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This paper presents an investigation of a fluidic-based impedance biosensor for rapid and accurate detection of Salmonella Typhimurium in raw chicken carcass rinsate. The biosensor is engineered with multiple distinct regions that concentrates Salmonella antigens to a detectable level, subsequently trapping the concentrated Salmonella samples on top of the detection interdigitated electrode array coated with a specific Salmonella antibody, maximizing the number of captured antigens. Detection is achieved through the antibody-antigen binding process, where binding events changes impedance values, providing a reliable method for identifying and quantifying Salmonella. The biosensor demonstrated a low limit of detection (LOD) of 1–2 cells/ml within 40–50 min. The findings demonstrated that the biosensor distinguishes low concentrations of live Salmonella cells, even in the presence of high concentrations of dead Salmonella cells, and non-specific binding pathogens viz., Listeria monocytogenes and E. coli O157:H7. 

This study presents the development of a highly sensitive microfluidic-based impedance biosensor designed for rapid detection and identification of Salmonella Infantis in raw turkey samples, with a limit of detection (LOD) as low as 1 CFU/ml in 70 minutes detection time. The biosensor is equipped with novel focusing and trapping regions, significantly enhancing its sensitivity by concentrating and trapping Salmonella cells in the detection region. Salmonella cells labeled with fluorescent dyes were used to validate the functionality of the focusing and trapping mechanism, confirming the biosensor's ability to concentrate and trap Salmonella cells. 

This study validates a fiber optics-based Surface Enhanced Raman Spectroscopy (SERS) sensor for detecting Salmonella in raw turkey samples. The sensor uses nanoantenna arrays on a side-polished optical fiber core with a fixed periodicity of 0.77 µm to maximize the SERS signal intensity. A 3D-printed chamber and microstructure optimize light reflection, improving sensitivity. The sensor detects Salmonella at 0.4-0.5 CFU/ml in 10 minutes, offering cost-effective, portable pathogen detection. 

Microsphere Photolithography (MPL) is a nanopatterning technique that utilizes a self-assembled monolayer of microspheres as an optical element to focus incident radiation inside a layer of photoresist. The microspheres produces a sub-diffraction limited photonic-jet on the opposite side of each microsphere from the illumination. When combined with pattern transfer techniques such as etching/lift-off, MPL provides a versatile, low-cost fabrication method for producing hexagonal close-packed metasurfaces. This article investigates the MPL process for creating refractive index (RI) sensors on the cleaved tips of optical fiber. The resonant wavelength of metal elements on the surface is dependent on the local dielectric environment and allows the refractive index of an analyte to be resolved spectrally. A numerical study of hole arrays defined in metal films shows that the waveguide mode provides good sensitivity to the analyte refractive index. This can be readily tuned by adjusting the MPL exposure and the simulation results guide the fabrication of a defect tolerant refractive index sensor on the tip of a fiber tip with a sensitivity of 613 nm/RIU. The conformal nature of the microsphere monolayer simplifies the fabrication process and provides a viable alternative to direct-write techniques such as Focused Ion Beam (FIB) milling