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.

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.

Validated Technology

Physicians at Harvard Medical School demonstrate the application of HD-tDCS using a Soterix 4x1 tDCS device.

Soterix Medical HD-tDCS Highlights

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

  • The only hardware validated for safe and tolerated stimulation in multi-center clinical trials.
    Other technologies and devices marketed for “small electrode transcranial stimulation” are not endorsed by Soterix Medical and are counter-indicated for use with any Soterix Medical stimulator or software, including 4x1 HD-tDCS. Soterix Medical is committed to the advancement of rational non-invasive neuromodulation through application of the highest scientific and medical standards.
  • Exclusive Neurotargeting Software for dose optimization.
    Given the flexibility of HD-tDCS, with independently controlled electrodes deployed anywhere on the head, software that allows simple and optimized set-up is critical. Soterix Medical developed Neurotargeting Software exactly for this purpose including a range of exclusive features all designed to make dose optimization for your clinical trial simple and convenient.
  • Conduct clinical studies with state-of-the-art control and safety features.
    Soterix Medical developed HD-tDCS and clinicians trust our team of scientists and biomedical engineers to ensure every HD-tDCS devices if designed and manufactured based on the most state-of-the-art evidence and techniques. Soterix Medical is the industry standard for non-invasive brain stimulation and nowhere is this more important than in HD-tDCS.
  • Provide for simple and comfortable set-up and stimulation.
    Usability and simplicity underpin every Soterix Medical device and HD-tDCS is no exception. We recognize that state-of-the-art neuromodulation tools are only as effective as they can be understood and controlled by operators. Our human factors engineers review every aspect of HD-tDCS stimulator and accessories to ensure that advanced neuromodulation does not come at the cost of complexity in use. Our unparalleled customer support ensures you have all the guidance and support, when you need it.

Additional Resources

  • Gyri –precise head model of transcranial DC stimulation: Improved spatial focality using a ring electrode versus conventional rectangular pad. Brain Stimulation. 2009; 2(4):201-207.
    Datta A, Bansal V, Diaz J, Patel J, Reato D, Bikson M.
  • Focal modulation of primary motor cortex in Fibromyalgia using 4x1-Ring High-Definition Transcranial Direct Current Stimulation (HD-tDCS): Immediate and delayed analgesic effects of cathodal and anodal stimulation. J Pain 2013; 14(4): 371-83.
    Villamar MF, Wivatvongvana P, Patumanond J, Bikson M, Truong DQ, Datta A, Fregi F.
  • A Pilot Study of the Tolerability and Effects of High-Definition Transcranial Direct Current Stimulation (HD-tDCS) on Pain Perception. Journal of Pain . 2012; 13(2): 112-120.
    Borckardt JJ, Bikson M, Frohman H, Reeves ST, Datta A, Bansal V, Madan A, Barth K, George MS.
  • Comparing cortical plasticity induced by conventional and high-definition 4x1 ring tDCS: a neurophysiological study Brain Stimulation 2013; 6(4):644-8.
    Kuo HI, Datta A, Bikson M, Minhas P. Paulus W, Kuo MF, Nitsche MA.
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 but 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 increased 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 allow 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.

Caution! Investigational Device. Federal (or United States) law limits device to investigational use. The information provided on High-Definition tDCS function is for information purpose only. The safety and efficacy of HD-tDCS has not been evaluated by the FDA outside of clinical trials.

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 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 clinical 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.

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 approach produce current flow through >50% of the brain including deep brain structures and that with conventional tDCS inter-individual anatomical difference means the location of peak brain electric field will vary widely. Therefore, by guaranteed 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 produce change in brain excitability that significantly exceed both the magnitude and duration of conventional tDCS (Kuo 2013).

Arbitrary HD electrode placement. Number and precision.

In advanced neuromodulation design, software and hardware that allows 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, Soterix Medical.

