGROUND: The therapeutic potential of non-invasive transcranial electric stimulation (tES) is growing, but challenges in tailoring treatments to individual patients persist. We demonstrated that personalized montages, informed by biophysical modeling, can reduce dose variability and improve target engagement. However, traditional setups are prone to electrode placement errors, leading to inconsistent dosage, localization and potential off-target engagement. METHODS: We developed a pipeline for creating patient-specific 3D-printed caps based on individual MRI scans to allow custom placement of up to 34 electrodes. Hybrid brush electrodes were incorporated to facilitate the use on with-hair regions of the head. The patient-specific caps are integrated within a Neurostimulator/EEG device, enabling precise electrode placement for recording of neural activity and optimized, personalised tES therapies based on individual biophysical brain models. RESULTS: A proof-of-concept in-silico study highlighted the importance of positional accuracy in electrode placement, particularly in minimizing off-target stimulation in case of the personalized montage configuration. To mitigate positional displacement, we introduced the pipeline for generating patient-specific 3D-printed caps, ensuring precise anatomical fit. The flexible design of these caps supports high-density electrode arrays tailored to various therapeutic montages. Integrated brush electrodes function in both dry and wet modes and are powered by electronics embedded in a neckpiece, enabling multi-step tES and EEG recording with minimal setup for at-home use. Electrical and mechanical evaluations confirmed the system's feasibility, and a clinical trial with eight healthy subjects showed improved comfort and increased willingness for home use. CONCLUSION: This customized cap-electrode system provides a practical solution for self-administered, repeatable personalized tES and EEG session at home. TRIAL REGISTRATION: The study is registered on the Swiss National Clinical Trials Portal (SNCTP), (SNCTP000005598) and Clinicaltrials.gov (NCT05999916). The study was approved by the Independent Competent Ethics Committee (Ethikkommission Nordwest-und Zentralschweiz (EKNZ)) at the 14 August 2023 and the Competent Regulatory Authority Swissmedic at the 20 December 2023.