Two nodes, one picture of the air.
The prototype is a pair of Wi-Fi sensor nodes and a private analysis system. Nothing here is a finished product; this page describes what is being tested today.
Sentinel · indoors
The node in the room.
Sentinel sits in a living space and reports every few seconds. It measures what you breathe: particles of different sizes, carbon dioxide as a stand-in for how stale the air is, volatile organic compound and nitrogen oxide indices, and the temperature, humidity and pressure that shape how those readings behave.
It also watches itself. Every reading passes an integrity check before the rest of the system is allowed to trust it.
Scout · outdoors
The node outside.
Scout measures the same particles and gases just outside the home. It is the reference that makes Sentinel's readings meaningful: when indoor particles rise, the first question is whether they rose outside too, and how long before.
Outdoor air is not a perfect reference. Cooking fumes vented through a window can show up on Scout minutes later, and the system accounts for that rather than pretending the outside is always clean.
At a glance
Sentinel and Scout compared.
| Sentinel | Scout | |
|---|---|---|
| Where | Indoors, in a living space | Outdoors, just outside the home |
| Fine and coarse particles | Yes (PM1, PM2.5, PM10, counts by size) | Yes (PM1, PM2.5, PM10, counts by size) |
| Carbon dioxide | Yes | Not its job |
| Volatile compounds and nitrogen oxides | Yes (indices) | Yes (indices) |
| Temperature, humidity, pressure | Yes | Yes |
| Role | What is in the room | What the outside is doing |
Prototype hardware. Sensor selection and specifications will change as testing continues.
Behind the nodes
A private analysis system.
Both nodes send their readings to a private system in the home that stores them, checks them, learns what is normal, and detects and explains changes. It is not a cloud service you sign up to, and it is not open to the public.
For people taking part in testing, a protected account lets them see their own view over an encrypted connection. See how the analysis decides what to believe, and the privacy note for what is kept.
Want to follow along?
There is nothing to buy. If you would like progress updates or might like to take part in testing later, leave your details.