Summary
COURSE PROJECT · CHALMERS
WEARABLES
INTERACTION DESIGN
PHYSICAL PROTOTYPING
2025
CardioConnect
A heart-rate armband that makes solo workouts feel shared.
ROLE
TBD · Interaction Designer (team of 3)
TIMELINE
TBD · weeks
PLATFORM
Wearable armband + companion app
TEAM
Amanda Sundell, Andre Håkansson, Qiqi Zhu
Young adults who move to a new city often lose the social support that keeps them exercising. How can a wearable bring companionship into a workout, even when two people train apart?
TBD · e.g. Ideation · Prototyping · Pilot testing · Companion app design
Two prototype iterations with pilot testing. Vibration and light replaced voice as the main feedback channel, and the armband grew from a single device into a device plus companion app.
Watch prototype
See key decisions
Design decisions
Four key design decisions, plus one new feature.
01
Vibration, not voice, carries the message
Spoken prompts took too long and were easy to miss outdoors and during intense movement, so vibration became the main channel. Patterns follow heart-rate zones: tight, rapid pulses when it is too high, long gentle pulses when it is too low, and a single short pulse in the target zone. A short tone is kept only to confirm pairing with a partner.
02
Color shows your zone at a glance
Green means you are in the target zone, red means overexertion, grey means you can push harder. The LEDs sit inside the fabric for a soft, diffused glow, and each sport has its own pattern: soft for yoga, steady for running, pulsing for boxing.
03
Removing the screen
The first prototype had a small display for heart-rate trends, mood emojis and messages. In testing it was almost never read during arm movement, so we removed it and moved to a “Zero UI” approach inspired by calm computing.
04
Worn on the upper arm, measured with PPG
The upper arm stays stable during movement and has room for light, vibration and sound together. A PPG sensor was chosen over ECG for comfort, and the snug armband keeps the skin contact it needs for accurate readings.
NEW
Companion app
Testers wanted more control, personalization and social connection than the band alone could give. A Figma companion app adds pairing with friends, training modes and intensity zones, custom color cues, and workout statistics.
How it works
STEP 01
Pair
Connect with a friend in the companion app to start a shared session.
STEP 02
Choose
Pick a sport mode and a target intensity zone.
STEP 03
Train
Light and vibration tell you when to push or ease off, and keep you in sync with your partner.
STEP 04
Review
Look back at past workouts and progress in the app.
Research
Where it started
International students and young adults who move to a new city are especially prone to loneliness. Exercise helps mental health, but motivation is hard to find alone. Research shows that group exercise raises motivation, and that close bonds within the group matter even more.
6×
Participants who formed no close social ties in a group training program were almost six times more likely to drop out.
Christensen et al., 2006
THREE PAIN POINTS
01
Training alone lacks companionship
Relatedness, one of the three needs in Self-Determination Theory, is missing when you train by yourself.
02
Wearables track performance, not feelings
Today’s devices show data and ignore the emotional and social side of exercise.
03
Screens and voice don’t work mid-workout
Feedback has to be glanceable, or felt through the body.
Ideation details
Iteration
PROTOTYPE 1
WORKSHOP · WIZARD OF OZ
PROTOTYPE 2
PILOT EVALUATION
Prototype 1 — display, speaker, vibration motor and heart-rate sensor in a fabric band
Prototype 2 — smaller and smoother, LEDs inside the fabric, vibration feedback
Users found voice prompts slow and distracting. In noisy or high-intensity settings, vibration was more noticeable and precise than any sound, so it became the primary channel.
Comments that the band felt bulky were universal. An uncomfortable device fails no matter how good its feedback is, so the second version is smaller and smoother, with the LEDs built into the fabric.
“bulky”
not “sleek”
Testers found the light too bright for some sports. Calm feedback has to fit the activity, which led to the sport-specific light modes they asked for.
“too bright”
“could blind you when swimming”
“different sport modes”
They expected control, personalization and social features the band alone could not give. This turned the project from a device into a system: the armband plus a companion app.
Companion app
The Figma companion app shows how the armband fits into a small digital ecosystem, from pairing with a friend to reviewing past workouts.
Connect with friends
Pair to start a shared session
Modes & intensity
Pick a sport and a target zone
Custom color cues
Choose your own push / ease colors
Workout statistics
See progress over time
Reflection
Sound was our starting point, not the answer.
We began with sound as the core medium, inspired by earlier work such as Sports over a Distance. Testing in real settings showed its limits outdoors and during intense movement, so the project became multisensory: vibration and light carry most of the signal, and sound is kept for key moments. The biggest lesson was to design feedback for the context it will be felt in.
NEXT STEPS
Feedback that adapts its strength and rhythm to each activity
Softer, breathable textile materials for longer sessions
Shared goals and milestones in the companion app
Group feedback, such as synchronized light that reflects several people’s combined heart rhythm
Team project with Amanda Sundell and Andre Håkansson · Chalmers University of Technology