{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,9]],"date-time":"2026-05-09T15:16:45Z","timestamp":1778339805268,"version":"3.51.4"},"reference-count":31,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2023,6,29]],"date-time":"2023-06-29T00:00:00Z","timestamp":1687996800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>The fabrication of low-electrical-percolation-threshold polymer composites aims to reduce the weight fraction of the conductive nanomaterial necessary to achieve a given level of electrical resistivity of the composite. The present work aimed at preparing composites based on multiwalled carbon nanotubes (MWCNTs) and magnetite particles in a polyurethane (PU) matrix to study the effect on the electrical resistance of electrodes produced under magnetic fields. Composites with 1 wt.% of MWCNT, 1 wt.% of magnetite and combinations of both were prepared and analysed. The hybrid composites combined MWCNTs and magnetite at the weight ratios of 1:1; 1:1\/6; 1:1\/12; and 1:1\/24. The results showed that MWCNTs were responsible for the electrical conductivity of the composites since the composites with 1 wt.% magnetite were non-conductive. Combining magnetite particles with MWCNTs reduces the electrical resistance of the composite. SQUID analysis showed that MWCNTs simultaneously exhibit ferromagnetism and diamagnetism, ferromagnetism being dominant at lower magnetic fields and diamagnetism being dominant at higher fields. Conversely, magnetite particles present a ferromagnetic response much stronger than MWCNTs. Finally, optical microscopy (OM) and X-ray micro computed tomography (micro CT) identified the interaction between particles and their location inside the composite. In conclusion, the combination of magnetite and MWCNTs in a polymer composite allows for the control of the location of these particles using an external magnetic field, decreasing the electrical resistance of the electrodes produced. By adding 1 wt.% of magnetite to 1 wt.% of MWCNT (1:1), the electric resistance of the composites decreased from 9 \u00d7 104 to 5 \u00d7 103 \u03a9. This approach significantly improved the reproducibility of the electrode\u2019s fabrication process, enabling the development of a triboelectric sensor using a polyurethane (PU) composite and silicone rubber (SR). Finally, the method\u2019s bearing was demonstrated by developing an automated robotic soft grip with tendon-driven actuation controlled by the triboelectric sensor. The results indicate that magnetic patterning is a versatile and low-cost approach to manufacturing sensors for soft robotics.<\/jats:p>","DOI":"10.3390\/polym15132870","type":"journal-article","created":{"date-parts":[[2023,6,30]],"date-time":"2023-06-30T01:02:41Z","timestamp":1688086961000},"page":"2870","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Development of MWCNT\/Magnetite Flexible Triboelectric Sensors by Magnetic Patterning"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6303-7079","authenticated-orcid":false,"given":"David Seixas","family":"Esteves","sequence":"first","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"CENTI, Centre for Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalic\u00e3o, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7932-8062","authenticated-orcid":false,"given":"Manuel F. C.","family":"Pereira","sequence":"additional","affiliation":[{"name":"CERENA, Center for Natural Resources and Environment, IST, University of Lisbon, 1049-001 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2379-0004","authenticated-orcid":false,"given":"Ana","family":"Ribeiro","sequence":"additional","affiliation":[{"name":"CENTI, Centre for Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalic\u00e3o, Portugal"}]},{"given":"Nelson","family":"Dur\u00e3es","sequence":"additional","affiliation":[{"name":"CENTI, Centre for Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalic\u00e3o, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3538-5804","authenticated-orcid":false,"given":"Maria C.","family":"Paiva","sequence":"additional","affiliation":[{"name":"Department of Polymer Engineering, Institute for Polymers and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5295-5648","authenticated-orcid":false,"given":"Elsa W.","family":"Sequeiros","sequence":"additional","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"INEGI\u2014Institute of Science and Innovation in Mechanical and Industrial Engineering, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1038\/nature14543","article-title":"Design, Fabrication and Control of Soft Robots","volume":"521","author":"Rus","year":"2015","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1903558","DOI":"10.1002\/adma.201903558","article-title":"Flexible Neuromorphic Electronics for Computing, Soft Robotics, and Neuroprosthetics","volume":"32","author":"Park","year":"2020","journal-title":"Adv. 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