Picture this: you are in a meeting with your client setting requirements for their new medical device and the subject of the user interface comes up (and I mean the interface, not the GUI). Of course the client wants a sexy solution to his/her device, therefore a touchscreen must be the solution.
Furthermore, it has to be sleek and shiny so it must be capacitive and further still, he/she wants a massive screen size. Most people with smartphones demand this kind of interactivity and sleekness be implemented into their devices, forgetting about the whole reason for the screen in the first place: to tie the interaction between the user and their device.
When it comes to interfaces, whether they are a hard plastic button or a digital one on a screen, less is always more in medical devices. Listening to your users who live and breathe these devices everyday instead of marketing’s penchant for shiny things (and we designers love shiny things!) is always a wise choice. A good example of this came out a few years back during a research session with ultrasound technicians at a hospital. We wondered why they still preferred to use their older style ultrasound carts with the trackball and big tactile buttons instead of the new, much sleeker looking carts with touchscreens. They explained that while the new carts were nicer to look at, they missed a big mark when it came to the workflow of a typical ultrasound tech: they don’t look at where their fingers are during a screening and therefore rely on tactile feedback to tell them what they are doing. As we all know this is an area that touchscreens fall short: ever tried to text someone on your smartphone without looking at it? Practically impossible. Therefore out into the hall of shame (literally), go the sleek carts, joining the hospital’s other unused medical devices.
So let’s say you get past this and touchscreens are the definite choice, then there is the issue of technology. Many wonder why most medical devices still opt for the resistive flavor over capacitive. This really comes down to numbers. While resistive screens are generally the older, uglier and clumsier sibling of capacitive screens, they are more established and therefore reliable sources of reputable suppliers are more readily available. In order to obtain regulatory approval for your device you’d prefer to source parts that will be available for a minimum of 5-7 years to minimize production disruptions. Sourcing a cap touch screen that will still be available in that timeframe is difficult in an industry where most touch screen users are companies such as large smartphone manufacturers whose product lines change more often than the weather. This is improving as capacitive touch screen technology matures, more stable supply chains materialize and better long term solutions become available for medical device manufacturers.
Then finally there is the issue of practicality. While it is true that nowadays touchscreens are often the cheaper solution, is it wise to introduce another layer of software abstraction into a potentially life-supporting application that used to be simply done by reliable hardware and big tactile buttons? A good example that comes to mind was Hospira’s Symbiq infusion pump system recall in which incorrect inputs to patient’s drug metering quantities could potentially have catastrophic results such as patient death. In this case, one of the issues was improper finger-to-touchscreen calibration, a non-existent problem with a physical tactile button setup. We must also consider the ergonomic challenges, such as the lack of tactile feedback and how the hand and fingers shadow certain bits of information when the user reaches for a function (although that’s a whole other story for a later date).
Having said all that, touchscreens do have their significant advantages such as: cleanability (a huge plus in most clinical settings), ease of interface reconfiguration (especially when you’re still in the development stage) and durability (no mechanical elements). Just make sure that when a client brings up the question of touchscreens it’s for the right reasons and not just to up the bling factor.