Investigating the Performance of Metal-Assisted Guided Mode Resonance Based Structures for Biosensing Applications

The sensing abilities of a metal-assisted guided mode resonance (MAGMR)-based structure are compared with that of a conventional guided mode resonance (GMR)-type structure operating at the same resonance wavelength. By studying the electric field intensities at resonance, it has been found that the MAGMR sensor offers a superior and more uniform sensitivity over the entire sensor surface as compared to the GMR sensors, where the sensing takes place primarily at the trenches between the grating elements. The MAGMR sensor also shows an asymmetric field profile with 44.96% of the total field extending into the sensing region at resonance in comparison with that value of 25.62% for the GMR sensor. The bulk and surface sensitivity values have also been evaluated for a range of refractive indices and analyte thicknesses, and it has been observed that the MAGMR sensor offers superior sensitivity values over the GMR sensor for all the considered cases. The limit of detection has then been calculated for both the structures, where the MAGMR structure shows a 9-fold improvement in comparison with the GMR structure for an identical readout scheme.