Статті в журналах з теми "Temperature and RH sensors"
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1
Ivanov, I. I., A. M. Baranov, V. A. Talipov, S. M. Mironov, I. V. Kolesnik, and K. S. Napolskii. "DEVELOPMENT OF EFFECTIVE SENSORS FOR DETECTING PRE-EXPLOSIVE H2 CONCENTRATIONS." NAUCHNOE PRIBOROSTROENIE 31, no. 3 (August 31, 2021): 25–36. http://dx.doi.org/10.18358/np-31-3-i2536.
Повний текст джерелаАнотація:
We studied the response of catalytic sensors to hydrogen with various types of platinum-group catalysts (Pt, Pd, Ir, Rh, Pt+Pd) in the pre-explosive concentration range. Temperature dependences of sensory response are analysed. Dependences of the sensory response on the applied voltage demonstrates hysteresis behavior that can be explained by the partial transition of the oxides of the platinum group metals into the metallic phase at temperatures above 500 °С and the reverse oxidation of metals if temperature is below 400 °С. Catalytic sensors with Ir and Rh catalysts are more preferable for practical use in the detection of hydrogen.
2
Li, Hongyong, Yujiao Zhu, Yong Zhao, Tianshu Chen, Ying Jiang, Ye Shan, Yuhong Liu, et al. "Evaluation of the Performance of Low-Cost Air Quality Sensors at a High Mountain Station with Complex Meteorological Conditions." Atmosphere 11, no. 2 (February 19, 2020): 212. http://dx.doi.org/10.3390/atmos11020212.
Повний текст джерелаАнотація:
Low-cost sensors have become an increasingly important supplement to air quality monitoring networks at the ground level, yet their performances have not been evaluated at high-elevation areas, where the weather conditions are complex and characterized by low air pressure, low temperatures, and high wind speed. To address this research gap, a seven-month-long inter-comparison campaign was carried out at Mt. Tai (1534 m a.s.l.) from 20 April to 30 November 2018, covering a wide range of air temperatures, relative humidities (RHs), and wind speeds. The performance of three commonly used sensors for carbon monoxide (CO), ozone (O3), and particulate matter (PM2.5) was evaluated against the reference instruments. Strong positive linear relationships between sensors and the reference data were found for CO (r = 0.83) and O3 (r = 0.79), while the PM2.5 sensor tended to overestimate PM2.5 under high RH conditions. When the data at RH >95% were removed, a strong non-linear relationship could be well fitted for PM2.5 between the sensor and reference data (r = 0.91). The impacts of temperature, RH, wind speed, and pressure on the sensor measurements were comprehensively assessed. Temperature showed a positive effect on the CO and O3 sensors, RH showed a positive effect on the PM sensor, and the influence of wind speed and air pressure on all three sensors was relatively minor. Two methods, namely a multiple linear regression model and a random forest model, were adopted to minimize the influence of meteorological factors on the sensor data. The multi-linear regression (MLR) model showed a better performance than the random forest (RF) model in correcting the sensors’ data, especially for O3 and PM2.5. Our results demonstrate the capability and potential of the low-cost sensors for the measurement of trace gases and aerosols at high mountain sites with complex weather conditions.
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Liu, Zhuofu, Jianwei Li, Meimei Liu, Vincenzo Cascioli, and Peter McCarthy. "In-Depth Investigation into the Transient Humidity Response at the Body-Seat Interface on Initial Contact Using a Dual Temperature and Humidity Sensor." Sensors 19, no. 6 (March 26, 2019): 1471. http://dx.doi.org/10.3390/s19061471.
Повний текст джерелаАнотація:
Relative humidity (RH) at the body-seat interface is considered an important factor in both sitting comfort and generation of health concerns such as skin lesions. Technical difficulties appear to have limited research aimed at the detailed and simultaneous exploration of RH and temperature changes at the body-seat interface; using RH sensors without the capability to record temperature where RH is recorded. To explore the causes of a spike in RH consistently produced on first contact between body and seat surface, we report data from the first use of dual temperature and RH (HTU21D) sensors in this interface. Following evaluation of sensor performance, the effect of local thermal changes on RH was investigated. The expected strong negative correlation between temperature and RH (R2 = −0.94) supported the importance of considering both parameters when studying impact of sitting on skin health. The influence of sensor movement speed (higher velocity approach: 0.32 cm/s ± 0.01 cm/s; lower velocity approach: 0.17 cm/s ± 0.01 cm/s) into a static RH region associated with a higher local temperature were compared with data gathered by altering the rate of a person sitting. In all cases, the faster sitting down (or equivalent) generated larger RH outcomes: e.g., in human sitting 53.7% ± 3.3% RH (left mid-thigh), 56.4% ± 5.1% RH (right mid-thigh) and 53.2% ± 2.7% RH (Coccyx). Differences in size of RH change were seen across the measurement locations used to study the body-seat interface. The initial sitting contact induces a transient RH response (duration ≤ 40 s) that does not accurately reflect the microenvironment at the body-seat interface. It is likely that any movement during sitting would result in similar artefact formation. As a result, caution should be taken when investigating RH performance at any enclosed interface when the surfaces may have different temperatures and movement may occur.
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Montero, Ander, Gotzon Aldabaldetreku, Gaizka Durana, Iagoba Jorge, Idurre Sáez de Ocáriz, and Joseba Zubia. "Influence of Humidity on Fiber Bragg Grating Sensors." Advances in Materials Science and Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/405250.
Повний текст джерелаАнотація:
We demonstrate the influence of the relative humidity (RH) on the wavelength of fiber Bragg grating sensors (FBGS), performing tests with five FBGS at different humidity and temperature conditions. These tests were performed in a climate chamber whose RH changes according to a scheduled profile from 30% to 90%, in steps of 10%. These profiles were repeated for a wide range of temperatures from10∘Cto70∘C, in steps of10∘C. Two different types of instrumentation methods have been tested, spot welding and epoxy bonding, in two different materials, steel and carbon fiber reinforced polymer (CFRP). We discuss the results for each type of sensor and instrumentation method by analyzing the linearity of the Bragg wavelength with RH and temperature.
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Ahumada, Sofía, Matias Tagle, Yeanice Vasquez, Rodrigo Donoso, Jenny Lindén, Fredrik Hallgren, Marta Segura, and Pedro Oyola. "Calibration of SO2 and NO2 Electrochemical Sensors via a Training and Testing Method in an Industrial Coastal Environment." Sensors 22, no. 19 (September 26, 2022): 7281. http://dx.doi.org/10.3390/s22197281.
Повний текст джерелаАнотація:
Low-cost sensors can provide inaccurate data as temperature and humidity affect sensor accuracy. Therefore, calibration and data correction are essential to obtain reliable measurements. This article presents a training and testing method used to calibrate a sensor module assembled from SO2 and NO2 electrochemical sensors (Alphasense B4 and B43F) alongside air temperature (T) and humidity (RH) sensors. Field training and testing were conducted in the industrialized coastal area of Quintero Bay, Chile. The raw responses of the electrochemical (mV) and T-RH sensors were subjected to multiple linear regression (MLR) using three data segments, based on either voltage (SO2 sensor) or temperature (NO2). The resulting MLR equations were used to estimate the reference concentration. In the field test, calibration improved the performance of the sensors after adding T and RH in a linear model. The most robust models for NO2 were associated with data collected at T < 10 °C (R2 = 0.85), while SO2 robust models (R2 = 0.97) were associated with data segments containing higher voltages. Overall, this training and testing method reduced the bias due to T and HR in the evaluated sensors and could be replicated in similar environments to correct raw data from low-cost electrochemical sensors. A calibration method based on training and sensor testing after relocation is presented. The results show that the SO2 sensor performed better when modeled for different segments of voltage data, and the NO2 sensor model performed better when calibrated for different temperature data segments.
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Lee, Chi Yuan, Shuo Jen Lee, and Guan Wei Wu. "Integration of Micro Array Sensors in the MEA on Diagnosis of Micro Fuel Cells." Key Engineering Materials 364-366 (December 2007): 855–60. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.855.
