{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,9]],"date-time":"2026-10-09T03:14:29Z","timestamp":1791515669555,"version":"4.3.4"},"reference-count":91,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,22]],"date-time":"2025-12-22T00:00:00Z","timestamp":1766361600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100019783","name":"National AGENCY FOR RESEARCH AND DEVELOPMENT","doi-asserted-by":"crossref","award":["24.80012.5007.15TC"],"award-info":[{"award-number":["24.80012.5007.15TC"]}],"id":[{"id":"10.13039\/100019783","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>A novel two-in-one sensor for both carbon dioxide and hydrogen detection has been obtained based on a hybrid heterostructure. It consists of a 30 nm thick TiO2 nanocrystalline film grown by atomic layer deposition (ALD), thermally annealed at 610 \u00b0C, and subsequently coated with bimetallic AgAu nanoparticles and covered with a PV4D4 nanolayer, which was thermally treated at 430 \u00b0C. Two types of gas response behaviors have been registered, as n-type for hydrogen gas and p-type semiconductor behavior for carbon dioxide gas detection. The highest response for carbon dioxide has been registered at an operating temperature of 150 \u00b0C with a value of 130%, while the highest response for hydrogen gas was registered at 350 \u00b0C with a value of 230%, although it also attained a relatively good gas selectivity at 150 \u00b0C. It is considered that a thermal annealing temperature of 610 \u00b0C is better for the properties of TiO2 nanofilms, since it enhances gas sensor sensitivity too. Polymer coating on top is also believed to contribute to a higher influence on selectivity of the sensor structure. Accordingly, to our previous research where PV4D4 has been annealed at 450 \u00b0C, in this research paper, a lower temperature of 430 \u00b0C for annealing has been used, and thus another ratio of cyclocages and cyclorings has been obtained. Knowing that the polymer acts like a sieve atop the sensor structure, in this study it offers increased selectivity and sensitivity towards carbon dioxide gas detection, as well as maintaining a relatively increased selectivity for hydrogen gas detection, which works as expected with Ag and Au bimetallic nanoparticles on the surface of the sensing structure. The results obtained are highly important for biomedical and environmental applications, as well as for further development of the sensor industry, considering the high potential of two-in-one sensors. A carbon dioxide detector could be used for assessing respiratory markers in patients and monitoring the quality of the environment, while hydrogen could be used for both monitoring lactose intolerance and concentrations in cases of therapeutic gas, as well as monitoring the safe handling of various concentrations.<\/jats:p>","DOI":"10.3390\/bios16010005","type":"journal-article","created":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T14:27:47Z","timestamp":1766500067000},"page":"5","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Two-in-One Hybrid Sensor Based on PV4D4\/AgAu\/TiO2 Structure for Carbon Dioxide and Hydrogen Gas Detection in Biomedical and Industrial Fields"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8438-3800","authenticated-orcid":false,"given":"Mihai","family":"Brinza","sequence":"first","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"},{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-3790-6893","authenticated-orcid":false,"given":"Lynn","family":"Schw\u00e4ke","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"},{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"},{"name":"Chair for Composite Materials, Faculty of Engineering, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9996-2637","authenticated-orcid":false,"given":"Stefan","family":"Schr\u00f6der","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"},{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"},{"name":"Chair for Composite