UX design · Health tech
CardioPal
A companion app for a handheld EKG device, designed across 25-plus screens. The job of this interface isn't to look impressive — it's to make someone tracking their own heart health feel calm, not alarmed, at every step.
Solo project: every screen, flow, and testing round was designed and run independently.
This is the actual clickable prototype across all 25-plus screens, the closest thing this project has to a real screenshot. Try the onboarding flow, then add a caregiver to see where testers actually got stuck.
Context and the design challenge
CardioPal supports people recording and reviewing EKG data through a connected handheld device. Because it sits in a health context, the interface has to feel clear, comfortable and trustworthy for users of very different ages and technical comfort levels, rather than just usable in the abstract. By Submission 1 this was a handful of early wireframes and some sketches hinting at a direction; the idea was clear in my head, the design hadn't caught up to it yet.
The biggest shift since then was learning to think in user journeys instead of isolated screens. Onboarding is the clearest example: I initially didn't think it was necessary, until I considered someone using a handheld EKG device for the first time and realised the first screens they see have to reassure them before anything else. Clarity, in a health context, is itself a form of comfort.
What CardioPal does
Every one of the 25-plus screens sits under a small set of jobs the app has to do. None of them are about looking impressive — each exists because a real task or a testing result made it necessary.
Feature set
Capture a reading from the connected handheld device and review it without wading through raw waveform data.
See how a reading sits against earlier ones, so a single number isn't read in isolation.
Add a caregiver and send them a report directly, so a reading isn't a number only you see alone.
Flags patterns worth a second look, including possible arrhythmia indicators. It's a prompt to check with a clinician, not a diagnosis or medically validated functionality.
Recordings and history stay available even without a live connection.
Usability testing
Two participants, aged 25 and 45, both with intermediate experience using health and wellness apps but no prior exposure to CardioPal specifically.
Sessions ran remotely, 15 to 20 minutes each, with each participant completing a fixed set of tasks: log in, view the how-to guide, add a caregiver, send a report, interact with recommended actions, toggle auto-sharing, and edit account details.
What this doesn't tell us
Two remote sessions is an exploratory sample, not a statistically significant one. These numbers describe what happened in two specific sessions — where two people hesitated, and what they said out loud — not a validated success rate for a wider population. That's a real limitation, not a caveat to skim past.
What changed because of it
Growing the prototype from a handful of screens to more than twenty-five forced real decisions about navigation, layout and consistency that a smaller prototype could comfortably avoid. Four changes came directly out of testing and that growth:
A complete onboarding flow was added, plus a clear how-to section for EKG recording, so the first screens someone sees reassure them before anything else.
A structured bottom navigation bar became the anchor for the whole app, replacing what had been a more linear stack of screens.
Smaller tasks (editing details, adding a caregiver, previewing insights, sending a report) moved into modal pop-ups instead of full pages, so the interface stopped feeling like an endless stack.
Copy was tightened throughout, spacing and components made consistent, and quick insight previews were added so checking a number doesn't require a separate screen.
That scale is also where the calmer, more grounded visual tone actually started to hold together as a system, rather than a collection of nice individual screens.
What I'd still improve
The caregiver and report flows still need clearer step-by-step guidance so users aren't left guessing at field meanings or action order. The edit affordance needs a proper icon rather than relying on users to discover it. I'd also like the trends section to surface key insights directly rather than relying purely on charts, and to push harder on accessibility (contrast, touch target sizing, and screen reader friendliness), none of which got dedicated attention in this pass. In Submission 1, I was making screens because that was the task in front of me. By this version, I was designing with intention, thinking about where someone might hesitate before they ever told me. That shift matters more than any individual screen in here.