Compensated Surface Plasmon Resonance Sensor for Long-Term Monitoring Applications

This paper presents an optical sensor capable of detecting small changes in the concentration of chemicals by exploiting the surface plasmon resonance principle. A two sensing area layout allows implementing a differential configuration to compensate the perturbations—such as mechanical instabilities and temperature fluctuations—that greatly impair the accuracy especially during long-term monitoring applications. The proposed solution can be easily implemented in different geometries, including optical fibers. An analysis of the impact of unwanted changes in the measurement setup is provided and an example of a compensation procedure applied to angular misalignments is given. Experimental validation and analysis of uncertainty sources affecting the proposed compensation procedure are reported.