Повний текст джерелаАнотація:
The temperature and humidity conditions of a membrane electrode assembly (MEA) determine the performance of fuel cells. The volume of traditional temperature and humidity sensors is too large to allow them to be used to measure the distribution of temperature and humidity in the MEA of fuel cells. Measurements cannot necessarily be made where required. They measure only the temperature and humidity distribution outside the fuel cells and yield results with errors that exceed those of measurements made in MEA. Therefore, in this study, micro-electro-mechanical-systems (MEMS) fabrication technology was employed to fabricate an array of micro sensors to monitor in situ the temperature and humidity distributions within the MEA of fuel cells. In this investigation, an array of micro temperature and humidity sensors was made from gold on the MEA. The advantages of array micro gold temperature and humidity sensors are their small volume, which enable them to be placed on MEA and their high sensitivity and accuracy. The dimensions of the temperature and humidity sensors are 180μm × 180μm and 180μm × 220μm, respectively. The experiment involves temperatures from 30 to 100 °C. The resistance varied from 23.084 to 28.196 /. The experimental results reveal that the temperature is almost linearly related to the resistance and the accuracy and sensitivity are less than 0.3 °C and 3.2×10-3/°C, respectively. The humidity sensor showed that the capacitance changed from 15.76 to 17.95 pF, the relative humidity from 20 to 95 %RH, and the accuracy and sensitivity were less than 0.25 %RH and 0.03 pF/%RH.
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Carvajal, Sergio A., and Ciro A. Sánchez. "Temperature effect in the calibration of capacitive humidity sensors." International Journal of Metrology and Quality Engineering 9 (2018): 9. http://dx.doi.org/10.1051/ijmqe/2018010.
Повний текст джерелаАнотація:
Capacitive hygrometers are widely used in industrial and environmental measurements. One of the limitations of these sensors is their temperature dependence. While in temperatures beyond 50 °C the effect has been proven to be significant, for standard conditions in calibration laboratories the magnitude of this dependence has not been rigorously studied. This paper presents the analysis and results of a study of the temperature influence in the calibration of capacitive hygrometers designed for monitoring environmental conditions. Ninety measurements were taken on 15 models of capacitive hygrometers using a two-pressure humidity generator between 30%rh and 80%rh and temperatures from 20 to 30 °C. A three-way analysis of variance (ANOVA) was used to evaluate the data. The results show that the calibration correction is independent of the temperature for the conditions considered; however, there is a correlation between the temperature and the devices, indicating that the gradients in temperature affect each technology of fabrication in a different way.
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Chen, Hsuan-Yu, and Chia-Chung Chen. "An Empirical Equation for Wet-Bulb Temperature Using Air Temperature and Relative Humidity." Atmosphere 13, no. 11 (October 26, 2022): 1765. http://dx.doi.org/10.3390/atmos13111765.
Повний текст джерелаАнотація:
Climate change causes extreme heat and high humidity in some regions. The wet-bulb temperature (Tw) is a heat stress index, and the threshold is 35 °C. It is difficult to measure the value of Tw using a psychrometer, but the Tw value can be calculated using the air temperature and humidity. To provide accuracy for the Tw calculation, an empirical equation is established using regression analysis. This study defines the empirical equation as , where Td is the air temperature in °C and RH is the relative humidity in %. This equation applies to a temperature of 20~45 °C and RH of 40~99%. The fit is better than that for the Stull equation in this range. The prediction accuracy is 0.022 °C and there is no fixed pattern for the error distribution for the range of Td and RH. The measurement uncertainty for Tw values for thermometer and humidity sensors that are not calibrated is 1.4~2.2%. If these sensors are calibrated, the measurement uncertainty for Tw values is 0.16~0.28 °C. Therefore, well-calibrated sensors are necessary to enhance the accuracy of the Tw predictive equation.
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Rakesh, Balaji, Nipun Sharma, Rupali Nagar, Vipul Dhongade, Krishna Daware, and Suresh Gosavi. "Mechanistic understanding of the sensing process by analyzing response curves of TiO2 based humidity sensors." Advances in Natural Sciences: Nanoscience and Nanotechnology 12, no. 4 (December 1, 2021): 045010. http://dx.doi.org/10.1088/2043-6262/ac4107.
Повний текст джерелаАнотація:
Abstract Sensors function by interacting with an appropriate stimulus, undergo a change in property, which is then diagnosed by making some measurements. For any sensor, the type of interaction between analyte and sensor surface determines its overall performance. This article explores the philosophy in which primary measurements like response curves can hold information on the “type” of interaction occurring between analyte and sensing material. As case study, titanium oxide (TiO2) pellet sensors fabricated by sol-gel growth of TiO2 nanoparticles (as-grown and annealed) are investigated for humidity sensing at room temperature. The sensors display a very fast response in the 0%–30% relative humidity (%RH) range and return to their initial state without applying any external heat treatment. The response curves are analysed in view of adsorption processes guided by Langmuir isotherms. Correlation between sensor microstructure, adsorption processes and response curve is used to build the mechanistic understanding of the sensing process. The results bring out a unique correlation between sensor microstructure, interaction of analyte with sensing material and profile of response curves. Further, the synthesised sensors exhibit a linear response in the 0%–30% RH range making them suitable for low humidity environments like food packaging industry.
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Pelino, Mario, Carlo Cantalini, and Marco Faccio. "Principles and Applications of Ceramic Humidity Sensors." Active and Passive Electronic Components 16, no. 2 (1994): 69–87. http://dx.doi.org/10.1155/1994/91016.
Повний текст джерелаАнотація:
This paper presents a brief review of the state of the art in humidity and gas ceramic sensors R&D; it also describes the principle, fabrication and application of the humidity-sensitive Si-doped a-hematite (α-Fe2O3) sintered compacts. The humidity signal response is characterized by volt-amperometric and impedance spectroscopy techniques in the 0-97% relative humidity (RH) range. The response time of the sensor is evaluated by 0-60% RH variations. Experimental techniques used to measure the hysteresis, drift, and aging of the humidity setasor are presented and the results are discussed. The CO sensitivity is investigated by activating the sensor in the 350-450℃ temperature range. A humidity-meter prototype, based on the α-Fe2O3ceramic compact is described, and its electronics and features are presented in this paper.
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Jäger, Jonas, Adrian Schwenck, Daniela Walter, André Bülau, Kerstin Gläser, and André Zimmermann. "Inkjet-Printed Temperature Sensors Characterized According to Standards." Sensors 22, no. 21 (October 24, 2022): 8145. http://dx.doi.org/10.3390/s22218145.
Повний текст джерелаАнотація:
This paper describes the characterization of inkjet-printed resistive temperature sensors according to the international standard IEC 61928-2. The goal is to evaluate such sensors comprehensively, to identify important manufacturing processes, and to generate data for inkjet-printed temperature sensors according to the mentioned standard for the first time, which will enable future comparisons across different publications. Temperature sensors were printed with a silver nanoparticle ink on injection-molded parts. After printing, the sensors were sintered with different parameters to investigate their influences on the performance. Temperature sensors were characterized in a temperature range from 10 °C to 85 °C at 60% RH. It turned out that the highest tested sintering temperature of 200 °C, the longest dwell time of 24 h, and a coating with fluoropolymer resulted in the best sensor properties, which are a high temperature coefficient of resistance, low hysteresis, low non-repeatability, and low maximum error. The determined hysteresis, non-repeatability, and maximum error are below 1.4% of the full-scale output (FSO), and the temperature coefficient of resistance is 1.23–1.31 × 10−3 K−1. These results show that inkjet printing is a capable technology for the manufacturing of temperature sensors for applications up to 85 °C, such as lab-on-a-chip devices.
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Smith, Katie R., Peter M. Edwards, Mathew J. Evans, James D. Lee, Marvin D. Shaw, Freya Squires, Shona Wilde, and Alastair C. Lewis. "Clustering approaches to improve the performance of low cost air pollution sensors." Faraday Discussions 200 (2017): 621–37. http://dx.doi.org/10.1039/c7fd00020k.
Повний текст джерелаАнотація:
Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported. The sensitivity of Metal Oxide Sensors (MOS) to volatile organic compounds (VOCs) changed with relative humidity (RH) by up to a factor of five over the range of 19–90% RH and with an uncertainty in the correction of a factor of two at any given RH. The short-term (second to minute) stabilities of MOS and electrochemical CO sensor responses were reasonable. During more extended use, inter-sensor quantitative comparability was degraded due to unpredictable variability in individual sensor responses (to either measurand or interference or both) drifting over timescales of several hours to days. For timescales longer than a week identical sensors showed slow, often downwards, drifts in their responses which diverged across six CO sensors by up to 30% after two weeks. The measurement derived from the median sensor within clusters of 6, 8 and up to 21 sensors was evaluated against individual sensor performance and external reference values. The clustered approach maintained the cost competitiveness of a sensor device, but the median concentration from the ensemble of sensor signals largely eliminated the randomised hour-to-day response drift seen in individual sensors and excluded the effects of small numbers of poorly performing sensors that drifted significantly over longer time periods. The results demonstrate that for individual sensors to be optimally comparable to one another, and to reference instruments, they would likely require frequent calibration. The use of a cluster median value eliminates unpredictable medium term response changes, and other longer term outlier behaviours, extending the likely period needed between calibration and making a linear interpolation between calibrations more appropriate. Through the use of sensor clusters rather than individual sensors, existing low cost technologies could deliver significantly improved quality of observations.
