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Electrical Properties of Metal-Porous GaAs Structure at Water Adsorption
摘要： This paper reports the morphological, optical, luminescent and electrical properties of electrochemically made porous GaAs in order to evaluate their humidity sensing performance. The obtained porous GaAs exhibits non-homogenous surface morphology, which consists of pyramid-shaped crystallites and micropores. Photoluminescent and FTIR study shows that the surface of such material is covered by an oxide of As and Ga. The impedance spectroscopy was applied to analyze the influence of water vapor on electrical properties of metal-porous GaAs. It was shown that water adsorption results in the Nyquist plots shift to the region of higher frequencies. In humid atmosphere resistance Rv and characteristic time of charge accumulation s are decreased by 1.4 times and 5 times, respectively; resistance Rb and capacity Cb decreased by 1.4 times and 4.4 times, respectively. The response of the metal-porous GaAs structure to the adsorption of water is attributed to the decreasing of the bulk resistivity and potential barrier height. The formed oxide layer on the surface of porous GaAs plays a dual role—it increases the ability to adsorb water molecules and prevents the surface from receiving structural degradation.
关键词： SEM,DRIFT spectrum,impedance spectroscopy,Nyquist plot,Porous GaAs,humidity sensor
更新于2025-09-19 17:15:36
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A novel quartz-crystal microbalance humidity sensor based on solution-processible indium oxide quantum dots
摘要： Having a large surface area, like the quantum con?nement e?ect also caused by the nano-level size of quantum dots (QDs), creates fantastic potential for humidity sensing. A high concentration of surface adsorption sites initiates an increased response. Porosity between QDs allows fast water vapor penetration and out?ow. Here, a quartz-crystal microbalance (QCM) humidity sensor was prepared using indium oxide (In2O3) QDs, synthesized via a solvothermal method. After the In2O3 QDs were directly spin-coated onto the QCM, an annealing process removed organic long chains and exposed more moisture adsorption sites on the surfaces of the QDs. The annealed QCM humidity sensor exhibited high sensitivity (56.3 Hz per %RH at 86.3% RH), with a fast response/recovery time (14 s/16 s). Long carbon chains were broken down, and hydrogen-bonded hydroxyl groups were chemisorbed to the QDs. The chemical reaction was reduced by these chemisorbed hydrogen-bonded hydroxyl groups. Mass change was mostly caused by fast multilayer physisorption. Thus, the transducer can e?ectively and precisely monitor the moisture from a person's breath. In2O3 QD-modi?ed QCM sensors demonstrate promising humidity-sensing applications in daily life.
关键词： indium oxide quantum dots,annealing process,solvothermal method,humidity sensor,quartz-crystal microbalance
更新于2025-09-16 10:30:52
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Semiconducting single-walled carbon nanotube/graphene van der Waals junctions for highly sensitive all-carbon hybrid humidity sensors
摘要： Van der Waals (vdW) heterojunctions composed of diverse atomic-thin nanomaterials have great potential as building blocks for innovative nanodevices due to the unique electron coupling effect. However, previous researches have mainly focused on the light-mater interactions and charge transfer process, and the interactions between gas/vapor and vdW heterojunctions still remain to be verified. Herein, we firstly demonstrate the charge transfer based on the interaction between water (H2O) molecules and the all-carbon vdW junctions, which are formed by stacking non-carboxylated (6, 5) single-walled carbon nanotube (SWCNT) on the surface of chemical vapor deposition synthesized graphene. Based on these interaction mechanism and charge transfer process, a proof-of-concept all-carbon vdW junction humidity sensor has been fabricated. The device exhibits good reproducibility and high sensitivity of 24% per 1% RH change in a wide relative humidity range of 5~80 % with short response/recovery time of 198/110 ms. Furthermore, the effect of H2O molecule absorption on the charge transfer dynamics at the SWCNT/graphene vdW junctions has been demonstrated via Raman spectra, giving a novel humidity sensing mechanism. Our finding provides a new strategy to fabricate high performance humidity sensors using vdW heterojuctions as sensing layers.
