EMC of medical devices (IEC 60601-1-2)
How EMC applies to medical electrical equipment: the IEC 60601-1-2 standard, use environments, essential performance, risk management, emissions and immunity.
In medical devices EMC is a safety issue as well as a compatibility issue: interference must not endanger the patient or the operator, or stop a device from delivering its essential performance.
The standard
IEC 60601-1-2 is the collateral standard for electromagnetic disturbances in the IEC 60601 family of safety standards for medical electrical equipment and systems. The 4th edition (2014, with amendment 1 in 2020) is in widespread use; in Europe it is adopted as EN 60601-1-2. Regulators recognise it: the EU medical device rules and the US FDA both refer to it in their processes.
Use environments
The immunity requirements depend on where the equipment will be used:
- Professional healthcare facility environment (hospitals, clinics): controlled facilities with generally predictable electromagnetic conditions, but with strong sources (diathermy, mobile devices).
- Home healthcare environment (patients at home, ambulances, public places): less controlled conditions and higher exposure to radio transmitters and to mains disturbances; immunity levels are higher for some tests.
- Special environments (for example near high-power medical equipment).
The manufacturer declares the intended environments in the documents that accompany the device.
Essential performance and risk management
The standard links EMC to risk management (ISO 14971). The manufacturer identifies the device’s basic safety and essential performance, defines what behaviour during and after a disturbance is acceptable, and demonstrates it by testing. For example, a patient monitor may be allowed to show a transient artefact but must not display a wrong value as if it were valid, or must raise an alarm.
Tests
- Emissions: radio-frequency emissions (CISPR 11, group 1 or 2, class A or B depending on environment and use), harmonic current and flicker for mains-powered equipment.
- Immunity: ESD (up to 8 kV contact and 15 kV air), radiated radio-frequency fields, proximity fields from wireless communication equipment, electrical fast transients, surges, conducted radio-frequency disturbance, voltage dips and interruptions, and power-frequency magnetic fields.
- Test levels and ports depend on the type of equipment and on the use environment; a risk file justifies any deviation.
Special aspects
- Life-supporting equipment, implantable devices and in-vitro diagnostic equipment may have additional or different standards (for example IEC 61326-2-6 for in-vitro diagnostics).
- Wireless functions also fall under the radio rules, and coexistence with other wireless systems is part of the assessment.
- Software changes can affect EMC behaviour; changes should be re-assessed.
Where to check
The current edition of IEC 60601-1-2, the transition dates of regulators and the list of recognised standards of the market concerned.