Feb 27, 2018

When designing mobile applications for medical purposes, developers should keep the issue of safe and effective use top of mind.

There are several millions of apps available through such sources as Apple and Google. There are also plenty of apps that serve medical purpose. Some apps support the work of healthcare professionals, such as providing them with convenient access to medical information databases. Some make it convenient for patients to share information with their doctors, such as in the case of individuals being treated for Multiple Sclerosis who are on a precise medication regimen.

The latter example, in particular, raises questions about the apps’ safe and effective use. This is even more the case when the apps are directly involved in determining medication doses, monitoring a person’s physical condition, and even triggering a particular medical device’s performance (e.g., directing an infusion pump to release a bolus of insulin).

Avoiding harmful use errors

Accordingly, mobile medical app designers need to make sure they are preventing potentially harmful use errors. A developer’s user interface design and evaluation experience should help ensure that an app has the following positive features:

  • Text that is still legible when the device is held at an arm’s reach, suggesting that letterforms should be at least 10 pt. (10/72 inch) and perhaps larger if the app might be used by people with poor vision.
  • User is required to confirm critical actions before they take effect.
  • The mobile app can only connect to the correct, associated medical device and none other.
  • Clear indication if displayed information is current (i.e., real time) or aged to some degree.
  • No toggle ambiguities; cases in which it is difficult to tell if a feature is already turned on, or it is off and able to be turned on.
  • Record of actions, where appropriate, so that users can tell if they already performed an action or not.
  • On-screen controls are protected against unintended actuation, such as due to brushing the touchscreen.
  • Critical information appears on the main screen.
  • Audible alerts (e.g., warnings) are loud enough to be heard in the intended use environment.
  • Critical functions do not depend on Internet access.

In addition to designing apps that prevent harmful use errors, there is a need for good cybersecurity; a separate topic from human factors engineering.

Michael Wiklund is General Manager of Human Factors Engineering at UL. Read more about medical device design and usability on the UL Wiklund website.

More resources on medical device and app regulations:



  • Michael Wiklund