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

Abstract

<p>Light exposure is a vital regulator of physiology and behaviour in humans. However, monitoring of light exposure is not included in current wearable Internet-of-Things (IoT) devices, and only recently have international standards defined <em>alpha-opic equivalent daylight illuminance</em> measures for how the eye responds to light. This paper reports a wearable light sensor node that can be incorporated into the IoT to provide monitoring of equivalent daylight illuminance exposure in real-world settings. We present the system design, electronic performance testing, and accuracy of equivalent daylight illuminance measurements when compared to a calibrated spectral source. This includes consideration of the directional response of the sensor, and a comparison of performance when placed on different parts of the body, and a demonstration of practical use over 7 days. Our device operates for 3.5 days between charges, with a sampling period of 30 s. It has 10 channels of measurement, over the range 415-910 nm, balancing accuracy and cost considerations. Measured alpha-opic Equivalent Daylight Illuminance results for 13 devices show a mean absolute error of less than 0.07 log lx, and a minimum between device correlation of 0.99. These findings demonstrate that accurate light sensing is feasible, including at wrist worn locations. We provide an experimental platform for use in future investigations in real-world light exposure monitoring and IoT based lighting control.</p>

Human-Centric Lighting Research and Policy in the Melanopsin Age

“…However, for sample sizes that may yield evidence for the genetic underpinnings, there are no convenient assays for NIF function that can be deployed at scale. Ways forward could lie in a variety of different techniques, including miniaturized wearable light sensors (Casson, 2023; Hartmeyer & Andersen, 2023; Hartmeyer et al, 2022; Joyce et al, 2020; Mohamed et al, 2021; Spitschan et al, 2022; Stampfli et al, 2023); smartphone-deployed apps probing alertness, cognition, and other parameters (Gardesevic et al, 2022; Klein et al, 2021; Shatte & Teague, 2020); ambulatory systems for measuring hormone concentrations continuously (Grant et al, 2022); and novel nonintrusive ways of measuring sleep–wake rhythms over long periods (Alkalih et al, 2022).…”