Materials, Faculty of Engineering, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2268-6181","authenticated-orcid":false,"given":"Cristian","family":"Lupan","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5046-8611","authenticated-orcid":false,"given":"Nicolai","family":"Ababii","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7006-3443","authenticated-orcid":false,"given":"Nicolae","family":"Magariu","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2163-8735","authenticated-orcid":false,"given":"Maxim","family":"Chiriac","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3367-1655","authenticated-orcid":false,"given":"Franz","family":"Faupel","sequence":"additional","affiliation":[{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexander","family":"Vahl","sequence":"additional","affiliation":[{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"},{"name":"Chair for Composite Materials, Faculty of Engineering, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"},{"name":"Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7913-9712","authenticated-orcid":false,"given":"Oleg","family":"Lupan","sequence":"additional","affiliation":[{"name":"Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Av., MD-2004 Chisinau, Moldova"},{"name":"Department of Materials Science, Chair for Multicomponent Materials, Kiel University, Kaiserstra\u00dfe 2, D-24143 Kiel, Germany"},{"name":"Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstra2, 24143 Kiel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Nazpal, R., Chiriac, M., Sugihara, M., Litra, D., Ababii, N., Magariu, N., Lupan, C., Zinicovschi, V., Ameloot, R., and Lupan, O. (2024, January 14\u201315). Sensory Properties of CuO\/Cu2O Nanostructures Coated with Zeolitic Imidazolate Frameworks. Proceedings of the 2024 E-Health and Bioengineering Conference (EHB), Iasi, Romania.","DOI":"10.1109\/EHB64556.2024.10805729"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.jbusres.2021.12.044","article-title":"The Negative Effect of Air Pollution on People\u2019s pro-Environmental Behavior","volume":"142","author":"Ming","year":"2022","journal-title":"J. Bus. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1609","DOI":"10.1093\/restud\/rdy016","article-title":"Something in the Air: Pollution and the Demand for Health Insurance","volume":"85","author":"Chang","year":"2018","journal-title":"Rev. Econ. Stud."},{"key":"ref_4","unstructured":"Sontea, V., Tiginyanu, I., and Railean, S. (2025). Polymer-Coated Cd-Doped ZnO Nanostructures for Dual Sensing of Volatile Organic Compounds and Battery Vapours. Proceedings of the 7th International Conference on Nanotechnologies and Biomedical Engineering. (ICNBME 2025), Chisinau, Moldova, 7\u201310 October 2025, Springer."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Litra, D., Chiriac, M., Ababii, N., and Lupan, O. (2024). Acetone Sensors Based on Al-Coated and Ni-Doped Copper Oxide Nanocrystalline Thin Films. Sensors, 24.","DOI":"10.3390\/s24206550"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Sontea, V., Tiginyanu, I., and Railean, S. (2025). Hybrid Nanomaterials for Biomedical Sensors. Proceedings of the 7th International Conference on Nanotechnologies and Biomedical Engineering. (ICNBME 2025), Chisinau, Moldova, 7\u201310 October 2025, Springer.","DOI":"10.1007\/978-3-032-06494-3"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Lupan, O., Brinza, M., Schr\u00f6der, S., Ababii, N., Strunskus, T., Viana, B., Pauport\u00e9, T., Adelung, R., and Faupel, F. (2024, January 8\u201313). Sensors Based on Hybrid Materials for Environmental, Industrial and Biomedical Applications. Proceedings of the 2024 IEEE 14th International Conference Nanomaterials: Applications and Properties (NAP), Riga, Latvia. pp. MTFC09-1\/MTFC09-4.","DOI":"10.1109\/NAP62956.2024.10739678"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Nagpal, R., Lupan, C., B\u00eernaz, A., Sereacov, A., Greve, E., Gronenberg, M., Siebert, L., Adelung, R., and