A symmetrical optical waveguide based surface plasmon resonance biosensing system

In this work, we propose a MgF2/Au/MgF2/Analyte based, angle-interrogation surface plasmon resonance sensor. This symmetrical structure results in higher surface electric field strengths, and longer surface propagation lengths and depths. A refractive index resolution of 8.1 × 10−8 RIU in fluid protocol and 3.5 × 10−7 RIU in atmosphere protocol is acquired by a simple SPR imaging system. In order to demonstrate the biomedical applications of this system, we detect Escherichia coli with different concentrations using dopamine film on the sensor surface to immobilize antibodies. A detection limit of 103 cfu/mL of E. coli bacteria is acquired from this system.