Highly textured and transparent RF sputtered Eu 2 O 3 doped ZnO films

LED-controlled tuning of ZnO nanowires’ wettability for biosensing applications

Heavy metal ion pollution emerges as a potential threat to humankind and the ecosystem due to their increased spreading into the environment. Detection of highly toxic heavy metal ions requires rapid, simple, sensitive and selective detection methods in water environments. Optical fibre sensors facilitate the remote, continuous and in-situ detection due to their inherent properties. Herein, we report a fibre optic sensor based on evanescent wave absorption to detect heavy metal ions in water environments. Fibre optic sensor has been developed by coating dithizone on the surface of an optical fibre. Selectivity of the mercury, copper and chromium ions using dithizone has been illustrated using spectroscopy based detection approach. Effect of pH on the sensor has been investigated. The possibility of simultaneous multi-ion detection has been investigated. Copper ions concentrations in water has been detected using the developed fibre optic sensor.

Surface plasmon resonance (SPR) is a well-known, rapid and sensitive technique used for probing the biomolecular interactions in real time. Several new approaches have been suggested to improve the sensitivity of SPR sensors over the last two decades. Recently, there have been few reports on using graphene on a metal film based SPR sensor in order to improve the sensitivity. The role of incident light wavelength and graphene layers in sensitivity enhancement is unclear. This paper reports computational investigations on sensitivity enhancement of SPR biosensor using tunable wavelength and graphene layers. The reflectivity of p-polarized incident light has been calculated using the N-layer model for the most common Kretschmann configuration. Sensitivity enhancements over a conventional angular interrogated SPR sensor have been calculated within the wavelength range 600 -1600 nm and up to ten graphene layers. Results indicate that the sensitivity can be enhanced by the increasing the graphene layers on conventional gold coating based SPR biosensor. Sensitivity enhancement is highly dominated by the wavelength of interrogation used in this design. By tuning the wavelength and graphene layers sensitivity of the graphene-based SPR biosensor can be increased.

A fiber optic sensor for the measurement of total cholesterol is designed and developed. The developed chitosan coated long period grating (LPG) sensor shows a sensitivity of 5.025×10⁶ pm·mL/g in the measurement range of the sensor. The sensor also shows a linear response in the measured range of cholesterol levels, which is highly desirable for exploitation as a commercial cholesterol sensor.

The curing of epoxy resin is a complex thermo-chemical process that is difficult to monitor using existing sensing systems. We monitored the curing process of an epoxy resin by using long-period fiber gratings. The refractive index of the epoxy resin increases during the curing process and can be measured to determine the degree of curing. We employed long-period fiber gratings that are sensitive to the refractive index of an external medium for the measurement of refractive index changes in the resin. We observed that the resonances of long-period fiber gratings increased their depth with the increased refractive index of the resin, which was well described by our simulation taking the coupling to radiation modes into account. We demonstrated that the degree of cure can be estimated from the depth of the grating resonances using a phenomenological model. At the same time, long-period fiber gratings are sensitive to temperature variations and internal strains that are induced during curing. These factors may affect the measurements of curing degree and should also be addressed.