Safety & transparency
What Guardian can and cannot detect
This page states plainly what Guardian detects, how reliably it detects it, and where it will fail. We do not publish performance numbers we have not validated. Placeholder values are clearly marked.
What Guardian detects
| Event type | Detection method | Status |
|---|---|---|
| Fall (impact + stillness) | Accelerometer: high-magnitude impact followed by prolonged low movement | Active |
| Prolonged immobility | Accelerometer: no significant movement for a configurable period (default 20 min) | Active |
| Heart-rate out of range | Optical PPG: sustained reading below 40 bpm or above 150 bpm | Active |
| Device removal | Optical PPG signal loss sustained for >5 minutes | Active |
| Cardiac arrhythmia | Not detected — consumer PPG cannot reliably identify arrhythmia | Not supported |
| Stroke | Not detected — no neurological monitoring capability | Not supported |
| Seizure | May trigger fall detection in some cases; not a reliable seizure detector | Partial / unreliable |
Performance metrics
Validation in progress
We are conducting structured validation testing before publishing performance numbers. The values below are placeholders. We will replace them with real figures once validation is complete and independently reviewed.
| Metric | Value |
|---|---|
| Fall detection sensitivity | [detection sensitivity — to be published after validation] |
| Fall detection specificity | [detection specificity — to be published after validation] |
| False alarm rate (per day of use) | [false alarm rate — to be published after validation] |
| Median time from event to S3 alert | [median alert latency — to be published after validation] |
| Heart-rate detection accuracy vs. ECG | [PPG accuracy — to be published after validation] |
Known failure modes
Slow falls
A person who lowers themselves to the floor slowly — due to dizziness or weakness — may not generate the impact signature that triggers detection. Guardian may not detect this event.
Device not worn
If the wearer removes the device, monitoring stops. Guardian will detect device removal after 5 minutes, but cannot detect events that occur before that.
Connectivity loss
If the smartwatch loses Bluetooth connection to the phone, or the phone loses internet connectivity, alerts may be delayed or not delivered.
Vigorous activity
High-impact exercise (running, jumping) may trigger false positives. The check-in prompt at S2 is designed to catch these, but if the wearer does not respond, a false alert will be sent to the circle.
Wrist position
Optical heart-rate sensors are sensitive to watch fit and wrist position. A loose watch or unusual wrist anatomy may produce inaccurate readings.
This is a demonstration build
The current build of Guardian is a demonstration. No real emergency-service connection exists. Alerts sent during simulation or testing do not reach any monitoring service. Do not rely on this build in a real emergency.