The Effects of Adding Different Adhesive Layers with a Microstructure Fiber Sensor Based on Surface Plasmon Resonance: A Numerical Study

The adhesive layer plays a significant role in the fabrication process of plasmonic nanoantennas, micro-biosensors, nanostructures, solar cells, etc., as it delivers support to plasmonic material coating. This article discusses a study on the effects of using five different adhesive materials with an externally gold-screened microstructure fiber plasmonic sensor within the refractive index (RI) sensing range of 1.37-1.40. Numerical analyses are conducted to examine the effects of using titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), indium tin oxide (ITO), zinc oxide (ZnO), and SU-8 3000 photoresist to support gold covering on the exterior portion of the fiber. The influences of each of the adhesive materials are investigated with respect to the sensor's sensitivity for thickness variations between 5 and 20 nm. Without any adhesive layer, the proposed sensor exhibits about 1136.10 RIU-1 of amplitude interrogated sensitivity (AIS) at RI of 1.38, 14,500 nm/RIU of wavelength interrogated sensitivity (WIS), and 6.89 x 10(-6) RIU of resolution at RI of 1.39. According to the analyses, it is observed that the AIS of the sensor decreases as the thickness of the adhesive layer increases. Moreover, with 5 nm of TiO2, Ta2O5, ITO, ZnO, and SU-8 3000, photoresist adhesive layers with gold, respectively, 9.29%, 7.13%, 12.38%, 5.85%, and 1.17% reductions in the AIS of the sensor have been found.