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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.

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.