Lupan, O. (2024). Multifunctional Three-in-One Sensor on t-ZnO for Ultraviolet and VOC Sensing for Bioengineering Applications. Biosensors, 14.","DOI":"10.3390\/bios14060293"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Chen, X., Leishman, M., Bagnall, D., and Nasiri, N. (2021). Nanostructured Gas Sensors: From Air Quality and Environmental Monitoring to Healthcare and Medical Applications. Nanomaterials, 11.","DOI":"10.3390\/nano11081927"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"172247","DOI":"10.1016\/j.ijleo.2025.172247","article-title":"Effect of Pd Functionalization on Optical and Hydrogen Sensing Properties of ZnO: Eu Films","volume":"325","author":"Nagpal","year":"2025","journal-title":"Optik"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1016\/j.snb.2006.03.040","article-title":"Fire Detection with Low Power Fet Gas Sensors","volume":"120","author":"Pohle","year":"2007","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1007\/s11947-008-0154-y","article-title":"Carbon Dioxide (CO2) Sensors for the Agri-Food Industry\u2014A Review","volume":"2","author":"Neethirajan","year":"2009","journal-title":"Food Bioprocess Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"100596","DOI":"10.1016\/j.mtnano.2025.100596","article-title":"Hydrogen Nanosensors Based on Core\/Shell ZnO\/Al2O3 and ZnO\/ZnAl2O4 Single Nanowires","volume":"29","author":"Lupan","year":"2025","journal-title":"Mater. Today Nano"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1149\/08901.0085ecst","article-title":"Early Detection for Li-Ion Batteries Thermal Runaway Based on Gas Sensing","volume":"89","author":"Cai","year":"2019","journal-title":"ECS Trans."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"100100","DOI":"10.1016\/j.etran.2020.100100","article-title":"Detection of Li-Ion Battery Failure and Venting with Carbon Dioxide Sensors","volume":"7","author":"Cai","year":"2021","journal-title":"eTransportation"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Dervieux, E., Th\u00e9ron, M., and Uhring, W. (2021). Carbon Dioxide Sensing\u2014Biomedical Applications to Human Subjects. Sensors, 22.","DOI":"10.3390\/s22010188"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/j.mehy.2008.08.026","article-title":"The Potential Use of Carbon Dioxide as a Carrier Gas for Drug Delivery into Open Wounds","volume":"72","author":"Persson","year":"2009","journal-title":"Med. Hypotheses"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"El-Betany, A.M.M., Behiry, E.M., Gumbleton, M., and Harding, K.G. (2020). Humidified Warmed CO2 Treatment Therapy Strategies Can Save Lives With Mitigation and Suppression of SARS-CoV-2 Infection: An Evidence Review. Front. Med., 7.","DOI":"10.3389\/fmed.2020.594295"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3588","DOI":"10.1097\/00003246-200011000-00003","article-title":"Effectiveness of End-Tidal Carbon Dioxide Tension for Monitoring of Thrombolytic Therapy in Acute Pulmonary Embolism","volume":"28","author":"Wiegand","year":"2000","journal-title":"Crit. Care Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1097\/ALN.0000000000003967","article-title":"Carbon Footprint of General, Regional, and Combined Anesthesia for Total Knee Replacements","volume":"135","author":"McGain","year":"2021","journal-title":"Anesthesiology"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"645","DOI":"10.1513\/AnnalsATS.201311-387FR","article-title":"Techniques for the Measurement and Monitoring of Carbon Dioxide in the Blood","volume":"11","author":"Huttmann","year":"2014","journal-title":"Ann. Am. Thorac. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"152616","DOI":"10.1016\/j.apsusc.2022.152616","article-title":"Carbon Dioxide Detection Using Polymer-Coated Fiber Bragg Grating Based on Volume Dilation Mechanism and Molecular Dynamics Simulation","volume":"584","author":"Xu","year":"2022","journal-title":"Appl. Surf. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Long, W., Zhou, R., Du, Z., Ling, Q., Zhang, Y., Zhao, D., Shao, J., Luo, S., and Chen, D. (2022). A Dual-Band Carbon Dioxide Sensor Based on Metal\u2013TiO2\u2013Metal Metasurface Covered by Functional Material. Photonics, 9.","DOI":"10.3390\/photonics9110855"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Decker, M., Oel\u00dfner, W., and Zosel, J. (2019). Electrochemical CO2 Sensors with Liquid or Pasty Electrolyte. Carbon Dioxide Sensing, Wiley.","DOI":"10.1002\/9783527688302.ch4"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"25","DOI":"10.3390\/gases3010002","article-title":"The Hydrogen Color Spectrum: Techno-Economic Analysis of the Available Technologies for Hydrogen Production","volume":"3","author":"Arcos","year":"2023","journal-title":"Gases"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2462","DOI":"10.1016\/j.ijhydene.2010.04.176","article-title":"An Overview of Hydrogen Safety Sensors and Requirements","volume":"36","author":"Buttner","year":"2011","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1443","DOI":"10.1016\/j.ijhydene.2023.11.115","article-title":"Exploring the Promise of One-Dimensional Nanostructures: A Review of Hydrogen Gas Sensors","volume":"50","author":"Sangchap","year":"2024","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"23334","DOI":"10.1016\/j.ijhydene.2017.02.124","article-title":"The Meeting of Hydrogen and Automotive: A Review","volume":"42","author":"Gurz","year":"2017","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"593","DOI":"10.1016\/S0360-3199(97)00112-2","article-title":"An Overview of Industrial Uses of Hydrogen","volume":"23","author":"Ramachandran","year":"1998","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"41196","DOI":"10.1021\/acsami.2c10975","article-title":"Nanosensors Based on a Single ZnO:Eu Nanowire for Hydrogen Gas Sensing","volume":"14","author":"Lupan","year":"2022","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"175385","DOI":"10.1016\/j.jallcom.2024.175385","article-title":"Ultra-Selective Hydrogen Sensors Based on CuO-ZnO Hetero-Structures Grown by Surface Conversion","volume":"1002","author":"Chakraborty","year":"2024","journal-title":"J. Alloys Compd."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Russell, G., Nenov, A., and Hancock, J.T. (2024). How Hydrogen (H2) Can Support Food Security: From Farm to Fork. Appl. Sci., 14.","DOI":"10.3390\/app14072877"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"29331","DOI":"10.1021\/acsami.2c03704","article-title":"Al2O3\/ZnO Heterostructure-Based Sensors for Volatile Organic Compounds in Safety Applications","volume":"14","author":"Lupan","year":"2022","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"e3","DOI":"10.1017\/gmb.2023.17","article-title":"Hydrogen Gas and the Gut Microbiota Are Potential Biomarkers for the Development of Experimental Colitis in Mice","volume":"5","author":"Fujiki","year":"2024","journal-title":"Gut Microbiome"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1038\/ajg.2017.46","article-title":"Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus","volume":"112","author":"Rezaie","year":"2017","journal-title":"Am. J. Gastroenterol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"353","DOI":"10.1080\/10408363.2022.2038075","article-title":"Breathing New Life into Clinical Testing and Diagnostics: Perspectives on Volatile Biomarkers from Breath","volume":"59","author":"Haworth","year":"2022","journal-title":"Crit. Rev. Clin. Lab. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1177\/00045632231159288","article-title":"Testing for Lactase Non-Persistence in a Dutch Population: Genotyping versus the Hydrogen Breath Test","volume":"60","author":"Stouten","year":"2023","journal-title":"Ann. Clin. Biochem. Int. J. Lab. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.pharmthera.2014.04.006","article-title":"Molecular Hydrogen as a Preventive and Therapeutic Medical Gas: Initiation, Development and Potential of Hydrogen Medicine","volume":"144","author":"Ohta","year":"2014","journal-title":"Pharmacol. Ther."