{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T23:27:23Z","timestamp":1787959643106,"version":"build-2784847793"},"reference-count":29,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2022,10,1]],"date-time":"2022-10-01T00:00:00Z","timestamp":1664582400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MUR in the frame of project PON \u201cR&amp;I\u201d 2014\u20132020\u2013Asse II, \u201cSostegno all\u2019innovazione\u201d, Avviso n. 1735\/Ric del 13 Luglio 2017","award":["ARS01_00345"],"award-info":[{"award-number":["ARS01_00345"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the present study, the development of a conductometric gas sensor based on Al,Ca-doped zinc oxide composite which is finalized to the detection of formaldehyde (HCHO) at a low concentration in air is investigated. The electrical and sensing properties of the composite based on ZnO doped with different loadings of Al and\/or Ca (from 0 up to 5 at%) were evaluated. The gas-sensing mechanism of Al,Ca-doped zinc oxide nanocomposite-based sensors was also discussed. The optimized 3%Al,3%Ca-ZnO sensor displayed a formaldehyde response of 3.5 (@ 4 ppm HCHO\/air) and an experimental low detection limit of 125 ppb HCHO\/air, at the operating temperature of 400 \u00b0C. The sensor was also shown to be selective to HCHO with respect to many interferent indoor gases, but NO2 changed the baseline resistance in an opposite way compared to the target gas. The developed device for monitoring HCHO in indoor and workplace environments has the advantage of a simple planar structure and can be easily fabricated for mass production by using low-cost materials and easy fabrication methods.<\/jats:p>","DOI":"10.3390\/s22197465","type":"journal-article","created":{"date-parts":[[2022,10,10]],"date-time":"2022-10-10T03:07:28Z","timestamp":1665371248000},"page":"7465","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Development of a Conductometric Sensor Based on Al,Ca-Doped ZnO for the Detection of Formaldehyde"],"prefix":"10.3390","volume":"22","author":[{"given":"Simona","family":"Crispi","sequence":"first","affiliation":[{"name":"Department of Engineering, University of Messina, 98122 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8999-060X","authenticated-orcid":false,"given":"Giovanni","family":"Neri","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Messina, 98122 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,1]]},"reference":[{"key":"ref_1","unstructured":"(2022, August 20). Indoor Air Quality, Available online: https:\/\/www.epa.gov\/indoor-air-quality-iaq\/introduction-indoor-air-quality."},{"key":"ref_2","unstructured":"Norb\u00e4ck, D., Kishi, R., and Araki, A. (2020). Indoor Environmental Quality and Health Risk toward Healthier Environment for All, Springer."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"e00116","DOI":"10.1016\/j.teac.2021.e00116","article-title":"Exposure to airborne formaldehyde: Sampling and analytical methods\u2014A review","volume":"29","author":"Dugheri","year":"2021","journal-title":"Trends Environ. Anal. Chem."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1021\/es801621f","article-title":"A laser induced fluorescence-based instrument for in-situ measurements of atmospheric formaldehyde","volume":"43","author":"Hottle","year":"2009","journal-title":"Environ. Sci. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1016\/j.snb.2016.11.015","article-title":"Fluctuation-enhanced and conductometric gas sensing with nanocrystalline NiO thin films: A comparison","volume":"242","author":"Cindemir","year":"2017","journal-title":"Sens. Actuators B"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"125352","DOI":"10.1016\/j.jhazmat.2021.125352","article-title":"A high-response formaldehyde sensor based on fibrous Ag-ZnO\/In2O3 with multi-level heterojunctions","volume":"413","author":"Liu","year":"2021","journal-title":"J. Hazard. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"416","DOI":"10.1007\/s11706-021-0559-3","article-title":"Formaldehyde vapour sensing property of electrospun NiO nanograins","volume":"15","author":"Kampara","year":"2021","journal-title":"Front. Mater. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"12808","DOI":"10.1021\/acsami.9b01465","article-title":"Mesoporous Ultrathin SnO2 Nanosheets In-situ Modified by Graphene Oxide for Extraordinary Formaldehyde Detection at Low Temperature","volume":"11","author":"Wang","year":"2019","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"8230","DOI":"10.1007\/s10854-020-03358-y","article-title":"Formaldehyde sensing characteristics of calcium-doped zinc oxide nanoparticles-based gas sensor","volume":"31","author":"Jaballah","year":"2020","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.snb.2017.04.083","article-title":"Light-activated humidity and gas sensing by ZnO nanowires grown on LED at room temperature","volume":"249","author":"Hsua","year":"2017","journal-title":"Sens. Actuators B"},{"key":"ref_11","unstructured":"Ghamsari, M.S., and Dhara, S. (2018). ZnO Nanorods for Gas Sensors. Nanorods and Nanocomposites, IntechOpen."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"115544","DOI":"10.1016\/j.ssi.2020.115544","article-title":"Review of ZnO-based nanomaterials in gas sensors","volume":"360","author":"Kang","year":"2021","journal-title":"Solid State Ion."