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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 

A MEMS‐based impedance biosensor was designed, fabricated, and tested to effectively detect the presence of bacterial cells includingE. coli O157:H7andSalmonella typhimurium in raw chicken products using detection region made of multiple interdigitated electrode arrays. A positive dielectrophoresis based focusing electrode was used in order to focus and concentrate the bacterial cells at the centerline of the fluidic microchannel and direct them toward the detection microchannel. The biosensor was fabricated using surface micromachining technology on a glass substrate. The results demonstrate that the device can detectSalmonellawith concentrations as low as 10 cells/mL in less than 1 h. The device sensitivity was improved by the addition of the focusing electrodes, which increased the signal response by a factor between 6 and 18 times higher than without the use of the focusing electrodes. The biosensor is selective and can detect other types of pathogen by changing the type of the antibody immobilized on the detection electrodes. The device was able to differentiate live from dead bacteria.