Army nurse device operator

A device user interfacing with the equipment. An Army nurse perhaps trying to figure out how to silence an alarm


Device user interface includes all components of a device with which the user interacts, such as controls and displays (i.e., those parts of the device that users see, touch, and hear). The user interface also includes the device labeling, which includes package labels, any instructions for use in user manuals, package inserts, instructions on the device itself, and any accompanying informational materials.

To gain an understanding of the potential HFE/UE analyses that should be conducted for a particular device, you should consider:

Device user interface:

  • E.g., functions, capabilities, features, maintenance requirements
  • Indicated uses

These considerations, discussed in the following sections, will help you identify specific aspects of device use that are associated with potential use-related hazards that should be investigated through HFE/UE analysis and testing.

The user interface (see Figure 4) includes all components of a device with which users interact while using the device, preparing it for use (e.g., unpacking, set up, calibration), or performing maintenance (e.g., cleaning, replacing a battery, repairing). It includes:

  • The hardware components that control device operation such as switches, buttons, and knobs,
  • Device elements that provide information to the user such as indicator lights, displays, auditory and visual alarms,
  • The design of menu-driven interface systems,
  • The logic that directs how the system responds to user actions including how, when, and in what form information (feedback) is provided to the user,
  • The size and configuration of the device (particularly for hand-held devices), and
  • Device labeling, packaging, training materials, operating instructions, and other reference materials.

The most effective strategies to address use-related hazards in the premarket setting focus on improvements to the design of the device user interface. To the greatest extent possible, the user interface should convey the concept for correct operation through its appearance and operation (“look and feel”) so that safe and effective use is intuitive. A well-designed user interface will facilitate correct actions and will prevent or discourage actions that could result in hazards. Addressing use-related hazards by modifying the device design is generally more effective than revising the labeling or training. Labeling might not be accessible when needed, and training depends on memory, which might not be complete or accurate.

An important aspect of the user interface is the extent to which the logic of information display and control actions is consistent with users’ abilities, expectations, and likely behaviors. Users will expect devices and device components to operate in ways that are consistent with their experience with other similar devices or user interface elements. For example, users may expect the flow rate of a liquid or gaseous substance to increase or to decrease by turning a control knob in a specific direction based on their previous experience with other similar devices. Hazards result when, for example, an electronically-driven device control is designed to operate in the opposite direction of controls that were previously mechanical.

Increasingly, user interfaces for new medical devices are computer-based. In these cases, the interface controls may include: keyboards, mouses, styluses , and touchscreens. Other essential features of the user interface include the manner in which data is organized and presented, control and monitoring screens, screen components, prompts, navigation logic, alerting mechanisms, data entry requirements, and help functions. The design of these elements should take HFE/UE considerations into account.[1]


  1. FDA. Draft Guidance for Industry and Food and Drug Administration Staff - Applying Human Factors and Usability Engineering to Optimize Medical Device Design. June 22, 2011.