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Luminescent mesoporous films containing europium III complex
摘要： Mesoporous materials have large speci?c area and pore volume, low density, and high mechanical and thermal stability. These materials can be applied as catalysts, shape-selective adsorbents, chemical sensors, and capsules for controlled release of therapeutic agents; they can also be employed in microelectronics, electro-optics, and other emerging nanotechnologies. In this study, we used the sol–gel process to obtain mesoporous silica ?lms by dip coating. A trispyrazolyl borate, or scorpionate (Tp), complex containing europium III was incorporated into a mesoporous silica ?lm via wet impregnation. The silica precursor solution was prepared by homogenizing tetraethylorthosilicate, deionized water, ethanol, and cetyltrimethylammonium bromide. The ?lms were obtained by the dip-coating technique (between one and two depositions) at a deposition rate of 300 mm/min; borosilicate glasses were used as substrates. The ?lms were characterized by X-ray di?raction, infrared spectroscopy, transmittance, and europium III photoluminescence analyses. X-ray di?raction showed that mesoporous silica was present in the substrate. Silica without thermal treatment and silica treated at 200 °C presented pore diameters of 3.75 and 3.45 nm, respectively. Thermal treatment eliminated the surfactant. The excitation and emission spectra con?rmed that the luminescent europium III complex was incorporated into the mesoporous silica ?lm, which can be employed as sensor.
关键词： Mesoporous ?lm,Luminescent sensor,Sol–gel,Dip coating
更新于2025-09-04 15:30:14
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Temperature-independent refractive index sensor based on fiber Bragg grating and spherical-shape structure
摘要： A fiber-optic refractive index (RI) sensor consisting of a fiber Bragg grating (FBG) spliced in downstream of a spherical-shape structure in a single-mode fiber (SMF) is proposed and experimentally demonstrated. The cladding modes with different effective refractive indices can be efficiently excited by the spherical-shape structure. By measuring the difference of the wavelength shifts between the reflected cladding Bragg mode and the core mode, we have achieved a maximum sensitivity of 2.87 nm/RIU with range of the RI from 1.357 to 1.458. When the temperature changes from 25 °C to 225 °C, the relative wavelength shift between the cladding mode and the core mode has no significant changes, which indicates that this fiber-optic sensor allows for temperature-independent RI measurement.
关键词： Refractive index sensor,Temperature-independent,Spherical-shape structure,Fiber Bragg grating
更新于2025-09-04 15:30:14
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Cuk Converter Based BLDC Motor for Water Pumping System Using Solar Energy Source
摘要： Background: The Cuk converter is used to control DC link voltage between the PV and VSI. The CCM is implemented in Cuk converter to control the DC bus voltage and this helps to minimize the losses in DC-DC converter. Methods: The speed of the BLDC motor is controlled by voltage source inverter with PWM control. The PWM pulse is generated by using Hall Effect sensor. Results: The PWM switching of BLDC motor provides reduced switching losses and increasing the efficiency. Conclusions: The prototype model of this circuit also developed and its performance characteristics also verified. The switching losses are reduced by using Cuk converter. The VSI also reduced the switching losses by operation in 120 degree conduction mode. The speed of the BLDC motor is effectively controlled by hall signals.