关键词： humidity sensor,single-walled carbon nanotube,graphene,charge transfer,van der Waals heterojunctions
更新于2025-09-16 10:30:52
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Optical characterization of different waist diameter on microfiber loop resonator humidity sensor
摘要： In this paper, the effect of different waist diameter on silica microfiber loop resonator (MLR) relative humidity (%RH) sensor is reported. The silica fiber was tapered to vary the waist diameter to 3 μm, 4 μm, 5 μm,7 μm, 8 μm and 10 μm using flame brushing technique. The MLR with a 300 μm diameter loop was formed by manually twisted the tapered fiber under an optical microscope into a self-touching loop. Initially, the effect of whispering gallery modes (WGMs) on the MLR was observed. Transmission mode spectra were observed to determine the number of resonated wavelength and quality factor (Q-factor). The Q-factor is observed to be >105 for all samples and MLR with 3 μm diameter achieve the highest Q-factor value. A significant response to %RH from 35% to 85% was observed due to the change of refractive index between the MLR and the surrounding medium resulting different light attenuation in the microfiber. The sensitivity increased by a factor of 12.2 for the MLR with diameter of 7 μm as compared to the smaller diameter MLRs and a factor of 13.7 as compared to straight microfiber (SmF). As for resolution, the MLR with waist diameter of 7 μm improve by a factor of 5 as compared to the smaller waist diameter and a factor of 6.5 as compared to SmF. The proposed humidity sensor employs the microfiber loop resonator without any sensitive material coated on it which reduced the complexity during the fabrication and manufacturing process. The reported results may contribute to the optimal waist diameter of microfiber loop resonators for humidity sensing application.
关键词： sensitivity,resolution,humidity sensor,microfiber loop resonator,Whispering gallery mode
更新于2025-09-10 09:29:36
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Layer-edge device of two-dimensional hybrid perovskites
摘要： Two dimensional layered organic-inorganic hybrid perovskites (2D perovskites) are potential candidates for next generation photovoltaic device. Especially, the out-of-plane surface perpendicular to the superlattice plane of 2D perovskites (layer-edge surface) has presented several exotic behaviors, such as layer-edge states which are found to be crucial for improving the efficiency of 2D perovskite solar cells. However, fundamental research on transport properties of layer-edge surface is still absent. In this report, we observe the electronic and opto-electronic behavior in layer-edge device of 2D perovskites. The dark and photo currents are demonstrated to strongly depend on the crystallographic orientation in layer-edge device, and such anisotropic properties, together with photo response, are related to the thickness of inorganic layers. Finally, due to the abundant hydroxyl groups, water molecules are easy to condense on the layer-edge surface, and the conductance is extremely sensitive to the humidity environment, indicating a potential application of humidity sensor.
关键词： opto-electronic behavior,humidity sensor,layer-edge surface,2D perovskites,electronic transport
更新于2025-09-10 09:29:36
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[ACM Press the 2nd International Symposium - Stockholm, Sweden (2018.09.21-2018.09.23)] Proceedings of the 2nd International Symposium on Computer Science and Intelligent Control - ISCSIC '18 - Embedded Automatic Control System for Temperature, Humidity and Light Intensity in Agricultural Greenhouses
摘要： Based on the science and technology plan project of Shandong province, this paper designs an automatic control system based on the temperature, humidity and light intensity of the embedded agricultural greenhouse. The system uses DHT11 temperature and humidity sensor and BH1750 light intensity sensor to collect environmental information and transmit the collected data to the STM32F103ZET6 microcontroller for processing and sending out control signals. The system is simple in operation, low in cost and high in precision.
