Enhanced Photocatalytic Efficiency and Biosensing in Plasmonic Nanostructures for the Detection of Bacteria in Various Analytes

The interaction of transverse magnetic (TM) plane waves with 1D metallic bowtie gratings on glass substrate has been used for surface plasmon polaritons (SPPs) excitation. Silver (Ag) bowtie metallic grating has been modelled in COMSOL Multiphysics 5.6 Licensed version, for different gap widths (GWs) and film thickness by keeping the periodicity constant. The 0th order transmission spectra for this grating with various geometrical parameters at normal incidence has been extracted and studied by far-field analysis. To check the photocatalytic enhancement, the method of enhanced field confinement is used by exciting SPPs at TiO2/air interface. The enhancement factor is examined by changing gap width (50–450 nm with step size of 100 nm) with fixed thickness and periodicity. The photocatalytic efficiency is also calculated and degradation of three dyes (Methyl Red (MR), Methyl Orange (MO) and Phenol (Ph)) by calculating their concentrations and photodegradation rate constant ‘k’ are studied as well. Far and near-field analysis are employed to study the optimum structure for effective absorption of light. The results of far-field are supported by applying near-field analysis at resonance wavelength. A brief comparison of enhancement factor and photocatalytic degradation with literature is also presented. Additionally, the plasmonic biosensor has been analyzed that can be used for wavelength range 400–1200 nm for the detection of bacteria in liquid analytes. The sensitivity of the proposed model has been calculated as 627.27 nm per RIU. This research provides a pathway to real-time applications which are helpful in fabrication of efficient plasmonic based photocatalytic devices for highest degradation efficiency and also for the plasmonic based biosensors for the detection of bacteria. Such grating devices with optimized parameters can also be used in the field plasmonic based solar cells for the improved efficiency.