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Polydiacetylene capacitive artificial nose
摘要： Polydiacetylenes are a class of conjugated polymers exhibiting unique color and fluorescence properties and employed as useful sensing vehicles. Here we demonstrate for the first time that the dielectric properties of polydiacetylenes can be exploited for vapor sensing. Specifically, electrodes coated with polydiacetylenes, embedded within a porous polyvinylpyrrolidone (PVP) matrix, exhibit significant capacitance transformations upon exposure to different vapors. The capacitive response of the polydiacetylene/PVP films depended upon both the structures of the diacetylene monomers, and the extent of ultraviolet irradiation (i.e. polymerization), underscoring a unique sensing mechanism affected by conjugation, structure, and dielectric properties of the polydiacetylene/polymer matrix. Importantly, the variability of polydiacetylene structures allow vapor identification through an array-based pattern recognition (i.e. artificial nose). This study opens new avenues for applications of polydiacetylene systems, particularly pointing to their dielectric properties as powerful sensing determinants.
关键词： polydiacetylene,polyvinylpyrrolidone,artificial nose,dielectric properties,capacitive vapor sensing
更新于2025-09-23 15:22:29
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Hyperspectral and Color Imaging of Solvent Vapor Sorption Into Porous Silicon
摘要： A porous silicon thin film photonic crystal (rugate) sample with both a radial gradient in the rugate reflectance band wavelength and two spatially separated pore-wall surface chemistries (methylated and oxidized) was monitored by hyperspectral and color imaging while it was dosed with vapors of acetone, ethanol, heptane, 2-propanol, and toluene at concentrations ranging from 100 to 3,000 mg m?3. The shift in the wavelength of the rugate reflectance band maximum at each position along a transect across the two surface chemistries, as derived from the hyperspectral imaging, could discriminate between the different solvents and concentrations of solvents, while the change in hue derived from the color camera data along an analogous transect did not provide discrimination. The discrimination between solvents was mainly due to the two different surface chemistries, and the gradient associated with the change in the rugate reflectance band wavelength did not affect the selectivity significantly. There was spatial variability in the spectral and color responses along the transect independent of the overall rugate reflectance band wavelength gradient and pore-wall surface chemistries, and this was attributed to factors such as the presence of striations in the silicon wafer from which the porous silicon was prepared.
关键词： sensor,porous silicon,hyperspectral imaging,surface modification,vapor sensing
更新于2025-09-23 15:22:29
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A Film-based Fluorescent Sensor for Monitoring Ethanol-Water Mixture Composition via Vapor Sampling
摘要： In situ, on line, non-contact and fast monitoring of compositions of ethanol-water mixtures via vapor phase sampling remains challenge for years. In this work, we report for the first time of a film-based fluorescent sensor showing unprecedented discriminative ability to the compositions of ethanol-water mixtures. Importantly, ethanol content in the mixtures could vary from 0 to 100% (v/v), the response time is less than 2 s, and the sensing is fully reversible. More importantly, the monitoring was performed via vapor phase sampling, avoiding sample contamination. The principle behind is ascribed to the big difference of the fluorescent quantum yield of the sensing unit, a newly designed and synthesized mono-substituted fluorescent o-carborane derivative (ZPCarb), in the two solvents. In addition, the sensor as developed was successfully used for the determination of ethanol contents in four commercial liquors, suggesting its potential applications in quality control of beverages, monitoring fermentation processes, etc. in a quantitative way.
关键词： Vapor sensing,Ethanol-water mixture,Film-based fluorescent sensor,Fluorescent o-carborane derivative
更新于2025-09-23 15:21:01
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Photophysical Impact of Diacetylenic Conjugation on Classical Donor-Acceptor Electronic Energy Pair
摘要： Organic fluorophores with extended π-conjugation are important for their wide-spread applications. The present work provides photophysical insights of a diacetylene bridged classical donor-acceptor electronic energy pair, naphthalene-pyrene, in comparison with its part molecular structures, naphthyl and pyrenyl acetylenes as well as parent naphthalene and pyrene chromophores. The diacetylenic dye loses individual spectral identities of the donor and acceptor fluorophores exhibiting a locally excited (LE) emission (~411 nm) from the overall molecular entity with high fluorescence quantum yields (0.55–0.84) in non-aqueous media. In contrast to parent pyrene, the hybrid derivative shows strongly allowed S0→S1 transition. In mixed-aqueous media, the dye forms J-aggregates displaying a new red-shifted absorption (~425 nm) as well as emission (~510 nm) band. Unlike the hybrid dye, the naphthyl and pyrenyl acetylenes do not form aggregates. In the aggregate state of the hybrid fluorophore, electronic energy transfer takes place from the naphthyl moiety to pyrenyl ring. The excited state photophysical properties of the dye is exploited to vapor sensing in solid state.
关键词： vapor sensing,Organic fluorophores,donor-acceptor electronic energy pair,diacetylene bridged,naphthalene-pyrene,locally excited emission,J-aggregates,electronic energy transfer,π-conjugation,fluorescence quantum yields
更新于2025-09-23 15:19:57
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Nanoscale lighta??matter interactions in metala??organic frameworks cladding optical fibers
摘要： The utilization of refractive index (RI) change due to guest–host interactions between the guest volatile organic compound vapor and porous metal–organic frameworks (vapor–MOF interactions) is promising in photonic vapor sensors. Therefore, the study of light–matter interactions in nanoporous metal–organic frameworks (MOFs) is fundamental and essential for MOF-based photonic devices. In this work, the manipulation of light in MOFs to investigate the vapor–MOF interactions by using optical fiber devices is demonstrated. The vapor–MOF interactions and the light–vapor interactions (light in MOFs to sense the RI changes resulting from the vapor–MOF interactions) are investigated. The cladding mode is excited by a long-period fiber grating (LPFG) for evanescent field sensing in a ZIF-8 sensitive coating. The experimental results combining quantum chemical calculations and optical simulations reveal the relationships between the microscopic energy of vapor desorption, RI changes and evanescent field enhancement in ZIF-8 during the vapor–MOF interactions. With exceptionally large RI changes, the evanescent field of cladding mode in ZIF-8 is greatly enhanced to sense the vapor–MOF interactions. As a proof-of-concept, a LPFG sensor with ZIF-8 coating showed a high sensitivity of 1.33 pm ppm?1 in the linear range from 9.8 ppm to 540 ppm for the sensing of ethanol vapor. The investigation of light–matter interactions in ZIF-8 provides a useful guideline for the design and fabrication of MOF-based optical waveguide/fiber sensors.
关键词： Nanoscale,metal–organic frameworks,light–matter interactions,vapor sensing,optical fibers
更新于2025-09-19 17:13:59