The direct exposure of volatile organic compounds (VOCs) is widely related to several adverse health effects. Therefore, an accurate amount of its usage is necessary required depending on the ...threshold limit. There have been a variety of sensors developed to measure an amount of VOC for safety use. Optical fiber-based VOC sensors offer huge advancements in technologies to overcome several limitations from the convectional VOC sensors that appeared over the past decade. Real-time monitoring and detection of VOCs are important to maintain a safe and healthy domestic/industrial environment. The optical fibers are highly-sensitive and widely applied to several ranges of parameters including gas sensing, and have also been used to monitor VOCs at the sub-ppm range. Recognizing the major developments in the field of the optical fiber, this article aims to review the recent progress in VOC monitoring, resulting in a wide range of sensing configurations are being discussed. Additionally, the article highlights the advantages, limitations, and future possibilities in this area.
Display omitted
In this letter, we propose a novel approach to develop a highly sensitive surface plasmon resonance (SPR) based fiber optics biosensor. The sensor comprises a dual-drilled channel (DDC) with ...gold-nanowire (AuNW) contained in each channel to excite the plasmon modes. The SPR effect between the core guided mode and the surface plasmon polariton (SPP) modes of the DDC is used to evaluate the sensing response with respect to different analytes. The sensing performance, coupling characteristics, and the fabrication tolerance of the sensor are numerically analyzed and characterized by using a full-vectorial Finite Element Method (FEM). The designed sensor shows a minimum sensitivity of 3150 nm/RIU for refractive index (RI) = 1.310. While, the sensor exhibits an extremely high sensitivity varying from 10250 nm/RIU to 90500 nm/RIU for RI varied over the range of 1.370 to 1.400. Various structural parameters, e.g., separation of the channel from the core, the radius of the AuNW, the fabrication tolerance, etc., have been studied in this work. In addition, the possible fabrication steps of such a design have been discussed indicating its simple practical realization.
Recent advances have allowed the monitoring of several volatile organic compounds (VOCs) in human exhaled breath, and many of them are being utilized as a biomarker to diagnose several diseases, ...including diabetes. Among several VOCs, isopropanol (IPA) has been reported as a common volatile compound in the exhaled breath of patients with type 1 and type 2 diabetes. In this article, an experimental approach is discussed to develop a highly selective and sensitive IPA vapor sensor system. The fabricated sensor is comprised of a small and portable glass slide coated with molecularly imprinted polymer containing specific binding sites compatible with IPA molecules. The developed sensor is based on the wavelength interrogation technique. The fabricated device is analyzed for the detection of IPA vapor with different concentrations varying from 50% to 100%. The sensor exhibits maximum sensitivities of 0.37, 0.30, and 0.62 nm/%IPA, respectively, for 30, 60, and 90 min, respectively, and an excellent sensitivity of 0.63 nm/%IPA for 120 min exposure along with good selectivity among a similar class of VOCs. The major features of the sensor i.e., small size, portability, cost-effectiveness, high sensitivity, and good selectivity, make it a potential candidate for diabetes monitoring. The promising results of the sensor illustrate its potential in diabetes monitoring applications.
This work introduces design, fabrication and characterization of an optical based integrated flow rate sensor where the light- fluid interaction is maximized by allowing the liquid and light to ...propagate along the same direction. This is achieved by placing a 10 μm deep channel between two waveguides. The optical waveguides are tapered down to the channel width to feed the light in and out, where tapering is done to minimize the coupling and propagation loss. The output signal is detected by a fast receiver (higher than 1MHz) that records the dynamic change of the light intensity when fluid flows through the channel. The initial results showed a dynamic range of measurement up to 0.18.
