Regulatory pathways
Device classes, 510(k) versus De Novo versus PMA, predicates, breakthrough designation, and the guidance written specifically for implanted BCIs. Twenty hours of reading that make you sound like a third-year employee.
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A device that touches a patient in the United States needs the FDA’s permission to be sold, and the kind of permission depends on how risky the device is and whether something like it already exists. Three classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. Related: 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate., Premarket approval (PMA)Premarket approval (PMA) The strictest FDA pathway, requiring clinical evidence of safety and effectiveness; the route for Class III implants., De NovoDe Novo The FDA pathway for a low-to-moderate-risk device that has no predicate.. Glossary entry, three main pathways, one special program, and a set of public databases that let you read exactly how every device on the market got there. Learn the vocabulary here and read three real submissions; after that, regulatory conversations stop being intimidating.
Three classes
Class I: low risk. Tongue depressors, manual wheelchairs, most electrodesElectrode The conductor that turns ion currents in tissue into electron currents in a wire; its chemistry and contact quality set the noise you live with. Related: Silver/silver-chloride (Ag/AgCl)Silver/silver-chloride (Ag/AgCl) The standard electrode material for biopotentials, because its chemistry produces a stable, low-noise, low-drift interface with salty gel. , Electrode impedanceElectrode impedance How hard it is to push current through the skin-electrode contact, typically 5 to 50 kilohms with gel and megohms dry, higher at low frequencies. , Half-cell potentialHalf-cell potential The DC voltage that appears wherever a metal meets an electrolyte; two electrodes with different half-cell potentials produce an offset that can swamp the signal. . Glossary entry. General controls (registration, labelling, good manufacturing) and usually no premarket submission.
Class II: moderate risk. Most EEGElectroencephalography (EEG) Recording the brain's electrical activity from electrodes on the scalp, a few tens of microvolts of blurred, summed cortical activity. Related: Electrocorticography (ECoG)Electrocorticography (ECoG) Recording from electrodes placed on the surface of the brain under the skull, usually during epilepsy surgery evaluation; cleaner and sharper than EEG. , Magnetoencephalography (MEG)Magnetoencephalography (MEG) Recording the tiny magnetic fields produced by cortical currents with superconducting sensors in a shielded room; less blurred by the skull than EEG, and far more expensive. , Volume conductionVolume conduction The spreading of currents from a source through the conductive tissues of the head, which is why one source shows up on many electrodes and why scalp EEG is blurry. , Microvolt (µV)Microvolt (µV) One millionth of a volt. Scalp EEG is tens of microvolts; a AA battery is 1.5 million of them. . Glossary entry amplifiers, powered wheelchairs, infusion pumps, sleep monitors, many BCIBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry software products. Requires a premarket submission, almost always a 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. Related: Predicate devicePredicate device The already-legal device a 510(k) submission compares itself to. , FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry, plus “special controls” specific to the device type.
Class III: highest risk, life-sustaining or implanted with significant risk. Pacemakers, deep brain stimulators, cochlear implantsCochlear implant The most successful neural prosthesis: an electrode array in the inner ear that stimulates the auditory nerve in up to 22 bands. Related: Vocoder (noise vocoder)Vocoder (noise vocoder) A simulation of what a cochlear implant delivers: the loudness envelope of each frequency band, applied to noise in that band. . Glossary entry, implanted BCIsBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry. Requires premarket approval with clinical evidence.
The class is set by the device’s intended use and indications. The same EEGElectroencephalography (EEG) Recording the brain's electrical activity from electrodes on the scalp, a few tens of microvolts of blurred, summed cortical activity. Related: Electrocorticography (ECoG)Electrocorticography (ECoG) Recording from electrodes placed on the surface of the brain under the skull, usually during epilepsy surgery evaluation; cleaner and sharper than EEG. , Magnetoencephalography (MEG)Magnetoencephalography (MEG) Recording the tiny magnetic fields produced by cortical currents with superconducting sensors in a shielded room; less blurred by the skull than EEG, and far more expensive. , Volume conductionVolume conduction The spreading of currents from a source through the conductive tissues of the head, which is why one source shows up on many electrodes and why scalp EEG is blurry. , Microvolt (µV)Microvolt (µV) One millionth of a volt. Scalp EEG is tens of microvolts; a AA battery is 1.5 million of them. . Glossary entry amplifier is Class II as a diagnostic aid and unregulated as a “wellness” product that makes no medical claim, which is the line consumer neurotech companies walk. Change the claim and you change the class.
