A preliminary study of optical biosensor towards blood-glucose measurements

Surface plasmons are the collective electron wave on the nanoscale thin film of metals. Under suitable conditions, these surface waves can be excited to create surface plasmon resonance. The resonance condition is extremely sensitive to the refractive index of the medium, making it a suitable technique for sensing purposes. The objective of the present work was to study the dependence of SPR curve on various parameters theoretically and to study SPR curve for air, water and aqueous solution of glucose using an SPR experimental set up. To construct the set up, parameters were calculated using a simulation program (in MATLAB) based on the three layer solution of the Fresnel equation. Dependence of the excitation wavelength and the thickness of the metal film on the SPR signature were investigated. Also, the limit of detection was estimated for given parameters. Experimentally, the dielectric media, air, water and aqueous solution of glucose were measured using the home built experimental set up. The obtained data were corrected for the refraction inside the glass prism. In case of the solutions, the refractive index change up to 9.7x10-4 RIU was detected successfully.