Foc.us V3 / Go Flow

Overview

Foc.us launched its first consumer transcranial direct current stimulation headset in 2012 — which in this category counts as a deep lineage. While most tDCS brands were still finding their footing, Foc.us was already shipping hardware, building a DIY community, and iterating toward the V3, its most capable device to date. That history matters: the biohacker forums and tDCS subreddits where power-users share montage protocols are full of Foc.us devices. The brand has become a kind of lingua franca for the self-experimentation community.

What the V3 delivers, and what no other consumer device matches, is waveform breadth. Most devices stimulate with fixed direct current — tDCS — and that is the end of it. The Foc.us V3 runs six distinct stimulation modes from a single device: tDCS (transcranial direct current stimulation), tACS (alternating current, which cycles through a frequency rather than maintaining a constant polarity), tRNS (random noise stimulation, which delivers small random-amplitude fluctuations across a noise bandwidth), tPCS (pulsed current stimulation, which sends current in discrete pulses rather than continuous flow), sotDCS (slow-oscillation tDCS, which modulates current at very low frequencies intended to ride natural sleep or cortical oscillation rhythms), and tRCS (repetitive current stimulation, exclusive to the V3). Each of these has a distinct electrical profile, and each maps to a different body of research literature. None of that research is conclusive in the consumer context — which we address in detail below — but for users who want to track closely with specific laboratory protocols, the V3 is the only consumer device that gives them the flexibility to attempt it.

The Go Flow variant extends the current ceiling to 4 mA, which is meaningfully above the 1–2 mA used in most academic tDCS studies. That power-user headroom is the Go Flow’s main distinction within the Foc.us lineup. It comes with an important caveat, covered in the safety section.

The honest picture alongside those capabilities: Foc.us carries zero regulatory clearances anywhere, its customer support has historically been uneven, and the interface complexity is real. This is a power-user instrument built for a power-user audience. Mainstream consumers looking for something to switch on and follow a preset program will find better-suited options elsewhere.

What the device delivers

The V3 and Go Flow share the same six-mode waveform architecture. The V3 covers the full stimulus library — tDCS, tACS, tRNS, tPCS, sotDCS, tRCS — with current output specifications appropriate for the modes in the standard academic range. The Go Flow adds the 4 mA ceiling, Bluetooth app control, and a 3D head-model electrode placement interface that shows users where to position electrodes for common montages. There is also an optional EEG integration pathway for users who want to add brainwave-reading capability alongside stimulation, though that requires additional hardware.

Protocols are fully programmable: current intensity, waveform type, ramp-up duration, and session length are all adjustable parameters. For users who follow published tDCS research and want to attempt to replicate specific montages from academic papers, that programmability is the point. For users who simply want a device to follow, the same programmability becomes overhead.

Pricing runs $188–$399 depending on the variant and configuration. There is no subscription requirement.

The electrode placement guidance via 3D head model is worth noting: correct electrode placement is not a cosmetic detail in tDCS. The anode and cathode positions determine which brain regions receive net depolarizing versus hyperpolarizing current, and off-target placement can stimulate unintended areas with unknown effect. A visual placement guide that reduces that error is a genuine safety-adjacent feature.

What we have not done is bench-test a unit. Our sample source is published specifications and community-documented experience. We will note that customer support has been described as sparse by users in the DIY community, and Foc.us has no active clinical program or published peer-reviewed validation of its specific consumer hardware.

Regulatory status & safety

Foc.us V3 and Go Flow are not FDA-cleared for any indication. They are also not CE-marked under EU medical device regulation, and carry no regulatory clearance in any jurisdiction that we are aware of. This is the most significant fact in this review.

Consumer tDCS sits in a difficult regulatory position. The broader tDCS literature — mostly conducted with research-grade devices at 1–2 mA in institutional settings — does not transfer straightforwardly to consumer self-administration. The FDA has generally not cleared consumer tDCS devices for cognitive enhancement, mood, or any other indication. Flow Neuroscience’s FL-100 holds FDA premarket approval (PMA P230024) for major depressive disorder (as monotherapy or adjunctive treatment) — that is the only consumer-facing tDCS device with meaningful FDA authorization at the time of writing. The FL-100 is a different product category from the Foc.us V3: it is a prescription-adjunct device prescribed and supervised by a clinician, not a self-experimentation platform.

On the 4 mA ceiling of the Go Flow: most published tDCS research uses 1–2 mA, with good reason. Higher current intensities increase the risk of adverse skin effects — specifically, the risk of skin irritation, redness, and at the extreme, localized skin burns at the electrode contact site. The risk is not hypothetical: it scales with current density (mA per electrode area), contact quality, and session duration. The Go Flow’s 4 mA ceiling is available; whether any given user should use it at that setting is a different question. Users exploring higher current levels should understand that they are operating beyond the envelope most tDCS research protocols used.

