Design study of nanograting-based surface plasmon resonance biosensor in the near-infrared wavelength

Abstract

A key issue with surface plasmon resonance (SPR) biosensors, which are the focus of many researchers, is improving their sensitivity to detect lower amounts of analyte in a solution. Most SPR developments have focused on the grating-based sensitivity-enhancement approach. In addition to sensitivity, a substantial enhancement of other sensor characteristics such as resolution and signal-to-noise ratio (SNR) is desired for designing a practical sensor. So, in this paper, the characteristics of surface plasmon polaritons sustained by 1D subwavelength metallic gratings on a thin metal slab (under the Krestchmann configuration) have been investigated numerically for the analyte-ligand interactions detection. Effects of different structural parameters, such as grating period, grating depth, metal film thickness, and fill factor have been evaluated on the sensor sensitivity as well as resolution and SNR. Numerical results indicate that the sensor working in the near-infrared wavelength has a better performance than that in the visible one. The result of numerical investigation has been used to design an optimized sensor with the best figure of merit.

Design of a high figure of merit subwavelength grating based plasmonic sensor for detection of DNA hybridization

“…It has been demonstrated in our previous work that a laser wavelength of 984 nm allows the biosensor with parameters of P and f.f equal 50 nm and 0.5, respectively, operates near the band edge wavelength related to the highest dg of 40 nm which is located in flattened part of dispersion map [12]. As described the sensor at this band edge wavelength shows the highest sensitivity.…”

“…From our previous study using an angle interrogation type of SPR biosensor such as proposed sensor in this letter, dispersion curve study revealed that high sensitivities can be obtained in the sensor working in operating wavelength near the band edge wavelength which is located in the flattened part of the dispersion curve [12]. It has been described that operating near the bandgap is more sensitive [21].…”

“…The highest obtainable value of FOM is 1.12 with considering the optimum value of dm (i. e. 40 nm) and a high value of dg equals 40 nm. 6 As reported in our recent numerical study higher diffraction orders can be neglected in the P values up to 250 nm and P is required to be kept small due to the stronger excitation of SP in the smaller grating periods [12]. By decreasing the period, coverage or surface concentration of the metal wires gets higher which induces a stronger coupling of the SPs [11].…”

“…Also, the effects of other grating heights and flat metal layer thicknesses were investigated for sensor performance parameters including sensitivity, FWHM and MRR in operating wavelength of 984 nm [12]. The numerical results showed that the variation of metal film layer thickness has significant influence on MRR rather than the sensitivity.…”

“…3 In this letter, nanograting based SPR sensor is demonstrated and used for detection of DNA hybridization which its performance is numerically investigated by finite element method (FEM). From our previous work about metallic nanograting based SPRB, evaluating the effects of grating thickness and period on the dispersion curve showed that this structure has a good potential to provide a better performance in NIR wavelengths [12]. Following that work, a comprehensive evaluation of grating geometry parameters specially f.f on the dispersion curve of nanograting based SPR sensor is done here which results in obtaining higher sensitivities and FOMs by optimizing the structural parameters in the near-infrared (NIR) wavelength of 984 nm.…”