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.snb.2016.07.155","article-title":"Enhanced performance of novel calcium\/aluminum co-doped zinc oxide for CO2 sensors","volume":"239","author":"Dhahri","year":"2017","journal-title":"Sens. Actuators B"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Jaballah, S., Alaskar, Y., AlShunaifi, I., Ghiloufi, I., Neri, G., Bouzidi, C., Dahman, H., and El Mir, L. (2021). Effect of Al and Mg Doping on Reducing Gases Detection of ZnO Nanoparticles. Chemosensors, 9.","DOI":"10.3390\/chemosensors9110300"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1016\/j.snb.2014.01.068","article-title":"Al-doped ZnO for highly sensitive CO gas sensors","volume":"196","author":"Hjiri","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Istrate, A.I., Mihalache, I., Romanitan, C., Tutunaru, O., Vulpe, S., Nastase, F., and Veca, L.M. (2021). Ca-Doped ZnO:Al Thin Films: Synthesis and Characterization. Coatings, 11.","DOI":"10.3390\/coatings11091023"},{"key":"ref_17","unstructured":"(2022, August 20). Sigma Aldrich. Available online: https:\/\/www.sigmaaldrich.com\/IT\/it\/technical-documents\/technical-article\/analytical-chemistry\/photometry-and-reflectometry\/ir-spectrum-table."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"012001","DOI":"10.1088\/1742-6596\/1093\/1\/012001","article-title":"Structural, Optical, and Antifungal Characters of Zinc Oxide Nanoparticles Prepared by Sol-gel Method","volume":"1093","author":"Taufiq","year":"2018","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Kudasova, D., Mutaliyeva, B., Vlahov\u012dcek-Kahlina, K., Juri, S., Marijan, M., Khalus, S.V., Prosyanik, A.V., \u0160egota, S., \u0160pani, N., and Vincekovi, M. (2021). Encapsulation of Synthesized Plant Growth Regulator Based on Copper(II) Complex in Chitosan\/Alginate Microcapsules. Int. J. Mol. Sci., 22.","DOI":"10.3390\/ijms22052663"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"15920","DOI":"10.1080\/19443994.2015.1077745","article-title":"Removal of phosphate from industrial wastewater using uncalcined MgAl-NO3 layered double hydroxide: Batch study and modeling","volume":"57","author":"Khitous","year":"2016","journal-title":"Desalinat. Water Treat."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"15119","DOI":"10.1016\/j.ceramint.2016.06.145","article-title":"Detection of hazardous volatile organic compounds (VOCs) by metal oxide nanostructures-based gas sensors: A review","volume":"42","author":"Mirzaei","year":"2016","journal-title":"Ceram. Int."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2611","DOI":"10.1021\/acssensors.0c01074","article-title":"Atomically Dispersed Au on In2O3 Nanosheets for Highly Sensitive and Selective Detection of Formaldehyde","volume":"5","author":"Gu","year":"2020","journal-title":"ACS Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"511","DOI":"10.1007\/s12274-017-1661-9","article-title":"Fiber gas sensor-integrated smart face mask for room temperature distinguishing of target gases","volume":"11","author":"Gao","year":"2018","journal-title":"Nano Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1016\/j.apsusc.2013.01.038","article-title":"In situ diffuse reflectance infrared Fourier transform spectroscopy study of formaldehyde adsorption and reactions on nano \u03b3-Fe2O3 films","volume":"270","author":"Huang","year":"2013","journal-title":"Appl. Surf. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.snb.2009.12.052","article-title":"Fabrication and formaldehyde gas-sensing property of ZnO\u2013MnO2 coplanar gas sensor arrays","volume":"145","author":"Xie","year":"2010","journal-title":"Sens. Actuators B"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/j.snb.2009.01.054","article-title":"Improving humidity selectivity in formaldehyde gas sensing by a two-sensor array made of Ga-doped ZnO","volume":"138","author":"Han","year":"2009","journal-title":"Sens. Actuators B"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1007\/s00894-021-04921-y","article-title":"Computational investigation of sensing properties of Ca-doped zinc oxide nanotube toward formaldehyde","volume":"27","author":"Zhou","year":"2021","journal-title":"J. Mol. Model."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Goletto, V., Mialon, G., Faivre, T., Wang, Y., Lesieur, I., Petigny, N., and Vijapurapu, S.S. (2020). Formaldehyde and total VOC (TVOC) commercial low-cost monitoring devices: From an evaluation in controlled conditions to a use case application in a real building. Chemosensors, 8.","DOI":"10.3390\/chemosensors8010008"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3390\/chemosensors3010001","article-title":"First fifty years of chemoresistive gas sensors","volume":"3","author":"Neri","year":"2015","journal-title":"Chemosensors"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/19\/7465\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:45:15Z","timestamp":1760143515000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/19\/7465"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,10,1]]},"references-count":29,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2022,10]]}},"alternative-id":["s22197465"],"URL":"https:\/\/doi.org\/10.3390\/s22197465","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,10,1]]}}}