Soterix Medical HD-tDCS®

High Definition-transcranial Direct Current Stimulation

High-Definition transcranial Direct Current Stimulation (HD-tDCS) is a transformative technology for targeting cortical and deep brain structures with weak DC currents. Unlike any other neuromodulation technique, HD-tDCS is non-invasive, targeted, and can leverage the therapeutic potential, convenience, safety, and cost-advantages of tDCS. Soterix medical is the exclusive manufacturer and provider of HD-tDCS technology.

Targeted tDCS

High Definition transcranial Direct Current Stimulation (HD-tDCS) was developed by Soterix Medical in 2009. With integrated hardware (4x1, MxN), software (Neurotargeting) and accessories (HD electrodes, Neuronavigation), Soterix Medical HD-tDCS is the only validated technology for non-invasive targeted neuromodulation with weak direct currents. HD-tDCS redefined the possibilities with low-intensity non-invasive neuromodulation

Soterix Medical devices provide unique performance as these products, the methods of manufacturing are the subject to one or more U.S. or foreign patients or pending applications including but not limited to US9956395B2, US8818515B2, US8718778B2.

HD-tDCS® Overview

Soterix Medical High-Definition transcranial Direct Current Stimulation (HD-tDCS) is a non-invasive technique where brain regions are targeted using arrays of electrodes on the scalp. In contrast to conventional tDCS, which uses large sponge electrodes, HD-tDCS uses our exclusive Soterix Medical “High-Definition” small gel based electrodes. This proprietary technology is the only hardware that allows safe and tolerated passage of current through small electrodes on the scalp, as validated in clinical trials. HD-tDCS provides users with tremendous flexibility in determining brain targets through the use of Soterix Medical Neurotargeting Software. Fully integrated with every HD-tDCS hardware system, Neurotargeting makes optimized and individualized therapy as easy as a push of a button.

Soterix Medical HD-tDCS® Highlights

Discovery of 4x1 HD-tDCS montage. Datta et al. 2009

Caution! Investigational Device. Federal (or United States) law limits device to investigational use.


Exclusively from Soterix Medical, HD-tDCS is the only clinically validated system for non-invasive and targeted neuromodulation.

Do not be compromised by un-tested copycat devices. Soterix Medical's unmatched team of biomedical engineers and scientists is ready to support you to deploy the right HD-tDCS system for your application.

Four things about HD-tDCS

4×1 HD-tDCS

High-Definition transcranial Direct Current Stimulation (HD-tDCS) was invented at The City University of New York with the introduction of the 4x1 HD-tDCS montage (Datta 2009). The 4x1 HD-tDCS montage categorically transformed the possibilities with non-invasive neuromodulation by allowing precise targeting of cortical structures. How focal is 4x1 HD-tDCS? The region of current flow is circumscribed by the area of the 4x ring, such that decreasing ring radius increases focality. Soterix Medical Neurotargeting software makes HD montage design fast and easy, but the innovation did not stop there. Scientists went on to demonstrate that 4x1 HD-tDCS allows for unifocal stimulation, meaning the polarity of the center 1x electrode will determine the direction of neuromodulation under the ring (Villamar 2013). This is in contrast to conventional tDCS where the need for one anode and one cathode always produces bidirectional modulation (even when an extra-cephalic electrode is used). 4x1 HD-tDCS thus provides the ability not only to select a cortical brain region to target, but to modulate the excitability of that brain region with a designed polarity without having to consider return counter-electrode flow.

Peak Neuromodulation

A critical question given the targeting of 4x1 HD-tDCS is “when is focality desired?” There is no simple answer to this question, but is it important to recognize that most conventional tDCS approaches produce current flow through >50% of the brain, including deep brain structures and that with conventional tDCS inter-individual anatomical difference, which means the location of peak brain electric field will vary widely. Therefore, by guaranteeing peak brain electric field at the target and restricting brain current flow to a limited region, 4x1 HD-tDCS confers some theoretical clinical benefits. In ongoing clinical trials, 4x1 HD-tDCS has consistently produced effects size comparable or exceeding alternative neuromodulation protocols, including in control of experiment and clinical pain (Borckardt 2012, Villamar 2013). More striking, in a direct comparison with conventional tDCS, Nitsche and Paulus demonstrated that 4x1 HD-tDCS produces change in brain excitability that significantly exceeds both the magnitude and duration of conventional tDCS (Kuo 2013).

High-Definition Electrodes

There is only one electrode design that has been engineered for HD-tDCS, validated in extensive clinical testing, and used in clinical trials. The High Definition electrode was designed at The City University Of New York (Minhas 2010) and has been proven safe and well tolerated in multi-center clinical trials (Borckardt 2012, Villamar 2013, Kuo 2013). It is critical investigators do not attempt multi-electrode stimulation with non-validated “off-brand” devices under the assumption these approaches have any relevance to Soterix Medical HD-tDCS technology or clinically validated approaches. Use of off-brand electrodes and devices compromise research integrity, patient safety, and interferes with the rational development of HD-tDCS by the research community.

Arbitrary HD electrode placement. Number and precision.

In advanced neuromodulation design, software and hardware that allow arbitrary placement of HD electrodes on the head is required. Precision of montage matters critically, which is why stimulation software and supporting hardware must provide user with flexibility and precision in control. Don't be confused by copycat hardware and software that provides neither flexibility nor precision. State of the art neurotargeting software and hardware, with flexibility and precision, exclusively from the industry leader in non-invasive electrical stimulation, brought to you by Soterix Medical.

