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Clinical / medical-grade · Ring · by Sky Labs
Sky Labs CART-I
The world's first medical-grade ring for continuous AFib detection — Korea-approved and more sensitive than the Apple Watch in a study, but not yet FDA-cleared.
2020Sky Labs CART-I (MFDS)
Late in cycle6 yr old
Part of the Sky Labs CART platform, alongside CART BP (cuffless blood pressure).
API access: No Raw data access: Yes — restricted Open source: No public repo
Clinical value
66/100
Continuous AFib ring (MFDS, not US)
Empowerment
36/100
App/clinician-mediated; not US-available
Everyday value
58/100
24/7 AFib ring, including sleep
The flagship of Sky Labs' CART platform: the world's first ring-type heart-rhythm medical device, continuously screening for atrial fibrillation via PPG with on-demand ECG records for a clinician. Cleared in Korea (MFDS) and shown more sensitive than the Apple Watch for AFib, but US FDA clearance is still pending.
What it measures
Continuous photoplethysmography (PPG) heart-rhythm monitoring with atrial-fibrillation detection and AFib-burden estimation, plus on-demand single-lead ECG records to share with a physician. Worn continuously without user intervention.
Regulatory status
Cleared by Korea's MFDS (the first ring-type heart-rhythm monitoring medical device, 2020). US FDA clearance is targeted but not yet granted; not sold in the US.
Validation & accuracy
In a head-to-head UK study published in Heart Rhythm O2, the CART-I ring reached 84.6% AFib sensitivity versus 69.1% for the Apple Watch.
Data control & export
Raw data: restricted — the app shows rhythm trends and lets you share ECG records with a clinician; no documented open export or developer API for consumers. API: none for patients.
Wearability & battery
A ring worn continuously, including during sleep, taking hands-free cardiac readings around the clock — far more passive than a watch or patch. Sold only through Korean/international channels.
Cost & access
Sold in Korea and select markets; not available in the US. Distribution is provider- and channel-dependent.
Who it serves
Patients (currently outside the US) who need continuous, passive AFib monitoring in a comfortable ring.
Who is left out or burdened
US patients cannot obtain it; data is app-locked with no open export; a single-purpose cardiac device from a smaller vendor.
✓ Strengths
- World's first ring-type heart-rhythm medical device (MFDS 2020)
- Continuous, hands-free AFib monitoring including during sleep
- More sensitive than the Apple Watch for AFib in a UK study (84.6% vs 69.1%)
- On-demand ECG records shareable with a clinician
✕ Weaknesses
- Not yet FDA-cleared or sold in the US
- App/clinician-mediated; no open export or developer API
- Single-purpose cardiac ring from a smaller vendor
- Availability limited to Korea and select markets
66
Why this clinical score. A medical-grade, MFDS-cleared ring that continuously screens for atrial fibrillation and outperformed the Apple Watch for AFib sensitivity in a peer-reviewed study — genuinely clinical. Held mid-axis because it is not yet FDA-cleared or available in the US.
36
Why this empowerment score. Data lives in the app and flows to a clinician, with no open export or API, and the device isn't sold in the US — among the lower empowerment scores for a US patient.
58
Why this everyday score. A comfortable ring that monitors heart rhythm around the clock, including during sleep, hands-free — but obtainable only outside the US.
Latest news
Reviews & coverage
Coverage highlights the world's first medical-grade ring for continuous AFib screening, with a study showing higher AFib sensitivity than the Apple Watch. The major caveats are no US FDA clearance yet and app/clinician-locked data.
Summary is a draft synthesis of public coverage, not an endorsement. Links open a search of each outlet.
Reddit communities
Independent user communities where this device (or its category) is discussed.
Get it · manuals & support
Draft profile · public-source review, June 2026 · scores describe direction and degree, not buying advice. News, links, and prices change — verify with the manufacturer. Image is representative.