Chemical Classification By Monitoring Liquid Evaporation Using Extrinsic Fabry-Perot Interferometer With Microwave Photonics

Identification of liquids is essential in chemical analysis, safety, environmental protection, quality control, and research. A novel liquid identification system based on Microwave Photonics (MWP) measured time transient evaporation signals is investigated. An extrinsic Fabry-Perot Interferometer (EFPI) based optical probe using single-mode fiber (SMF) is proposed to monitor evaporation of different liquids. The MWP system is used to measure the optical path changes during liquid evaporation due to its high sensitivity, selectivity, and Signal-to-Noise Ratio (SNR). The measured S21 continuous wave (CW) time Magnitude and Phase signals were processed to extract features such as histogram and Fast Fourier Transform (FFT) peaks. Using features extracted from droplet evaporation time transient events, machine learning classification accurately identified chemicals in each liquid with an accuracy rate of over 99%, employing three algorithms: Decision Trees, Support Vector Machine (SVM), and K-nearest neighbors (KNN). The classification results demonstrate accurate liquid identification based on evaporation measurements by the MWP system

Calculations of Adsorption-Dependent Refractive Indices of Metal-Organic Frameworks for Gas Sensing Applications

Detection of Volatile Organic Compounds (VOCs) is One of the Most Challenging Tasks in Modelling Breath Analyzers Because of their Low Concentrations (Parts-Per-Billion (Ppb) to Parts-Per-Million (Ppm)) in Breath and the High Humidity Levels in Exhaled Breaths. the Refractive Index is One of the Crucial Optical Properties of Metal-Organic Frameworks (MOFs), Which is Changeable Via the Variation of Gas Species and Concentrations that Can Be Utilized as Gas Detectors. Herein, for the First Time, We Used Lorentz–Lorentz, Maxwell–Ga, and Bruggeman Effective Medium Approximation (EMA) Equations to Compute the Percentage Change in the Index of Refraction (∆n%) of ZIF-7, ZIF-8, ZIF-90, MIL-101(Cr) and HKUST-1 Upon Exposure to Ethanol at Various Partial Pressures. We Also Determined the Enhancement Factors of the Mentioned MOFs to Assess the Storage Capability of MOFs and the Biosensors\u27 Selectivity through Guest-Host Interactions, Especially, at Low Guest Concentrations

Real-Time Air Gap And Thickness Measurement Of Continuous Caster Mold Flux By Extrinsic Fabry-Perot Interferometer

Mold Flux plays a critical role in continuous casting of steel. Along with many other functions, the mold flux in the gap between the solidifying steel shell and the mold serves as a medium for controlling heat transfer and as a barrier to prevent shell sticking to the mold. This manuscript introduces a novel method of monitoring the structural features of a mold flux film in real-time in a simulated mold gap. A 3-part stainless-steel mold was designed with a 2 mm, 4 mm and, 6 mm step profile to contain mold flux films of varying thickness. An Extrinsic Fabry-Perot Interferometer (EFPI) was installed at each of the three steps in the mold. Mold flux was melted in a graphite crucible at 1400 °C and poured into the instrumented step mold for analysis. Interferograms from the three EFPIs were acquired and processed in real-time to measure the air gap and thickness of each flux film during solidification. Measurements were performed on two different mold flux compositions. Results demonstrate that the proposed system successfully records structural features of the flux film in real-time during cooling. It has a large real-time impact on the process control of steel making and optimizing the quality of steel castings. In addition, the measurement method has potential to monitor crystal nucleation and growth in a variety of crystallizing glass systems

Advancing Aluminum Casting Optimization With Real-Time Temperature And Gap Measurements Using Optical Fiber Sensors At The Metal-Mold Interface

Accurate measurement of interfacial heat transfer during casting solidification is crucial for optimizing metal solidification processes. The gap between the mold wall and the casting surface plays a significant role in heat transfer and cooling rates. In this study, two innovative fiber-optic sensors are employed to measure real-time mold gaps and thermal profiles during the solidification of A356 aluminum in a permanent mold casting. The experimental setup consists of a specially designed mold system made of unheated, uncoated tool steel, which facilitates easy installation of the fiber-optic sensors. An Extrinsic Fabry-Perot interferometric (EFPI) sensor is utilized to monitor the evolving gap between the mold wall and the casting surface. This method relies on the unique concept of using molten metal as the second reflection interface for gap measurements. The EFPI gap measurements exhibit high accuracy and precision, with a maximum error of only 2μ m when compared to physical measurements. Simultaneously, a stainless steel-encased fiber utilizing the Rayleigh backscattering (RBS) technique is deployed across the mold wall and cavity to achieve real-time temperature measurements with a spatial resolution of 0.65 mm. The study demonstrates that leveraging high-resolution temperature profiles and gap evolution measurements enhances understanding of heat transfer dynamics at the mold-metal interface, particularly valuable for complex-shaped castings and continuously cast metals. Additionally, the ability to measure the cast shape exiting a continuous casting mold during operation presents a novel tool for real-time product quality monitoring and process safety enhancement by detecting conditions that may lead to slab cracking and breakouts

Miniature Optical Fiber Fabry–Perot Interferometer Based on a Single-Crystal Metal–Organic Framework for the Detection and Quantification of Benzene and Ethanol at Low Concentrations in Nitrogen Gas

This study reports for the first time, to the best of our knowledge, a real-time detection of ultralow-concentration chemical gases using fiber-optic technology, combining a miniaturized Fabry–Perot interferometer (FPI) with metal–organic frameworks (MOFs). The sensor consists of a short and thick-walled silica capillary segment spliced to a lead-in single-mode fiber (SMF), housing a tiny single crystal of HKUST-1 MOF, imparting chemoselectivity features. Ethanol and benzene gases were tested, resulting in a shift in the FPI interference signal. The sensor demonstrated high sensitivity, detecting ethanol gas concentrations (EGCs) with a sensitivity of 0.428 nm/ppm between 24.9 and 40.11 ppm and benzene gas concentrations (BGCs) with a sensitivity of 0.15 nm/ppm between 99 and 124 ppm. The selectivity study involved a combination of three ultralow concentrations of ethanol, benzene, and toluene gases, revealing an enhancement factor of 436% for benzene and 140% for toluene, attributed to the improved miscibility of these conjugated ring molecules with the alkane chains of the ethanol-modified HKUST-1. Experimental tests confirmed the sensor’s viability, demonstrating significantly improved response time and spectral characteristics through crystal polishing, indicating its potential for quantifying and detecting chemical gases at ultralow concentrations. This technology may prevent energy resource losses, and the sensor’s small size and robust construction make it applicable in confined and hazardous locations