Optical Detection of Fat Concentration in Milk Using MXene-Based Surface Plasmon Resonance Structure

MXene (Ti₃C₂T_x) has emerged very recently as an interacting material for surface plasmon resonance (SPR) configuration. It was discovered that Ti₃C₂T_x can facilitate the adsorption of biomolecules due to its higher binding energies, stronger interaction between matter and light, and larger surface area. In this work, a two-dimensional Ti₃C₂T_x and silicon layer-based SPR refractometric sensor is proposed for the sensitive and fast detection of milk fat concentration due to the high significance of this issue to people all over the world. The proposed SPR structure employs BK7 (BK7 is a designation for the most common Borosilicate Crown glass used for a variety of applications in the visible range) as a coupling prism and silver as a metal layer. The layer thicknesses and the number of Ti₃C₂T_x sheets are optimized for the highest performance. The highest reached sensitivity is 350 deg./RIU with 50 nm silver and 4 nm silicon with a monolayer of Ti₃C₂T_x, which is ultra-high sensitivity compared to the latest work that utilizes SPR configuration. The proposed SPR-based sensor's ultra-high sensitivity makes it more attractive for usage in a variety of biosensing applications.