{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,6]],"date-time":"2026-05-06T12:27:23Z","timestamp":1778070443680,"version":"3.51.4"},"reference-count":73,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,19]],"date-time":"2021-02-19T00:00:00Z","timestamp":1613692800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of European Funds","award":["Financial Agreement 51675 \/ 09.07.2019, SMIS code 125125"],"award-info":[{"award-number":["Financial Agreement 51675 \/ 09.07.2019, SMIS code 125125"]}]},{"DOI":"10.13039\/501100006595","name":"Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii","doi-asserted-by":"publisher","award":["364PED \u2013 23.10.2020"],"award-info":[{"award-number":["364PED \u2013 23.10.2020"]}],"id":[{"id":"10.13039\/501100006595","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Romanian Ministry of Research and Education","award":["MICRO-NANO-SIS PLUS\", grant number PN 19 16"],"award-info":[{"award-number":["MICRO-NANO-SIS PLUS\", grant number PN 19 16"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper reports, for the first time, on the electrical percolation threshold in oxidized carbon nanohorns (CNHox)\u2013polyvinylpyrrolidone (PVP) films. We demonstrate\u2014starting from the design and synthesis of the layers\u2014how these films can be used as sensing layers for resistive relative humidity sensors. The morphology and the composition of the sensing layers are investigated through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and RAMAN spectroscopy. For establishing the electrical percolation thresholds of CNHox in PVP, these nanocomposite thin films were deposited on interdigitated transducer (IDT) dual-comb structures. The IDTs were processed both on a rigid Si\/SiO2 substrate with a spacing of 10 \u00b5m between metal digits, and a flexible substrate (polyimide) with a spacing of 100 \u00b5m. The percolation thresholds of CNHox in the PVP matrix were equal to (0.05\u20130.1) wt% and 3.5 wt% when performed on 10 \u00b5m-IDT and 100 \u00b5m-IDT, respectively. The latter value agreed well with the percolation threshold value of about 4 wt% predicted by the aspect ratio of CNHox. In contrast, the former value was more than an order of magnitude lower than expected. We explained the percolation threshold value of (0.05\u20130.1) wt% by the increased probability of forming continuous conductive paths at much lower CNHox concentrations when the gap between electrodes is below a specific limit. The change in the nanocomposite\u2019s longitudinal Young modulus, as a function of the concentration of oxidized carbon nanohorns in the polymer matrix, is also evaluated. Based on these results, we identified a new parameter (i.e., the inter-electrode spacing) affecting the electrical percolation threshold in micro-nano electronic devices. The electrical percolation threshold\u2019s critical role in the resistive relative-humidity sensors\u2019 design and functioning is clearly emphasized.<\/jats:p>","DOI":"10.3390\/s21041435","type":"journal-article","created":{"date-parts":[[2021,2,19]],"date-time":"2021-02-19T03:14:41Z","timestamp":1613704481000},"page":"1435","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Electrical Percolation Threshold and Size Effects in Polyvinylpyrrolidone-Oxidized Single-Wall Carbon Nanohorn Nanocomposite: The Impact for Relative Humidity Resistive Sensors Design"],"prefix":"10.3390","volume":"21","author":[{"given":"Bogdan-Catalin","family":"Serban","sequence":"first","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"},{"name":"Research Center for Integrated System, Nanotechnologies, Carbon-Based Nanomaterials (CENASIC)-IMT, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"}]},{"given":"Cornel","family":"Cobianu","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"},{"name":"Research Center for Integrated System, Nanotechnologies, Carbon-Based Nanomaterials (CENASIC)-IMT, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"},{"name":"Academy of Romanian Scientists, Science, Technology of Information Section, 3 Ilfov Str., 077160 Bucharest, Romania"}]},{"given":"Niculae","family":"Dumbravescu","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"},{"name":"Research Center for Integrated System, Nanotechnologies, Carbon-Based Nanomaterials (CENASIC)-IMT, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5713-4304","authenticated-orcid":false,"given":"Octavian","family":"Buiu","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"},{"name":"Research Center for Integrated System, Nanotechnologies, Carbon-Based Nanomaterials (CENASIC)-IMT, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"}]},{"given":"Marius","family":"Bumbac","sequence":"additional","affiliation":[{"name":"Faculty of Sciences and Arts, Sciences and Advanced Technologies Department, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania"},{"name":"Institute of Multidisciplinary Research for Science Technology, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6286-1303","authenticated-orcid":false,"given":"Cristina Mihaela","family":"Nicolescu","sequence":"additional","affiliation":[{"name":"Institute of Multidisciplinary Research for Science Technology, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania"}]},{"given":"Cosmin","family":"Cobianu","sequence":"additional","affiliation":[{"name":"Electrical Engineering, Electronics and Information Technology Faculty, Valahia University of Targoviste, 13 Sinaia Alley, 130004 Targoviste, Romania"}]},{"given":"Mihai","family":"Brezeanu","sequence":"additional","affiliation":[{"name":"Faculty of Electronics, University Politehnica of Bucharest Telecommunications and Information Technology, 1\u20133 Iuliu Maniu Blvd., 6th District, 061071 Bucharest, Romania"}]},{"given":"Cristina","family":"Pachiu","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126 A Erou Iancu Nicolae Str., 077190 Voluntari, Romania"}]},{"given":"Matei","family":"Serbanescu","sequence":"additional","affiliation":[{"name":"Faculty of Electronics, University Politehnica of Bucharest Telecommunications and Information Technology, 1\u20133 Iuliu Maniu Blvd., 6th District, 061071 Bucharest, Romania"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1486","DOI":"10.1016\/j.compscitech.2008.06.018","article-title":"A review and analysis of electrical percolation in carbon nanotube polymer composites","volume":"69","author":"Bauhofer","year":"2009","journal-title":"Compos. 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