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A micrometer size, simple, and low-cost sensor for continuous monitoring of human blood during malarial infection at its various stages is proposed in this work. The sensor comprises a light source, silica fiber directional coupler, and an optoelectronic photodetector. The sensor is simulated for fiber diameters from 1–1.8 #x03BC;m and optimization is done. The sensor produces a photocurrent of a few mA, which gives the level of infection. It can detect a change in refractive index, of the order of 10−5, and needs a small sensing length of a few μm. It can be potentially built as an integrated embedded device.

A smallest amount of petrol adulterated with kerosene can cause adverse effect on the functioning of a vehicle engine. In this work, a simple, low cost, sensitive and miniature sensor based on fiber optic coupler and an optoelectronic detection system is developed. The sensor is modeled and simulated. It is found that the present sensor is capable of detecting less than 5 percent of kerosene adulteration in petrol. It is capable of detecting 1 percent variation in the adulteration. The sensor has micrometer dimension.

Present research article emphasizes the first report on a simple and cost-effective ‘dip and dry’ coating method to coat MWCNTs at room temperature as a counter electrode towards dye sensitized solar cells (DSSCs) with ZnO/Eosin-Y as a photoanode. Process optimization through the number of dips (10, 15, 18, and 20) have been performed and compared to standard platinum (Pt) as counter electrode with iodide-triiodide as a liquid electrolyte. Photovoltaic performance through current density-voltage characteristic under standard 1 Sun illumination condition (AM 1.5G, 100 ​mW/cm2) and external quantum efficiency have been well supported which are correlated through structural, surface morphological, and electrochemical studies. Interestingly, DSSCs device with 18 cycles of MWCNTs yields half of the power conversion efficiency than that of Pt device.

Simple chemical bath deposition method has been demonstrated to anchor MoS2 nanoflakes over ‘dip and dry’ coated thin-film of MWCNTs at room temperature (~30 ℃) to use as a counter electrode (CE) in ZnO/Eosin-Y photoanode based dye-sensitized solar cells (DSSCs) as the first report. Obtained materials are well confirmed through XRD, FESEM, TEM, and XPS analysis. Two-step chemical route explores the easy way of CE fabrication. DSSCs fabricated with MoS2/MWCNTs CE have gained more than three times (0.56%) power conversion efficiency compared to the bare MWCNTs CE (0.15%). External quantum efficiency and electrochemical impedance analysis for the boost in efficiency and improved electrocatalytic activity with low charge-transfer resistance at (CE)/ electrolyte interface are well in support for the synergistic effect of MoS2 and MWCNTs.

This work presents a simple and low cost, sensitive and miniature sensor based on fiber optic coupler with optoelectronic detection system, for detecting low levels of kerosene adulteration in petrol. The sensor can detect less than 5 percent of the adulteration and is capable of detecting 1 percent variation in the adulteration.

In the present work, a miniature optical gas sensor for the leakage detection of propane is proposed. It is constructed by employing single mode silica nanowire Mach–Zehnder interferometer (MZI). Suitable chemical treatment of silica nanowire for propane gas adsorption onto it is suggested. In the proposed sensor, the idea is that, the propane gas gets adsorbed on treated surface of silica nanowire, which changes the refractive index of few nanometer thick layer on the nanowire surface. In theoretical modeling and simulation, full vectorial analysis of two and three layers tightly guiding waveguide structures are presented. Simulations include calculation of phase difference at the output end of MZI, phase sensitivity, detection limit and measurable refractive index over a practicable sensing length such as 1 mm. Sensing characteristics are numerically investigated. The sensor shows merits over conventional gas sensors. The sensing characteristics show negligible dependence on temperature, vibration and humidity, which is discussed in details. The proposed gas sensor is featured by high sensitivity, low cost, low loss, miniaturize size, and shows possibility of early detection of leakage.

In the present work, electromagnetic field confinement in a subwavelength waveguide structure is obtained using concepts of quantum mechanics and uncertainty principle. Semi-macroscopic considerations of field interaction at the dielectric interfaces are used in this work. The modal field profile in the subwavelength waveguide is obtained by considering the photon as a particle in the waveguide having finite probability of tunneling. Thus, uncertainty of position is assigned to it. The momentum uncertainty is calculated from position uncertainty. Schrodinger wave equation for the photon is written by incorporating position-momentum uncertainty. The equation is solved and the field distribution in the waveguide is obtained. The field distribution and power confinement is compared with conventional waveguide theory. They were found in good agreement with each other.

In the present work, two types of miniature propane gas sensors using silica nanowire are modeled and simulated. Silica nanowires leave large amount of guided field outside the core as evanescent field, which is sensitive to cladding refractive index and hence utilized for sensing purpose. In this paper, two types of sensors are investigated from silica nanowire waveguiding properties In both models, silica nanowire initially has air as cladding which changes to gaseous layer of propane when exposed to the propane gas. Layer formation is achieved by adsorption. Silica nanowire treated with methyl-hydrogen silane is used in these models to increase adsorption tendency of propane on the silica nanowire surface. In the first model, Mach-Zehnder interferometer is used for measurements. In the second model, measurements are carried out with photodetector-comparator circuit. High sensitivity conditions are obtained in both models. Simulation of the models show that using nanowires diameters of 350nm-750nm, high sensitivity can be achieved, even with small sensing length in the first model, whereas in the second model, high photocurrent can be obtained by using 650nm-950nm nanowire diameters. These sensors can be helpful in early detection of hazardous liquefied petroleum gas leakage.