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Wang, Ning, Wenhao Tian, Haosheng Zhang, Xiaodan Yu, Xiaolei Yin, Yonggang Du, and Dailin Li. "An Easily Fabricated High Performance Fabry-Perot Optical Fiber Humidity Sensor Filled with Graphene Quantum Dots." Sensors 21, no. 3 (January 26, 2021): 806. http://dx.doi.org/10.3390/s21030806.
Повний текст джерелаАнотація:
An easily fabricated Fabry-Perot optical fiber humidity sensor with high performance was presented by filling Graphene Quantum Dots (GQDs) into the Fabry-Perot resonator, which consists of two common single mode optical fibers. The relative humidity sensing performance was experimentally investigated by an interference spectrum drift between 11 %RH to 85 %RH. 0.567 nm/%RH sensitivity and 0.99917 linear correlation were found in experiments that showed high sensitivity, good and wide-range linear responding. Meanwhile, its good responding repeatability was demonstrated by two circle tests with increasing and decreasing relative humidity. For investigating the measurement influence caused by a temperature jitter, the temperature responding was experimentally investigated, which showed its linear responding with 0.033 nm/°C sensitivity. The results demonstrate the humidity sensitivity is greatly higher than the temperature sensitivity. The wavelength shift influence is 0.0198 nm with 0.6 °C max temperature jitter in the experiment, which can be ignored in humidity experiments. The fast-dynamic responses at typical humidity were demonstrated in experiments, with 5.5 s responding time and 8.5 s recovering time. The sensors with different cavity lengths were also investigated for their humidity response. All sensors gave good linear responding and high sensitivity. In addition, the relation curve between cavity length and response sensitivity also had good linearity. The combination of GQDs and single mode optical fibers showed easy fabrication and good performance for an optical fiber relative humidity sensor.
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Lin, Jen-Yung, Huan-Liang Tsai, and Wen-Chi Sang. "Implementation and Performance Evaluation of Integrated Wireless MultiSensor Module for Aseptic Incubator of Cordyceps militaris." Sensors 20, no. 15 (July 31, 2020): 4272. http://dx.doi.org/10.3390/s20154272.
Повний текст джерелаАнотація:
This paper originally proposes a wireless multisensor module with illuminance, temperature, relative humidity (RH) and carbon dioxide (CO2) sensors in an aseptic jar incubator for a solid-state fermentation (SSF) of Cordyceps militaris culture. The light intensity, ambient temperature, RH and CO2 are the critical cultivation factors of C. militaris. First, these sensors are integrated in a multisensor platform which is installed inside a lid and covered with a high-efficiency particulate air (HEPA) membrane of class H14 for sterilization of bacteria and viruses. The observations of sensors are then transmitted by a wireless XBee network where the slave sensor node is fixed at the top of jar lid and the master radio node receives data and uploads to an on-site monitoring node. The acquired information is further transmitted to an iCloud database and displayed in a web-based monitoring system. The results illustrate the proposed wireless multisensor module was validated with sufficient accuracy, reliable confidence and well-tolerance for C. militaris cultivation biotechnology under aseptic conditions.
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Houston, Adam L., Roger J. Laurence, Tevis W. Nichols, Sean Waugh, Brian Argrow, and Conrad L. Ziegler. "Intercomparison of Unmanned Aircraftborne and Mobile Mesonet Atmospheric Sensors." Journal of Atmospheric and Oceanic Technology 33, no. 8 (August 2016): 1569–82. http://dx.doi.org/10.1175/jtech-d-15-0178.1.
Повний текст джерелаАнотація:
AbstractResults are presented from an intercomparison of temperature, humidity, and wind velocity sensors of the Tempest unmanned aircraft system (UAS) and the National Severe Storms Laboratory (NSSL) mobile mesonet (NSSL-MM). Contemporaneous evaluation of sensor performance was facilitated by mounting the Tempest wing with attached sensors to the NSSL-MM instrument rack such that the Tempest and NSSL-MM sensors could collect observations within a nearly identical airstream. This intercomparison was complemented by wind tunnel simulations designed to evaluate the impact of the mobile mesonet vehicle on the observed wind velocity.The intercomparison revealed strong correspondence between the temperature and relative humidity (RH) data collected by the Tempest and the NSSL-MM with differences generally within sensor accuracies. Larger RH differences were noted in the presence of heavy precipitation; however, despite the exposure of the Tempest temperature and humidity sensor to the airstream, there was no evidence of wet bulbing within precipitation. Wind tunnel simulations revealed that the simulated winds at the location of the NSSL-MM wind monitor were ~4% larger than the expected winds due to the acceleration of the flow over the vehicle. Simulated vertical velocity exceeded 1 m s−1 for tunnel inlet speeds typical of a vehicle moving at highway speeds. However, the theoretical noncosine reduction in winds that should result from the impact of vertical velocity on the laterally mounted wind monitor was found to be negligible across the simulations. Comparison of the simulated and observed results indicates a close correspondence, provided the crosswind component of the flow is small.
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Kinkeldei, Thomas, Giorgio Mattana, David Leuenberger, C. Ataman, F. Molina Lopez, A. Vasquez Quintero, Danick Briand, G. Nisato, N. F. de Rooij, and G. Tröster. "Feasibility of Printing Woven Humidity and Temperature Sensors for the Integration into Electronic Textiles." Advances in Science and Technology 80 (September 2012): 77–82. http://dx.doi.org/10.4028/www.scientific.net/ast.80.77.
Повний текст джерелаАнотація:
We demonstrate a woven textile with an integrated humidity and temperature sensor on flexible PI substrates. We discuss the fabrication process of the smart textile and compare two methods of sensor fabrication, first conventional photo lithography and second printing using ink jet. The humidity sensor is based on a capacitive interdigitated transducer covered with a sensing layer while the temperature sensor is made of a resistive metallic meander. An encapsulation method protecting the sensors during dicing, weaving and operation has been successfully implemented. The fabricated structures are tested to bending strain, a main source of failure during the fabrication of textiles. We were able to bend bare electrodes and complete sensors down to a minimal bending radius of 100 μm without loss of functionality. The woven temperature sensor has a temperature coefficient of 0.0027 /°C for lithography made and 0.0029 /°C for printed sensors. The humidity sensor shows a repeatable behaviour in the tested humidity range between 20 to 70 %RH. The weaving process does not damage or change the behaviour of the fabricated sensors. This contribution will highlight the challenges and promises of printing and laminating processes for the large scale fabrication of smart polymeric stripes to be woven into textiles.
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Hairi, H. M., M. H. Rosli, M. H. Mamat, N. H. M. Noor, S. N. Supardan, and S. A. Kamil. "Effect of dipping number of polyvinyl alcohol (PVA) -coated on optical Fiber for Humidity Sensor." Journal of Physics: Conference Series 2432, no. 1 (February 1, 2023): 012008. http://dx.doi.org/10.1088/1742-6596/2432/1/012008.
Повний текст джерелаАнотація:
Abstract Optical Fiber Humidity Sensors (OFHSs) have attracted significant research interest due to their several advantages including small size, high durability and can withstand the extreme environment regardless of high temperature, high pressure and high electromagnetic radiation. In this study, the proposed sensors were built from standard single-mode silica fibers working at telecommunication wavelengths and exhibited very good humidity sensing characteristics. Single-mode optical fibers were coated with different dipping numbers (2, 4, 6 8, and 10 times) of polyvinyl alcohol (PVA) solution using a dip coating method. The sensing performance of uncoated and PVA-coated optical fiber sensors in terms of its sensitivity for various relative humidity (RH) percentages ranging from 40 to 90 % RH was monitored using Ocean Optics spectrometer. The intensity peaks of PVA-coated optical fibers were increased linearly with dipping numbers. The optimum sensing performance was observed for 10 times dipping number of PVA solution with the highest intensity of 4100 counts at 60 % RH and exhibits good repeatability with precision error values in the range of 0 to 2 %. Furthermore, the gap difference between intensity counts due to % RH changes could be clearly observed for 10 times dipping numbers. These reported results are important to enhance the performance of humidity sensor for sensing and monitoring purposes.
