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FDA EMC of Medical Devices: Nearfield Emitters New Immunity Testing

Kevin Kenney “There is great fulfillment in helping people through meaningful innovation. Helping our customers get their technology to the people who need it most is extraordinarily rewarding.”

On June 6th 2022 FDA issued an update to the guidance on EMC of Medical Devices. This edition supersedes the prior guidance issued on November 17, 2020 and expands recommended testing to include AIM 7351731 or section 8.11 of 60601-1-2:2020. A major focus of this update was due to FDA acknowledgement that the current group of consensus standards may no longer adequately address some common EM emitters like the various radiofrequency identification (RFID) and near-field communications (NFC) systems which are becoming more common. The 4.1 edition of 60601-1-2 is still in transition and does not supersede 4.0 until Dec 2023. However, manufacturers should start familiarizing themselves with at least the new expectations regarding proximity magnetic fields. The following is a brief overview of the guidance and testing which the FDA expects in premarket submissions.

How do you know if you need to do this “extra” testing? As with most things, determination of V&V activities starts with risk. This is reflected in the guidance which first asks manufacturers to know their intended use environment, to determine common emitters therein and review their risk category. From this analysis a manufacturer should be able to establish whether there are additional requirements for labeling, testing, or both. 

From the guidance:

“For medical devices in the risk category “Medical device-related events without reported or potential harm,” we recommend that the medical device labeling (e.g., user manual, instructions for use) mention the potential for EMI from emitters expected to be nearby. If you make specific claims or specify a specific intended use regarding any particular emitter, we recommend that those claims be supported with additional testing, engineering analysis, or computer modeling. For medical devices in the risk category “Medical device-related deaths and serious injuries” or “Medical device-related non-serious adverse events” we recommend that:

  • testing be performed according to FDA-recognized consensus standards (e.g., FDA recognized AIM 7351731 Medical Electrical Equipment and System Electromagnetic Immunity Test for Exposure to Radio Frequency Identification Readers - An AIM Standard or IEC 60601-1-2:2020 Clause 8.11 for RFID emitters), or equivalent EMC test methods, with justification. If no consensus standards exist, specific immunity testing should be performed to demonstrate that the medical device is safe with regard to each identified emitter that is foreseeable in the intended use environment; and
  • labeling be specific to the risks to patients and operators and include any mitigations and warnings needed, based on the test results.” 

At a minimum FDA is looking for some labeling (instructions for use) information related to emitters. Or maybe you find that you are in a higher risk category, so you need to do the new proximity fields testing too? The answer is… It depends. IEC 60601-1-2:2020, Clause 8.11, IMMUNITY to proximity magnetic fields in the frequency range 9 kHz to 13.56 MHz starts with a set of criteria to evaluate if your device may be exempt from the new testing. A vast oversimplification of this is that if your device does not contain sensitive components or circuits where voltages (9 kHz to 13.56 MHz) induced into wiring, or the interconnect structure might alter the intended function OR these components are sufficiently distanced (0.15m) from other equipment during use by design OR your risk analysis finds that the risks are sufficiently low, then you may not need to test. Subclause 8.11 summarizes this review in a decision tree figure A.3.

Once you have determined you need to test, what is next? Ask if your test lab is prepared to test according to IEC 61000-4-39 (Electromagnetic compatibility (EMC) - Part 4-39: Testing and measurement techniques - Radiated fields in close proximity - Immunity test and 60601-1-2:2020 Table 11 or AIM 7351731. Depending on your device one may be more rigorous than the other, so you will also need to discuss this with your design owners.

Maybe you don’t need to test because the design meets the criteria in figure A.3, and you have a good justification. Right? Based on the experience of the author, if you are not completely sure that you meet the criteria laid down for exemption and are not sure that you have the data to back your claims of exemption, then you should test. Even if you think you are certain that there is no need to test, you might still want to do so. It is often more practical to perform the test, which can be less costly, time consuming and burdensome than researching, writing, reviewing, and maybe ultimately defending your justification!

We hope this helps illuminate some of the new information in this latest guidance from the FDA on EMC, specifically RFID.

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