This work intends for sensitivity analysis of different metasurface array-based biosensors. The array designs in the form of circle array, square array, square circle array, circle square array, five-element square array, plus array, five-element plus square array. The sensitivity of these metasurface biosensors are compared and optimized design is presented. Circle array design shows the best sensitivity performance amongst them. The optimized circle array design is analyzed by varying different physical parameters of the design such as SiO ₂ substrate thickness and metasurface array thickness. The optimized results for this variation are also presented. The sensitivity of the current biosensor design is also compared with the previously published similar designs. The results are also presented for electric field intensity and current field density for the optimized design. The proposed sensitive biosensor can become a building block of future biomedical devices and photovoltaic devices.

This paper describes simulation and experimental methods for designing a D-shaped surface plasmon resonance (SPR) fibre sensor. The sensor consists of two set-up approaches. Finite element method is used in simulation on the fibre sensor device. Two experimental methods for detecting relative intensity are used by varying the wavelength of the optical signal sources and the thickness of gold layer coated on the D-shaped fibre. In the first method, the sensor device works by detecting the relative intensity of two optical signal sources having different wavelengths. In the second set-up, the relative intensity between two D-shaped fibres coated with different thicknesses of gold is measured when a single signal source is launched at the input. The difference in intensities of the signal outputs is used to estimate the refractive index at the sensing region. A prototype SPR D-shaped fibre sensor has been fabricated and the experimental results show good agreement with simulation.

Hybrids plasmonic nanoparticles (NPs) and unique 2D graphene significantly enhanced the photoresponse of the photodetectors. The metallic NPs that exhibit localized surface plasmon resonance (LSPR) improves strong light absorption, scattering and localized electromagnetic field by the incident photons depending on the optimum condition of NPs. We report high-performance photodetectors based on reduced graphene oxide (rGO) integrated with monometallic of Au and Ag nanoparticles via a familiar fabrication technique using an electron beam evaporation machine. Under 680 nm illumination of light, our rGO photodetector exhibited the highest performance for Au-rGO with the highest responsivity of 67.46 AW⁻¹ and the highest specific detectivity (2.39 × 10¹³ Jones). Meanwhile, Ag-rGO achieved the highest responsivity of 17.23 AW⁻¹, specific detectivity (7.17 × 10¹¹ Jones) at 785 nm. The response time are 0.146 µs and 0.135 µs for Au-rGO and Ag-rGO respectively for both wavelengths. The proposed photodetector with combining monometallic and graphene provide a new strategy to construct reliable and next-generation optoelectronic devices at VIS–NIR region.

We propose a novel graphene-based metasurface plasmonic biosensor. The gold split-ring resonator is used as a metasurface element in the biosensor. Split Ring Resonator structures are used to localize and increase electromagnetic field incidents. Two types of split-ring resonator based metasurface (Single split-ring resonator and Double split-ring resonator) designs are analyzed to observe its effect on biosensing. The proposed biosensor is used to sense hemoglobin and urine biomolecules for their different concentrations. The design results in the form of absorption, electric field, and magnetic field are presented. The sensitivity for hemoglobin biomolecules and urine biomolecules are calculated from their absorption peak difference and refractive index difference. The sensitivity results are compared with previously published designs. The proposed single split ring resonator metasurface design has the highest sensitivity for hemoglobin-urine concentrations. The proposed biosensor can become a building block for future medical biosensing devices.