Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7140972 | Sensors and Actuators B: Chemical | 2018 | 8 Pages |
Abstract
In this article, the design and application of an optical sensor for fluid monitoring based on two tunable Fabry-Pérot filters is presented. The sensor enables fluid transmission measurements in the spectral ranges from 1818â¯cmâ1 to 1250â¯cmâ1 and from 1250â¯cmâ1 to 952â¯cmâ1 at wavenumber-dependent resolutions between approximately 20â¯cmâ1 and 33â¯cmâ1. A novel method is proposed to ensure a correct wavenumber representation of the obtained spectra, correcting for an oblique light path in the optical system. The sensor shows high linearity and a low noise level for absorbance measurements. As an example for a fluid monitoring application, the transmission spectra of deteriorated automotive engine oil samples were measured and compared to spectra obtained with a Fourier-transform infrared spectrometer. We used partial least squares (PLS) regression to construct calibration models for the prediction of significant oil condition parameters, like oxidation, sulfation, water content and viscosity, from the obtained spectra. The values predicted from the absorption spectra show high correlation with reference values of the oil condition parameters determined in a laboratory according to appropriate standards. These results indicate that the sensor can be a useful supplementary tool for fast and cost-effective engine oil condition monitoring.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Markus S. Rauscher, Michael Schardt, Michael H. Köhler, Alexander W. Koch,