Eligibility criteria

The inclusion criteria relate to the review's guiding questions and objectives. The following will be eligible: INCL1. Study types: Original articles (experimental, quasi-experimental, modelling, engineering, bench studies, clinical studies) and reviews that describe technical aspects of devices. INCL2. Object of analysis: Studies that describe transcranial direct current stimulation (tDCS) devices, with a focus on electrode montages. INCL3. Context: Publications in technical contexts (engineering, device development, modelling) and/or experimental clinical contexts (applications in human populations or animal models). The following will be excluded from the review: EXCL1. Study types: Opinion articles, editorials, commentaries, letters to the editor, conference abstracts without complete data. EXCL2. Device modalities: Devices for other neuromodulation modalities (e.g., TMS, tACS, tRNS, invasive stimulation) when they do not include specific tDCS data. EXCL3. Duplicity: Duplicate studies