Using Pre-Certified Radio Modules in Medical Devices: What Approvals Transfer and What Don't

Pre-certified radio modules can reduce development effort when adding wireless functionality to a medical device, but do not remove the manufacturer's compliance responsibility. In this article, Alex Toohie of Element explains what module approvals actually cover across FCC, ISED, CE, and UKCA, and why host-level testing remains essential.  

What pre-certified radio module approvals actually cover

When adding wireless functionality to a medical device, manufacturers generally choose between designing a radio in-house or integrating an off-the-shelf module — a Wi-Fi, Bluetooth, cellular, or multi-radio unit from a module supplier. Modules reduce the need for in-house radio expertise and often come with prior test evidence or formal approvals.

A module is not a chipset. A chipset is a semiconductor component within a radio design and cannot hold approvals on its own. A module is a more complete unit that integrates the chipset with RF filtering, antenna connections, and often a power supply circuit. It may carry an FCC ID, ISED ID, CE marking, or UKCA marking in its own right.

That distinction leads to a common assumption: that the module's approvals carry forward to the finished product. In practice, they rarely transfer cleanly under FCC and ISED, and in the EU and UK they do not transfer at all as a matter of law.

 

Types of modular approval under FCC rules

The FCC distinguishes between several types of modular approval, each with different conditions and implications for host manufacturers.

Single Modular Approval

Single modular approval is the most comprehensive type. A module with single modular approval has been tested and certified as a standalone product and meets all the conditions set out in FCC KDB 996369 D04: it has its own power supply regulation, RF shielding, buffered data or modulation inputs, a tested standalone antenna, and has been fully tested to all applicable FCC rule parts. When a single modular approval is in place and the host manufacturer preserves all grant conditions, the module can be placed in a host without the host undergoing re-certification of the radio function — though host testing for emissions and RF exposure is still expected.

Limited Modular Approval

Limited modular approval is granted where a module meets most but not all the conditions for single modular approval — for example, where the module is intended to be used only with specific host board designs and cannot be considered fully standalone. Limited modular approval carries tighter restrictions on the host environments in which it may be used, and the host manufacturer typically needs to confirm in more detail that those conditions are met.

Split Modular Approval

Split modular approval applies to modules tested in portions — for example where the radio is on one board and the antenna on another. Each portion is tested separately, and the combination assessed. It is the most complex type to administer.

Understanding which type of modular approval a specific module holds and what conditions are attached is essential before assuming that host certification can be avoided. For more detail on FCC and ISED requirements for wireless medical devices, read our article on FCC and ISED certification.

 

Grant conditions that invalidate modular approval in medical integrations

All modular approvals come with conditions attached to the FCC Grant of Equipment Authorization or ISED certificate. These conditions define the valid scope of the approval. Common examples include:

• The antenna must be installed at a minimum separation distance from all persons (commonly 20 cm)
• Only antenna types identical to those tested, or antennas with the same or lower gain in the same radiation pattern, may be used
• The host manufacturer must provide end-users with the installation instructions needed to maintain RF exposure compliance
• The module must not be co-located with other transmitters unless additional RF exposure assessment is performed

These conditions are not administrative formalities. They define what integration scenarios the approval actually covers.

A module carrying an approval for a separation distance of 20 cm from all persons cannot be integrated into a wearable medical device worn directly on the skin without additional RF exposure assessment— the grant condition is broken the moment the intended use changes, and recertification effort becomes mandatory at this point.

This is one of the most common sources of modular approval invalidation in wireless medical device projects, because body-worn use is the rule rather than the exception for many connected medical products.

Similarly, if the host design places the module's antenna at a different orientation or uses a different antenna element than was tested, the antenna condition may be broken even if the physical module has not changed, and recertification effort again becomes mandatory. Antenna design decisions in the host are compliance decisions, not just engineering decisions.

 

Wireless Co-Existence

Although not an FCC or ISED requirement, wireless medical devices sold into the North American market have one more obligation to address – wireless co-existence testing.

This requirement applies if the device’s wireless functionality forms part of the medical function of the device, e.g. if the wireless function failed the device would no longer be able to perform all of its essential medical functions.

The required tests involve subjecting the device to real-world-simulating RF signals to check for immunity to interference. This testing is often done using complex test equipment, but in some cases can be done using off-the-shelf products to provide the interference.

This requirement cannot have been considered at module level, as it is inherently tied to the end product function. Therefore manufacturers of medical devices with functional wireless performance must have this test carried out on the end product. For a detailed overview of co-existence requirements, see our wireless co-existence testing for medical devices article.

 

Why host-level testing is still expected even when the module is certified 

FCC guidance in KDB 996369 D04 strongly recommends that host manufacturers test the transmitter in its host configuration even when the module already holds a single modular approval. This is not a bureaucratic requirement — it reflects a real technical risk. The module was tested standalone, in controlled lab conditions, without the host's PCB layout, enclosure materials, other electronic circuitry, or proximity to battery packs and displays. Once integrated, all of those factors can, and often do, affect the radio's emissions profile.

