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Liquid crystal nose, chiral case: towards increased selectivity and low detection limits
摘要： In this paper, we describe a simple prototype of an olfaction system based on chiral liquid crystals (LCs) and suitable for sensing volatile organic compounds (VOCs). The detection of small concentrations of VOCs is based on measuring weak colour fluctuations on the surface of the LC droplet. Detection of larger concentrations is based on measuring colour changes (or shift of the selective reflection band) and isotropisation transition of the whole droplet. Thus, a broad range of VOC concentrations can be detected by this LC nose.
关键词： gas detection,LC nose,volatile organic compound,olfaction,electronic nose,VOC,liquid crystals,cholesteric
更新于2025-09-23 15:22:29
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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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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - A CMUT - Based Electronic Nose for Real- Time Monitoring of Volatiles Emitted by Plants: Preliminary Results
摘要： Plants give off a unique profile of volatile organic compounds (VOCs) in response to abiotic and biotic stresses. The ability to discern specific VOC profiles provides for the early detection and subsequent treatment of insect infestation and pathogen infection. This work presents an electronic nose (e-nose) system based on a capacitive micromachined ultrasonic transducer (CMUT) with real-time monitoring capability for detecting and discriminating VOCs. Preliminary results show the almost instantaneous detection of the plant volatiles released systemically in response to physical wounding of plant tissue.
关键词： e-nose,real-time monitoring,plant stressors,volatile profile,gravimetric sensing,response fingerprint
更新于2025-09-23 15:22:29
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Orthogonal gas sensor arrays by chemoresistive material design
摘要： Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2–5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R2 of 0.68.
关键词： Ethanol,WO3,SnO2,Electronic nose,Ammonia,Gas sensor,Acetone,Flame spray pyrolysis,MoO3
更新于2025-09-23 15:21:21
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - IETS in MIS Contacts: Towards a Quantum Biomimetic Electronic Nose
摘要： Inelastic electron tunneling spectroscopy (IETS) has been used to detect the vibrational modes of molecules and has been proposed as the mechanism of olfaction according to the so-called Vibration Theory. Motivated by the promise of an electronic nose that will be biomimetic - in the sense of the Vibration Theory - we demonstrate here IET spectroscopy of vibrational modes in metal-insulator-semiconductor (MIS) devices consisting of ultrathin HfO2 deposited on silicon by Atomic Layer Deposition (ALD). Low-noise IETS measurements at 10K are carried out using second harmonic detection by a standard lock-in procedure. Parallely, a filtering algorithm is applied to the measured I-V data to compute its second derivative. The IETS peaks in the filtered data and experimentally measured lock-in data are compared and are found to be in agreement with each other; as well as with other experimental vibrational energy data measured through IETS or other techniques.
关键词： smoothening algorithm,Inelastic Electron Tunneling Spectroscopy,Electronic nose
更新于2025-09-19 17:15:36
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Development of an optoelectronic nose based on surface plasmon resonance imaging with peptide and hairpin DNA for sensing volatile organic compounds
摘要： Nowadays, the analysis of volatile organic compounds (VOCs) is very important in various domains. In the last decades, electronic noses have emerged as promising alternatives to traditional analytical methods. Nevertheless, their wide use is still limited by their performances such as low selectivity. Herein, we developed an optoelectronic nose using virtually screened peptides and hairpin DNA (hpDNA) with improved selectivity as sensing materials and surface plasmon resonance imaging (SPRi) as the detection system. Thanks to the complementarity of their binding properties towards target VOCs, the obtained optoelectronic nose has very good selectivity, being able to discriminate not only between VOCs of different chemical families, but also VOCs of the same family with only 1-carbon difference. The combination of these sensing materials with SPRi is relevant for the development of optoelectronic nose with large sensor arrays and improved performances.
关键词： Volatile organic compounds,Surface plasmon resonance imaging,E-nose,Peptides,Optoelectronic nose,Hairpin DNA
更新于2025-09-19 17:13:59
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Non-invasive prediction of lung cancer histological types through exhaled breath analysis by UV-irradiated electronic nose and GC/QTOF/MS
摘要： Lung cancer (LC) is one of the most lethal diseases from the last decades. Accurate diagnosis of LC histology could lead to the prescription of personalized medical treatment to the affected subjects, which could reduce the mortality rate. We present here an experimental study performed in the pulmonology units of three hospitals from Morocco to non-invasively detect LC and predict LC histology via the analysis of the volatile organic compounds (VOCs) emitted through breathing. Gas chromatography coupled to a quadrupole time-of-flight mass spectrometer (GC/QTOF/MS) employed to detect the breath VOCs, revealed 30 discriminative VOCs in the breath of healthy subjects and LC patients; among them, 4 unique of LC (non-small cell LC and small cell LC), as well as between two of the major subtypes of employed to characterize the overall composition of the collected breath samples, providing a non-small cell LC, namely squamous cell carcinoma (SCC) and adenocarcinoma (ADC). The satisfactory discrimination between the breath patterns of LC patients and healthy subjects. novel sensing technique in breath analysis, based on UV-irradiation of the gas sensors, was Importantly, the e-nose could further discriminate with high accuracy between the two types breath VOCs were found for the first time in the breath of LC patients, and could be used as new biomarkers for future LC diagnosis. Besides, an electronic nose (e-nose) system using a Keywords: Breath analysis, Lung cancer, Histology, GC/QTOF/MS, Electronic nose, UV- can provided an accurate mean for the non-invasive diagnosis of LC and LC histology. reported results prove that breath analysis with chemical gas sensors and analytical techniques irradiated WO3 sensors.