关键词： BLDC motor,Cuk converter,VSI,PWM pulse,Hall effect sensor,Solar power
更新于2025-09-04 15:30:14
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<i>In Situ</i> IR Spectroscopy of Mesoporous Silica Films for Monitoring Adsorption Processes and Trace Analysis
摘要： Adsorption of molecules on high-surface-area materials is a fundamental process critical to many fields of basic and applied chemical research; for instance, it is among the simplest and most efficient principles for separating and remediating polluted water. However, established experimental approaches for investigating this fundamental process preclude in situ monitoring and thus obtaining real-time information about the ongoing processes. In this work, mid-infrared attenuated total reflection (ATR) spectroscopy is introduced as a powerful technique for quantitative in situ monitoring of adsorption processes and thus enrichment of traces of organic pollutants from aqueous solution in ordered mesoporous silica films. The synthesis, functionalization, and characterization of two silica films with 3D hexagonal and cubic pore structure on silicon ATR crystals are presented. Benzonitrile and valeronitrile as model compounds for aromatic and aliphatic water pollutants are enriched in hydrophobic films, while the matrix, water, is excluded from the volume probed by the evanescent field. Enrichment times of <5 s are observed during in situ measurements of benzonitrile adsorbing onto the film from aqueous solution. The sensing system is calibrated using the Freundlich adsorption equation as a calibration function. Enrichment factors of benzonitrile and valeronitrile within the film were determined to be >200 and >100, respectively, yielding detection limits in the low ppm range. Furthermore, fast and complete desorption of the analyte, ensuring reliable regeneration of the sensor, was verified. Lastly, we derive and experimentally validate equations for ATR spectroscopy with thin film adsorption layers to quantify the absolute mass of adsorbed pollutant in the film. The excellent agreement between recorded absorptions at target wavenumbers of the target analytes and corresponding simulations corroborates the validity of the chosen approach.
关键词： infrared spectroscopy,functional coatings,sensor,porous materials,thin film
更新于2025-09-04 15:30:14
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Design of zinc oxide-based surface acoustic wave sensors using a graphene electrode
摘要： Continuous monitoring of skin moisture by using a wearable moisture sensor consisting of the materials that have no risk of skin sensitization, such as zinc oxide (ZnO), is essential to optimize the healing process in wound care. Here we tackled the investigation of the optimum electrode for ZnO-based surface acoustic wave (SAW) sensors to achieve this goal. Al and Au electrodes commonly used were compared with a graphene electrode by simulation in terms of the frequency characteristics of the SAW device. Graphene and Al showed the same tendency in frequency characteristics as the 0 thickness electrode (ideal electrode). Since graphene is suitable for flexible devices due to its stretchability and for the long-term stability due to its chemical innerness, it was concluded that graphene is more suitable than the conventional Al and Au electrodes for flexible SAW sensor devices.
关键词： flexible devices,surface acoustic wave sensors,wearable moisture sensor,zinc oxide,graphene electrode
更新于2025-09-04 15:30:14
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Multiplexed functionalization of nanoelectromechanical systems with photopatterned molecularly imprinted polymers
摘要： Implementing dedicated and reliable biochemical recognition functionalities onto nanoelectromechanical systems (NEMS) is of primary importance for their development as ultra-sensitive and highly-integrated biosensing devices. In this paper, we demonstrate the large-scale and multiplexed integration of molecularly imprinted polymers (MIPs) as highly stable biomimetic receptors onto arrays of nanocantilevers. Integration is carried out by spin-coating and photopatterning the polymer layers before releasing the nanostructures. We demonstrate that these biomimetic layers are robust enough to withstand the wet-etch of the sacrificial layer making this functionalization strategy compatible with further MEMS/NEMS processing. As a proof of concept, we fabricate NEMS resonators coated with a MIP using Boc-L-phenylalanine (Boc-L-Phe) as the template molecule. We demonstrate the preserved molecular recognition ability of the patterned sensitive layer through the fluorescence detection of dansyl-L-phenylalanine (dansyl-L-Phe), a fluorescent derivative of the template, and the mechanical integrity of the resonators by means of resonant frequency measurements.