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Liu, Hai-Ying, Philipp Schneider, Rolf Haugen, and Matthias Vogt. "Performance Assessment of a Low-Cost PM2.5 Sensor for a near Four-Month Period in Oslo, Norway." Atmosphere 10, no. 2 (January 22, 2019): 41. http://dx.doi.org/10.3390/atmos10020041.
Повний текст джерелаАнотація:
The very low-cost Nova particulate matter (PM) sensor SDS011 has recently drawn attention for its use for measuring PM mass concentration, which is frequently used as an indicator of air quality. However, this sensor has not been thoroughly evaluated in real-world conditions and its data quality is not well documented. In this study, three SDS011 sensors were evaluated by co-locating them at an official, air quality monitoring station equipped with reference-equivalent instrumentation in Oslo, Norway. The sensors’ measurement results for PM2.5 were compared with data generated from the air quality monitoring station over almost a four-month period. Five performance aspects of the sensors were examined: operational data coverage, linearity of response and accuracy, inter-sensor variability, dependence on relative humidity (RH) and temperature (T), and potential improvement of sensor accuracy, by data calibration using a machine-learning method. The results of the study are: (i) the three sensors provide quite similar results, with inter-sensor correlations exhibiting R values higher than 0.97; (ii) all three sensors demonstrate quite high linearity against officially measured concentrations of PM2.5, with R2 values ranging from 0.55 to 0.71; (iii) high RH (over 80%) negatively affected the sensor response; (iv) data calibration using only the RH and T recorded directly at the three sensors increased the R2 value from 0.71 to 0.80, 068 to 0.79, and 0.55 to 0.76. The results demonstrate the general feasibility of using these low cost SDS011 sensors for indicative PM2.5 monitoring under certain environmental conditions. Within these constraints, they further indicate that there is potential for deploying large networks of such devices, due to the sensors’ relative accuracy, size and cost. This opens up a wide variety of applications, such as high-resolution air quality mapping and personalized air quality information services. However, it should be noted that the sensors exhibit often very high relative errors for hourly values and that there is a high potential of abusing these types of sensors if they are applied outside the manufacturer-provided specifications particularly regarding relative humidity. Furthermore, our analysis covers only a relatively short time period and it is desirable to carry out longer-term studies covering a wider range of meteorological conditions.
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Ngoune, Bernard Bobby, Hamida Hallil, Bérengère Lebental, Guillaume Perrin, Shekhar Shinde, Eric Cloutet, Julien George, Stéphane Bila, Dominique Baillargeat, and Corinne Dejous. "Selective Outdoor Humidity Monitoring Using Epoxybutane Polyethyleneimine in a Flexible Microwave Sensor." Chemosensors 11, no. 1 (December 23, 2022): 16. http://dx.doi.org/10.3390/chemosensors11010016.
Повний текст джерелаАнотація:
The rise of gas-sensing applications and markets has led to microwave sensors associated to polymer-based sensitive materials gaining a lot of attention, as they offer the possibility to target a large variety of gases (as polymers can be easily functionalised) at ultra-low power and wirelessly (which is a major concern in the Internet of Things). A two-channel microstrip sensor with one resonator coated with 1,2 epoxybutane-functionalised poly(ethyleneimine) (EB-PEI) and the other left bare was designed and fabricated for humidity sensing. The sensor, characterised under controlled laboratory conditions, showed exponential response to RH between 0 and 100%, which is approximated to −1.88 MHz/RH% (−0.03 dB/RH%) and −8.24 MHz/RH% (−0.171 dB/RH%) in the RH ranges of 30–80% and 80–100%, respectively. This is the first reported use of EB-PEI for humidity sensing, and performances, especially at high humidity level (RH > 80%), as compared with transducer working frequencies, are better than the state of the art. When further tested in real outdoor conditions, the sensor shows satisfying performances, with 4.2 %RH mean absolute error. Most importantly, we demonstrate that the sensor is selective to relative humidity alone, irrespective of the other environmental variables acquired during the campaign (O3, NO, NO2, CO, CO2, and Temperature). The sensitivities obtained outdoors in the ranges of 50–70% and 70–100% RH (−0.61 MHz/%RH and −3.68 MHz/%RH, respectively) were close to lab results (−0.95 MHz/%RH and −3.51 MHz/%RH, respectively).
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Yan, Wenjun, Shiyu Zhou, Min Ling, XinSheng Peng, and Houpan Zhou. "NH3 Sensor Based on ZIF-8/CNT Operating at Room Temperature with Immunity to Humidity." Inorganics 10, no. 11 (October 31, 2022): 193. http://dx.doi.org/10.3390/inorganics10110193.
Повний текст джерелаАнотація:
Humidity effects on resistive gas sensors operating at room temperature remain a serious bottleneck. In this work, we introduce a resistive gas sensor based on a zeolitic imidazolate framework-8/carbon nanotube (ZIF-8/CNT) composite for the detection of ammonia gas at room temperature. The composite was prepared using a facile solution method. In this sensor, the basic mechanism was the charge transfer between ammonia molecules and CNTs; meanwhile, the ZIF-8 facilitated the adsorption of ammonia molecules as a preconcentrator, and prevented the adsorption of H2O molecules due to its hydrophobicity; CNTs were threaded through the ZIF-8 to form a great conductive network for charge transfer. The obtained sensor showed good ammonia sensing, especially at room temperature, with great selectivity and immunity to humidity under moderately humid conditions (45 – 70 % RH). However, the ammonia response was reduced at very high humidity (90% RH) due to the competitive adsorption of H2O molecules. This proved that the NH3 sensor based on ZIF-8/CNT could be suitable for practical applications under moderately humid conditions.
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Serban, Bogdan-Catalin, Cornel Cobianu, Octavian Buiu, Marius Bumbac, Niculae Dumbravescu, Viorel Avramescu, Cristina Mihaela Nicolescu, et al. "Ternary Nanocomposites Based on Oxidized Carbon Nanohorns as Sensing Layers for Room Temperature Resistive Humidity Sensing." Materials 14, no. 11 (May 21, 2021): 2705. http://dx.doi.org/10.3390/ma14112705.
Повний текст джерелаАнотація:
This paper presents the relative humidity (RH) sensing response of a resistive sensor employing sensing layers based on a ternary nanocomposite comprising graphene oxide-oxidized carbon nanohorns-polyvinylpyrrolidone (GO-CNHox–PVP), at 1/1/1, 1/2/1, and 1/3/1 w/w/w mass ratios. The sensing structure is composed of a silicon substrate, a SiO2 layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The morphology and the composition of the sensing layers are investigated through scanning electron microscopy (SEM) and RAMAN spectroscopy. The RH sensing capability of each carbonaceous nanocomposite-based thin film was analyzed by applying a current between the two electrodes and by measuring the voltage difference when varying the RH from 0% to 100% in humid nitrogen. The sensors have a room temperature response comparable to that of a commercial humidity sensor and are characterized by a rapid response, excellent linearity, good sensitivity, and recovery time. The manufactured sensing devices’ transfer functions were established, and we extracted the response and recovery times. While the structures with GO/CNHox/PVP at 1/1/1 ratio (w/w/w) had the best performance in terms of relative sensibility, response time, and recovery time, the sensors employing the GO/CNHox/PVP nanocomposite at the 1/2/1 ratio (w/w/w) had the best linearity. Moreover, the ternary mixture proved to have much better sensing properties compared to CNHox and CNHox-PVP-based sensing layers in terms of sensitivity and linearity. Each component of the ternary nanocomposites’ functional role is explained based on their physical and chemical properties. We analyzed the potential mechanism associated with the sensors’ response; among these, the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of the PVP, was dominant and led to increased resistance of the sensing layer.
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Carotenuto, Federico, Lorenzo Brilli, Beniamino Gioli, Giovanni Gualtieri, Carolina Vagnoli, Mauro Mazzola, Angelo Pietro Viola, et al. "Long-Term Performance Assessment of Low-Cost Atmospheric Sensors in the Arctic Environment." Sensors 20, no. 7 (March 30, 2020): 1919. http://dx.doi.org/10.3390/s20071919.
