Strategies for sensitivity improvement of localized surface plasmon resonance sensors: experimental and mathematical approaches in plasmonic gold nanostructures

Abstract Localized surface plasmon resonance (LSPR) sensors using metallic nanoparticles are extensively used for refractive index (RI) measurements in chemical and biological studies, and their sensitivity is highly influenced by the material and structure of the nanoparticle. Despite the great advantages of LSPR sensors using frequency shifts, there are still major challenges in terms of detection sensitivity as well as the broadening and asymmetry of LSPR peaks. This article provides a general background of the fundamentals of LSPR and RI-based LSPR sensing. Thereafter, recent advances in the improvement of LSPR sensitivity are discussed in the viewpoints of two experimental and mathematical approaches. The experimental approaches, including the fabrication of plasmonic array nanostructures with high uniformity and site-selective immobilization, are briefly discussed. Later, we discuss recent studies using a simple mathematical approach with LSPR inflection point to improve the RI sensitivity in gold nanoparticles with different shapes, sizes, shells, etc.