{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T03:11:15Z","timestamp":1773889875132,"version":"3.50.1"},"reference-count":36,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2011,11,10]],"date-time":"2011-11-10T00:00:00Z","timestamp":1320883200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Real time oil quality monitoring techniques help to protect important industry assets, minimize downtime and reduce maintenance costs. The measurement of a lubricant\u2019s complex permittivity is an effective indicator of the oil degradation process and it can be useful in condition based maintenance (CBM) to select the most adequate oil replacement maintenance schedules. A discussion of the working principles of an oil quality sensor based on a marginal oscillator to monitor the losses of the dielectric at high frequencies (&gt;1 MHz) is presented. An electronic design procedure is covered which results in a low cost, effective and ruggedized sensor implementation suitable for use in harsh environments.<\/jats:p>","DOI":"10.3390\/s111110675","type":"journal-article","created":{"date-parts":[[2011,11,10]],"date-time":"2011-11-10T11:10:58Z","timestamp":1320923458000},"page":"10675-10690","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":47,"title":["Low-Cost Oil Quality Sensor Based on Changes in Complex Permittivity"],"prefix":"10.3390","volume":"11","author":[{"given":"Angel Torres","family":"P\u00e9rez","sequence":"first","affiliation":[{"name":"Sustainable Design Research Centre, Bournemouth University, Fern Barrow, Talbot Campus, Poole, Dorset, BH12 5BB, UK"}]},{"given":"Mark","family":"Hadfield","sequence":"additional","affiliation":[{"name":"Sustainable Design Research Centre, Bournemouth University, Fern Barrow, Talbot Campus, Poole, Dorset, BH12 5BB, UK"}]}],"member":"1968","published-online":{"date-parts":[[2011,11,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"940","DOI":"10.1063\/1.1721406","article-title":"A new method for continuous viscosity measurement: General theory of the ultra-viscoson","volume":"7","author":"Roth","year":"1953","journal-title":"J. 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