This research presents an innovative L-shaped plasmonic refractive index (RI) sensor combined with a straight metal-insulator-metal (MIM) waveguide configuration. Using the finite element method (FEM), a detailed numerical analysis was conducted to explore the sensor's structure. The sensor detects changes in RI by monitoring shifts in the resonant wavelength. The sensing mechanism relies on the interaction between light and the plasmonic structure, where changes in the surrounding medium's RI cause shifts in the resonant wavelength. This is significant for chemical analysis. Through geometric parameter optimization, the sensor achieved a maximum sensitivity of 1638 nm/RIU, enabling the detection of minute molecular quantities. The sensor was also tested for alcohol detection, demonstrating its versatility. Surface plasmon polaritons (SPPs) are crucial for confining light at the nanoscale, enhancing data transmission efficiency. MIM waveguides are promising for sensor technology due to their flexibility, customizable designs, and ability to support multiple resonance modes. They are compatible with various wavelengths and offer robust light confinement, low loss, and cost-effective fabrication. These features make them suitable for nanophotonic and optoelectronic applications. Recent research has focused on developing MIM waveguides for RI sensors, which offer real-time monitoring, label-free detection, high reusability, and fast response times. They are well-suited for biomedical, environmental, and industrial applications. Researchers have explored various topologies, including ring resonators and optical switches, achieving high sensitivity and figures of merit. Despite progress, there is still potential to enhance sensitivity through structural modifications. Continued research into novel designs and innovative strategies is essential to advance plasmonic sensors and their applications.This research presents an innovative L-shaped plasmonic refractive index (RI) sensor combined with a straight metal-insulator-metal (MIM) waveguide configuration. Using the finite element method (FEM), a detailed numerical analysis was conducted to explore the sensor's structure. The sensor detects changes in RI by monitoring shifts in the resonant wavelength. The sensing mechanism relies on the interaction between light and the plasmonic structure, where changes in the surrounding medium's RI cause shifts in the resonant wavelength. This is significant for chemical analysis. Through geometric parameter optimization, the sensor achieved a maximum sensitivity of 1638 nm/RIU, enabling the detection of minute molecular quantities. The sensor was also tested for alcohol detection, demonstrating its versatility. Surface plasmon polaritons (SPPs) are crucial for confining light at the nanoscale, enhancing data transmission efficiency. MIM waveguides are promising for sensor technology due to their flexibility, customizable designs, and ability to support multiple resonance modes. They are compatible with various wavelengths and offer robust light confinement, low loss, and cost-effective fabrication. These features make them suitable for nanophotonic and optoelectronic applications. Recent research has focused on developing MIM waveguides for RI sensors, which offer real-time monitoring, label-free detection, high reusability, and fast response times. They are well-suited for biomedical, environmental, and industrial applications. Researchers have explored various topologies, including ring resonators and optical switches, achieving high sensitivity and figures of merit. Despite progress, there is still potential to enhance sensitivity through structural modifications. Continued research into novel designs and innovative strategies is essential to advance plasmonic sensors and their applications.