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"495","DOI":"10.1097\/SHK.0b013e3181def9aa","article-title":"Hydrogen Gas Improves Survival Rate and Organ Damage in Zymosan-Induced Generalized Inflammation Model","volume":"34","author":"Xie","year":"2010","journal-title":"Shock"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"107583","DOI":"10.1016\/j.intimp.2021.107583","article-title":"Hydrogen Gas Alleviates Sepsis-Induced Neuroinflammation and Cognitive Impairment through Regulation of DNMT1 and DNMT3a-Mediated BDNF Promoter IV Methylation in Mice","volume":"95","author":"Yu","year":"2021","journal-title":"Int. Immunopharmacol."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Rahman, M.H., Bajgai, J., Fadriquela, A., Sharma, S., Trinh Thi, T., Akter, R., Goh, S.H., Kim, C.-S., and Lee, K.-J. (2021). Redox Effects of Molecular Hydrogen and Its Therapeutic Efficacy in the Treatment of Neurodegenerative Diseases. Processes, 9.","DOI":"10.3390\/pr9020308"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1016\/j.snb.2017.06.141","article-title":"Low-Temperature Prototype Hydrogen Sensors Using Pd-Decorated SnO2 Nanowires for Exhaled Breath Applications","volume":"253","author":"Nguyen","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1039\/D1MA00683E","article-title":"Integrated Co-Axial Electrospinning for a Single-Step Production of 1D Aligned Bimetallic Carbon Fibers@AuNPs\u2013PtNPs\/NiNPs\u2013PtNPs towards H2 Detection","volume":"3","author":"Nair","year":"2022","journal-title":"Mater. Adv."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1016\/j.sna.2019.07.040","article-title":"UV Nanophotodetectors: A Case Study of Individual Au-Modified ZnO Nanowires","volume":"296","author":"Lupan","year":"2019","journal-title":"Sens. Actuators A Phys."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1016\/j.snb.2016.11.025","article-title":"Hydrogen Sensing Properties of Pt-Au Bimetallic Nanoparticles Loaded on ZnO Nanorods","volume":"241","author":"Fan","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"32115","DOI":"10.1021\/acsami.9b08598","article-title":"Low-Temperature Solution Synthesis of Au-Modified ZnO Nanowires for Highly Efficient Hydrogen Nanosensors","volume":"11","author":"Lupan","year":"2019","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Lupan, O., Brinza, M., Piehl, J., Ababii, N., Magariu, N., Zimoch, L., Strunskus, T., Pauporte, T., Adelung, R., and Faupel, F. (2024). Influence of Silsesquioxane-Containing Ultra-Thin Polymer Films on Metal Oxide Gas Sensor Performance for the Tunable Detection of Biomarkers. Chemosensors, 12.","DOI":"10.3390\/chemosensors12050076"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Schr\u00f6der, S., Ababii, N., Br\u00eenz\u0103, M., Magariu, N., Zimoch, L., Bodduluri, M.T., Strunskus, T., Adelung, R., Faupel, F., and Lupan, O. (2023). Tuning the Selectivity of Metal Oxide Gas Sensors with Vapor Phase Deposited Ultrathin Polymer Thin Films. Polymers, 15.","DOI":"10.3390\/polym15030524"},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Brinza, M., Schr\u00f6der, S., Ababii, N., Gronenberg, M., Strunskus, T., Pauporte, T., Adelung, R., Faupel, F., and Lupan, O. (2023). Two-in-One Sensor Based on PV4D4-Coated TiO2 Films for Food Spoilage Detection and as a Breath Marker for Several Diseases. Biosensors, 13.","DOI":"10.3390\/bios13050538"},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Brinza, M., Schw\u00e4ke, L., Zimoch, L., Strunskus, T., Pauport\u00e9, T., Viana, B., Ameri, T., Adelung, R., Faupel, F., and Schr\u00f6der, S. (2025). Influence of P(V3D3-Co-TFE) Copolymer Coverage on Hydrogen Detection Performance of a TiO2 Sensor at Different Relative Humidity for Industrial and Biomedical Applications. Chemosensors, 13.","DOI":"10.3390\/chemosensors13040150"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"100642","DOI":"10.1016\/j.mtchem.2021.100642","article-title":"Sensing Performance of CuO\/Cu2O\/ZnO:Fe Heterostructure Coated with Thermally Stable Ultrathin Hydrophobic PV3D3 Polymer Layer for Battery Application","volume":"23","author":"Ababii","year":"2022","journal-title":"Mater. Today Chem."