Повний текст джерелаАнотація:
The Arctic is an important natural laboratory that is extremely sensitive to climatic changes and its monitoring is, therefore, of great importance. Due to the environmental extremes it is often hard to deploy sensors and observations are limited to a few sparse observation points limiting the spatial and temporal coverage of the Arctic measurement. Given these constraints the possibility of deploying a rugged network of low-cost sensors remains an interesting and convenient option. The present work validates for the first time a low-cost sensor array (AIRQino) for monitoring basic meteorological parameters and atmospheric composition in the Arctic (air temperature, relative humidity, particulate matter, and CO2). AIRQino was deployed for one year in the Svalbard archipelago and its outputs compared with reference sensors. Results show good agreement with the reference meteorological parameters (air temperature (T) and relative humidity (RH)) with correlation coefficients above 0.8 and small absolute errors (≈1 °C for temperature and ≈6% for RH). Particulate matter (PM) low-cost sensors show a good linearity (r2 ≈ 0.8) and small absolute errors for both PM2.5 and PM10 (≈1 µg m−3 for PM2.5 and ≈3 µg m−3 for PM10), while overall accuracy is impacted both by the unknown composition of the local aerosol, and by high humidity conditions likely generating hygroscopic effects. CO2 exhibits a satisfying agreement with r2 around 0.70 and an absolute error of ≈23 mg m−3. Overall these results, coupled with an excellent data coverage and scarce need of maintenance make the AIRQino or similar devices integrations an interesting tool for future extended sensor networks also in the Arctic environment.
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Deb, Moumita, Mei-Yu Chen, Po-Yi Chang, Pin-Hsuan Li, Ming-Jen Chan, Ya-Chung Tian, Ping-Hung Yeh, Olivier Soppera, and Hsiao-Wen Zan. "SnO2-Based Ultra-Flexible Humidity/Respiratory Sensor for Analysis of Human Breath." Biosensors 13, no. 1 (January 3, 2023): 81. http://dx.doi.org/10.3390/bios13010081.
Повний текст джерелаАнотація:
Developing ultraflexible sensors using metal oxides is challenging due to the high-temperature annealing step in the fabrication process. Here, we demonstrate the ultraflexible relative humidity (RH) sensor on food plastic wrap by using 808 nm near-infrared (NIR) laser annealing for 1 min at a low temperature (26.2–40.8 °C). The wettability of plastic wraps coated with sol-gel solution is modulated to obtain uniform films. The surface morphology, local temperature, and electrical properties of the SnO2 resistor under NIR laser irradiation with a power of 16, 33, and 84 W/cm2 are investigated. The optimal device can detect wide-range RH from 15% to 70% with small incremental changes (0.1–2.2%). X-ray photoelectron spectroscopy reveals the relation between the surface binding condition and sensing response. Finally, the proposed sensor is attached onto the face mask to analyze the real-time human breath pattern in slow, normal, and fast modes, showing potential in wearable electronics or respiration monitoring.
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Ali, Salman, Mohammed A. Jameel, Christopher J. Harrison, Akhil Gupta, Richard A. Evans, Mahnaz Shafiei, and Steven J. Langford. "Enhanced Capacitive Humidity Sensing Performance at Room Temperature via Hydrogen Bonding of Cyanopyridone-Based Oligothiophene Donor." Chemosensors 9, no. 11 (November 15, 2021): 320. http://dx.doi.org/10.3390/chemosensors9110320.
Повний текст джерелаАнотація:
Cyanopyridone-based oligothiophene donors with both hydrophobic and hydrophilic characters have been evaluated as active layers within simple capacitive devices for humidity sensing at room temperature. Surface studies using atomic force microscopy revealed a self-assembled nanofibrous network with a thin needle-like structure for the terminal hydroxy example (CP6), devoid in the methyl example (CP1). The sensing performance of each sensor was investigated over a broad range of relative humidity levels as a function of capacitance at room temperature. The sensor CP6 demonstrated favourable features such as high sensitivity (12.2 pF/%RH), quick response/recovery (13 s/20.7 s), wide working range of relative humidity (10%–95% RH), low hysteresis (0.57%), outstanding recyclability, and excellent long-term stability. From the results obtained, hydrophilicity and hydrogen bonding appear to play a vital role in enhancing humidity sensing performance, leading to possible new design directions for simple organic semiconductor-based sensors.
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Ramírez, Sandra, Manuel Zarzo, Angel Perles, and Fernando-Juan García-Diego. "A Methodology for Discriminant Time Series Analysis Applied to Microclimate Monitoring of Fresco Paintings." Sensors 21, no. 2 (January 9, 2021): 436. http://dx.doi.org/10.3390/s21020436.
Повний текст джерелаАнотація:
The famous Renaissance frescoes in Valencia’s Cathedral (Spain) have been kept under confined temperature and relative humidity (RH) conditions for about 300 years, until the removal of the baroque vault covering them, carried out in 2006. In the interest of longer-term preservation and in order to maintain these frescoes in good condition, a unique monitoring system was implemented to record both air temperature and RH. Sensors were installed in different points at the vault of the apse, during the restoration process. The present study proposes a statistical methodology for analyzing a subset of RH data recorded in 2008 and 2010, from the sensors. This methodology is based on fitting different functions and models to the time series, in order to classify the sensors. The methodology proposed, computes classification variables and applies a discriminant technique to them. The classification variables correspond to estimates of parameters of the models and features such as mean and maximum, among others. These features are computed using values of the functions such as spectral density, sample autocorrelation (sample ACF), sample partial autocorrelation (sample PACF), and moving range (MR). The classification variables computed were structured as a matrix. Next, Sparse Partial Least Squares Discriminant Analysis (sPLS-DA) was applied in order to discriminate sensors according to their position in the vault. It was found that the classification of sensors derived from Seasonal ARIMA-TGARCH showed the best performance (i.e., lowest classification error rate). Based on these results, the methodology applied here can be useful for characterizing the differences in RH, measured at different positions in a historical building.
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Haidry, A. A., N. Kind, and B. Saruhan. "Investigating the influence of Al-doping and background humidity on NO<sub>2</sub> sensing characteristics of magnetron-sputtered SnO<sub>2</sub> sensors." Journal of Sensors and Sensor Systems 4, no. 2 (August 31, 2015): 271–80. http://dx.doi.org/10.5194/jsss-4-271-2015.
Повний текст джерелаАнотація:
Abstract. Elevated temperatures and humidity contents affect response, lifetime and stability of metal-oxide gas sensors. Remarkable efforts are being made to improve the sensing characteristics of metal-oxide-based sensors operating under such conditions. Having versatile semiconducting properties, SnO2 is prominently used for gas sensing applications. The aim of the present work is to demonstrate the capability of the Al-doped SnO2 layer as NO2 selective gas sensor working at high temperatures under the presence of humidity. Undoped SnO2 and Al-doped SnO2 (3 at. % Al) layers were prepared by the radio frequency (r.f.) reactive magnetron sputtering technique, having an average thickness of 2.5 μm. The sensor response of Al-doped SnO2 samples was reduced in the presence of background synthetic air. Moreover, under dry argon conditions, Al doping contributes to obtain a stable signal and to lower cross-sensitivity to CO in the gas mixtures of CO + NO2 at temperatures of 500 and 600 °C. The Al-doped SnO2 sensors exhibit excellent chemical stability and sensitivity towards NO2 gas at the temperature range of 400–600 °C under a humid environment. The sensors also showed satisfactory response (τres = 1.73 min) and recovery (τrec = 2.7 min) towards 50 ppm NO2 in the presence of 10 % RH at 600 °C.
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Guo, Miao, Yue Li, and Jingmin Gao. "Relative Humidity Measurement of Air in Low-Temperature Ranges Using Low-Frequency Acoustic Waves and Correlation Signal Processing Techniques." Sensors 22, no. 16 (August 19, 2022): 6238. http://dx.doi.org/10.3390/s22166238.
Повний текст джерелаАнотація:
Air relative humidity (RH) is an important control parameter in many industrial processes. The acoustic method is a novel technique to measure air humidity non-intrusively. Relevant research is limited. Existing methods use ultrasonic waves as a sound source and air humidity is measured by measuring the sound attenuation. In this paper, a novel air humidity measurement system using low-frequency sound waves as a sound source and two acoustic sensors is proposed. Air humidity is acquired by measuring sound speed in the air. Sound speed mainly depends on air temperature, humidity, atmospheric pressure, and air composition. The influence of air temperature, atmospheric pressure, and air constituent concentrations on the RH measurement is analyzed theoretically. A 0.1 s linear chirp signal in the frequency range of 200–500 Hz is selected as the sound source. Sound travel time is calculated by cross-correlating the sound signals received by the two acoustic sensors. To improve the accuracy of the sound speed measurement, sound speed under different RH points is obtained through reference RH experiments and substituted into the calibration equation. Then, equivalent sound path length and systematic delay are estimated using the least squares method. After obtaining these two parameter values, the sound speed measured by the system is closer to the theoretical value at the same RH point. In validation experiments using RH measured by a thermo-hygrometer as a comparison, the relative errors of the acoustically measured RH are within 9.9% in the RH range of 40.7–87.1%, and the standard deviation is within 4.8%.
