The Light-Dosimeter – A New Device to Help Advance Research on the Non-Visual Responses to Light

Abstract

Research on the non-visual responses to light under real-world conditions has been hindered by the lack of suitable measuring devices. Here, we present a novel, portable and miniaturised light-dosimeter attached to a spectacle frame, taking measurements in the near-corneal plane. The recorded data is processed with the help of the custom-made software package Lido Studio. In addition to commonly used metrics such as illuminance and correlated colour temperature (CCT), it also provides metrics standardised in CIE S 026:2018. Data can be analysed directly in Lido Studio or exported as a PDF report or a comma-separated values (CSV) file for further in-depth time-series analyses. The Federal Institute of Metrology (METAS) optics laboratory (Bern-Wabern, Switzerland) assessed the light-dosimeter’s spectral and geometric properties. Subsequentially, the team at the Centre for Chronobiology (Basel, Switzerland) confirmed that measurements performed with a light-dosimeter were comparable to those from a commercial spectroradiometer.

A Wrist-Worn Internet of Things Sensor Node for Wearable Equivalent Daylight Illuminance Monitoring

“…Regarding the number of light sensor channels, [26] utilised a light sensor with 256 channels. In contrast [25], [27], [28], and this work used 14, 6, and 10 channels respectively. Our headline error rate is approximately doubled compared to the very high channel count approach in [26], but with the benefit of more than three times the battery life.…”

“…[26] developed a wearable light sensor designed to be worn as a pendant to measure Spectral Power Density (SPD) data in the visible wavelength range 380-780 nm using 256 channels. [27] developed a wearable light dosimeter using a light sensor with 6 channels covering a wavelength range of 400-1000 nm, which can be attached to spectacle frames. This was updated in [28].…”

“…[27] developed a wearable light dosimeter using a light sensor with 6 channels covering a wavelength range of 400-1000 nm, which can be attached to spectacle frames. This was updated in [28]. [29] described a sensor unit which produced CIE S026:2018 based measures in a miniature form factor, but focused on skin spectrum measurements (for example for the cosmetics industry) rather than as a light dosimeter for monitoring light exposure.…”

Verification, analytical validation and clinical validation (V3) of wearable dosimeters and light loggers

“…), and allow for prolonged monitoring of light exposure in free-living conditions. [21][22][23][24][25][26][27][28][29][30] Critical factors influencing the measurements include the position of the sensor (and e.g., the possibility of the sensor being covered by clothing such as sleeves or scarves), the vulnerability of the sensor (e.g., waterproof grading, ruggedness, position on the body and variability of that position [31][32][33][34] ), battery life, primary function of the sensor (e.g., is it a primary actigraphy monitor, optical monitor, or a light sensor designed to capture different dimensions of environmental light exposure), and acquisition-related parameters such as the recording interval. Systematic in-laboratory comparisons of the optical performance of light-logging sensors show large differences in their ability to capture biologically relevant light in commonly used sensors.…”

Metadata recommendations for light logging and dosimetry datasets

“…However, many of them do not estimate melanopic effects (i.e., effects on melanopsin-containing intrinsically photosensitive retinal ganglion cells [ipRGCs]) of light and thus fail to predict its circadian impact. More recently, light dosimeters have been developed that also incorporate the spectral sensitivity of melanopsin (blue wavelength) [18][19][20]. Individual light exposure patterns from such sensors have further been included in mathematical models to predict parameters of circadian physiology [21,22].…”