A wrist worn Internet-of-Things sensor node for wearable equivalent daylight illuminance monitoring

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Summary

This paper presents a wrist-worn IoT sensor node capable of accurately measuring melanopic and α-opic equivalent daylight illuminance (EDI) across 10 spectral channels, providing a practical tool for real-world circadian light exposure monitoring. The device's accuracy and inter-device consistency make it suitable for both research applications and IoT-based adaptive lighting control systems in healthcare, workplace, and consumer settings.

Key Findings

Mean absolute error of less than 0.07 log lx for α-opic EDI measurements across 13 devices compared to a calibrated spectral source.
Minimum between-device correlation of 0.99, indicating high consistency across units.
Device operates for 3.5 days between charges with a 30-second sampling period.
10 spectral channels spanning 415–910 nm balance measurement accuracy with cost considerations.
Wrist placement demonstrated as a feasible location for accurate light exposure monitoring over a 7-day practical demonstration.

Categories

The Science of Light: Develops and validates a wearable sensor for measuring melanopic and α-opic equivalent daylight illuminance (EDI) across 10 spectral channels (415–910 nm), directly implementing international lighting standards for human-centric light monitoring.

Sleep & Circadian Health: Enables real-world monitoring of circadian-relevant light exposure parameters, providing a practical tool for studying light's effects on physiology and behavior in free-living conditions.