Optical portable instrument for the determination of CO2 in indoor environments

Fernández-Ramos, M.D., Moreno-Puche, F., Escobedo, P. , García-López, P.A., Capitán-Vallvey, L.F. and Martínez-Olmos, A. (2020) Optical portable instrument for the determination of CO2 in indoor environments. Talanta, 208, 120387. (doi: 10.1016/j.talanta.2019.120387)

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Abstract

A portable device based on a colorimetric sensor to determine the atmospheric level of CO2 gas is presented in this work. The system is based on a low-cost, low-power System on a Chip (SoC) microcontroller with integrated Wi-Fi. A user-friendly application was developed to monitor and log the CO2 measurements when the system is connected to a Wi-Fi network. The sensing membrane is directly deposited on the surface of the colour detector, thus reducing the complexity of the system. This sensing membrane is formed by a pH indicator α-naphtholphthalein, tetramethylammonium hydroxide pentahydrate, 1-ethyl-3-methylimidazolium tetrafluoroborate, Tween 20 and hydroxypropyl methylcellulose as the hydrophilic polymer. The system has been fully characterized, obtaining response and recovery times of 1.3 and 2.5 s, respectively, a limit of detection of 51 ppm, and an average resolution of 6.3 ppm. This portable device was applied for the in-situ determination of CO2 gas in the atmosphere inside classrooms in several secondary schools. The measurements were taken during complete workdays and the results were statistically compared with the same measurements taken using a commercially available non-dispersive infra-red (NDIR) device. No significant statistical differences were found between the results obtained using both devices. A complete statistical treatment of the measurements made with the proposed portable device was carried out. The obtained results show that the concentration of CO2 gas in some schools was higher than the desired concentration, with regard to influencing the student's health, safety, productivity and comfort. This demonstrates the need to control this parameter to ensure appropriate indoor environmental quality (IEQ).

Item Type:Articles
Additional Information:This study was supported by projects from Ministerio de Economia y Competitividad, Spain (CTQ2013-44545-R and CTQ2016-78754-C2-1- R). The project was partially supported by European Regional Development Funds (ERDF).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Escobedo, Dr Pablo
Authors: Fernández-Ramos, M.D., Moreno-Puche, F., Escobedo, P., García-López, P.A., Capitán-Vallvey, L.F., and Martínez-Olmos, A.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Talanta
Publisher:Elsevier
ISSN:0039-9140
ISSN (Online):1873-3573
Published Online:24 September 2019
Copyright Holders:Copyright © 2019 Elsevier B.V.
First Published:First published in Talanta 208:120387
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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