# Sentia

> Sentia Patch One is a square adhesive sensor patch with strongly rounded corners and a 2.5 mm profile that measures skin temperature, hydration and activity for up to 14 days without a phone. It reaches Sentia Cloud through the Find My network or LoRaWAN, never through a cellular radio.

## Sentia Patch One

- Profile: 2.5 mm. Weight: 3.1 g.
- Wear time: up to 14 days, single use, IP67.
- Radios: Bluetooth Low Energy 5.0 and LoRaWAN Class A.
- Tagline: Measurements that find their own way home.

## What it measures

- Skin temperature: Thermistor array, reported in °C
- Hydration: Bioimpedance electrodes, reported as a hydration index from 0 to 100
- Activity and posture: Three axis accelerometer, steps equivalent and posture class
- Sweat rate: Microfluidic channel, reported in µL/min

## How it works

- Sense: the patch samples its sensors every few minutes and builds a small encrypted measurement digest.
- Whisper: in covered areas it broadcasts a 16 byte digest over Bluetooth Low Energy, following the Find My network accessory pattern.
- Relay: nearby Apple devices forward the opaque digest. They cannot read it and learn nothing about the wearer.
- Rural path: outside phone coverage the patch sends a 19 byte LoRaWAN frame to any gateway within a few kilometres.
- Server: Sentia Cloud decodes the payloads, stores the time series and evaluates alert rules.
- Battery logic: Bluetooth Low Energy first, LoRaWAN only when no relay has carried a digest for a while, alerts escalate at once.

## Sentia Cloud API

- GET https://sentia.info-693.workers.dev/api/patches : the fleet
- GET https://sentia.info-693.workers.dev/api/patches/{id} : one patch status
- GET https://sentia.info-693.workers.dev/api/patches/{id}/measurements?hours=24 : time series
- GET https://sentia.info-693.workers.dev/api/alerts : open alerts
- GET https://sentia.info-693.workers.dev/api/network/stats : relay counts by path and relay type

## Sentia MCP Server

- Endpoint: POST https://sentia.info-693.workers.dev/mcp (JSON-RPC 2.0, protocol version 2024-11-05)
- Tools: list_patches, get_patch_status, get_measurements, get_alerts, get_network_stats, simulate_uplink

## Links

- Product site: https://sentia.info-693.workers.dev/
- Full facts: https://sentia.info-693.workers.dev/llms-full.txt
- Source of this concept build: https://github.com/arananet/sentia
- Built with ANVIL, an open source software factory: https://github.com/arananet/anvil-factory