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Updated: May 18, 2026
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Updated Technique for Reliable, Easy, and Tolerated Transcranial Electrical Stimulation Including Transcranial Direct Current Stimulation
Published on: January 3, 2020
Methods for extra-low voltage transcranial direct current stimulation: current and time dependent impedance decreases
Christoph Hahn1, Justin Rice, Shiraz Macuff
1Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY, United States.
Summary
This study explored lower voltages for transcranial direct current stimulation (tDCS), finding reduced voltage requirements due to impedance changes. This supports safer, more robust tDCS protocols.
Area of Science:
- Neuroscience
- Biomedical Engineering
Background:
- Transcranial direct current stimulation (tDCS) is generally well-tolerated.
- Optimizing tDCS device design and enhancing safety necessitates further voltage reduction.
Purpose of the Study:
- To determine the minimum voltage required for effective tDCS at 1.5mA and 2.5mA currents.
- To investigate the impact of impedance changes on voltage requirements during tDCS.
Main Methods:
- Collected impedance data across 18 tDCS sessions at 1.5mA and 2.5mA.
- Analyzed impedance data using t-tests and modeled it with a RLC circuit and double integrator.
- Investigated three different test current magnitudes.
Main Results:
- A significant impedance drop upon tDCS initiation reduces required voltage compliance (14.5V for 1.5mA, 18.5V for 2.5mA).
- A 4th order linear impedance model effectively approximated the collected data.
Conclusions:
- Reduced-voltage tDCS is feasible, enhancing safety and device design.
- A 'Limited Total Energy' approach is proposed, utilizing impedance decrease over time.
- These methods offer more protective and robust tDCS protocols.
