{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,4]],"date-time":"2026-07-04T01:01:40Z","timestamp":1783126900176,"version":"3.54.6"},"reference-count":30,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2024,6,12]],"date-time":"2024-06-12T00:00:00Z","timestamp":1718150400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Smart-AirQ R&amp;D project","award":["TED2021-131114B-C21"],"award-info":[{"award-number":["TED2021-131114B-C21"]}]},{"name":"European Union NextGenerationEU\/PRTR","award":["TED2021-131114B-C21"],"award-info":[{"award-number":["TED2021-131114B-C21"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In recent years, there has been a growing interest in developing portable and personal devices for measuring air quality and surrounding pollutants, partly due to the need for ventilation in the aftermath of COVID-19 situation. Moreover, the monitoring of hazardous chemical agents is a focus for ensuring compliance with safety standards and is an indispensable component in safeguarding human welfare. Air quality measurement is conducted by public institutions with high precision but costly equipment, which requires constant calibration and maintenance by highly qualified personnel for its proper operation. Such devices, used as reference stations, have a low spatial resolution since, due to their high cost, they are usually located in a few fixed places in the city or region to be studied. However, they also have a low temporal resolution, providing few samples per hour. To overcome these drawbacks and to provide people with personalized and up-to-date air quality information, a personal device (smartwatch) based on MEMS gas sensors has been developed. The methodology followed to validate the performance of the prototype was as follows: firstly, the detection capability was tested by measuring carbon dioxide and methane at different concentrations, resulting in low detection limits; secondly, several experiments were performed to test the discrimination capability against gases such as toluene, xylene, and ethylbenzene. principal component analysis of the data showed good separation and discrimination between the gases measured.<\/jats:p>","DOI":"10.3390\/s24123808","type":"journal-article","created":{"date-parts":[[2024,6,13]],"date-time":"2024-06-13T06:23:11Z","timestamp":1718259791000},"page":"3808","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Development of a Smartwatch with Gas and Environmental Sensors for Air Quality Monitoring"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-8724-638X","authenticated-orcid":false,"given":"V\u00edctor","family":"Gonz\u00e1lez","sequence":"first","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Javier","family":"Godoy","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5918-1788","authenticated-orcid":false,"given":"Patricia","family":"Arroyo","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8534-7788","authenticated-orcid":false,"given":"F\u00e9lix","family":"Mel\u00e9ndez","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5740-0236","authenticated-orcid":false,"given":"Fernando","family":"D\u00edaz","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-0941-963X","authenticated-orcid":false,"given":"\u00c1ngel","family":"L\u00f3pez","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7961-0244","authenticated-orcid":false,"given":"Jos\u00e9 Ignacio","family":"Su\u00e1rez","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0905-9546","authenticated-orcid":false,"given":"Jes\u00fas","family":"Lozano","sequence":"additional","affiliation":[{"name":"Industrial Engineering School, University of Extremadura, 06006 Badajoz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"115115","DOI":"10.1088\/1361-6501\/ac14f4","article-title":"High-Sensitive Metal Oxide Gas Sensor for BTEX Gases Based on Ternary Composite of CeXMn1\u2212XO2\/SnO2","volume":"32","author":"Zhang","year":"2021","journal-title":"Meas. Sci. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"235840","DOI":"10.4303\/jdar\/235840","article-title":"Review of Toluene Actions: Clinical Evidence, Animal Studies, and Molecular Targets","volume":"3","author":"Cruz","year":"2014","journal-title":"J. Drug Alcohol. Res."},{"key":"ref_3","first-page":"1167","article-title":"A Review of Environmental and Occupational Exposure to Xylene and Its Health Concerns","volume":"14","author":"Niaz","year":"2015","journal-title":"EXCLI J."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"103518","DOI":"10.1016\/j.etap.2020.103518","article-title":"Effects of Inhaled Combined Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX): Toward an Environmental Exposure Model","volume":"81","author":"Davidson","year":"2021","journal-title":"Environ. Toxicol. Pharmacol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1900826","DOI":"10.1002\/ente.201900826","article-title":"Methane Activation and Utilization: Current Status and Future Challenges","volume":"8","author":"Sun","year":"2020","journal-title":"Energy Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1016\/j.apenergy.2015.10.039","article-title":"Assessing CO2 Emissions in China\u2019s Iron and Steel Industry: A Dynamic Vector Autoregression Model","volume":"161","author":"Xu","year":"2016","journal-title":"Appl. Energy"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.envint.2018.08.059","article-title":"Effects of Low-Level Inhalation Exposure to Carbon Dioxide in Indoor Environments: A Short Review on Human Health and Psychomotor Performance","volume":"121","author":"Azuma","year":"2018","journal-title":"Environ. Int."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"120","DOI":"10.4046\/trd.2013.74.3.120","article-title":"Acute respiratory distress due to methane inhalation","volume":"74","author":"Jo","year":"2013","journal-title":"Tuberc. Respir. Dis."},{"key":"ref_9","unstructured":"Instituto Nacional de Seguridad y Salud en el Trabajo (INSST) (2024). L\u00edmites de Exposici\u00f3n Profesional Para Agentes Qu\u00edmicos En Espa\u00f1a, INSST."