Self-Abrading Servo Electrode Helmet for Electrical Impedance Tomography

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Neuroscience

Background:

• Electrical Impedance Tomography (EIT) shows promise for acute stroke diagnosis.
• Clinical translation is hindered by electrode misplacement and poor skin contact.
• Current methods are too slow for acute stroke settings.

Purpose of the Study:

• To develop a novel electrode helmet system for rapid and accurate electrode application in EIT.
• To overcome the limitations of scalp electrode mislocation and poor skin contact.
• To facilitate the clinical use of EIT for acute stroke management.

Main Methods:

• Designed a 32-channel self-abrading electrode helmet with individual impedance control.
• Implemented a feedback loop combining impedance, rotation, and position sensing.
• Utilized potentiometers for precise electrode tip displacement measurement (within 0.1 mm).
• Characterized performance on a large-scale test rig and a simplified self-contained unit.

Main Results:

• Achieved target 5 kΩ contact impedance at 20 Hz with ~20 kPa pressure and 5 rotations.
• Demonstrated successful replication in a servo-motor driven unit.
• Developed a 32-channel helmet and controller that minimized impedance and located electrodes in <5 minutes.

Conclusions:

• The novel electrode helmet system significantly reduces electrode application and localization time.
• This approach removes a key barrier to using EIT for rapid acute stroke imaging.
• Enables faster differentiation between ischemic and hemorrhagic stroke, potentially reducing time to treatment.