Fig 1.
FDTD simulation schematic for the nano-laminated gold thin film on BSG substrate as a SPR-based sensor.
The plane-wave source is directed to the metal layer. The back-power monitor placed behind the source measured the reflection from the structure.
Fig 2.
SPR Navi 200 instrument schematic with Kretschmann configuration measurement setup.
This instrument’s optics comprises a prism, moving laser diode (wavelength 670 and 785 nm) and a photo-detector, which monitors the intensity of the reflected light as a function of angle. When nanolaminated gold sensor was inserted in the instrument and the flow cell is closed, the glass side of the sensor slide is connected via a refractive index matching elastomer onto the prism, as indicated by optical interface, and the flow cell is connected to the nanolaminate gold film side of the sensor slide.
Fig 3.
Reflectivity versus incident angle for nano-laminated gold film Kretschmann and SPR-based sensor using FDTD simulation for gold (Au) thin film thickness ranging from 20 to 80 nm.
Fig 4.
Reflectivity versus incident angle at various wavelengths on SPR sensor slide with nano-laminated gold film.
Fig 5.
SPR response curve of 50 nm-thick gold nano-laminated film from FDTD simulations and experiments at a) 670 nm and b) 785 nm optical wavelengths.
Fig 6.
Resonance angle shift of 50 nm-thick nano-laminated gold film sensor towards various concentrations a) urea and b) creatinine at 670 and 785 nm optical wavelengths.
Fig 7.
SPR response curves of 50 nm-thick nano-laminated gold film towards various concentrations of urea and creatinine with their enzymes at a) 670 nm and b) 785 nm optical wavelengths.
Fig 8.
Sensorgram of 50 nm-thick nano-laminated gold with mixed urea-urease and creatinine-creatininase with different concentrations at optical wavelengths of 670 and 785 nm.
Fig 9.
Sensitivity trend of 50 nm-thick nano-laminated gold film with enzymatic and non-enzymatic solutions in various concentrations at optical wavelength of 670 and 785 nm.
a) urea-urease and b) creatinine-creatininase.
Table 1.
Refractive index value of the enzymatic and non-enzymatic solutions in various urea and creatinine concentrations at 670 nm optical wavelength.