Azume One is a 2.8mm-thick sensor module intended to give traditional mechanical and quartz watches fitness and wellness tracking without replacing their movements or changing their faces. The 30mm disc attaches to the back of a watch and sends measurements including heart rate, sleep, stress and activity data to an Android or iOS app.
Developed by a Munich startup, the 5g module uses a nano-suction mounting system rather than adhesive or magnets. It can be removed and transferred to another watch, provided the watch has a sufficiently flat case back. The trade-off is straightforward: it adds 2.8mm to a watch’s thickness, which may affect comfort or fit.
There is no display, vibration motor or notification system. Instead, Azume One combines optical PPG and motion sensors, connecting to a phone over Bluetooth 5.4. The company says the platform supports the following measurements and estimates:
- Heart metrics: heart rate, heart-rate variability (HRV) and blood-oxygen measurements.
- Sleep tracking: sleep duration, stages and a quality score.
- Stress and recovery estimates based on collected data and personal history.
- Activity tracking: steps, distance, calories and automatic recognition of more than 28 workout types.
- Skin-temperature and respiratory-rate monitoring.
Battery life is rated at up to 48 hours, and the module is said to fully recharge in about 30 minutes through a USB-C dock. A textile FitBand is included for overnight use when the sensor is not attached to a watch. Azume One is rated for rain and sweat exposure, but is not recommended for swimming or showering.
Crowdfunding pricing and data processing
The project is currently being crowdfunded on Kickstarter, where early pricing starts at €109. A Founders Edition with additional accessories is listed at €179, while the planned standard retail price is €149. Azume says all app features will be available without a monthly subscription.
The company stores data on servers in Ireland. It does not currently offer a fully local operating mode: according to a company co-founder, Ferdinand, data analysis and calculation of personalized scores take place on Azume’s servers.
Unlike hybrid watches such as the Withings ScanWatch Light, Azume One is an add-on rather than a complete watch platform. Its appeal depends on preserving an existing watch while adding connected health features, although it cannot avoid adding bulk to the case.
Azume estimates first deliveries for December 2026. CE and FCC certifications are still in progress, and delivery timing may change. As a crowdfunding project, backing does not amount to purchasing an already available retail product. The device is positioned for general wellness monitoring, not medical diagnosis.