Harmonic and spurious emissions are particularly sensitive to host integration. A module that produces clean harmonics in isolation can produce elevated harmonics when its ground plane is coupled to the host PCB's ground, when a display cable runs close to the antenna, or when the module's power supply is loaded by other components. Host-level RF testing confirms that the original approval evidence still represents the product as built. Without it, the manufacturer is relying on an untested assumption.

For wireless medical devices, where the consequences of non-compliance can include regulatory action, market withdrawal, or clinical risk, relying on an untested assumption is a planning failure.

Remember: every decision not to carry out a test is a decision to accept some level of risk that the product may later be found to be non-compliant. Thorough testing before placing the product on the market reduces the risk of repairs or product recalls afterwards.

The position on modules under CE and UKCA marking 

In the EU and UK, the position is straightforward but often misunderstood. If the finished product qualifies as radio equipment, Radio Equipment Directive (RED)  applies*** — regardless of whether the radio comes from an integrated module, a chipset design, or any other architecture. There is no legal concept of modular approval under CE or UKCA marking equivalent to the FCC or ISED routes.

A module supplier may describe a module as "CE compliant" and provide a Declaration of Conformity. That declaration means the module was assessed against its own configuration. It does not transfer any legal approval to the host product. The manufacturer placing the finished medical device on the market is the legal manufacturer under RED and remains fully responsible for demonstrating compliance with all essential requirements — including radio performance testing of the finished product. For more detail on RED, CE and UKCA requirements for wireless medical devices, read our article.

***Certain categories of product are specifically exempt from RED, for example some types of civil aviation equipment.

Using module test reports as baseline evidence in Europe 

Although there is no modular approval to carry forward, module test reports are still valuable. Manufacturers should obtain complete test reports from module suppliers, not just declarations. ETSI Guide EG 203 367 describes how host integrators can use module test data as a baseline for their own assessment — comparing the host's measured performance against the module's original evidence to determine whether the existing data remains representative.

Where host performance closely matches module data — same antenna, similar environment, similar power configuration — the existing evidence may support the Article 3.2 assessment with limited additional testing. Where performance diverges, additional testing against the applicable ETSI standard is needed. The starting point is always the module test report, not the supplier's declaration.

 

Integrating modular radios responsibly

Module selection and integration is a compliance decision, not a component sourcing decision. At selection stage, obtain the full certificate and test report, confirm the approval type (single, limited, or split for FCC), and read all grant conditions. Assess each condition against the intended use before finalising the host design — for body-worn devices, RF exposure conditions are almost always the deciding factor. Plan host-level testing regardless of module certification status. For EU and UK, use module test reports as baseline evidence but treat the Article 3.2 assessment as a finished-product responsibility.

For a full overview of FCC, ISED, CE, and UKCA requirements for connected medical devices, download our free Global Wireless Medical Device Compliance Guide.

 

Frequently Asked Questions

Does a pre-certified radio module eliminate the need for FCC testing of the finished medical device?

No. FCC modular approval reduces the scope of testing required but does not eliminate it. The host manufacturer must still verify that all grant conditions from the module's FCC authorization are met in the final integration, and host-level emissions and RF exposure testing remain expected regardless of the module's certification status.

 

What happens to FCC modular approval if a medical device is worn on the body?

Most FCC modular approvals include a grant condition requiring a minimum separation distance of 20 cm from all persons. A body-worn medical device worn directly on the skin breaks that condition, which invalidates the approval for that integration and triggers mandatory recertification. Wireless medical device testing must account for the intended use from the outset.

Does a module's CE marking transfer to the finished medical device under the Radio Equipment Directive?

No. There is no legal concept of modular approval under CE or UKCA marking. A module supplier's Declaration of Conformity covers only the module in its own configuration. The manufacturer of the finished device remains fully responsible for demonstrating compliance with all RED essential requirements, including radio performance testing of the completed product. See Element's RED directive testing services for more detail.

Is wireless co-existence testing required for medical devices that use a pre-certified module?

Yes, where the wireless function forms part of the device's medical function. This requirement is tied to the end product, not the module, so it cannot have been addressed at module level. Wireless co-existence testing to ANSI C63.27 must be carried out on the finished device.

Conclusion  

The practical implications of integrating radio modules in medical devices are consistent across regions: module selection is a compliance decision. Reviewing grant conditions, obtaining full module test reports, and planning host-level testing early avoids late-stage rework and reduces the risk of regulatory action or product recall.

Element’s wireless and radio compliance team supports medical device manufacturers from early design review through to certification across the US, Canada, EU, and UK.

Learn more about our wireless medical device testing services, explore our wireless testing capabilities, or read our wireless medical device compliance whitepaper for a full overview of regional regulatory requirements. Find out more about Element on our About Us page.