  • Scalable Channels
    Flexibility of choosing 4 or 8 channels, based on your application.
  • True Control
    Complete control over current with indication of actual current supplied at the moment.
  • HD Software Compatible
    Compatible with our revolutionary neurotargeting software: HD-Targets and HD-Explore.
  • SMARTscan
    Continuous visual indication of electrode quality before and during stimulation.
  • Duration up to 40 min
    Stimulation duration can be adjusted on each session using a simple dial.
  • Intensity up to 2 mA
    Easy adjustment of stimulation intensity.
  • Pioneering Technology. Designed for the most advanced neuromodulation.
  • Explore M×N HD-tDCS »
  • 4×1 HD Montage
    The most common HD-tDCS deployment. With option to select a center anode or cathode.
  • HD Software Compatible
    Compatible with our revolutionary neurotargeting software: HD-Targets and HD-Explore.
  • SMARTscan
    Continuous visual indication of electrode quality before and during stimulation.
  • Integrate with any 1×1 device
    Continuous visual indication of electrode quality before and during stimulation.
  • Duration as set on 1×1
    Stimulation duration can be adjusted on each session using a simple dial.
  • Intensity as set on 1×1
    Easy adjustment of stimulation intensity.
  • Tickle
    May be used to supply a very weak current prior to tsDCS to help condition the skin.
  • Explore 4×1 HD-tDCS »
  • 4×1 HD Montage
    The most common HD-tDCS deployment. With option to select a center anode or cathode.
  • HD Software Compatible
    Compatible with our revolutionary neurotargeting software: HD-Targets and HD-Explore.
  • SMARTscan
    Continuous visual indication of electrode quality before and during stimulation.
  • Tickle
    May be used to supply a very weak current prior to tsDCS to help condition the skin.
  • Relax
    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.
  • Duration up to 40 min
    Stimulation duration can be adjusted on each session using a simple dial.
  • Intensity up to 2 mA
    Easy adjustment of stimulation intensity.
  • -- NEW --

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 calculated and produces a sham waveform based on the 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 of stimulation, and again after 10 minutes, with the timer automatically adjusted such that the total run time us 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 continues 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 systems is engineering to allow for scalability. The exclusive SCALABLE features integrated into every MxN device allows 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 integrate 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 both condition skin prior to tDCS or for naïve subject 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 exclusive feature Relax™ 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.

Request Product Information Manual & Specifications

Four design principles of OpenPanel™ Device Interfaces

To understand the Soterix Medical's OpenPanel interface, one needs to consider how HD-tDCS are applied in the best clinical and academic centers. The risk of relying on a wireless connection with a computer to control and monitor the device is not acceptable. Similarly, complex and hidden drop-down menus create inherent risk in programming mistakes. A single mistake can compromise subject safety and the integrity of an entire clinical trial. For medical grade equipment, device status and subject monitors should be clearly visible on the device display. Soterix Medical devices, including features such as OpenPanel, are chosen when patient tolerability and trial integrity cannot be compromised.

OpenPanel™ Reproducibility Advantage

No drop down menus.
No hidden setting.

Avoid confusion and mistakes. Save time. HD-tDCS devices can be programmed in seconds with simple switches and controls.

No external computer.
All devices stand alone.

With stand-alone HD-tDCS stimulators, there is never a need to use a personal computer for interface. This reduces your cost, complexity and potential errors.

Elevated panels.
Backlit displays.

Easy to read displays, even at a distance and even in reduced light conditions, means you always can monitor stimulation status.

Optimized devices.
Customized interfaces.

In advanced neuromodulation, one size does not fit all. Display and control items are minimized to what you need. Clarity and simplicity without compromise.

OpenPanel™ Safety Advantage

A single programming error undermines reproducibility and safety of an entire trial. OpenPanel reduces errors even under multiple-user or high-throughout conditions.

No risk of computer or connection failure leading to loss of device control. Risks associated with computer failure (e.g. during a software update) are avoided.

Device settings and current state are always visible to their operator. Intelligent SmartScan testing provides early warning of poor contact conditions.

Devices prevent current transients even under unexpected conditions such as sudden re/dis-connection. Soterix Medical is the trusted leader in HD-tDCS by designing safety factors for the unexpected.

Simple to use

Open-Panel™ controls

In developing the HD-tDCS™, feedback from leading clinical centers was clear: HD-tDCS must be simple to program and stimulation status must always be apparent to the investigator. With easy-click control knobs to set stimulation duration and intensity, and backlit status displays visible in dim or bright room light, the Soterix Medical Open-Panel™ design takes the guess work out of tDCS. No drop-down menus. No hidden settings. Design for simple and clear clinical trials with Soterix Medical Open-Panel™.

No drop-down menus. No hidden settings. No external computer.

Design for simple and clear clinical trials with Soterix Medical Open-Panel™.

Revolutionary Neurotargeting Software

Optimization of electrode montage for brain targeting and individual subject customization has never been as easier 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, presentation and proposals.

Explore Software Solutions »

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 our unmatched biomedical expertise. And tDCS⁺ 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.