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Maciak, Erwin. "Low-Coherence Interferometric Fiber Optic Sensor for Humidity Monitoring Based on Nafion® Thin Film." Sensors 19, no. 3 (February 2, 2019): 629. http://dx.doi.org/10.3390/s19030629.
Повний текст джерелаАнотація:
The main aim of this work was the design and development simple fiber optic Fabry-Perot interferometer (FPI) sensor devices for relative humidity (RH) sensing with emphasis on high sensitivity and good stability. The RH fiber FPI sensor is fabricated by coating the end of a cleaved standard multi-mode (MM) fiber with hydrophilic Nafion® sensing film. The Nafion® thin film acts as an active resonance cavity of the low-coherence interferometric sensing structure. The fringe pattern, which is caused by interfering light beam in the Nafion® thin film will shift as the RH changes because the water molecules will swell the Nafion® film and thus change optical pathlength of the sensing structure. The operating principle of a FPI sensor based on the adsorption and desorption of water vapour in the Nafion® and the limitations of this sensor type are discussed in this work. The fiber optic hygrometer was tested in the visible (400–900 nm) region of spectra for measurement of relative humidity (RH) in the range of 5.5–80% at room temperature (RT) in air. The fiber optic humidity sensor has a very short response time (t90 = 5–80 s) and a fast regeneration time (t10 = 5–12 s) as good as commercial sensors.
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Ramírez, Sandra, Manuel Zarzo, Angel Perles, and Fernando-Juan García-Diego. "A Methodology for Discriminant Time Series Analysis Applied to Microclimate Monitoring of Fresco Paintings." Sensors 21, no. 2 (January 9, 2021): 436. http://dx.doi.org/10.3390/s21020436.
Повний текст джерелаАнотація:
The famous Renaissance frescoes in Valencia’s Cathedral (Spain) have been kept under confined temperature and relative humidity (RH) conditions for about 300 years, until the removal of the baroque vault covering them in 2006. In the interest of longer-term preservation and in order to maintain these frescoes in good condition, a unique monitoring system was implemented to record both air temperature and RH. Sensors were installed at different points at the vault of the apse during the restoration process. The present study proposes a statistical methodology for analyzing a subset of RH data recorded by the sensors in 2008 and 2010. This methodology is based on fitting different functions and models to the time series, in order to classify the different sensors.The methodology proposed, computes classification variables and applies a discriminant technique to them. The classification variables correspond to estimates of model parameters of and features such as mean and maximum, among others. These features are computed using values of functions such as spectral density, sample autocorrelation (sample ACF), sample partial autocorrelation (sample PACF), and moving range (MR). The classification variables computed were structured as a matrix. Next, sparse partial least squares discriminant analysis (sPLS-DA) was applied in order to discriminate sensors according to their position in the vault. It was found that the classification of sensors derived from Seasonal ARIMA-TGARCH showed the best performance (i.e., lowest classification error rate). Based on these results, the methodology applied here could be useful for characterizing the differences in RH, measured at different positions in a historical building.
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Rivadeneyra, Almudena, Marco Bobinger, Andreas Albrecht, Markus Becherer, Paolo Lugli, Aniello Falco, and Jose F. Salmerón. "Cost-Effective PEDOT:PSS Temperature Sensors Inkjetted on a Bendable Substrate by a Consumer Printer." Polymers 11, no. 5 (May 7, 2019): 824. http://dx.doi.org/10.3390/polym11050824.
Повний текст джерелаАнотація:
In this work, we report on a fabrication protocol to produce fully inkjet-printed temperature sensors on a bendable polyethylene terephthalate (PET) substrate. The sensing layer is made of polymer-based Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink that is electrically contacted by an underlying interdigitated electrode (IDE) structure based on a silver nanoparticle (AgNP) ink. Both inks are available commercially, and no further ink processing is needed to print them using a cost-effective consumer printer with standard cartridges. The fabricated sensor modules are tested for different IDE dimensions and post-deposition treatments of the AgNP film for their response to a temperature range of 20 to 70 °C and moisture range of 20 to 90% RH (relative humidity). Attributed to the higher initial resistance, sensor modules with a larger electrode spacing of 200 µm show a higher thermal sensitivity that is increased by a factor of 1.8 to 2.2 when compared to sensor modules with a 150 µm-spacing. In all cases, the sensors exhibit high linearity towards temperature and a response comparable to state of the art.
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Kumar, Jitender, Vinod Kumar, Vinay Kumar Singh, Fahim Fahim, and A. T. Nimal. "Temperature based rapid SAW humidity sensor." Defence Science Journal 72, no. 3 (July 1, 2022): 402–8. http://dx.doi.org/10.14429/dsj.72.17280.
Повний текст джерелаАнотація:
This paper investigates the effect of temperature on the sensitivity of a thin-film Polyvinyl alcohol (PVA) based SAW humidity sensor. A PVA coated 433.92 MHz SAW resonator-based humidity sensor was fabricated and tested with different levels of humidity (0.5 to 95% RH) at different operating temperatures (10°C to 70°C). The sensor response was recorded through in-house developed data acquisition software and it was observed that PVA thin film coated SAW sensor shows the maximum sensitivity for trace level moisture detection at a lower temperature (≤10 °C). The sensor sensitivity has been recorded >400Hz/% RH for trace level detection (0.5–30% RH). It has been observed that sensor sensitivity deteriorates when temperature increased to 40 °C from 10 °C. The sensor has a fast response (~1s) and recovery time (<3s) for trace level humidity detection. The proposed sensor can be used in many applications, including fabrication of electronic devices, IC fabrication, pharmaceutical, textile industries, food processing, semiconductor device fabrication, and packaging.
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He, X. L., J. Zhou, W. B. Wang, W. P. Xuan, D. J. Li, S. R. Dong, H. Jin, Y. Xu, and J. K. Luo. "Flexible Surface Acoustic Wave Based Temperature and Humidity Sensors." MRS Proceedings 1659 (2014): 75–80. http://dx.doi.org/10.1557/opl.2014.111.
Повний текст джерелаАнотація:
ABSTRACTFlexible surface acoustic wave (SAW) based temperature and humidity sensors were fabricated and characterized. ZnO piezoelectric films were deposited on polyimide substrates by DC magnetron sputtering. ZnO films possess (0002) crystal orientation with large grain sizes of 50∼70 nm. SAW devices showed two wave modes, namely the Rayleigh and Lamb modes, with the frequencies at fR ∼132MHz and fL∼427MHz respectively for a wavelength of 12 μm device. The two resonant frequencies have a temperature coefficient of frequency (TCF) of −423ppm/K and −258ppm/K for the Rayleigh and Lamb waves, respectively. The SAW sensors exhibited a good repeatability in responding to cyclic change of humidity. The responses of the sensors increase with the increase in humidity, and the sensitivity increases with the decrease in wavelength. A high sensitivity of 34.7 kHz/10%RH has been obtained from a SAW device without any surface treatment, demonstrated that the flexible SAW humidity sensors are very promising for application in flexible sensors and microsystems.
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Zhang, Li, and Li Hua Dong. "Optochemical Film Sensor for the Determination of Free Chlorine in Water." Advanced Materials Research 79-82 (August 2009): 251–54. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.251.
Повний текст джерелаАнотація:
An thin reagent containing optochemical film sensor for detecting and measuring free chlorine in water is described. The film sensor has been manufactured by immobilisation indicator of 3,5-dimethyl-4-hydroxybenzaldazine in a permeable transparent polymeric membrane. A linear calibration for free available chlorine can be obtained in the range between 0.05 and 3ppm. The limit of quantitation is 0.3 ppm, and the accuracy exceeds 7%. It takes about 150s to measure the relatively low occupational exposure concentration of 0.1ppm. The interference of combined chlorine has been studied. The sensor has no response to combined chlorine. And the stability of the sensors and the effect of external parameters like relative humidity (RH), temperature on the sensor response have been investigated. The sensor response is affected by varying the temperature; however, humidity in the range between 0 and 90% RH does not affect sensor response. The 3,5-dimethyl-4-hydroxybenzaldazine remained stable inside the polymeric film and no chemical reaction, crystallization or leaching occurred during 6 months of observation. Proper choice of indicator dye and polymeric material and successful application of kinetic evaluation method for the exposure experiments determine the desired features of the sensor. Introduction
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Hurst, D. F., E. G. Hall, A. F. Jordan, L. M. Miloshevich, D. N. Whiteman, T. Leblanc, D. Walsh, H. Vömel, and S. J. Oltmans. "Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE 2009." Atmospheric Measurement Techniques Discussions 4, no. 4 (July 11, 2011): 4357–401. http://dx.doi.org/10.5194/amtd-4-4357-2011.