关键词： Sensor,Molecularly Imprinted Polymer,Photolithography,Microfabrication,NanoElectroMechanical Systems
更新于2025-09-04 15:30:14
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Enhanced NO2 gas sensing of a single-layer MoS2 by photogating and piezo-phototronic effects
摘要： NO2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However, traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO2 sensor based on single-layer MoS2. The flexible sensor exhibits high sensitivity to NO2 gas due to ultra-large specific surface area and the nature of two-dimensional (2D) semiconductor. When the NO2 is 400 ppb (parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a 625 nm red light-emitting diode (LED) illumination of 4 mW/cm2 power under 0.67% tensile strain. More important, the response time is dramatically reduced to ～16 s and it only needs ～65 s to complete 90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoeletricity and adsorption-desorption induced charges transfer in the single-layer MoS2 Schottky junction based device. Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS2 by introducing photogating and piezo-phototronic effects in mesoscopic systems.
关键词： photogating effect,single-layer MoS2,ultrahigh sensitivity,flexible NO2 sensor,piezo-phototronic effect
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Nara, Japan (2018.10.9-2018.10.12)] 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - A Non-Contact Detection and Measurement Method of Conversation and Mastication using a Doppler sensor
摘要： Conversation and mastication are related to the quality of life. If one is healthy in a comfortable situation, the time length of the conversation and the mastication will be long. In addition, the time length of the conversation is an index to measure the sociality while that of the mastication is an index of health. Therefore, the measurement of the conversation and the mastication must be key factors of the monitoring in, for example, nursing homes for the elderly. A Doppler sensor is a device which enables us to realize non-contact sensing of the movement of a body. It means that there is no need to put electrodes on the body. We can naturally think about the non-contact sensing of the jaw movement caused by the conversation and the mastication. However, it is not easy to distinguish the conversation from the mastication. In this paper, we apply a signal processing scheme CARS for this problem and experimentally verify the possibility of the time length measurement for the conversation and the mastication.
关键词： Vital sensing,Mastication,QoL,Quality of life,Conversation,Doppler sensor
更新于2025-09-04 15:30:14
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Primitive and O-functionalized R-graphyne-like BN sheet: Candidates for SO <sub/>2</sub> Sensor with High Sensitivity and Selectivity at Room Temperature
摘要： In recent years, the successful obtained of various boron nitride allotropes have raised exciting prospects of 2D material for nano device area. Herein, two novel two-dimensional boron nitride allotropes, a rectangular graphyne-like sheet (R-BNyne) and an O-functionalized R-BNyne nanosheet (R-BNOyne), are proposed and investigated by first principle calculations. The structural stabilities of metallic R-BNyne and indirect gap semiconducting R-BNOyne are proved through the phonon dispersion and Molecular Dynamic calculations. Furthermore, the adsorptions of CH4, CO, CO2, SO2 and H2 on R-BNyne and R-BNOyne have been calculated to explore the possibilities of being as gas sensors. The significant change of the current-voltage curve with and without SO2 adsorption on R-BNyne and R-BNOyne implies that both of them could be used as candidates for SO2 superior sensor with high sensitivity and selectivity at room temperature. Our studies not only reveal a new solution to modulate the electronic properties of 2D nanosheets, but also are helpful for designing novel boron nitride allotropes for expanding the possibilities of being as gas sensors as well as superior capturer of SO2 with high sensitivity.
关键词： O-functionalized,R-graphyne-like boron nitride sheet,Electronic properties,Sensor,In-plane stiffness
更新于2025-09-04 15:30:14
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[IEEE 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Qingdao, China (2018.10.31-2018.11.3)] 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Simulation of a Novel Integrated 4H-SiC Temperature Sensor
摘要： This paper presents a novel integrated Schottky barrier diode temperature sensor in a 4H-SiC power MOSFET. Dual electrical isolation and additional current path are applied to this temperature sensor, allowing the sensor to work properly in any operating state of power MOSFET. Due to the sufficient electrical isolation, the crosstalk between sensor and power MOSFET is almost eliminated. Furthermore, high sensitivity S=1.21mV/K is observed for a constant bias current of Id=1mA. The temperature sensor exhibits a good degree of linearity with a root mean square error R2=0.99996.
关键词： Temperature sensor,4H-SiC,Power MOSFET,Self-heating,Crosstalk
更新于2025-09-04 15:30:14