The user interface (German: Benutzungsschnittstelle) comprises, according to IEC 62366-1, all means by which a user interacts with a medical device, deliberately defined broadly and extending beyond the device itself. This includes displays and controls as well as packaging, labeling, instructions for use, and training materials.
Why the standard deliberately defines the term broadly
In everyday language, "user interface" is often equated with what can be seen on a screen. This narrowing is one of the most common reasons why usability assessments remain incomplete: A use error often arises at a point that does not appear at all in a purely device-oriented view: a misleading packaging label, an unclear passage in the instructions for use, or training that does not reflect the actual workflow.
The standard addresses this by defining the user interface as the totality of all touchpoints. This breadth is not a regulatory formality but a substantive necessity: A user does not experience a product as a device alone but as a continuous experience from the first contact with the packaging to disposal.
The components in detail
- Hardware controls: buttons, dials, switches, connectors; see human-machine interface.
- Software interfaces: displays, menu navigation, softkeys, app connections.
- Displays and signals: visual, acoustic, and haptic feedback on the system state.
- Labeling: rating plate, symbols, warnings on the product itself.
- Packaging: often the very first interaction, especially for sterile or single-use products.
- Instructions for use and accompanying materials: paper or electronic IFU, quick guides, labels on accessories.
- Training materials: instruction documents, e-learning, manufacturer on-site training.
Each of these components can contribute to a use error on its own and must therefore be considered separately in analysis and evaluation, not merely as a side note to the actual operation of the device.
Consequences for analysis and evaluation
The broad definition directly determines the scope of the task analysis and the use-related risk analysis: Both must include all components of the user interface, not just device operation. A task analysis that begins at the first button press has skipped the moment when the user opens the packaging, checks the labeling, or consults the instructions for use, and experience shows that distinct types of errors arise precisely there.
The same applies to formative and summative studies: If only device operation is tested, it remains unclear whether users open the packaging correctly, interpret the labeling correctly, or consult the instructions for use at all when needed. A complete test setup therefore reflects the entire sequence, from first contact to the end of use.
The requirements for the individual components of the user interface are usually documented in the user interface specification, which builds on the use specification with its information on users, tasks, and use environments. For critical tasks, the user interface must also be designed so that use errors can be prevented, detected, or limited in their effects.
How the components interact
The components of the user interface do not act independently of one another but must be consistent with each other. A symbol on the device that does not match the explanation in the instructions for use, or training that teaches a different operating sequence than the actual software interface, creates exactly the kind of violated expectation that promotes use errors.
In practice, this consistency is particularly at risk when different teams are responsible for the device, packaging, documentation, and training and work without joint coordination. A central responsibility for the user interface as a whole, not just for the device, is therefore an effective organizational countermeasure.
Typical gaps in practice
- Packaging as an afterthought. Opening sterile packaging under time pressure or while wearing gloves is rarely tested with the same care as the actual operation of the device.
- Training as a black box. Training content is created but not checked for whether it actually leads to correct behavior in real use.
- Documentation written after the fact. Instructions for use and labeling are created only after the device design is complete and are therefore no longer included in the use-related risk analysis.
- Inconsistent terminology. Software, labeling, and documentation use different terms for the same thing.
Regulatory reference
IEC 62366-1 defines the user interface broadly, as all means by which the user and the medical device interact, including the accompanying documentation. Packaging and documentation thus belong in the risk assessment. IEC 62366-2 makes this definition more concrete with practical examples.
The EU Medical Device Regulation (MDR) requires in Annex I minimum content for labeling and instructions for use as part of product safety. The FDA Human Factors Guidance takes the same broad view and explicitly includes packaging, labeling, and accompanying materials in human factors validation testing.
The user interface is more than the device: It comprises every touchpoint between user and product, from packaging through labeling and instructions for use to training. This breadth is not a formality but reflects where use errors actually arise in practice.
Analysis and evaluation must accordingly include all components. A test setup that begins only at device operation does not test the complete user experience.
Frequently asked questions (FAQ)
Is the user interface the same as the human-machine interface?
No. The human-machine interface typically describes the direct hardware and software elements of a product, such as display, buttons, and dials. The user interface according to IEC 62366-1 is the more comprehensive term and additionally includes labeling, packaging, instructions for use, and training materials.
Does packaging really belong to the user interface?
Yes. According to IEC 62366-1, every touchpoint between user and product belongs to the user interface. For sterile or single-use products, opening the packaging is often the first and sometimes most error-prone interaction of all and must be analyzed and tested accordingly.
Does training have to be included in the use-related risk analysis?
Yes, if it is part of the intended use sequence. If instruction is assumed, it must be checked whether it actually leads to correct behavior, not just whether it is complete in content. Training that does not work does not compensate for a design deficit.
What happens if the device, packaging, and documentation use different terminology?
This creates violated expectations that promote use errors: A user who interprets a symbol on the device differently than explained in the instructions for use makes a decision based on a wrong premise. Consistent terminology across all components is therefore a simple but effective design principle.
Is it enough to test only the device in usability tests?
No. A test setup that begins at device operation skips the moment of opening the packaging, checking the labeling, and consulting the IFU, moments in which experience shows that distinct types of errors arise. A complete test reflects the entire sequence from first contact to the end of use.
Do you want to consider your user interface as a whole, from opening the packaging to disposal? We support you throughout the usability engineering process.
More about our usability engineeringSources
- IEC 62366-1:2015+AMD1:2020, Medical devices, Part 1: Application of usability engineering to medical devices
- IEC/TR 62366-2:2016, Medical devices, Part 2: Guidance on the application of usability engineering to medical devices
- Regulation (EU) 2017/745 on medical devices (MDR)
- FDA Guidance: Applying Human Factors and Usability Engineering to Medical Devices