Dry tDCS: Tolerability of a novel multilayer hydrogel composite non-adhesive electrode for transcranial direct current stimulation

Khadka, Niranjan; Borges, Helen; Zannou, Adantchede L.; Jang, Jongmin; Kim, Byunggik; Lee, Ki-Won; Bikson, Marom

doi:10.1016/j.brs.2018.07.049

Cited by 16 publications

(20 citation statements)

References 31 publications

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“…c Plate electrode was placed in the left external acoustic meatus on the inner side of the tragus; the cylindrical electrode was placed on the left lower limb (left middle shank). (Merrill et al, 2005) and tolerability (Minhas et al, 2010;Khadka et al, 2018).…”

Section: Proposed Checklist For Minimum Reporting Itemsmentioning

confidence: 99%

“…Specifically, if electrochemical products at the electrode-electrolyte interface reach the skin, skin irritation may ensue. Protocols to limit this include using charge-balanced waveforms (Sooksood et al, 2009(Sooksood et al, , 2010, judicious selection of metal and electrolyte materials (Merrill et al, 2005;Khadka et al, 2018), minimizing total stimulation time at a given location, or ensuring the electrolyte provides sufficient separation between the metal and skin (Minhas et al, 2010).…”

Section: Current-controlled Vs Voltage-controlled Stimulationmentioning

confidence: 99%

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International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Farmer

Strzelczyk

Finisguerra

et al. 2021

Front. Hum. Neurosci.

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179

182

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Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice.

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Section: Proposed Checklist For Minimum Reporting Itemsmentioning

confidence: 99%

Section: Current-controlled Vs Voltage-controlled Stimulationmentioning

confidence: 99%

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Farmer

Strzelczyk

Finisguerra

et al. 2021

Front. Hum. Neurosci.

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179

182

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“…Evidence from animal studies suggest that 4 mA does not approach injurious limits [16,17]. The past decade has introduced advancements in tDCS electrode [18,19] and stimulator technology [20,21] that may increase tolerability at higher currents. Despite extensive evidence that 1e2 mA tDCS relevant electric field modulate neuronal function [22e25], benefits of moderately increasing current intensity have been debated [26].…”

Section: Introductionmentioning

confidence: 99%

Adaptive current tDCS up to 4 mA

et al. 2020

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Background: Higher tDCS current may putatively enhance efficacy, with tolerability the perceived limiting factor. Objective: We designed and validated electrodes and an adaptive controller to provide tDCS up to 4 mA, while managing tolerability. The adaptive 4 mA controller included incremental ramp up, impedancebased current limits, and a Relax-mode where current is transiently decreased. Relax-mode was automatically activated by self-report VAS-pain score >5 and in some conditions by a Relax-button available to participants. Methods: In a parallel-group participant-blind design with 50 healthy subjects, we used specialized electrodes to administer 3 daily session of tDCS for 11 min, with a lexical decision task as a distractor, in 5 study conditions: adaptive 4 mA, adaptive 4 mA with Relax-button, adaptive 4 mA with historical-Relaxbutton, 2 mA, and sham. A tablet-based stimulator with a participant interface regularly queried VAS pain score and also limited current based on impedance and tolerability. An Abort-button provided in all conditions stopped stimulation. In the adaptive 4 mA with Relax-button and adaptive 4 mA with historical-Relax-button conditions, participants could trigger a Relax-mode ad libitum, in the latter case with incrementally longer current reductions. Primary outcome was the average current delivered during each session, VAS pain score, and adverse event questionnaires. Current delivered was analyzed either excluding or including dropouts who activated Abort (scored as 0 current). Results: There were two dropouts each in the adaptive 4 mA and sham conditions. Resistance based current attenuation was rarely activated, with few automatic VAS pain score triggered relax-modes. In conditions with Relax-button option, there were significant activations often irrespective of VAS pain score. Including dropouts, current across conditions were significantly different from each other with maximum current delivered during adaptive 4 mA with Relax-button. Excluding dropouts, maximum current was delivered with adaptive 4 mA. VAS pain score and adverse events for the sham was only significantly lower than the adaptive 4 mA with Relax-button and adaptive 4 mA with historical-Relaxbutton. There was no difference in VAS pain score or adverse events between 2 mA and adaptive 4 mA. Conclusions: Provided specific electrodes and controllers, adaptive 4 mA tDCS is tolerated and effectively blinded, with acceptability likely higher in a clinical population and absence of regular querying. Indeed, presenting participants with overt controls increases rumination on sensation.

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“…[247] To address this issue, Khadka and colleagues developed the first "dry" tDCS electrodes comprising a flexible, printed circuit board sensor based on PVA polymers to monitor current distribution during electric stimulation. [248] Weak current electric stimulation on human subjects revealed a lack of significant adverse effects with hydrogel electrodes, while the conventional sponge electrode had a higher incidence of adverse events.…”

Section: State Of the Fieldmentioning

confidence: 99%

Electroresponsive Hydrogels for Therapeutic Applications in the Brain

Khan

Wilts

Vlaisavljevich

et al. 2021

Macromolecular Bioscience

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Electroresponsive hydrogels possess a conducting material component and respond to electric stimulation through reversible absorption and expulsion of water. The high level of hydration, soft elastomeric compliance, biocompatibility, and enhanced electrochemical properties render these hydrogels suitable for implantation in the brain to enhance the transmission of neural electric signals and ion transport. This review provides an overview of critical electroresponsive hydrogel properties for augmenting electric stimulation in the brain. A background on electric stimulation in the brain through electroresponsive hydrogels is provided. Common conducting materials and general techniques to integrate them into hydrogels are briefly discussed. This review focuses on and summarizes advances in electric stimulation of electroconductive hydrogels for therapeutic applications in the brain, such as for controlling delivery of drugs, directing neural stem cell differentiation and neurogenesis, improving neural biosensor capabilities, and enhancing neural electrode-tissue interfaces. The key challenges in each of these applications are discussed and recommendations for future research are also provided.

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Dry tDCS: Tolerability of a novel multilayer hydrogel composite non-adhesive electrode for transcranial direct current stimulation

Cited by 16 publications

References 31 publications

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Adaptive current tDCS up to 4 mA

Electroresponsive Hydrogels for Therapeutic Applications in the Brain

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Dry tDCS: Tolerability of a novel multilayer hydrogel composite non-adhesive electrode for transcranial direct current stimulation

Cited by 16 publications

References 31 publications

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Adaptive current tDCS up to 4 mA

Electroresponsive Hydrogels for Therapeutic Applications in the Brain

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Product

Resources

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Adaptive current tDCS up to 4 mA