Three pathways
510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. Related: Predicate devicePredicate device The already-legal device a 510(k) submission compares itself to., FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review.. Glossary entry. Show that your device is “substantially equivalent” to a legally marketed predicatePredicate device The already-legal device a 510(k) submission compares itself to. Related: 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate.. Glossary entry: same intended use, and either the same technology or technology that raises no new questions of safety and effectiveness. Bench testing and sometimes small clinical data. Most Class II devices, and around three thousand clearances a year. Ninety days nominal, six to twelve months typical. “Cleared,” not “approved.”
De NovoDe Novo The FDA pathway for a low-to-moderate-risk device that has no predicate. Related: 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate.. Glossary entry. For a low-to-moderate-risk device with no predicate. The FDA creates a new classification and special controls, and your device becomes the predicate for everyone after you. More work than a 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. Related: Predicate devicePredicate device The already-legal device a 510(k) submission compares itself to. , FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry, far less than a PMAPremarket approval (PMA) The strictest FDA pathway, requiring clinical evidence of safety and effectiveness; the route for Class III implants. Related: FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry. Several novel neurotech devices took this path.
Premarket approvalPremarket approval (PMA) The strictest FDA pathway, requiring clinical evidence of safety and effectiveness; the route for Class III implants. Related: FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review.. Glossary entry. For Class III. Requires clinical trials demonstrating safety and effectiveness, a manufacturing inspection, and often an advisory panel. Years and tens of millions of dollars. “Approved.” Every implanted stimulator went this way.
A company builds a new EEG headband that estimates sleep stages and markets it as helping you 'understand your sleep.' A second company sells the identical headband to 'detect sleep apnea.' What is the regulatory difference?
The claim decides. “Understand your sleep” is a general wellness claim the FDA has said it will not regulate as a device. “Detect sleep apnea” is a diagnostic claim for a disease, making the same hardware a Class II device that needs a 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. Related: Predicate devicePredicate device The already-legal device a 510(k) submission compares itself to. , FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry, clinical validationValidation Testing that the device meets the user's need in real use; did you specify the right thing. Related: VerificationVerification Testing that the device meets its requirements; did you build what you specified. . Glossary entry of its detection performance, and special controls. Regulatory strategy is largely the art of choosing claims, and most consumer neurotech lives on the wellness side of this line on purpose.
Getting to a trial
A device that is not yet cleared can be studied in people under an investigational device exemptionInvestigational device exemption (IDE) FDA permission to use an unapproved device in a clinical study. Glossary entry, with IRBInstitutional review board (IRB) The committee that must approve any research on people before it starts, to protect the participants. Related: Informed consentInformed consent A participant's agreement to take part after understanding the risks, in language they can follow; a process, not a signature. , CITI trainingCITI training The online human-subjects research course most universities require before you can touch participant data. . Glossary entry approval and, for significant-risk devices, FDA approval of the study. Every implanted BCIBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry participant is in an IDEInvestigational device exemption (IDE) FDA permission to use an unapproved device in a clinical study. Glossary entry study. Early feasibility studies with a handful of participants are the first step, and they are what the BCIBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry companies are running now.
Breakthrough designation
The Breakthrough Devices ProgramBreakthrough Device designation An FDA program that speeds review for devices treating serious conditions with no good alternative; most invasive BCI companies have it. Glossary entry gives priority review and more frequent FDA interaction to devices for life-threatening or irreversibly debilitating conditions with no adequate alternative. Most implanted BCIBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry companies have it. It speeds communication; it does not lower the evidence bar.