关键词： Temperature and humidity sensor,Light intensity sensor,STM32 microcontroller
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore, India (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Differential Pressure Sensor Using Silicon on Insulator Back to Back Cantilever Structure
摘要： In our day to day life differential pressure sensor can be used in much application. This type of pressure sensors are used for measuring the difference between two different pressure levels. Mostly bulk micro machined fabrication tool is used for fabrication process. Hence these type sensors have low cost and reliable than normal conventional sensor. This sensor is designed mainly to compare both the pressure below and above the liquid and flow rates and measures changes in pressure across restriction. The output differential pressure sensor varies with respect to the change in pressure level at up (or) down cantilever beam. When the pressure value at bottom side is high, when the membrane deflect towards forward direction (i.e.) moves upward. when the pressure value at which the bottom side is lower than the membrane deflects to backward direction (moves downward). This design is mainly used in domestic and industrial application.
关键词： Agriculture Applications,MEMS,Humidity Sensor,Temperature Sensor,Finite Element Method (FEM),micro-Cantilever
更新于2025-09-04 15:30:14
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Organic nanostructure sensing layer developed by AAO template for the application in humidity sensors
摘要： The present study demonstrates a novel nanoporous structure of aluminium 1,8,15,22-tetrakis 29H,31H phthalocyanine chloride (AlPcCl) prepared by template-assisted method for a humidity sensor. The nanoporous sensing layer was fabricated by solution wetting of anodic aluminium oxide template. The solutions of AlPcCl in different concentrations were spun cast over the template at various speeds. Both capacitive and resistive responses were measured as a function of different relative humidity levels. The sensor showed wide operating relative humidity range and responded at quite low humidity levels. Morphological changes were investigated by field emission scanning electron microscopy. The sensor showed wide operating relative humidity range. The sensor demonstrated better performance with improved sensing parameters, highlighting unique advantages of the low-molecular nanostructured sensing layer for the humidity sensors.
关键词： humidity sensor,AlPcCl,anodic aluminium oxide,nanoporous structure,template-assisted method
更新于2025-09-04 15:30:14
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Planar capacitive type humidity sensor fabricated using PTB7-Th by facile solution processing approach
摘要： A capacitive humidity sensor using coplanar electrodes coated with poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PTB7-Th) thin film (Al/PTB7-Th/Al) has been fabricated and investigated. In the present work, we show that increased sensitivity is obtained by rough and non-uniform surface morphology of the polymer thin film which comprises distinct peaks and valleys. The sensor shows good sensing behavior with enhanced sensitivity, better linearity and larger bandwidth. The device showed sensitivity over an appreciable range of relative humidity levels (between 20 and 95% RH). Typical adsorption and desorption response times were measured to be 20 s each.
关键词： Sensitivity,Bandwidth,Linearity,PTB7-Th,Solution processing,Capacitive humidity sensor
更新于2025-09-04 15:30:14
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Low-Cost Integrated Zinc Oxide Nanorods Based Humidity Sensors for Arduino Platform
摘要： Realization of a simple integrated and low-cost intensity modulation/direct detection (IM/DD) based humidity and vapor detection system utilizing zinc oxide (ZnO) nanorods as the active material is demonstrated. The sensing device comprises of ZnO nanorods optimally grown on a glass substrate and mounted on 3D printed platform for the alignment with a green light-emitting diode (LED) set-up for edge excitation. An Arduino platform was used for signal processing of the detection of the transmitted light. Both forward and backward scattering are affected due to light leakage while propagating through the glass substrate that are further attenuated in the presence of humidity. In this work, backward scattering was found to be dominant and thus with increasing humidity a reduction in the transmitted light was monitored. When the sensor was tested in a humidity controlled environment, it was found that the output voltage drops by approximately 750 mV upon changing the relative humidity (RH) level from 35% to 90% in a non-linear fashion. The average sensitivity of the sensor was observed to be -12 mV/% throughout the tested RH levels. Sensitivity was found to be higher at -24.6 mV/% for RH’s beyond 70%. An average response time of 3.8 s was obtained for RH levels of 85% with respect to the standard ambient humidity conditions (RH 50%), which showed a quicker recovery time of 2.2 s. The proposed sensor device provides numerous advantages including low cost production, simplicity in design, ease of use and stability during handling.
关键词： light scattering,humidity sensor,nanorods,fast sensing,zinc oxide,arduino
更新于2025-09-04 15:30:14