Design validation for an insulin delivery device
Several interaction patterns that looked entirely reasonable in design reviews created measurable hesitation the moment real users tried them in realistic conditions. Testing found this before manufacturing locked anything in.
Design decisions that feel obvious until someone actually uses the device
Medical devices must be intuitive, safe, and reliable in everyday environments - not in the controlled conditions of a design studio. For insulin delivery devices, the stakes are particularly high: errors in operation aren't abstract usability failures, they are clinical risks.
Early stage design decisions carry disproportionate weight. Device shape, control placement, interaction sequences, feedback mechanisms - these choices, once committed to tooling and manufacturing, are expensive and time-consuming to reverse. And yet the standard design review process - internal teams evaluating prototypes against specifications - has a systematic blind spot: it cannot surface the moments of hesitation, misinterpretation, and operational uncertainty that only emerge when someone who hasn't spent months thinking about the device tries to use it in conditions that resemble real life.
The product team had five viable design directions. They needed evidence to choose between them, and to know which specific interaction patterns would create problems before any decision was final.
Five variants, real users, realistic conditions
Participation Studio designed and facilitated an in-person design validation programme with participants recruited specifically because they lived with diabetes and would realistically be users of the product category being developed. Recruitment screened for relevant experience, ensuring that participants' interactions with the prototypes would reflect genuine user behaviour rather than first-contact novelty.
Five prototype device variants were created using 3D-printed test units - a manufacturing approach that allowed realistic physical interaction with alternative design concepts without committing to full production tooling. Each variant represented a distinct configuration of key design parameters: form factor, control placement, operational sequence, and physical feedback.
Participants completed realistic usage scenarios with each device while researchers observed behaviour in detail - not asking "what do you think of this?" but watching what people actually did: where they hesitated, where they looked, what they tried first, where they corrected themselves. Sessions were filmed with participant consent to support frame-by-frame behavioural analysis after the fact.
Timed task completion was incorporated alongside observational methods, providing quantitative signal to complement qualitative insight about user confidence and operational fluency.
What the research involved
What testing revealed
Testing revealed clear preferences between device configurations, with specific design elements shown to significantly affect user confidence and ease of operation. Several interaction patterns that had appeared viable in design review created measurable hesitation or operational uncertainty during real use scenarios - findings that would have been invisible until post-launch complaint data arrived.
The comparison between variants was productive precisely because it was structured: participants interacted with all five configurations, allowing direct comparison rather than isolated evaluation. This surfaced not just which elements worked better, but why - the specific physical and cognitive factors that shaped the user experience of each design direction.
Behavioural observation proved essential here. Post-use questionnaires alone would have missed many of the most important findings - the moments of confusion that participants resolved and didn't report, the compensatory strategies people developed to work around interface elements that weren't quite right, the physical interactions that video analysis later revealed were being performed incorrectly despite the participant being unaware of the issue.
Several specific interaction patterns that appeared viable in the design brief were shown to create hesitation in real use. These were identifiable, addressable design problems - surfaced before any manufacturing decisions were final.
Evidence before commitment
The research allowed the product team to refine the final device design on the basis of evidence from real users in realistic conditions - before committing to manufacturing. This prevented costly redesign cycles that would have been required had usability issues emerged after the product launch.
The study also provided human factors evidence that supports regulatory submission processes - documentation of how the device performs for its intended user population under realistic use conditions, produced through a structured methodology.
We fully recognise the effort your team invested in recruitment, moderation, and analysis, and we genuinely appreciate the quality of the discussions and reporting.
- Usability problems in an insulin device surfaced before manufacturing locked anything in, with human factors evidence supporting the regulatory submission.
- An NHS patient portal team got a prioritised, evidenced list of adoption barriers, and the highest-leverage fix wasn't the one they expected.
- Patient involvement changed a trial's primary endpoint before the protocol was finalised, cited by the ethics committee as a model for evidencing PPIE.
Trusted PPI and PPIE delivery partner to the NIHR HealthTech Research Centre in Accelerated Surgical Care.
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