The problem with smart rings today
If you've ever looked at a smart ring, you've noticed the pattern: pay $299 upfront, then $6-$12/month for a subscription to see your own data. Oura does it. WHOOP does it in a different way. The data is locked behind a paywall.
I've been building Adola (https://adola.app) — a smart health ring that tracks 6 sensors with no subscription, ever.
What the ring tracks
- Heart rate (PPG-based, 24/7)
- SpO2 blood oxygen
- Skin temperature (medical-grade, not wrist-estimated)
- HRV (heart rate variability)
- Skin conductance (stress/arousal)
- Accelerometer/gyroscope for sleep + movement
The hardware architecture
The ring uses a custom PCB designed with KiCad, with custom Zen DSL for the layout. BLE 5.0 for data transfer, ~7 day battery life target, titanium body.
The firmware stack is bare-metal C on an nRF52840. The companion app handles data sync + visualization.
Subscription-free model
The business model is simple: one-time hardware sale. All data stays on-device and local — we have zero incentive to lock it behind an API paywall. Export to CSV/JSON anytime.
Pre-orders open today
We're taking $5 pre-order deposits to gauge demand before committing to the first manufacturing run. If you're tired of paying monthly fees to read your own HRV data, check it out: https://adola.app/reserve
Happy to discuss the hardware design, sensor choices, or BLE firmware stack in the comments.
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