IEC 62366 Explained – Usability Engineering for Medical Devices

Why is usability engineering essential for medical devices?

A medical device can have flawless engineering yet still cause harm if its interface is confusing or prone to misuse. Many device errors aren’t device failures—they’re use errors. IEC 62366 exists to prevent exactly that.

Usability engineering ensures devices are intuitive, safe, and aligned with how real users behave under real conditions, including stress, fatigue, and distraction.

IEC 62366 has become a cornerstone of medical device design because regulators require manufacturers to show that human factors have been systematically addressed.

What is IEC 62366, and why does it matter?

IEC 62366 is the international standard defining how to apply usability engineering to medical devices. It provides a structured process for identifying use errors, reducing risks, and validating that the final interface supports safe and effective use.

The standard is split into:

• IEC 62366-1: The mandatory usability engineering process
  
  
• IEC 62366-2: Non-mandatory guidance and best practices
  
  

Global regulators—including the FDA and EU MDR—expect manufacturers to follow the principles of IEC 62366 when seeking device approval.

What is the usability engineering process under IEC 62366?

1. Define intended use and users

Identify:

• Who will use the device (clinicians, patients, caregivers)
  
  
• Where it will be used (hospital, home, emergency)
  
  
• What tasks they must perform
  
  

This shapes every design decision.

2. Identify use-related hazards

Usability engineers analyze:

• Steps where mistakes could happen
  
  
• Potential misunderstandings
  
  
• Environmental challenges (lighting, noise, stress)
  
  

These insights feed into risk management.

3. Identify critical tasks

Critical tasks are those where mistakes could result in harm. These become the primary focus of usability design and testing.

4. Create user interface (UI) design requirements

These requirements describe:

• Display readability
  
  
• Button placement
  
  
• Alerts and feedback
  
  
• Interaction flows
  
  
• Error prevention mechanisms
  
  

They form the blueprint for the UI.

5. Mitigate risks through design

Examples include:

• Autolocking features
  
  
• Confirmation dialogs
  
  
• Standardized icons
  
  
• Simplified workflows
  
  
• Physical design changes
  
  

Usability is risk reduction.

6. Conduct formative testing

Formative tests explore how users interact with prototypes to uncover problems early. They inform iterative design improvements.

This stage answers questions like:

• “Do users understand this step?”
  
  
• “Are they misinterpreting this icon?”
  
  
• “Where are they hesitating?”
  
  

7. Conduct summative (validation) testing

Summative testing validates the final design by observing representative users performing critical tasks without assistance.
Regulators expect:

• Realistic simulated environments
  
  
• Representative users
  
  
• Defined acceptance criteria
  
  
• Clear evidence that risks are mitigated
  
  

Failure here requires redesign—and potentially a repeat of testing.

8. Document everything in the Usability Engineering File

Documentation includes:

• User profiles
  
  
• Hazard analyses
  
  
• Task flows
  
  
• Test plans and reports
  
  
• UI requirements
  
  
• Traceability to risk management
  
  

Regulatory reviewers pay close attention to this file.

How does IEC 62366 support innovation?

Good usability isn’t a regulatory burden—it’s an innovation accelerator. It:

• Reduces costly post-launch fixes
  
  
• Minimizes training needs
  
  
• Improves market adoption
  
  
• Enhances clinical trust
  
  
• Lowers the risk of recalls
  
  

Products that meet IEC 62366 aren't just compliant—they’re safer, more intuitive, and more competitive.

Why is usability engineering more important than ever?

Modern devices increasingly combine software, hardware, automation, and AI. As complexity rises, so does the potential for user error.

IEC 62366 gives medtech teams a systematic way to:

• Understand user limitations
  
  
• Design for real environments
  
  
• Reduce avoidable harm
  
  
• Demonstrate safety to regulators
  
  
• Differentiate on usability
  
  

Medical devices succeed when real users can use them safely and effectively. IEC 62366 ensures that happens.

‍