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Arroyo, P., Herrero, J.L., Su\u00e1rez, J.I., and Lozano, J. (2019). Wireless Sensor Network Combined with Cloud Computing for Air Quality Monitoring. Sensors, 19.","DOI":"10.3390\/s19030691"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1038\/s41370-022-00515-9","article-title":"Personal Exposure Monitoring Using GPS-Enabled Portable Air Pollution Sensors: A Strategy to Promote Citizen Awareness and Behavioral Changes Regarding Indoor and Outdoor Air Pollution","volume":"33","author":"Park","year":"2023","journal-title":"J. Expo. Sci. Environ. Epidemiol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1002\/inf2.12029","article-title":"Chemoresistive Materials for Electronic Nose: Progress, Perspectives, and Challenges","volume":"1","author":"Park","year":"2019","journal-title":"InfoMat"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"129601","DOI":"10.1016\/j.snb.2021.129601","article-title":"Humidity Compensation Based on Power-Law Response for MOS Sensors to VOCs","volume":"334","author":"Yan","year":"2021","journal-title":"Sens. Actuators B Chem."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Gaiardo, A., Valt, M., Tosato, P., Magoni, M., Guidi, V., Dolci, C., and Bellutti, P. (2024). Development and Deployment of Portable Sensor Platforms Based on a Micro-Electro-Mechanical-System Chemoresistive Gas Sensor Array for Outdoor Air Quality Monitoring. Proceedings, 97.","DOI":"10.3390\/proceedings2024097036"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"119955","DOI":"10.1016\/j.atmosenv.2023.119955","article-title":"Long-Term Field Calibration of Low-Cost Metal Oxide VOC Sensor: Meteorological and Interference Gas Effects","volume":"310","author":"Hong","year":"2023","journal-title":"Atmos. Environ."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Li, H., Luo, D., Sun, Y., and GholamHosseini, H. (2019). Classification and Identification of Industrial Gases Based on Electronic Nose Technology. Sensors, 19.","DOI":"10.3390\/s19225033"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"114692","DOI":"10.1016\/j.sna.2023.114692","article-title":"Identification of Industrial Exhaust Based on an Electronic Nose with an Interleaved Grouped Residual Convolutional Compression Network","volume":"363","author":"Yang","year":"2023","journal-title":"Sens. Actuators A Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"135948","DOI":"10.1016\/j.chemosphere.2022.135948","article-title":"Wearable System for Outdoor Air Quality Monitoring in a WSN with Cloud Computing: Design, Validation and Deployment","volume":"307","author":"Arroyo","year":"2022","journal-title":"Chemosphere"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Gonz\u00e1lez, V., Mel\u00e9ndez, F., Arroyo, P., Godoy, J., D\u00edaz, F., Su\u00e1rez, J.I., and Lozano, J. (2023). Electro-Optical Nose for Indoor Air Quality Monitoring. Chemosensors, 11.","DOI":"10.3390\/chemosensors11100535"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Al-Okby, M.F.R., Junginger, S., Roddelkopf, T., Huang, J., and Thurow, K. (2024). Ambient Monitoring Portable Sensor Node for Robot-Based Applications. Sensors, 24.","DOI":"10.3390\/s24041295"},{"key":"ref_21","unstructured":"Boyle, B. (2012). The Complete Guide to Testing Chemical Sensors. The Complete Guide to Testing Chemical Sensors Owlstone Whitepaper, Owlstone Nanotech Inc."},{"key":"ref_22","unstructured":"(2024, April 18). Owlstone How to Build Permeation Tubes. Available online: https:\/\/www.owlstoneinc.com\/products\/build-your-own-permeation-tubes\/."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Umweltbundesamt (2007). Beurteilung von Innenraumluftkontaminationen Mittels Referenz- Und Richtwerten. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz, 50, 990\u20131005.","DOI":"10.1007\/s00103-007-0290-y"},{"key":"ref_24","unstructured":"(2024, April 18). ScioSense ENS160 Datasheet. Available online: https:\/\/www.sciosense.com\/wp-content\/uploads\/2023\/12\/ENS160-Datasheet.pdf."},{"key":"ref_25","unstructured":"(2024, April 18). Sensirion SGP40 Datasheet. Available online: https:\/\/sensirion.com\/media\/documents\/296373BB\/6203C5DF\/Sensirion_Gas_Sensors_Datasheet_SGP40.pdf."},{"key":"ref_26","unstructured":"(2024, April 18). Bosch BME688 Datasheet. Available online: https:\/\/www.bosch-sensortec.com\/media\/boschsensortec\/downloads\/datasheets\/bst-bme688-ds000.pdf."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"A211","DOI":"10.1016\/B978-044452701-1.00043-0","article-title":"Principal Component Analysis: Concept, Geometrical Interpretation, Mathematical Background, Algorithms, History, Practice","volume":"Volumes 1\u20134","author":"Esbensen","year":"2009","journal-title":"Comprehensive Chemometrics: Chemical and Biochemical Data Analysis"},{"key":"ref_28","unstructured":"(2024, May 29). MathWorks PCA-Principal Component Analysis of Raw Data. Available online: https:\/\/es.mathworks.com\/help\/stats\/pca.html."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Arroyo, P., Mel\u00e9ndez, F., Su\u00e1rez, J.I., Herrero, J.L., Rodr\u00edguez, S., and Lozano, J. (2020). Electronic Nose with Digital Gas Sensors Connected via Bluetooth to a Smartphone for Air Quality Measurements. Sensors, 20.","DOI":"10.3390\/s20030786"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1699","DOI":"10.1351\/pac199567101699","article-title":"Nomenclature in evaluation of analytical methods including detection and quantification capabilities (IUPAC Recommendations 1995)","volume":"67","author":"Currie","year":"1995","journal-title":"Pure Appl. Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/12\/3808\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:57:36Z","timestamp":1760108256000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/12\/3808"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,12]]},"references-count":30,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2024,6]]}},"alternative-id":["s24123808"],"URL":"https:\/\/doi.org\/10.3390\/s24123808","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,6,12]]}}}