Повний текст джерелаАнотація:
Abstract. We compare coincident, balloon-borne, in situ measurements of temperature and pressure by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and measurements of relative humidity (RH) by Vaisala RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with mixed payloads are analyzed in 1-km altitude bins to quantify measurement biases between sensors and how they vary with altitude. The disparities between sensors determined here are compared to measurement uncertainties quoted by the two radiosonde manufacturers. Our comparisons expose several flight profiles with anomalously large measurement differences. Excluding these anomalous profiles, 33 % of RS92-iMet median temperature differences exceed the uncertainty limits calculated from manufacturer-quoted uncertainties. A statistically significant, altitude-independent bias of about 0.5 ± 0.2 °C is revealed for the RS92-iMet temperature differences. Similarly, 23 % of RS92-iMet median pressure differences exceed the quoted uncertainty limits, with 83 % of these excessive differences above 16 km altitude. The pressure differences are altitude dependent, increasing from −0.6 ± 0.9 hPa at the surface to 0.7 ± 0.1 hPa above 15 km. Temperature and pressure differences between redundant RS92 sondes on the same balloon exceed manufacturer-quoted reproducibility limits 20 % and 2 % of the time, respectively, with most of the excessive differences belonging to anomalous difference profiles. Relative humidity measurements by RS92 sondes are compared to other RS92 sondes and to RH values calculated using frost point hygrometer measurements and coincident radiosonde temperature measurements. For some flights the RH differences are anomalously large, but in general are within the ±5 % RH measurement uncertainty limits quoted for the RS92. The quantitative effects of RS92 and iMet pressure and temperature differences on frost point-based water vapor mixing ratios and RH values, respectively, are also presented.
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Tang, Dan, Li Feng Wang, and Qing An Huang. "Passive Wireless Multi-Parameter Sensor System for Hermetic Environment Monitoring." Key Engineering Materials 645-646 (May 2015): 583–88. http://dx.doi.org/10.4028/www.scientific.net/kem.645-646.583.
Повний текст джерелаАнотація:
This paper presents a passive wireless multi-parameter sensor system, which is suitable for monitoring the environment in hermetic space like industrial painting room, coal mine, and so on. The system consists of two subsystems: the primary system and the secondary system. The primary system transmits power and receives modulated data through a coupled transformer composed of primary and secondary inductors printed in their subsystems, respectively. The secondary system comprises micro capacitive temperature, pressure and relative humidity sensors and uses a relaxation oscillator to convert capacitance to frequency. Using time division multiplexing unit, it can simultaneously measure multiple sensors. The converted frequency signal is used to vary the amplitude of the waveforms on the coupling inductors. The modulating signal is recovered from the carrier using the envelope detection unit. The measurement results indicate that the pressure, temperature, and relative humidity sensitivities of the passive wireless multi-parameter sensor system are 5.6 fF/hPa, 250fF/°C and 71.4 fF/%RH, respectively. Three sensors linearly response to the change of the environment and the system has good consistency.
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Prayitno, Eko, and Desi Amirullah. "SISTEM PEMANTAUAN KONSENTRASI CO KEBAKARAN HUTAN RIAU MENGGUNAKAN TEKNOLOGI WIRELESS SENSOR NETWORK (WSN) DAN INTERNET OF THINGS (IOT)." Jurnal Teknologi Informasi dan Terapan 4, no. 2 (April 1, 2019): 135–40. http://dx.doi.org/10.25047/jtit.v4i2.71.
Повний текст джерелаАнотація:
The purpose of this research is how to make an air condition monitoring system by considering the concentration value of carbon monoxide in Riau Province. The technology used to support monitoring system of carbon monoxide concentration, using Wireless Sensor Network Technology (WSN) and Internet of Things (IoT). One of the WSN concepts to be used is a combination of several sensors, the only sensors used to detect the level of carbonmonoxide concentration include: carbon monoxide, temperature and humidity sensors. Air condition data derived from the sensor in the form of concentration value of carbon monoxide, temperature and humidity of air sent to server connected to network using IoT technology. Based on the test results it can be concluded that the air condition monitoring system using WSN and IoT technology can be applied in realtime, this can be proven with the data shown in the monitoring tool. the detection of a fire source using a sensor can be done by using a distance between a smoke source (hotspot) and a device 90cm. From the observation result there is difference between sensing data without smoke and using smoke, such as temperature has 60C difference, humidity 20 rh and carbon monoxide about 17ppm
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Mulianda, P., K. Fahmy, and Andasuryani. "Design of Green Tea Drying System Using Smoke and Temperature Sensors Based on Microcontroller." IOP Conference Series: Earth and Environmental Science 1059, no. 1 (July 1, 2022): 012022. http://dx.doi.org/10.1088/1755-1315/1059/1/012022.
Повний текст джерелаАнотація:
Abstract The green tea drying process still uses wood as its fuel because it can reduce production costs. However, the smoke produced by the bottom firewood enters the drying chamber, thus affecting the quality of the green tea produced. Therefore, it is necessary to have a drying system that can detect and control the smoke entering the drying chamber and control the temperature during the drying process. The tea drying system is designed using a smoke sensor and a temperature sensor based on a microcontroller. This system is also equipped with an RH sensor that can monitor the RH value during the drying process. From the device performance test results, it was found that the system designed can control the smoke and temperature in the drying chamber to be applied to the green tea drying process in tea factories.
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Tousi, Maryam Mesgarpour, Yujing Zhang, Shaowei Wan, Li Yu, Chong Hou, Ning Yan, Yoel Fink, Anbo Wang, and Xiaoting Jia. "Scalable Fabrication of Highly Flexible Porous Polymer-Based Capacitive Humidity Sensor Using Convergence Fiber Drawing." Polymers 11, no. 12 (December 2, 2019): 1985. http://dx.doi.org/10.3390/polym11121985.
Повний текст джерелаАнотація:
In this study, we fabricated a highly flexible fiber-based capacitive humidity sensor using a scalable convergence fiber drawing approach. The sensor’s sensing layer is made of porous polyetherimide (PEI) with its porosity produced in situ during fiber drawing, whereas its electrodes are made of copper wires. The porosity induces capillary condensation starting at a low relative humidity (RH) level (here, 70%), resulting in a significant increase in the response of the sensor at RH levels ranging from 70% to 80%. The proposed humidity sensor shows a good sensitivity of 0.39 pF/% RH in the range of 70%–80% RH, a maximum hysteresis of 9.08% RH at 70% RH, a small temperature dependence, and a good stability over a 48 h period. This work demonstrates the first fiber-based humidity sensor fabricated using convergence fiber drawing.
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Dyakonov, V. P., S. Piechota, K. Piotrowski, A. Szewczyk, H. Szymczak, V. Mikhaylov, A. Shemiakov, A. Pashchenko, and V. P. Pashchenko. "Sensor of Current or Magnetic Field Based on Magnetoresistance Effect in (La0.7Ca0.3)0.8Mn1.2O3 Manganite Film." Solid State Phenomena 154 (April 2009): 157–61. http://dx.doi.org/10.4028/www.scientific.net/ssp.154.157.
Повний текст джерелаАнотація:
The main objective of the performed investigations was to enhance sensitivity of a current sensor to weak changes of magnetic field. New design of the sensor of current based on magnetoresistance effect – MRE (MRE = (RH - R0)/R0 , where RH is the resistance in magnetic field and R0 is the resistance without magnetic field) was developed. The sensor was produced in the form of an annular magnet with a gap, in which the (La0.7Sr0.3)0.8Мn1.2О3 manganite film possessing large negative MRE was inserted. Nominal current in a controllable electric circuit can change from a few tenths parts of ampere to a hundred of amperes. The limit detectable change of current value depends on the size of gap in the annular magnet. The operation time of sensor at current overload and short circuit is less than 0.3 sec. These magnetoresistors are thermally stable over the temperature range from (- 50 ° С) to (+ 50 ° С). Proposed sensors based on MRE can be applied in many electrical arrangements and devices.
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Perillo, P. M., and D. F. Rodríguez. "HUMIDITY SENSOR USING CuO NANORICES THIN FILM." Anales AFA 32, no. 3 (2021): 76–82. http://dx.doi.org/10.31527/analesafa.2021.32.3.76.