General safety framework for any consumer tDCS device:

• Electrode placement is not optional to understand. Misplacing electrodes can stimulate unintended brain regions. The 3D head model in the app mitigates this risk but does not eliminate it.
• Do not use tDCS if you have an implanted electronic device (pacemaker, cochlear implant, deep brain stimulator), a history of seizures, significant neurological conditions, or open wounds on the scalp. Consult a physician before any neurostimulation if you have any neurological or cardiac history.
• Skin irritation is the most common adverse effect. Proper electrode prep and saline-wetted sponges reduce but do not eliminate this risk.
• Cognitive enhancement evidence in consumer settings is mixed and early. Research on tDCS for attention, memory, mood, and executive function exists but is methodologically contested. Meta-analyses are divided on effect sizes, reproducibility, and the relevance of laboratory protocols to home use. This is an area of active investigation, not settled science. Do not purchase this device expecting a proven cognitive outcome.

3-year cost of ownership

Device	Price	Subscription	3-year total
Foc.us V3 / Go Flow	$188–$399	None	$188–$399
Caputron ActivaDose	$249–$449	None	$249–$449
Flow Neuroscience FL-100	$400+	Varies	$400+
TheBrainDriver V2.1	$127–$150	None	$127–$150
Brain Premier	$99–$175	None	$99–$175

The Foc.us V3’s cost sits in the middle of the consumer tDCS market. TheBrainDriver and Brain Premier are cheaper but are fixed-current tDCS-only devices. Caputron’s ActivaDose is in a similar tier but carries off-label FDA 510(k) clearance for iontophoresis drug delivery (not cognitive enhancement). Flow Neuroscience commands a premium because it is a clinician-prescribed system. No subscription is required for the Foc.us V3, and electrode sponges are the main ongoing consumable cost.

Where it fits

• Consider the Foc.us V3 if you have experience with tDCS, you want to follow specific montage protocols from academic literature, you want to explore stimulation modes beyond basic direct current, and you understand and accept that consumer tDCS is unregulated and its cognitive benefits are unproven.
• Consider the Go Flow specifically if you want the same waveform flexibility with a higher current ceiling and Bluetooth app control, and you understand that the 4 mA ceiling should be approached cautiously, not as a target setting.
• Look at Caputron ActivaDose instead if you want a device that has FDA 510(k) clearance for iontophoresis (note: not cleared for cognitive enhancement) and a more mainstream support structure.
• Look at Flow Neuroscience FL-100 instead if you are interested in tDCS as an adjunct to depression treatment and want to do so under clinical supervision — it is the only consumer tDCS device with meaningful FDA clearance for a mood indication.
• Look at TheBrainDriver V2.1 instead if you want a simpler, single-current device and are new to tDCS.
• This is not the right device if you are looking for something mainstream, well-supported, and easy to hand to a non-technical person.

Verdict: Recommended

Foc.us V3 / Go Flow earns a recommended verdict for a specific audience: experienced biohackers and DIY tDCS users who want the widest waveform library on the consumer market, a 12-year track record in the category, and programmable protocols that allow them to attempt to replicate published laboratory montages. That recommendation comes with the caveats this audience already knows, stated plainly: no regulatory clearance anywhere, genuine complexity in operation, uneven historical support, and a 4 mA ceiling that warrants caution rather than enthusiasm. The cognitive outcomes users seek are not established in the consumer context.

For power-users who understand the territory and want the most flexible instrument available, Foc.us V3 is the honest answer. For everyone else, the alternatives below the “where it fits” section will serve better.

How we’ll test this

Hands-on testing is pending. When we run it, we will verify electrode contact quality across the sponge configurations, test Bluetooth app reliability and protocol programming, and document the actual current accuracy at multiple settings against a calibrated reference meter. We will not attempt to measure cognitive outcomes — that is not a valid assessment methodology for a single-unit, non-blinded review. See our methodology.

Changelog

• 2026-06-15: Expanded review — added full section on regulatory status and safety (FDA clearance reality, 4 mA current ceiling caution, electrode placement risk, contraindications), explained all six stimulation modes (tDCS/tACS/tRNS/tPCS/sotDCS/tRCS), expanded buyer guidance and cost comparison table, removed template boilerplate language. Hands-on testing still pending.
• 2026-05-07: Initial review published based on Foc.us V3 / Go Flow published specifications.