Human Factors and Accessibility in Medical Device Interface Design

A radiographer prepping a CT injector has seconds to make a call. If an interface makes them pause, guess, or hunt for a setting, the delay carries risk. If you get the interface wrong, you’re facing failed usability studies, regulatory pushback, and a product that clinicians hesitate to trust.

Below, we unpack how the ANSI/AAMI HE75:2025 Human Factors Engineering (HFE) standard shapes the design of safe, effective interfaces at IDE. We also explain why following the standard alone isn’t enough to get a device to market with confidence.

ANSI/AAMI HE75:2025 is the reference standard for human factors engineering in medical devices. It guides teams on reducing user error, supporting clinical workflows, and designing interfaces people can operate under pressure.

While a substantial update was delivered in 2026 there were minimal changes in addressing digital interfaces and the digital habits users now bring to every screen they touch. HE75 was written with physical devices in mind and doesn’t fully address the interface paradigms clinicians and patients now expect as standard.

That leaves a real question for any team building a digital interface: what else is needed beyond a standard to design a safe medical device?

The Web Content Accessibility Guidelines (WCAG) is a technical standard for designing digital interfaces that work for people with different visual, auditory, cognitive, and motor needs. It covers requirements like contrast, readability, keyboard access, and screen reader compatibility.

For a buyer bringing a device to market, incorporating WCAG is a commercial decision with three direct payoffs:

• Inclusivity. Users with visual, auditory, or motor impairments can operate your device without a workaround.
• Compliance. Regulators and health institutions increasingly expect accessibility as standard, not an add-on.
• Consistency. Your interface behaves the way users already expect from the digital products they use every day, which shortens the learning curve.

At IDE, every Graphical User Interface (GUI) is designed to be perceivable, operable, understandable, and robust. In practice, that means contrast checking, text alternatives, colour-independent information, clear navigation, and testing labels for comprehension with real users, not just design review.

Imaxeon, a Bayer Healthcare radiology device manufacturer, engaged IDE to help develop and commercialize an innovative CT injector. The goal was to improve setup efficiency, reduce interface confusion, and free radiographers to spend more time with their patient rather than the machine.

IDE tested the GUI iteratively with radiographers across multiple global locations. This early, distributed testing is what surfaced usability issues before they became expensive fixes late in development or, worse, field complaints after launch. The result was an interface that supported radiographers with the right information at the right time, fits smoothly into their existing workflows, and holds up across varied clinical settings.

The design relied on the same principles outlined above:

• High-contrast visuals kept text, icons, and controls visible and distinguishable, regardless of a user’s vision or the lighting in the room.
• Colour-independent information meant nothing critical depended on colour alone, cutting the risk of use errors or delayed decision-making.
• Clear text alternatives described icons, symbols, and controls plainly, so radiographers could read them accurately even under glare, fatigue, time pressure, or while wearing PPE.
• Logical navigation meant users always knew where they were, where they could go, and how to get there.

After formative usability testing and feedback analysis, we updated the GUI and repeated the process, as part of our commitment to iterative design.

Accessibility standards set a baseline. Modern UI/UX practices raise the bar. Responsive layouts, clear affordances, and consistent interaction patterns reduce the cognitive load on a user who’s already managing a clinical task.

Together, these practices close the gap between the safety-driven structure medical interfaces require, and the intuitive experience users have come to expect from consumer technologies. For a buyer, that gap is where your adoption risk lives. A device that’s technically compliant but feels unfamiliar risks slower uptake, increased training overheads, and more support calls after launch.

Software platform frameworks provide another layer of complexity. Google’s Material Design (for Android) and Apple’s Human Interface Guidelines (HIG) (for iOS) set the conventions users already know from the apps on their phones or tablets.

Material Design favours strong visual hierarchy, motion that gives feedback, and layouts that adapt across the wide range of devices in the market. HIG favours clarity and a clean, focused interface that stays out of the user’s way. Neither approach is better. They solve for different ecosystems, and a device that ignores its platform convention asks users to relearn habits they have already developed.

IDE applied this thinking when developing a home-use radiology image viewer, built as native apps for both iOS and Android. Every screen was built to match the conventions of its platform: menus, navigation, filter types, authentication, and input design were each designed to feel native, not ported. For a patient checking their own scan results at home, familiarity is the difference between confidence and confusion.

In short, standards like HE75 provide a safety-led foundation. WCAG and platform-specific design give you the fluency users already expect. Neither one on its own gets you to a device that people trust and adopt quickly. Together, coupled with modern UX/UI practices, they do.