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Physics of Transcranial Direct Current Stimulation Devices and Their History

Truong, Dennis Q., MS; Bikson, Marom, PhD

doi: 10.1097/YCT.0000000000000531
Special Issue on tDCS

Transcranial direct current stimulation (tDCS) devices apply direct current through electrodes on the scalp with the intention to modulate brain function for experimental or clinical purposes. All tDCS devices include a current controlled stimulator, electrodes that include a disposable electrolyte, and headgear to position the electrodes on the scalp. Transcranial direct current stimulation dose can be defined by the size and position of electrodes and the duration and intensity of current applied across electrodes. Electrode design and preparation are important for reproducibility and tolerability. High-definition tDCS uses smaller electrodes that can be arranged in arrays to optimize brain current flow. When intended to be used at home, tDCS devices require specific device design considerations. Computational models of current flow have been validated and support optimization and hypothesis testing. Consensus on the safety and tolerability of tDCS is protocol specific, but medical-grade tDCS devices minimize risk.

From the Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY.

Received for publication March 10, 2018; accepted June 15, 2018.

Reprints: Dennis Q. Truong, MS, Center for Discovery and Innovation, 85 Saint Nicholas Ter, CDI 3366, New York, NY 10031-1246 (e-mail:

The City University of New York has patents on brain stimulation with M.B. as inventor. M.B. has equity in Soterix Medical Inc and serves as a scientific advisor to Boston Scientific Inc. D.Q.T. has no conflicts of interest or financial disclosures to report.

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