The "Cocombola Study": A Physical Phantom Model for tDCS-Induced Electric Field Distribution

Area of Science:

• Neuroscience
• Biophysics
• Medical Engineering

Background:

• Controlling electric fields (EFs) induced by transcranial direct current stimulation (tDCS) in brain tissues is challenging.
• Watermelons possess dielectric properties similar to human head tissues, making them suitable as physical models (phantoms) in neuroscience research.
• Existing methods for modeling tDCS-induced EFs are often complex and costly.

Purpose of the Study:

• To establish an affordable and dependable technique for qualitatively assessing the spatial distribution of tDCS-induced EFs.
• To explore the utility of watermelons as a practical phantom model for tDCS research.

Main Methods:

• Simulated cranial foramina and electrode positions on a watermelon peel.
• Recorded voltage differences at 21 electrode locations and four depths during tDCS simulation.
• Utilized polar coordinates to graphically represent electric field data, approximating the watermelon as a sphere.

Main Results:

• Validated the watermelon model through three experiments using established tDCS montages.
• Observed electric field behaviors consistent with theoretical predictions.
• Demonstrated the qualitative spatial distribution of tDCS-induced EFs within the watermelon phantom.

Conclusions:

• Watermelon serves as a cost-effective and accessible phantom head model for characterizing tDCS-induced electric fields.
• This method holds potential for studying other non-invasive brain stimulation techniques.
• Provides a simple, visualizable approach to understanding tDCS electric field spread.