Application of surface plasmon resonance sensing to studying elastohydrodynamic lubricant films

Chi Lok Wong*, Ho Pui Ho, Kwok Sum Chan, Shu Yuen Wu

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

13 Scopus citations


We present a new technique based on the spectral characteristics associated with the surface plasmon resonance (SPR) effect for studying lubricants in elastohydrodynamic (EHD) dimples. The pressure inside the EHD dimple causes a localized change of the refractive index (RI) of the entrapped lubricant. This also results in a shift in the spectral SPR absorption dip. By monitoring the color changes within the SPR image, one can obtain a direct measurement of the RI of the entrapped lubricant, from which the pressure distribution within the elastohydrodynamic lubrication (EHL) dimple can be deduced by means of a predetermined relation of pressure and RI of the tested lubricant. Dimples formed with the lubricants PB 2400 and H 1900 were studied in our experiments. Because SPR is sensitive only to the RI variation within a thin region (approximately one wavelength) close to the sensor's surface, the new technique does not require any measurement of the absolute film thickness of the lubricant. This is much simpler than the existing two-beam interferometric technique for measuring the RI of lubricants in EHD dimples, which requires simultaneous measurements of optical film thickness by use of two beams of different angles of incidence. In light of this advantage we anticipate that the new technique can be applied to pressure field mapping in highly loaded rolling and sliding EHL contacts. copy; 2005 Optical Society of America.

Original languageEnglish
Pages (from-to)4830-4837
Number of pages8
JournalApplied Optics
Issue number23
StatePublished - 10 08 2005
Externally publishedYes


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