The BCI guidance
In 2021 the FDA published guidance specifically for implanted BCIBrain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. Related: DecoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. , Closed loopClosed loop A system in which the output feeds back to influence the input, such as a user adjusting their brain activity while watching the cursor it controls. . Glossary entry devices for patients with paralysis or amputationImplanted Brain-Computer Interface Devices for Patients with Paralysis or Amputation, non-clinical testing and clinical considerationsWhat testing the FDA expects before an implanted BCI reaches a person, in the agency own words.: what non-clinical testing to do (biocompatibility, electrical safety, software, cybersecurity, and specific tests for the implant and its wireless link), how to design early feasibility studies, and what outcome measures make sense. It is forty pages, it is written for exactly the devices this site is about, and reading it once puts you ahead of most people in the field.
Read three submissions
The FDA’s 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. Related: Predicate devicePredicate device The already-legal device a 510(k) submission compares itself to. , FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry database has a summary for every clearance: device, predicate, tests performed, sometimes clinical data. Search “EEGElectroencephalography (EEG) Recording the brain's electrical activity from electrodes on the scalp, a few tens of microvolts of blurred, summed cortical activity. Related: Electrocorticography (ECoG)Electrocorticography (ECoG) Recording from electrodes placed on the surface of the brain under the skull, usually during epilepsy surgery evaluation; cleaner and sharper than EEG. , Magnetoencephalography (MEG)Magnetoencephalography (MEG) Recording the tiny magnetic fields produced by cortical currents with superconducting sensors in a shielded room; less blurred by the skull than EEG, and far more expensive. , Volume conductionVolume conduction The spreading of currents from a source through the conductive tissues of the head, which is why one source shows up on many electrodes and why scalp EEG is blurry. , Microvolt (µV)Microvolt (µV) One millionth of a volt. Scalp EEG is tens of microvolts; a AA battery is 1.5 million of them. . Glossary entry” and read three. Then find one De NovoDe Novo The FDA pathway for a low-to-moderate-risk device that has no predicate. Related: 510(k)510(k) The FDA pathway that clears a device by showing it is substantially equivalent to one already on the market, its predicate. . Glossary entry decision summary for a neurotech device and one PMAPremarket approval (PMA) The strictest FDA pathway, requiring clinical evidence of safety and effectiveness; the route for Class III implants. Related: FDA device classesFDA device classes Class I is low risk (a tongue depressor), Class II moderate (most EEG amplifiers), Class III highest (implanted BCIs), each with heavier review. . Glossary entry summary for a neurostimulator. The pattern of what evidence was required, and how the intended use was worded, is the real education. Twenty hours total across this page and those documents.
Deep dive Software and adaptive algorithms 3 min
Software that is itself a medical device (a seizure detector, a sleep stager) follows the same classes and pathways, with its own guidance on documentation. A machine-learning model that is locked at clearance is treated like any software; one that keeps learning after deployment has no clean path yet, and the FDA’s “predetermined change control plan” is the current attempt to allow pre-approved updates. If your decoderDecoder The algorithm that maps neural signals to intended actions, such as a classifier or a Kalman filter. Related: ClassifierClassifier An algorithm that assigns each trial a label, such as left hand or right hand, after being trained on labelled examples. , Kalman filterKalman filter An estimator that blends a prediction from a motion model with a noisy measurement, weighting each by how much it trusts it; the decoder behind most intracortical cursor control. , Brain-computer interface (BCI)Brain-computer interface (BCI) A system that turns measured brain activity into control of something outside the body, from a cursor to a wheelchair to a speech synthesizer. . Glossary entry adapts to the user, this is your issue.
Deep dive Outside the United States 2 min
The European Union’s Medical Device Regulation uses a similar class structure with conformity assessment by notified bodies and a CE mark; since 2021 it is substantially stricter than before and slower than the FDA for many devices. Japan, China, and others have their own systems. A device company’s regulatory team plans the sequence of markets; the United States is usually first for neurotech because the pathways are the most predictable.
Explain what this page was about to your roommate in three sentences. No jargon they would not know.
We sort devices by risk into Class I for low risk tools, Class II for medium risk devices that usually need a 510(k) showing match to an already sold comparison device, and Class III for implanted devices that need full approval with human trial data. We expect a 510(k) to take 6 to 12 months even though 90 days is the nominal target, while full approval takes years and tens of millions of dollars. We study early implants under an investigational exemption with a handful of participants, and we read the 40 page FDA guidance from 2021 written for implanted brain interfaces for paralysis or amputation.
Yours does not have to match. Check that the three ideas are there.