zno nanostructures of different methods and sizes were grown in a controlled manner using a simple hydrothermal and sonochemical technique. controlling the content of concentration and temperature of the reaction mixture, spherical nanoparticles zno structures could be synthesized at temperatures 100-150 °c with excellent reproducibility in solvothermal and at different power and time in sonoch...

This study proposes a long period fiber grating (LPFG) with a zinc oxide (ZnO) nanoparticle layer for use as a carbon dioxide (CO2) gas sensor. Inductively coupled plasma (ICP) etching, corona treatment, and electrostatic spraying were used to fabricate this ZnO nanoparticle-coated LPFG CO2 gas sensor. Repeated gas sensor tests showed that, when a 15% CO2 mixture was injected (0.2 L/min) into a...

This paper presents an optical fiber gas sensor based on sandwiched long-period fiber grating (SLPFG) that is fabricated via the microelectromechanical systems (MEMS) process and coated with amino silica adsorbent for carbon dioxide (CO2) gas sensing. The amine-modified nanoporous silica foams were coated onto the SLPFG for CO2 adsorption. To characterize the CO2 adsorption of the SLPFG sensor,...

NDIR-based CO2 sensor is commonly used in the field of environmental monitoring due to relatively high accuracy compared with that of a chemical CO2 gas sensor. This paper presents a wireless sensing system with a low-cost Non-Dispersive InfraRed (NDIR) sensor module used to determine gas concentration in a remote air quality monitoring system. Unlike the chemical CO2 gas sensor, the proposed s...

CO2 gas sensing is of great importance because of the impact of CO2 on global climate change. Here, utilizing an inverse opal hydrogel, we describe a CO2 gas sensing method that allows highly sensitive and selective detection over a wide concentration range. The CO2 sensor is specific, quantitative, interference tolerant and without the need for special instruments.

We report a new proof-of-concept bubble-based gas sensor for a gas chromatography system, which utilizes the unique relationship between the diameters of the produced bubbles with the gas types and mixture ratios as a sensing element. The bubble-based gas sensor consists of gas and liquid channels as well as a nozzle to produce gas bubbles through a micro-structure. It utilizes custom-developed...

An optical absorption sensor for gas chromatography (GC) is presented. It consists of a quantum cascade laser along with a long piece of Hollow Waveguide for Infrared (HWIR) transmission inserted into the GC line. It measures the infrared absorption in each individual gas peak after separation by the GC column, and maintains the shapes of gas peaks after the HWIR sensor, making the gas samples ...

Based on a multi-gas solution-diffusion problem for a dense symmetrical membrane this paper presents a transient theory of a planar, membrane-based sensor cell for measuring gas from both initial conditions: dynamic and thermodynamic equilibrium. Using this theory, the ranges for which previously developed, simpler approaches are valid will be discussed; these approaches are of vital interest f...