},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Sontea, V., Tiginyanu, I., and Railean, S. (2025). Effect of PTFE Thickness on Gas Sensing Properties of TiO2\/Pd-Doped ZnO Nanostructures. Proceedings of the 7th International Conference on Nanotechnologies and Biomedical Engineering. (ICNBME 2025), Chisinau, Moldova, 7\u201310 October 2025, Springer.","DOI":"10.1007\/978-3-032-06494-3"},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Sontea, V., Tiginyanu, I., and Railean, S. (2024). A New Approach in Detection of Biomarker 2-Propanol with PTFE-Coated TiO2 Nanostructured Films. Proceedings of the 6th International Conference on Nanotechnologies and Biomedical Engineering. (ICNBME 2023), Chisinau, Moldova, 20\u201323 September 2023, Springer.","DOI":"10.1007\/978-3-031-42782-4"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"325501","DOI":"10.1088\/1361-6528\/abfd54","article-title":"Effect of Temperature and Humidity on the Sensing Performance of TiO2 Nanowire-Based Ethanol Vapor Sensors","volume":"32","author":"Shooshtari","year":"2021","journal-title":"Nanotechnology"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.mssp.2018.06.031","article-title":"Ultra-Thin TiO2 Films by Atomic Layer Deposition and Surface Functionalization with Au Nanodots for Sensing Applications","volume":"87","author":"Lupan","year":"2018","journal-title":"Mater. Sci. Semicond. Process."},{"key":"ref_56","first-page":"41","article-title":"Enhancement in UV Sensing Properties of Zno:Ag Nanostructured Films by Surface Functionalization with Noble Metalic and Bimetallic Nanoparticles","volume":"25","author":"Postica","year":"2018","journal-title":"J. Eng. Sci."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"16246","DOI":"10.1039\/D0TA03224G","article-title":"Surface Functionalization of ZnO:Ag Columnar Thin Films with AgAu and AgPt Bimetallic Alloy Nanoparticles as an Efficient Pathway for Highly Sensitive Gas Discrimination and Early Hazard Detection in Batteries","volume":"8","author":"Vahl","year":"2020","journal-title":"J. Mater. Chem. A"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"214758","DOI":"10.1016\/j.ccr.2022.214758","article-title":"Metal Oxide Resistive Sensors for Carbon Dioxide Detection","volume":"472","author":"Zhang","year":"2022","journal-title":"Coord. Chem. Rev."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"32363","DOI":"10.1021\/acsami.1c04379","article-title":"TiO2\/Cu2O\/CuO Multi-Nanolayers as Sensors for H2 and Volatile Organic Compounds: An Experimental and Theoretical Investigation","volume":"13","author":"Lupan","year":"2021","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_60","unstructured":"Socrates, G. (2004). Infrared and Raman Characteristic Group Frequencies: Tables and Charts, John Wiley & Sons, Ltd."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1002\/adfm.200900999","article-title":"Ultralow Dielectric Constant Tetravinyltetramethylcyclotetrasiloxane Films Deposited by Initiated Chemical Vapor Deposition (ICVD)","volume":"20","author":"Trujillo","year":"2010","journal-title":"Adv. Funct. Mater."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"112804","DOI":"10.1016\/j.sna.2021.112804","article-title":"Heterostructure-Based Devices with Enhanced Humidity Stability for H2 Gas Sensing Applications in Breath Tests and Portable Batteries","volume":"329","author":"Lupan","year":"2021","journal-title":"Sens. Actuators A Phys."