@inproceedings{75dcdbefe94740b4a52515cccd330bd4,
title = "Selectivity of glycerol droplet microresonator humidity sensor",
abstract = "We have created a highly sensitive humidity sensor that is based on glycerol droplet. Glycerol is hygroscopic and has a specific glycerol-water ratio for every relative humidity (RH) \%. It is cheap and environmentally friendly. We use the droplet as a whispering gallery mode (WGM) microresonator. WGMs are known for their high Q factors, which lead to high sensitivity and precision. As RH changes, the resonant wavelength shifts due to a change in the droplet's radius and refractive index. We have successfully created an experimental set-up and original data analysis method that allow us to follow the resonant wavelength shift in real-time. Results show that the sensor has an average sensitivity of 2.85 nm/\% RH in the 50-70 \% RH range, it is stable and has a long lifetime. To further investigate the properties of the glycerol droplet sensor, we tested its selectivity and tried two coupling methods (free-space and tapered fiber). We decided to test the sensor's response to two different gases - ethanol and acetone. Results show that glycerol is highly selective and does not absorb ethanol/acetone molecules, meaning that it can be used for trustworthy humidity measurements.",
keywords = "selectivity, whispering gallery mode, resonator, humidity, Optical sensor, tunable laser, glycerol",
author = "Lāse Mīlgrāve and Reinis, \{Pauls K.\} and Inga Brice and Jānis Alnis and Aigars Atvars",
note = "Publisher Copyright: {\textcopyright} 2022 SPIE.",
year = "2022",
doi = "10.1117/12.2621124",
language = "English",
isbn = "978-151065154-8",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
editor = "Francis Berghmans and Ioanna Zergioti",
booktitle = "Optical Sensing and Detection VII",
}