What is a medical device? MDR and FDA for manufacturers

An optical pulse sensor can go into a sports band or into a monitor that warns of an arrhythmia. The hardware can be very similar. What separates a consumer product from one regulated as a medical device is, above all, what the manufacturer says it does.

This article opens a series on medical devices from the electronics point of view. We work in this sector, for the European Union and the United States, on projects in point-of-care in vitro diagnostics, bedside measurement and dose control for a respiratory treatment, with firmware developed under IEC 62304.

What the MDR says

In the EU the rule is Regulation (EU) 2017/745, known as the MDR. Its Article 2 defines a medical device as any instrument, apparatus, appliance or software, among other things, intended by the manufacturer to be used on human beings for a specific medical purpose:

• Diagnosis, prevention, monitoring, prediction, prognosis, treatment or alleviation of disease.
• Diagnosis, monitoring, treatment, alleviation of, or compensation for, an injury or disability.
• Investigation, replacement or modification of the anatomy or of a physiological or pathological process.
• Providing information by in vitro examination of specimens from the human body.

The key is the intended purpose, which the Regulation defines as the use for which the device is intended according to the manufacturer's data on the label, in the instructions for use, in promotional or sales materials or statements, and in the clinical evaluation. In other words, your website, your brochure and what your sales team says all count.

What the FDA says

In the United States, section 201(h) of the FD&C Act defines a device as an instrument, apparatus or similar article intended for the diagnosis, cure, mitigation, treatment or prevention of disease, or intended to affect the structure or a function of the body. Software functions excluded by section 520(o) are left out.

The starting point is the same as in Europe: the FDA asks you to define the intended use, as it calls it, and the indications for use to determine whether the product is a device. Both systems look at what the product is for, not at what it is made of.

Same hardware, two products

The most delicate boundary is wellness. In January 2026 the FDA updated its non-binding General Wellness guidance, and it is very specific about non-invasive sensors. A product that estimates parameters such as blood pressure, oxygen saturation or glucose can be considered a wellness product if its outputs are for wellness only and, in addition:

• It is non-invasive and not implanted.
• It is not intended to diagnose, cure, mitigate, prevent or treat a disease.
• It does not substitute for an authorised device.
• It has no claims, functions or outputs that guide a specific clinical action.
• It does not show values that mimic clinical ones, unless they have been validated.

Conversely, it stops being a wellness product if it measures, estimates or reports physiological values for medical or clinical purposes, including screening, monitoring, alerting or managing a disease. With the same sensor, relating heart rate to sleep or recovery is one thing; warning of a possible arrhythmia is another.

The EU has no equivalent list. Recital 19 of the MDR makes clear that software intended for wellbeing or lifestyle purposes is not a medical device, and from there the definition has to be applied case by case.

Define the product before designing it:Hardware design

Cases worth a second look

• Accessories. An article that is not a medical device, but which the manufacturer intends to be used with one to enable its use or contribute to its medical functionality, is an accessory and also falls under the MDR.
• Software. A program intended for a medical purpose is a medical device in its own right, and its qualification does not depend on where it runs or how it connects to the equipment.
• Products with no medical purpose. Annex XVI lists groups to which the MDR applies even without a medical purpose, once their common specifications have been adopted. Some of them are electronic: intense pulsed light or laser equipment for hair removal and skin treatments, equipment for reducing adipose tissue, and brain stimulators.

What changes in development if it is one

If your product is a medical device, the MDR places it in class I, IIa, IIb or III according to its intended purpose and risk, and that class sets the route. In class I the manufacturer declares conformity itself, except for specific aspects of sterile, measuring or reusable surgical products, where a notified body steps in. We will explain the classes in the next article in the series.

In every class, the manufacturer needs a risk management system, a clinical evaluation, technical documentation and a quality management system proportionate to the risk. In electronics, this translates into standards such as IEC 60601 for medical electrical equipment, IEC 62304 for software, ISO 14971 for risk and ISO 13485 for quality.

That is why it matters to decide early. When the decision comes late, our experience is that you have to redo, or at the very least rework, almost everything: the electronics, its tests and the software.

Software and firmware under IEC 62304:Embedded firmware

Start as wellness and move to medical?

It is an understandable temptation, and it usually comes from the same place. Most of the people who consult us know perfectly well whether their product is a medical device; what holds them back is fear of the investment. In the lower risk classes there is some room for interpretation, but in the higher ones there is no way round it if you want to sell the product.

They are also two different market niches: a wellness product is designed around cost, while in a medical one quality comes first. We try to design every product as if it were a medical device, even when it will not be one. The extra documentation effort usually pays off in the long run.

It also helps when going abroad. Although the EU and the FDA differ in some respects, the type of documentation they ask for does not change much, and it is much easier to obtain a certification if there is already an earlier one.

How to decide before you design

1. Write down the intended purpose in one paragraph: what the product does, for whom and in what situation.
2. Review everything you will say about it: website, manual, app, sales material. If the interface gives a clinical alert, that counts too.
3. Look at similar products. The FDA has public databases of classifications and authorised devices.
4. If in doubt, ask whoever decides. In the EU, the competent authority or a notified body; in the United States there is a formal request, the 513(g).
5. Decide before freezing the design, because the architecture, tests and documentation all depend on that decision.

If you are at this point with a specific product, tell us about it and we will go through it with you.

Preparing for testing:Test and validation

Sources

• Regulation (EU) 2017/745 (MDR), Articles 1, 2, 10, 51 and 52 and Annex XVI, and Recital 19.
• FDA: How to Determine if Your Product is a Medical Device.
• FDA: General Wellness: Policy for Low Risk Devices, January 2026.