Human Factors

Human Factors and Usability in Medical Device Development

Understanding and applying human factors is essential to ensuring product usability and user satisfaction.  Consideration of human factors also helps to ensure patient safety by minimizing the risk introduced by user error.  Libra Medical understands the fundamental principles of human factors and how the core concept of human factors fit into the larger context of medical device software and hardware development.  We can help you with the integration of human factors and usability into the development lifecycle, regulatory considerations including applicable FDA guidance and standards (ANSI/IEC), and human factors methods and necessary documentation.

Design Process -Human Factors Usability Requirements 

As a manufacturer, you are required by the FDA to demonstrate how human factors considerations were met during your product’s development.  The underlying driver behind the FDA’s human factors requirements lay in Section 820.30 of the Quality Systems Regulation or QSR, in paragraphs c, f and g:


“Each manufacturer shall establish and maintain procedures to ensure that the design requirements relating to a device are appropriate and address the intended use of the device, including the needs of the users and patient.”

The FDA’s goal is to ensure that manufacturers make a systematic assessment of who will be using a device (user population), the conditions under which it will be used (use environment, situational factors), how it will be used (tasks, usage scenarios for the full life of the product), and whether there are use related hazards (can it be used safely).


Human factors activities for generating design inputs include things like user research studies (focus groups, one-on-one interviews, contextual inquiry), task analysis, Usability & Safety Bench Tests, and usability testing of design concepts.


“Each manufacturer shall establish and maintain procedures for verifying the design input.  Design verification shall confirm that the design output meets the design input requirements.” Verification pertains to inspection, analysis, and testing of your device against requirements.  Human Factors techniques for verification include Usability & Safety Bench Tests and usability testing.


“Design validation shall ensure that devices conform to defined user needs and intended uses, and shall include testing of production units under actual or simulated use conditions.” Validation addresses the broader issue of whether the device can be used safely in real-world situations.  The FDA expects you to conduct usability testing with actual users under simulated (but as real as possible) conditions, using production or pre-production models.  The primary human factors techniques for design validation is usability testing.

Section 820.30 of the Quality Systems Regulation or QSR, paragraph (g) also references risk analysis: “Design validation shall include… risk analysis…” Throughout product design and development, FDA expects manufactures to engage in risk management.  The human factors focus for risk management is on so-called use-related errors.  Risk management of use-related errors involves identifying user interface design changes that eliminate or mitigate risk, verifying that design changes do mitigate risk and that no new hazards are introduced, and validating that the final device can be used safely and effectively.  These goals can usually be met as part of the task analysis, expert review, and usability testing activities discussed above.

The FDA expects investments in human factors by manufacturers to be commensurate with a device’s inherent risk: the greater the risk associated with error, the more human factors effort is warranted.  However, there are no hard and fast rules (only guidelines) and in the end, it’s up to each manufacturer to decide what human factors work to conduct during product development.  Device manufacturers need to be satisfied that what they have done is sufficient to ensure that their device can be used safely and effectively, and that they can justify their level of human factors effort to the FDA, if needed.