Low-Cost Oil Quality Sensor Based on Changes in Complex Permittivity

Angel Torres Perez*, Mark Hadfield

*Corresponding author for this work

Research output: Contribution to JournalArticlepeer-review


Real time oil quality monitoring techniques help to protect important industry assets, minimize downtime and reduce maintenance costs. The measurement of a lubricant’s 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 (>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.
Original languageEnglish
Pages (from-to)10675–10690
JournalSensors (Switzerland)
Publication statusPublished - 1 Nov 2011


  • oil quality, impedance spectroscopy, marginal oscillator, dielectric, permittivity, lubrication oil, on-line monitoring


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