Clinical Trials

tDCS for the Treatment of Bipolar Depression

Soterix Medical 1x1 Clinical Trials device with Limited Total Energy (LTE) to be used in a trial to study the antidepressant effects of tDCS in bipolar disorder.

tDCS and Talking Therapy for Aphasia

Hunter College of The City University of New York will investigate the use of Soterix Medical 1x1 tDCS (transcranial direct current stimulation) in conjunction with speech-language therapy, for the improvement of language production in stroke survivors with aphasia.

Phase III Clinical Trial for major depressive disorder

Trial will compare Soterix Medical tDCS-LTE™ technology against a fully dosed, effective antidepressant Escitalopram oxalate (Lexapro). Recruitment ongoing.
Soterix Medical 1×1 Clinical Trials (CT) device using Limited Total Energy (LTE™) technology is being used in the study.

Effects of tDCS on Motor Learning in Children With Cerebral Palsy (CP)

Trial will assess the clinical and neurophysiological effects of a non-invasive brain stimulation technique - transcranial direct current stimulation (tDCS)- on cortical plasticity and motor learning in children with cerebral palsy.

Cognitive Stimulation Study (CogStim)

This study will evaluate the influence of non-invasive brain stimulation on different elements of cognitive function in healthy persons between the ages of 18-90 years. Soterix Medical 1×1 tDCS device is being used in this study.

Neuropathic Symptoms Following Burn Injury Trial

Spaulding Rehabilitation Hospital and the US Department of Education will investigate the effects of Soterix Medical 1x1 transcranial direct current stimulation (tDCS) on the pain and itching associated with burn injury. This study is part of the Boston-Harvard Burn Model System.

Phase II Fibromyalgia Trial

Follow up Phase II, HD-tDCS clinical trial underway for fibromyalgia at Harvard Medical School and Spaulding Rehabilitation Hospital, and in conjunction with Elminda Corporation. Exclusive Soterix 4x1 HD-tDCS being used.

Abdominal pain in patients with chronic pancreatitis Clinical Trial

This study is testing whether the addition Soterix Medical 1x1 transcranial direct current stimulation (tDCS) when combined with meditation helps decrease the abdominal pain in patients with chronic pancreatitis.

Corneal Pain Clinical Trial

Study focused on investigating effect of tDCS on chronic corneal pain as well as changes in thought processing as compared to healthy controls. Soterix 1×1 Device is being used.

Stroke Recovery Clinical Trial

Study focused on evaluating the effect of a combination of robotic arm therapy and transcranial Direct Current Stimulation for greater functional recovery after stroke.

Depression Clinical Trial

For the most comprehensive tDCS trial to-date, researchers selected the most advanced tDCS device and the only system optimized for clinical trials – The Soterix Medical 1x1-CT.

Pediatric Epilepsy Trial

Epilepsy Foundation awards a New Therapy Grant for a clinical trial of High-Definition tDCS in pediatric epilepsy. Dr. Alexander Rotenberg will lead a team of clinical investigators including at BCH and Harvard Medical School.

Stroke Rehabilitation Trial

NIH grants Burke Medical Research Institute $3m to conduct the most controlled trial of tDCS for stroke rehabilitation to date. The Soterix Medical 1x1 platform is the most advanced and the industry standard for tDCS clinical trials for rehabilitation.

Down Syndrome Trial

Soterix Medical Inc. receives FDA Clinical Trial IDE for High-Definition tDCS (HD-tDCS) to improve IQ in pediatric Down syndrome. HD-tDCS is the only non-invasive, brain targeted, and low-intensity technology designed to promote neuroplasticity.

Pediatric Hemiparesis Trial

Dr. Bernadette Gillick's Pediatric Rehabilitation Laboratory is supported by the NIH and University of Minnesota Clinical and Translational Science Institute to investigate the use of a form of tDCS for interventions in rehabilitation for children. Subject specific analysis with Soterix Medical Neurotargeting™ will guide current to brain cells in the injured part of the brain.

Fibromyalgia Clinical Trial

HD-tDCS clinical trial underway for fibromyalgia at Harvard Medical School and Spaulding Rehabilitation Hospital, Boston.

Stroke Rehabilitation Clinical Trial

NIH grants Soterix a Phase-1 STTR grant to develop HD-tDCS for stroke rehabilitation. The first technology capable of delivering therapeutic direct current to target brain regions involved in functional recovery.

Soterix Medical is committed to the advancement of science through research and education

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