Design and Optimization of Surface Plasmonic Sensor with Tunable Optical Actuation Angle Based on Microsystem Technology for Microfluidic Application

Surface plasmon resonance-based sensors are one of the most accurate detectors of chemical and biochemical components in microfluidic structures performed based on changes in the refractive index of the medium adjacent to the sensor surface. In such sensors, the performance is strongly influenced by the amount of light coupled with surface plasmons. Consequently, the electromagnetic waves should reach the metal layer much more accurately. Precise adjustment of the excitation angle and occupation volume of one kinds of such sensors are among their highlighted challenges that come from conventional light coupling technique. In this paper, a novel idea for designing this type of sensor in microsystem technology is devised, which is capable not only of adjusting angle of optical excitation using thermal-optical effect, but also of occupying the least amount of space. This design is optimized and validated using Finite Element Method, so that the sensor performance in exchange for changes in parameters such as refractive index and metal thickness is examined and displayed in the form of tables and graphs. Simulation results reveal that the proposed model is able to tune optical excitation angle such accurate that the SPR phenomenon occurs at an angle of 21.21° at the outer boundary of 42 nm thick of gold layer at its best.