We present results demonstrating real-time sensing of four different fluorocarbons at low part-per billion (ppb) concentrations using an external cavity quantum cascade laser (ECQCL) designed for infrared vibrational spectroscopy of molecules with broad absorption features. The ECQCL was repeatedly swept at 20 Hz over its full tuning range of 1145-1265 cm(-1) providing a scan rate of 3535 cm(-1) s(-1), and a detailed characterization of the ECQCL scan stability and repeatability is presented. The ECQCL was combined with a 100 meter path length multi-pass cell for direct absorption spectroscopy. A portable sensor system is described, which was deployed on a mobile automotive platform to provide spatially-resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times.
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http://dx.doi.org/10.1039/c3an01642k | DOI Listing |
Biosens Bioelectron
March 2025
College of Information Science and Engineering, Northeastern University, Shenyang, 110819, China; Hebei Key Laboratory of Micro-Nano Precision Optical Sensing and Measurement Technology, Qinhuangdao, 066004, China.
A novel dual-parameter optical fiber biosensor based on surface plasmon resonance (SPR) for simultaneous measurement of urea and uric acid concentrations is proposed in this paper. Based on the principle of positive and negative electric combination, ZnO nanoparticles is selected as the matrix for immobilizing urease and uricase with selective recognition ability, which can also be used as a sensitizing material to increase the refractive index detection sensitivity of SPR by 22%. Then, Nafion ion exchange membrane was introduced to wrap the urea sensing area to avoid crosstalk caused by the overlap of adjacent sensing areas.
View Article and Find Full Text PDFNano Lett
December 2024
School of Physics and Electronics, Shandong Normal University, Jinan 250014, People's Republic of China.
Int J Biol Macromol
January 2025
Research Center of Biomass Clean Utilization, MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, PR China; State Silica-based Materials Laboratory of Anhui Province, Bengbu 233000, PR China. Electronic address:
Flexible, stable, and highly sensitive pressure sensors have garnered significant interest for their potential applications in wearable electronics and human-computer interaction. However, pressure sensor substrates prepared by electrospinning currently face challenges related to inadequate mechanical properties and low conductivity. Therefore, fabricating films with high flexibility, excellent mechanical properties, and sensing capabilities is still a great challenge.
View Article and Find Full Text PDFACS Sens
November 2024
State Key Laboratory of Integrated Optoelectronics, Key Laboratory of Gas Sensors, Jilin Province, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
Sulfur dioxide (SO) is a common environmental pollutant with significant hazards. However, sensors for SO real-time monitoring at room temperature often face problems such as a poor response and sluggish recovery. In this work, a fuel cell-type gas sensor based on nitrogen-doped carbon nanotube (CNT) aerogels loaded with Cu particle electrode material and COF/Nafion composite electrolyte was developed, which exhibited excellent SO sensitivity and fast response/recovery.
View Article and Find Full Text PDFSci Adv
November 2024
Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, USA.
Biological nanopores are increasingly used in molecular sensing due to their single-molecule sensitivity. The detection of per- and polyfluoroalkyl substances (PFAS) like perfluorooctanoic acid and perfluorooctane sulfonic acid is critical due to their environmental prevalence and toxicity. Here, we investigate selective interactions between PFAS and four cyclodextrin (CD) variants (α-, β-, γ-, and 2-hydroxypropyl-γ-CD) within an α-hemolysin nanopore.
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