Jan 29, 2020

Emergo by UL’s Human Factors Research & Design division spends a lot of time with the users of medical devices, exploring their preferences for user interfaces. We’ve noticed a strong trend in which users bring their preferences for consumer products into the medical field.

For patients and users who wear medical devices (what we have come to call “wearables”), they bring the same set of needs, devices, preferences and motivations to bear on medical devices just as they do for consumer devices. For example, wearables usually include some type of sensor and include a user interface that communicates various data to the user in real-time.

So, if user preferences for wearable medical devices  are being shaped by consumer products, what lessons can we learn from the success of consumer wearables?

Lesson #1: People like wearing things on their wrists.

According to research, people prefer wearing devices on their wrists; of the 126 million wearable devices forecasted to be shipped in 2019, 80% are wristwear devices. Clearly, most people prefer to wear devices on their wrists; or maybe the technology is not exploring other options?

Perhaps the truth is a bit of both. In any case, consider a few human factors benefits the wrist can provide as an interface location:

  • Most users without impairments can easily move their wrist to gain a clearer or closer view of a device’s interface.
  • People are socially and physically accustom to wearing items on the wrist (e.g., watches, bracelets).
  • Accommodating different-sized wrists can typically be achieved without different-sized products.
  • A wrist-worn device does not require adhesive.
  • The larger hand shape and larger forearm shape creates a natural “valley” at the wrist, allowing the user to select a certain range of tightness without fear of the wrist device slipping off their body.
  • The skin around the wrist is exposed to daily friction against the body, clothes and surrounding environment (e.g., desk), arguably making it less sensitive to a band of material than perhaps other areas (for example, the skin at the inside of the upper arm).

Top tip – If in doubt, design a wearable that fits on the wrist.


Lesson #2: Provide real-time sensors

All elements of consumable wearables involve some type of sensor. Wearables are being used widely in sports coaching. For example, top-line sports coaches use wearable sensors to track their athletes’ vital signs, thus allowing them to tweak the coaching regime to maximize performance. Wearables are even worn during big sports games, enabling the touchline coach to monitor each player’s pitch position and running profile.

Medical devices can also use sensors to track patterns and provide a baseline on which conditions can be identified and/or therapies can be adjusted for maximum effectiveness. For example, trials are currently underway for wearable sensors that help clinicians diagnose ADHD in children. However, sensors can also track real-time data and alert users to emergent situations so they can take action, before potential harm occurs. Some continuous glucose monitors can track trend lines and alert the user if the software predicts that the blood glucose might rise above or dip below a healthy level in the near future.

Importantly, people are likely to expect real-time feedback from today’s technology. Wearable medical devices should provide clinical data to users when it is appropriate and accurate--which might mean that it cannot be real-time. However, designers should consider how a wearable can nonetheless converse with the user to facilitate confidence and awareness of the device’s status.

Top tip – Provide real-time feedback, whether it be clinically-based (if possible), or at least pertaining to a device’s status.


Lesson #3: The wearer’s self-image is powerful

Consider the humble wristwatch. It has a simple function, to tell the time. Wristwatches can be purchased for a couple of dollars. But one could also spend $30,000 on a Rolex. Why? It performs the same function as the $2 watch. Because of the power of self-image. An expensive branded watch makes the wearer feel better about themselves than a $2 watch would.

People who are seriously unwell and are relying on a wearable medical device are still people with a sense of self-image. They prefer devices that are visually appealing. We are becoming more familiar with wearables, and the manufacturers of consumer wearables understand the powerful force of fashion. Ugly wearables, and in particular wearables that look like prototypical “medical” devices will not succeed in this market. Given a choice between a medical device that looks overtly medical and one that looks like a consumer product, users consistently choose the consumer design. Moreover, manufacturers of modern hearing aids are making this medical device so discreet it almost disappears;  some new “in-ear” models have no externally visible signs that the wearer is wearing one.

Top tip – Design medical wearables that are discrete and visually appealing.


Lesson #4 – Make an app for that

According to online figures, there are upwards of 3 million apps available in the Google Play store, and more than 140 billion apps have been downloaded from the Apple store.

Now consider that wearable devices such as smartwatches and the FitBit, which are extremely popular, also include a corresponding app. The “Smartphone + App” model has become part of a wearable network that is here to stay. An app can reinforce a positive user experience at the digital touchpoint; a place where confidence, community, and guidance, among other things, can be provided in a vast degree of innovative presentations. Medical wearables are going to have to integrate seamlessly into this world, beyond just the utilitarian needs of managing a physical component on the body.

Taking even just an ergonomic perspective, including a smartphone app creates a multi-component interface with some inherent design advantages:

  • The app relieves the burden on the wearable component to convey all the use-related information, thereby enabling it to be smaller.
  • Similarly, the wearable component does not necessarily need to be positioned to maximize viewing, thereby enabling placement at the most clinically relevant location.
  • Apps can provide users with quick access to guidance and information about how the device functions and the experience they should expect.
  • Functions can potentially be split between the app and the wearable component to enhance reliability and usability. For example, subtle, infrequently used programming controls might be best in the app, thereby letting the wearable contain only a couple of robust, simple physical controls that might be needed frequently or in an emergency.  

It would be a brave manufacturer who tries to entice users away from this familiar, proven and ubiquitous model.

Top tip – Integrate medical wearables within the ‘smartwatch + app’ model.


Some final thoughts

Wearable medical devices coexist with consumer wearables, and increasingly (think Apple Watch), the two types of wearable inhabit the same world. Manufacturers of consumer wearables are driving most of the design decisions; medical devices are late to the wearable space and are playing catch-up. There’s an old saying – “if you can’t beat ‘em, join ‘em”.

Consumer wearables are developing at an accelerating rate and are shaping user preferences. The good news is that most of the early design disasters (think Google Glass) have made their mistakes, learned theie lesson and moved on.

The smart (forgive the pun) developer of medical wearables has a wealth of knowledge that can be learned from the consumer world. The four lessons in this blog just scratch the surface of potential sources of inspiration.

Cory Costantino is Director of User Interface Design and Richard Featherstone is Research Director at Emergo by UL’s Human Factors Research & Design division.

Related human factors engineering (HFE) and usability information:

  • HFE user research for medical devices and IVDs
  • Human factors design and prototype development support
  • Whitepaper: Applying human factors to wearable medical devices
  • Webinar: Methods for identifying potential use errors in medical devices



  • Cory Costantino and Richard Featherstone