Surface plasmon resonance sensor based on cross-linked chitosan immobilized onto the surface of optimization AgAu composite film for trace copper(II) ions detection
We propose an intensity-modulated surface plasmon resonance (SPR) sensor based on a four-layer Kretschmann structural model. To achieve high-sensitivity intensity detection for the measured sample, a silver/gold (Ag/Au) composite film structure is proposed and optimized by a numerical simulation method, and then the chitosan thin film modified by glutaraldehyde cross-linked as an active layer for adsorbing measured sample is applied and immobilized onto the surface of the Ag/Au composite film by spin-coating technique. In addition, a reference beam is introduced into the system to raise its resolution and stability. Measurements are taken while varying the trace copper(II) ion (Cu2 + ) concentration from 0 to 5 ppm, and the SPR sensor is found to possess sensitivities of 0.9147 and 0.4466 ppm - 1 at Cu2 + concentrations of 0 to 3 and 3 to 5 ppm, respectively. The concentration resolution is 0.015 and 0.030 ppm for the trace Cu2 + concentration of 0 to 3 and 3 to 5 ppm, respectively.