Human Factors and Usability are “hot topics” in the medical device world (and increasingly for drug/device combination products too), yet the concept and the disciplines are not new. Designers and Developers have, at some level, been considering the user for years. But, it’s not just about “User Centred Design”.

A toe in the water with Human Factors

When I started in Device Evaluation, more years ago than I care to remember, we thought we viewed the device designs from a user perspective. I conducted Failure Mode and Effect Analyses (FMEAs) looking at all the ways users could destroy or misuse our devices. We even did a lot of user trials, though they were mostly with colleagues. My first thought, when I came across “Usability” back then, was that it’s the stuff we did when we tested the instructions with others in the development team.

Device Evaluation and Human Factors

How perspectives change. Across more than 15 years in Device Evaluation , I spent many happy months destroying devices (known as robustness testing) in a materials testing lab. Looking back, Human Factors at that time seemed the forgotten twin sister of device testing. It was the element often overlooked or dismissed in favour of purely physical testing.

Sometimes, I started testing a device in a lab, only to discover that I used it incorrectly and had to start over. At the time I put these lapses down to being forgetful, not concentrating properly or that the device was “just annoying”.

In the intervening years, I’ve studied and practised Human Factors in depth. You might be expecting me to recount the story of my turning point. Yet I had no sudden epiphany, no ray of sunlight breaking through the clouds. Rather I had a growing appreciation of the rich variation in how people think and behave.

Study has armed me with a more extensive arsenal of tools with which to understand users better. Experience has taught me that we ask a lot of people, when they get hold of these devices. Even tasks as simple as removing a device cap can be tricky. In fact cap fit is one of the hardest things to get right with many devices, particularly combination products.

The dangers of focussing on just Device Evaluation

That reminds me of a combination drug / device project I worked on a few years ago. I spent many hours performing cap fit tests, passing and failing batches based on the axial force required to pull the caps off. Part way through the tests I observed a user study where most people applied a sideways bending action to pull the cap off. The sideways bend weakened the device, causing it to fall apart shortly after. I had to question the point of all that axial testing… so much for fine tuning the cap design for the axial pull apart force!

Performing user studies, or getting “real” user thoughts, can make a world of difference to what you classify as being critical to design. Yes, the axial pull apart force was important to cap removal, but critical to creating a robust design was how the device was really used.

Why Human Factors and Device Evaluation are closely related

old twin sistersYou can perhaps see why these two disciplines are twins. Often, one of the two seems to be ignored or forgotten by development teams. Perhaps that’s a result of the twins being very different in nature, as siblings often are. On the one hand, you have a discipline that is very method and results data driven, mechanical and “hands on”. On the other hand you have a discipline that’s focussed on thoughts, actions and reactions of uncontrollable test participants.

Development teams seem to have a natural preference for one or the other, a comfortableness that fits with their collective learning style. Similar to our development as human beings, recognising the potential weakness or blind spot is the first (and biggest) step to beefing it up, to get the balance right.

What happens if you focus too much on one twin?

Consider what happens when you do as much physical lab testing as you like, but miss something obvious like how people really remove a device cap. Then, it’s back to the drawing board for the design, with all the delays, costs and lost profits that entails.

Consider what happens when you do lots of Usability testing with your device design, get great results from the final design iteration, but the device falls apart or stops working as expected when subjected to repeated use. Again it’s back to the drawing board to improve the robustness of the design, with delays, cost increases and lost opportunities for profit.

It can be hard to recognise an imbalance between the twins and address it.

You may already be thinking about getting in touch with us to check if you’re treating both siblings equally and how to achieve balance. Pick up the phone or email us today.