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.physb.2017.07.041","article-title":"Structural Transformation and Enhanced Gas Sensing Characteristics of TiO2 Nanostructures Induced by Annealing","volume":"535","author":"Tshabalala","year":"2018","journal-title":"Phys. B Condens. Matter"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"1204","DOI":"10.1007\/s10854-025-15283-z","article-title":"Revival of Quantum Confinement Effect and Stabilization of Tetragonal Phase in TiO2 Nanopowders with Annealing Temperature","volume":"36","author":"Tokeser","year":"2025","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_65","doi-asserted-by":"crossref","unstructured":"Ciftyurek, E., Li, Z., and Schierbaum, K. (2022). Adsorbed Oxygen Ions and Oxygen Vacancies: Their Concentration and Distribution in Metal Oxide Chemical Sensors and Influencing Role in Sensitivity and Sensing Mechanisms. Sensors, 23.","DOI":"10.20944\/preprints202212.0037.v1"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"15963","DOI":"10.1021\/acs.jpcc.5b01397","article-title":"From the Surface Reaction Control to Gas-Diffusion Control: The Synthesis of Hierarchical Porous SnO2 Microspheres and Their Gas-Sensing Mechanism","volume":"119","author":"Wang","year":"2015","journal-title":"J. Phys. Chem. C"},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1007\/s00604-022-05254-0","article-title":"Metal Oxide Semiconducting Nanomaterials for Air Quality Gas Sensors: Operating Principles, Performance, and Synthesis Techniques","volume":"189","author":"Isaac","year":"2022","journal-title":"Microchim. Acta"},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"3221","DOI":"10.1021\/acs.jpcc.5b12101","article-title":"Effect of Oxygen Activity on the n\u2013p Transition for Pure and Cr-Doped TiO2","volume":"120","author":"Nowotny","year":"2016","journal-title":"J. Phys. Chem. C"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.snb.2018.07.082","article-title":"Cost-Effective Fabrication of Polycrystalline TiO2 with Tunable n\/p Response for Selective Hydrogen Monitoring","volume":"274","author":"Sun","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.apsusc.2012.09.061","article-title":"Sputtered TiO2 Thin Films with NiO Additives for Hydrogen Detection","volume":"269","author":"Kosc","year":"2013","journal-title":"Appl. Surf. Sci."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0925-4005(99)00133-1","article-title":"Semiconducting Oxides as Gas-Sensitive Resistors","volume":"57","author":"Williams","year":"1999","journal-title":"Sens. Actuators B Chem."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1016\/j.snb.2004.04.075","article-title":"A P- to n-Transition on \u03b1-Fe2O3-Based Thick Film Sensors Studied by Conductance and Work Function Change Measurements","volume":"102","author":"Gurlo","year":"2004","journal-title":"Sens. Actuators B Chem."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"44603","DOI":"10.1021\/acsami.8b15445","article-title":"Pd Nanoparticle Film on a Polymer Substrate for Transparent and Flexible Hydrogen Sensors","volume":"10","author":"Xie","year":"2018","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"3554","DOI":"10.1021\/am5073645","article-title":"A Highly Sensitive Hydrogen Sensor with Gas Selectivity Using a PMMA Membrane-Coated Pd Nanoparticle\/Single-Layer Graphene Hybrid","volume":"7","author":"Hong","year":"2015","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"27193","DOI":"10.1021\/acsami.7b07641","article-title":"Response Characteristics of Hydrogen Sensors Based on PMMA-Membrane-Coated Palladium Nanoparticle Films","volume":"9","author":"Chen","year":"2017","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"33373","DOI":"10.1021\/acsami.8b11689","article-title":"Switchable Single-Walled Carbon Nanotube\u2013Polymer Composites for CO2 Sensing","volume":"10","author":"Yoon","year":"2018","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"5413","DOI":"10.1021\/acs.chemmater.9b00504","article-title":"Porous Ion Exchange Polymer Matrix for Ultrasmall Au Nanoparticle-Decorated Carbon Nanotube Chemiresistors","volume":"31","author":"Koo","year":"2019","journal-title":"Chem. Mater."