Abstract
To our knowledge, this paper presents a novel plasmonic lab-on-chip (LoC) sensor with one input port and two output ports, allowing simultaneous detection of two distinct samples while preventing any cross-contamination. Finite element method (FEM) simulations were used to analyze the sensor's performance, resulting in a high sensitivity of 1780nm per refractive index unit (RIU). The sensor also achieved a figure of merit (FOM) of 65.7 within the NIR (Near-Infrared) wavelength region, with a detection limit (DL) of 5.617 x 10-7RIU. The metal-insulator-metal (MIM) structure of the sensor was evaluated and optimized with three different brass alloy compositions as the sensing surface. An optimal alloy composition of 70% copper and 30% zinc achieved a notable transmission coefficient (TC) of approximately-25 dB, surpassing standard optical performance while also enhancing analyte interaction through nanoscale light confinement. The MIM-based LoC sensor enables precise and accurate measurements of subtle changes in RI, making it ideal for portable, real-world applications in resource-limited environments. This sensor holds significant potential for seawater monitoring, efficiently detecting both crude oil contamination and salinity levels with minimal sample volume, contributing to improved environmental monitoring capabilities. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement