Abstract
The prolonged sensing of toxic gases in polluted particles and harsh environments is a challenging task that is also in high demand. In this work, the proof of principle of a sensitive, low-cost, and low-maintenance reconfigurable platform for filter-free and continuous ammonia (NH3) sensing in polluted environments is simulated. The platform can be modified for the detection of various toxic gases and includes three main modules: a microfluidic system for in-line continuous dust filtering; a toxic gas adsorption module; and a low-frequency microwave split-ring resonator (SRR). An inertia-based spiral microfluidic system has been designed and optimized through simulation for the in-line filtration of small particles from the intake air. Zeolite Y is selected as the adsorbent in the adsorption module. The adsorption module is a non-metallic thin tube that is filled with zeolite Y powder and precisely fixed at the drilled through-hole into the 3D microwave system. For the sensing module, a low-frequency three-dimensional (3D) split-ring resonator is proposed and optimally designed. A microwave resonator continuously monitors the permittivity of zeolite Y and can detect small permittivity alterations upon the presence of ammonia in the intake air. The microwave resonator is optimized at a frequency range of 2.5–3 GHz toward the detection of ammonia under different ammonia concentrations from 400 to 2800 ppm. The microwave simulation results show a clear contrast of around 4 MHz that shifts at 2.7 GHz for 400 ppm ammonia concentration. The results show the proof of principle of the proposed microfluidic-microwave platform for toxic gas detection.
Highlights
Introduction iationsGas detection has wide applications in environmental monitoring, security, industrial quality control, etc
The system encompasses three main modules including: (1) inertia-based spiral microfluidics for continuous gas filtration; (2) an adsorption module that selectively adsorbs the specific gas of interest; and (3) a microwave-split-ring resonator sensor that monitors the adsorption module
The Ansys Fluent package was used for the particle-flow interaction simulation of the proposed inertia-based particle separator using a discrete phase modeling (DPM) approach
Summary
Gas detection has wide applications in environmental monitoring, security, industrial quality control, etc. Ammonia (NH3 ) is a major industrial chemical product in the world while classified as dangerous for the environment [1,2,3,4]. Exposure to high concentrations of ammonia could be lethal, while in low concentrations, it can cause coughing, nose, and throat irritation in the short term. Before designing a toxic gas sensor, several key aspects should be considered such as sensitivity, the minimum concentration of target gases they can detect, response speed, reversibility, energy consumption, and fabrication costs [3,5,6,7]. The ammonia concentration varies from one industry to another. The level of atmospheric ammonia at industrial parks can go as high as 150 ppb [8]. Per the US CDC (Centers for Disease Control and Prevention) guidelines, the recommended exposure limit (REL)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
