Why can’t it be more like an iPad, only safety critical?

Published on: 31st March 2016

Improving user experience is an increasingly cited motivation in medical device development. To develop experiences for medical devices that match users’ expectations an approach is needed that can mirror the pace of iteration and experimentation seen in consumer devices. The challenge, however, is that this approach must continue to meet the needs of a controlled medical device development process. This article discusses the role of interaction prototyping in bringing rapid iteration, and design exploration within the constraints of safety critical device development.

It’s a question that most people working with medical devices will have faced, ‘why can’t it be more like my tablet or smartphone?’ It can be very tempting to dismiss the question, and explain away the differences, by pointing out that the medical devices are safety critical and, thus, must be developed in a different way. However, if we are to gain the engagement with medical devices we all hope for, it’s important to understand what we can learn from large tech companies and consider how this can be applied to the rather different world of medical devices.

The number of interactive medical devices is unquestionably growing. With processing power being used to tackle technical, safety and convenience challenges, the importance of usability within medical devices is becoming well understood. This growth of awareness has been accelerated by regulators mandating a structured human factors and usability process. Coupled with this general awareness of the need for usability, there is also a growing trend for patients (and to some extent untrained carers) to take greater control of their health care – often taking more responsibility for monitoring their condition and administering treatment.

The US Food and Drug Administration (FDA) is clear that medical devices need to be demonstrably safe and effective before they can go to market. Alongside this clear need to explicitly consider safety and effectiveness, the importance of user satisfaction or user experience is continuing to gain traction. The core argument being that users are likely to be more engaged with a device that they like using.

User acceptance of any device is often set not only through direct interaction but also through expectations set in other devices. Perhaps the greatest expectations are set by the devices that we use most often – our smartphones and tablets.

The user experiences (UX) created for mobile devices and online services have grown out of tools, platforms and approaches that encourage experimentation, building on ideas in an environment in which ‘failure’ is not only survivable, but a metric used to select the most appropriate concept. Ideas can easily be sent out into the market to see if they gain traction (eBay and facebook both expanded from niche positions to global success), sites and apps can live in permanent Beta, and powerful frameworks can be built upon to facilitate rapid iteration and evolution of ideas – quite literally survival of the fittest and rejection of the weak. It is, in this environment, that the experiences driving user expectations have been generated.

The environment that medical devices are developed within is, necessarily, quite different and the consequences of failure range up to and include fatalities. Medical device development requires controlled and documented procedures that result in the production of validated code, and where development cycles of years rather than weeks is the norm. However, this does not mean that users necessarily appreciate these constraints or, even if they do, forgive poor quality experiences.

To develop experiences for medical devices that match users’ expectations, we need to leverage the benefits of the interaction design tools and development environment that drive consumer device experiences, and apply these to a controlled medical device development process.


One of the interaction design approaches that can be leveraged to bring rapid iteration to embedded medical device design is interaction prototyping. The term ‘interaction prototyping’ covers a range of methods that pull together hardware and software user interfaces to enable rapid exploration, evaluation and iteration. Techniques can range from Paper Prototyping, Wizard of Oz (simulating functionality – the classic example of this is IBM’s simulation of speech recognition), hacking together of different components using miniature computers (e.g. Arduinos) or embedding small touch screens in prototypes to very quickly create models that are apparently functional from an interaction perspective.

In applying these tools to the development of novel interactive medical devices at DCA, we have seen the following four key benefits:

  1. Seeing something sooner
  2. Integrated iteration
  3. Improved communication and stakeholder buy-in
  4. Reduced design changes during formal development

These benefits can be explored in the context of a development cycle in the figure below. The diagram shows the ‘traditional’ medical device development process in grey with the activities of hardware and software design in green and blue respectively. 



The first benefit is that interaction prototyping tools and approaches can be applied very early in the design process – where the costs of change are much lower and before the product requirements have been finalised.

Interaction prototyping can be pulled upfront in the development process to inform requirements capture and communicate design intent. Prototypes can be rapidly created and evaluated with users to explore the extents of what could be possible, challenge assumptions and test constraints. For instance, should a device have a touchscreen? Does it need to be multi-touch, or have haptic feedback? How will it work in-context? The principle of interaction prototyping is to rapidly ‘mock it up’ and try it out, building an evidence base to inform device specifications.


The second benefit of incorporating interaction prototyping in the development process is that the hardware and software interfaces are iterated together, rather than considered as separate elements. This is critical as the two interfaces are interrelated. The hardware sets constraints on the software design early in the design process, and changes to the hardware architecture can rapidly become both expensive and slow to implement. At the same time, the requirements of the software user interface impact the inputs, outputs and screen real estate required from the embedded hardware. Early integration of mock-up or prototype hardware and software elements of the interface enables an iterative development process where user feedback can be incorporated throughout the development cycle, and design challenges can efficiently be tackled early using both hardware and software as integrated solutions.


Clear communication is not just important for gathering user feedback. It is not uncommon for medical device development teams to come from a range of backgrounds, interaction prototyping can help to encourage communication between the hardware and software development teams, with prototypes providing a common reference for stakeholders from a variety of backgrounds to engage in the project.


Exploring and iterating a design idea using interaction prototypes allows early insights and discovery of user feedback that will help identify and define the desired user interface experience. Investing in early interaction prototyping can help reduce the UX changes later in the formal design development process. This is particularly valuable as changes to design late in the development process are typically costly, cause delay and require very rigorous implementation and validation to avoid potentially hidden safety issues.


If the quality of user experience of medical devices is expected to try to keep pace with that of consumer products, innovative approaches are, unquestionably, required. As discussed, the key differentiator between these markets is the tolerance of failure. As such, the pool of methods that can be borrowed from the consumer market is, necessarily, reduced. Interaction prototyping is just one of the approaches prevalent in consumer device design that, when applied considerately, can be leveraged to tackle the challenges of interactive medical device development.

As an approach, it can support building an evidence base for decision making. Furthermore, it allows experimentation and exploration, supports stakeholder alignment, and integrates usability and acceptance feedback throughout the development cycle. Set within the context of an integrated approach to device development, it can be an exceptionally powerful tool; facilitating evidence-based experimentation and flexibility in the early stages of the development process.

To keep pace with the consumer market and optimise usability, it is increasingly becoming essential to adopt such an approach for interactive medical device design.