关键词： Lung cancer,Histology,UV-irradiated WO3 sensors,Electronic nose,Breath analysis,GC/QTOF/MS
更新于2025-09-19 17:13:59
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Nose-Cone Conformal Substrate-Integrated Waveguide Slot Array Antenna for X-Band Radar Applications
摘要： This paper presents the design of nose-cone conformal substrate-integrated waveguide (SIW) slot array antenna for modern radar applications. Firstly, the wave propagation characteristics have been investigated in doubly curved SIW, and it has been observed that they are non-uniform along the longitudinal direction of nose-cone conformal SIW. To ensure the constant wave propagation along the length of conformal SIW, the conventional design of SIW is reformulated for nose-cone conformal SIW and circuit model modification has been demonstrated. Secondly, the procedure for designing a SIW-based array on curved surfaces has been developed. In the proposed design, rectangular waveguide (RWG) to SIW feeding structure has been used to avoid spurious radiations. Finally, 1 × 6 element-based nose-cone conformal slotted array has been designed and compared with planar and cylindrical conformal arrays. It has been observed from the results that the nose-cone conformal slot array offers low sidelobe levels (SLLs) and high gain. For the validation of the proposed design, the conformal slotted array has been fabricated and measured, which exhibited a reasonable agreement between the measured and the simulated data.
关键词： substrate-integrated waveguide,high gain,X-band radar,nose-cone conformal,wave propagation,sidelobe levels,slot array antenna
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Symposium on Olfaction and Electronic Nose (ISOEN) - Fukuoka, Japan (2019.5.26-2019.5.29)] 2019 IEEE International Symposium on Olfaction and Electronic Nose (ISOEN) - Odorant-binding protein-based optoelectronic tongue and nose for sensing volatile organic compounds
摘要： We developed an array of odorant-binding protein mutants with various binding properties. The same design is suitable for the detection and identification of volatile organic compounds (VOCs) both in the liquid phase and in the gas phase by surface plasmon resonance imaging. The obtained optoelectronic tongue is highly selective at low concentrations of VOCs with a low detection limit, but a narrow linear range. In comparison, the optoelectronic nose gives a much higher signal to noise ratio, but the discrimination of VOCs from different chemical classes requires kinetic data to get rid of non-specific signals. This work shows that these optoelectronic tongue and nose are promising for numerous applications, each system having its own advantages.
关键词： electronic tongue,surface plasmon resonance imaging,electronic nose,Odorant-binding proteins,volatile organic compound
更新于2025-09-19 17:13:59
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Fabrication of a ball end nose micro milling tool by tangential laser ablation
摘要： The general trend towards miniaturization of components is leading to an increasing demand for micro cutting tools. Such tools are found in a variety of applications like optics manufacturing, mold machining or medical technology. Indeed, micromachining exhibits a high efficiency, accuracy and low cost in comparison to other micro processing technologies. Micro cutting tools are mostly produced by grinding, a mechanical process, which might damage the tool due to induced forces, vibrations and heat. These detrimental effects cause the high scrap rate in the manufacturing of micro cutting tools and limited geometrical flexibility. A new approach for the manufacturing of micro cutting tools is given by the ultrashort-pulsed laser technology: it enables material removal, which is independent of the hardness of the workpiece material and with only a negligible heat-affected zone. In most cases, laser ablation is disadvantaged in contrast to grinding because of its relatively low material-removal rate. When it comes to the manufacturing of micro cutting tools the small amount of material to be removed makes the ultra-short pulsed laser an interesting alternative to grinding. Furthermore, the laser ablation is a force and wear-free process, which ensures high precision. In this paper, a commercially available micro ball end mill geometry is measured by micro X-ray tomography and 3D microscopy. The movement of the mechanical axes and the path of the laser beam for manufacturing the desired tool are determined based on these measurements. The milling tools with a diameter of 100 μm are produced from cemented carbide blanks, on a 8-axis laser machining center. After machining, the tools are analyzed by SEM and using FIB: By creating a cross section perpendicular to the cutting edge the heat-affected zone is examined. Finally, the cutting tool is successfully applied for the manufacturing of micro electrodes in copper for an EDM process while recording the cutting forces.
关键词： ultrashort pulse laser ablation,tangential laser ablation,ball end nose micro milling tool
更新于2025-09-12 10:27:22