},{"key":"ref_78","doi-asserted-by":"crossref","unstructured":"Abdali, H., Heli, B., and Ajji, A. (2019). Cellulose Nanopaper Cross-Linked Amino Graphene\/Polyaniline Sensors to Detect CO2 Gas at Room Temperature. Sensors, 19.","DOI":"10.3390\/s19235215"},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"2537","DOI":"10.1002\/adfm.201500314","article-title":"When Nanoparticles Meet Poly(Ionic Liquid)s: Chemoresistive CO2 Sensing at Room Temperature","volume":"25","author":"Willa","year":"2015","journal-title":"Adv. Funct. Mater."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"66","DOI":"10.52326\/jes.utm.2024.31(1).06","article-title":"Propanol Detection Device for the Purpose of Monitoring the Quality of the Environment","volume":"31","author":"Chiriac","year":"2024","journal-title":"J. Eng. Sci."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"106241","DOI":"10.1016\/j.nanoen.2021.106241","article-title":"Tailoring the Selectivity of Ultralow-Power Heterojunction Gas Sensors by Noble Metal Nanoparticle Functionalization","volume":"88","author":"Lupan","year":"2021","journal-title":"Nano Energy"},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"5469","DOI":"10.3390\/s100605469","article-title":"Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring","volume":"10","author":"Fine","year":"2010","journal-title":"Sensors"},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"6326","DOI":"10.1021\/acs.langmuir.0c00701","article-title":"One-Dimensional Nanostructured Oxide Chemoresistive Sensors","volume":"36","author":"Kaur","year":"2020","journal-title":"Langmuir"},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"1756","DOI":"10.1039\/C9CS00459A","article-title":"Printed Gas Sensors","volume":"49","author":"Dai","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"24975","DOI":"10.1007\/s11356-022-21218-6","article-title":"Studies on Nanomaterial-Based p-Type Semiconductor Gas Sensors","volume":"30","author":"Ahmed","year":"2022","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_86","first-page":"126","article-title":"Gas Sensing Mechanism of Metal Oxides: The Role of Ambient Atmosphere, Type of Semiconductor and Gases\u2014A Review","volume":"4","author":"Shankar","year":"2015","journal-title":"Sci. Lett."},{"key":"ref_87","first-page":"15120","article-title":"Relationship between Exhaled Aerosol and Carbon Dioxide Emission Across Respiratory Activities","volume":"58","author":"Moseley","year":"2024","journal-title":"Environ. Sci. Technol."},{"key":"ref_88","doi-asserted-by":"crossref","unstructured":"Cavaliere, F., Volpe, C., Gargaruti, R., Poscia, A., Di Donato, M., Grieco, G., and Moscato, U. (2009). Effects of Acute Hypoventilation and Hyperventilation on Exhaled Carbon Monoxide Measurement in Healthy Volunteers. BMC Pulm. Med., 9.","DOI":"10.1186\/1471-2466-9-51"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"9752","DOI":"10.1038\/s41598-022-14210-0","article-title":"Modification of Baseline Status to Improve Breath Tests Performance","volume":"12","author":"Alegre","year":"2022","journal-title":"Sci. Rep."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"312","DOI":"10.5056\/jnm.2011.17.3.312","article-title":"How to Interpret Hydrogen Breath Tests","volume":"17","author":"Ghoshal","year":"2011","journal-title":"J. Neurogastroenterol. Motil."},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1177\/2050640614521124","article-title":"Symptomatic Fructose Malabsorption in Irritable Bowel Syndrome: A Prospective Study","volume":"2","author":"Melchior","year":"2014","journal-title":"United Eur. Gastroenterol. J."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/1\/5\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,24]],"date-time":"2025-12-24T05:15:03Z","timestamp":1766553303000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/1\/5"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,22]]},"references-count":91,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["bios16010005"],"URL":"https:\/\/doi.org\/10.3390\/bios16010005","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,22]]}}}