Device Features

Each Soterix Medical HD-tDCS feature was developed by our team of biomedical engineers consulting closely with leading clinical centers. Designed to simply set-up, provide intelligent warning of a fault condition, and allow for adjusting for patient comfort , these features facilitate reliable and tolerated HD-tDCS. The Soterix Medical SmartScan feature is central in all HD-tDCS and tDCS devices to allow reliable set-up and monitoring.

Provides a continuous visual indication of electrode quality before and during stimulation.

From pre-stimulation set-up, to during stimulation monitoring, to post-stimulation confirmation, the Soterix Medical SmartScan feature provides an intuitive and clear indication of electrode contact quality. Use the SmartScan during set-up to adjust electrodes and head-gear for optimal fit. During stimulation, SmartScan provides a constant indication of electrode quality and can be monitored during adjustments (e.g. addition of saline to drying electrodes). After stimulation, SmartScan confirms a successful trial. Because “resistance” is not meaningful for HD-tDCS, SmartScan was developed by Soterix Medical engineers to provide clinical investigators with a simple to read indication of contact quality.

Clearly indicates the actual current supplied at the moment.

What other devices promise, the Soterix Medical HD-tDCS delivers. The back-lit display can be monitored during stimulation ramp up and to confirm target current intensity is achieved.

Simple and intelligent sham waveforms.

An automatic stimulation sham feature that is engaged with a simple switch. Auto-sham automatically calculates and produces a sham waveform based on the indicated “real” waveform. For example, for a corresponding real waveform of 1.5 mA and 10 minutes, auto-sham will provide a ramp up/down to 1.5 mA at the start of stimulation, and again after 10 minutes, with the timer automatically adjusted such that the total run time is exactly matched to the real case. Based on the Soterix Medical OpenPanel™ design principle: with no complicated programming or hidden drop-down menus required.

Provides continues monitoring of conditions during HD-tDCS

An exclusive technology from the trusted leader in neuromodulation, Soterix Medical HD-monitor is an intelligent oversight system that provides continuous monitoring of current flow conditions and can engage automatic ramp-down should unusual performance be detected. HD-tDCS is the most advanced non-invasive neuromodulation system, providing tremendous flexibility to operators. HD-monitor provides a further level of automatic over-sight before, during, and after stimulation.

The only platform designed to allow channel upgrades.

No other multi-channel stimulation system is engineering to allow for scalability. The exclusive SCALABLE features integrated into every MxN device allow operators to feel comfortable knowing they can begin HD-tDCS with the most economical option without losing future scalability.

HD devices designed to integrate with Soterix Medical Neurotargeting Software.

Multichannel stimulation devices are only as customizable as the software used to design montages. With independent current control at each electrode with MxN devices, device power and flexibility requires intelligent montage design software. Neurotargeting software is the exclusive Soterix Medical solution to montage design and our HD-tDCS stimulator integrates seamlessly. Clinicians and scientists trust Soterix Medical engineers to provide the modeling and software sophistication to fully leverage HD-tDCS.

Optimized for the 4x1 HD-tDCS montage.

The 4x1 HD-tDCS montage remains the more popular and validated montage for unidirectional targeted brain neuromodulation. Devices optimized for 4x1 are designed to allow simple and consistent set-up including in high throughput clinical trials. Simple to use and designed by the inventors of 4x1 HD-tDCS, do not be confused by copycats and compromise the integrity of your trial and safety of your subjects. Soterix Medical Inc. (SMI) 4x1 certification is indicated on all validated 4x1 devices. *All MxN devices can provide 4x1 stimulation in addition to arbitrary configurations.

May be used to supply a very weak current prior to tDCS to help condition the skin.

Tickle may be used to condition skin prior to tDCS or for naïve subjects anxious about stimulation. A custom on-off waveform pattern generates mild and brief sensation under electrodes.

Allows the clinician to use a simple sliding bar to transiently decrease the current from the pre-set value, for example, based on subject feedback.

Based on feedback from leading clinical centers, Soterix Medical developed the exclusive feature Relax, which accommodates subjects who may be anxious when stimulation is initiated or during the course of stimulation. The Relax slider may be adjusted from full to reduced intensity based on subject perception without interrupting or aborting stimulation.

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Revolutionary Neurotargeting Software

Optimization of electrode montage for brain targeting and individual subject customization has never been as easy as with Soterix Medical's Neurotargeting software. With recognition that placing an electrode "over" a target dose not support rational tDCS does design, the Soterix Medical Suite of software tools allow simple and automatic optimization. Soterix Neurotargeting software also provides high-resolution current flow visualization that can be used to support publications, presentations and proposals.

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Advanced real-time control and optimization

Integration of stimulation with monitoring technologies

With increased interest in the use of monitoring, such as EEG, PET, MEG, Eye-tracking, NIR and fMRI in conjunction with Soterix tDCS and HD-tDCS, Soterix Medical remains the only company with the technology and expertise to ensure successful integration. Stimulation generates artifacts in all monitoring modalities including fMRI (Antal A et. al 2012), such that use of technically compatible devices without also integrating rational trial design can lead to errant findings.

Technology-informed integration of tDCS with monitoring technologies such as EEG, PET, MEG, NIR, fMRI, and eye tracking is essential. tDCS⁺ is a free service to every Soterix Medical tDCS and HD-tDCS user. Soterix Medical tDCS⁺ leverages the experience of our clinical partners and unmatched biomedical expertise and is open to cross-platform compatibility, so that you can use the monitoring technology you want and trust.

Soterix Medical biomedical engineers are available to discuss the combination of rational measurement with our industry standard Soterix tDCS and HD-tDCS, and only Soterix Neurotargeting allows co-registration of current flow and measured responses

4×1 HD-tDCS integrated with EEG.

Caution! Investigational Device. Federal (or United States) law limits device to investigational use.