Повний текст джерелаАнотація:
In this paper, a humidity sensor based on CuO has been successfully fabricated. Thin-film of CuO nanorices were synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR) method on silicon wafer with Si3N4thinlayer as a substrate. The microstructure and morphology of the samples were investigated using X-ray diffraction(XRD) and scanning electron microscopy (SEM). Humidity sensing properties of the thin films have been studied. The sensing response has been measured in the relative humidity (RH) range from 20 up to 80 % at room temperature. It was found that impedance of the system decreases as the RH was increased. The prepared sensor revealed good reversibility with response and recovery time of 130 s and 320 s respectively. The complex impedance spectra were analyzed in the range of 0.1 to 1 kHz. This type of humidity sensor can be used as a new generation of ecological sensors with low cost and good stability. It makes the sensor a candidate for practical applications.
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Gwiżdż, Patryk, Andrzej Brudnik, and Katarzyna Zakrzewska. "Hydrogen Detection With a Gas Sensor Array – Processing and Recognition of Dynamic Responses Using Neural Networks." Metrology and Measurement Systems 22, no. 1 (March 1, 2015): 3–12. http://dx.doi.org/10.1515/mms-2015-0008.
Повний текст джерелаАнотація:
Abstract An array consisting of four commercial gas sensors with target specifications for hydrocarbons, ammonia, alcohol, explosive gases has been constructed and tested. The sensors in the array operate in the dynamic mode upon the temperature modulation from 350°C to 500°C. Changes in the sensor operating temperature lead to distinct resistance responses affected by the gas type, its concentration and the humidity level. The measurements are performed upon various hydrogen (17-3000 ppm), methane (167-3000 ppm) and propane (167-3000 ppm) concentrations at relative humidity levels of 0-75%RH. The measured dynamic response signals are further processed with the Discrete Fourier Transform. Absolute values of the dc component and the first five harmonics of each sensor are analysed by a feed-forward back-propagation neural network. The ultimate aim of this research is to achieve a reliable hydrogen detection despite an interference of the humidity and residual gases.
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Polyakov, Maxim, Victoria Ivanova, Darya Klyamer, Baybars Köksoy, Ahmet Şenocak, Erhan Demirbaş, Mahmut Durmuş, and Tamara Basova. "A Hybrid Nanomaterial Based on Single Walled Carbon Nanotubes Cross-Linked via Axially Substituted Silicon (IV) Phthalocyanine for Chemiresistive Sensors." Molecules 25, no. 9 (April 29, 2020): 2073. http://dx.doi.org/10.3390/molecules25092073.
Повний текст джерелаАнотація:
In this work, the novel hybrid nanomaterial SWCNT/SiPc made of single walled carbon nanotubes (SWCNT) cross-linked via axially substituted silicon (IV) phthalocyanine (SiPc) was studied as the active layer of chemiresistive layers for the detection of ammonia and hydrogen. SWCNT/SiPc is the first example of a carbon-based nanomaterial in which an axially substituted phthalocyanine derivative is used as a linker. The prepared hybrid material was characterized by spectroscopic methods, thermogravimetry, scanning and transmission electron microscopies. The layers of the prepared hybrid were tested as sensors toward ammonia and hydrogen by a chemiresistive method at different temperatures and relative humidity as well as in the presence of interfering gases like carbon dioxide, hydrogen sulfide and volatile organic vapors. The hybrid layers exhibited the completely reversible sensor response to both gases at room temperature; the recovery time was 100–200 s for NH3 and 50–120 s in the case of H2 depending on the gas concentrations. At the relative humidity (RH) of 20%, the sensor response was almost the same as that measured at RH 5%, whereas the further increase of RH led to its 2–3 fold decrease. It was demonstrated that the SWCNT/SiPc layers can be successfully used for the detection of both NH3 and H2 in the presence of CO2. On the contrary, H2S was found to be an interfering gas for the NH3 detection.
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Hilal, Yousif Yakoub, Montaser Khairie Khessro, Jos van Dam, and Karrar Mahdi. "Automatic Water Control System and Environment Sensors in a Greenhouse." Water 14, no. 7 (April 6, 2022): 1166. http://dx.doi.org/10.3390/w14071166.
Повний текст джерелаАнотація:
Iraqi greenhouses require an active microcontroller system to ensure a suitable microclimate for crop production. At the same time, reliable and timely Water Consumption Rate (WCR) forecasts provide an essential means to reduce the amount of water loss and maintain the environmental conditions inside the greenhouses. The Arduino micro-controller system is tested to determine its effectiveness in controlling the WCR, Temperature (T), Relative Humidity (RH), and Irrigation Time (IT) levels and improving plant growth rates. The Arduino micro-controller system measurements are compared with the traditional methods to determine the quality of the work of the new control system. The development of mathematical models relies on T, RH, and IT indicators. Based on the results, the new system proves to reliably identify the amount of WCR, IT, T, and RH necessary for plant growth. A t-test for the values from the Arduino microcontroller system and traditional devices for both conditions show no significant difference. This means that there is solid evidence that the WCR, IT, T, and RH levels for these two groups are no different. In addition, the linear, two-factor interaction (2FI), and quadratic models display acceptable performance very well since multiple coefficients of determination (R2) reached 0.962, 0.969, and 0.977% with IT, T, and RH as the predictor variables. This implies that 96.9% of the variability in the WCR is explained by the model. Therefore, it is possible to predict weekly WCR 14 weeks in advance with reasonable accuracy.
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Kureshi, Rameez Raja, Bhupesh Kumar Mishra, Dhavalkumar Thakker, Reena John, Adrian Walker, Sydney Simpson, Neel Thakkar, and Agot Kirsten Wante. "Data-Driven Techniques for Low-Cost Sensor Selection and Calibration for the Use Case of Air Quality Monitoring." Sensors 22, no. 3 (January 31, 2022): 1093. http://dx.doi.org/10.3390/s22031093.
Повний текст джерелаАнотація:
With the emergence of Low-Cost Sensor (LCS) devices, measuring real-time data on a large scale has become a feasible alternative approach to more costly devices. Over the years, sensor technologies have evolved which has provided the opportunity to have diversity in LCS selection for the same task. However, this diversity in sensor types adds complexity to appropriate sensor selection for monitoring tasks. In addition, LCS devices are often associated with low confidence in terms of sensing accuracy because of the complexities in sensing principles and the interpretation of monitored data. From the data analytics point of view, data quality is a major concern as low-quality data more often leads to low confidence in the monitoring systems. Therefore, any applications on building monitoring systems using LCS devices need to focus on two main techniques: sensor selection and calibration to improve data quality. In this paper, data-driven techniques were presented for sensor calibration techniques. To validate our methodology and techniques, an air quality monitoring case study from the Bradford district, UK, as part of two European Union (EU) funded projects was used. For this case study, the candidate sensors were selected based on the literature and market availability. The candidate sensors were narrowed down into the selected sensors after analysing their consistency. To address data quality issues, four different calibration methods were compared to derive the best-suited calibration method for the LCS devices in our use case system. In the calibration, meteorological parameters temperature and humidity were used in addition to the observed readings. Moreover, we uniquely considered Absolute Humidity (AH) and Relative Humidity (RH) as part of the calibration process. To validate the result of experimentation, the Coefficient of Determination (R2), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE) were compared for both AH and RH. The experimental results showed that calibration with AH has better performance as compared with RH. The experimental results showed the selection and calibration techniques that can be used in designing similar LCS based monitoring systems.
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RAMAKRISHNAN, N., TALLA VAMSI, ASLAM KHAN, HARSHAL B. NEMADE, and ROY PAILY PALATHINKAL. "HUMIDITY SENSOR USING NIPAAm NANOGEL AS SENSING MEDIUM IN SAW DEVICES." International Journal of Nanoscience 10, no. 01n02 (February 2011): 259–62. http://dx.doi.org/10.1142/s0219581x11007880.
Повний текст джерелаАнотація:
In this paper we report poly N-isopropylacrylamide (NIPAAm) nanogel used as sensing medium in Rayleigh wave type surface acoustic wave (SAW) devices to measure relative humidity. NIPAAm is synthesized by single-step surfactant-free emulsion polymerization reaction method. The prepared nanogel particles have dimensions less than 180 nm. Dynamic light scattering (DLS) analysis of these particles shows increase in size of the particles up to 100% when dispersed in water at room temperature. In this work we have developed two types of relative humidity (RH) sensors. In the first type commercial SAW resonators with resonance frequency at 315 MHz from EPCOSTM were used in our experiment. The casings of two resonators were removed carefully and one of them was left as such to serve as the reference device. The other was coated with the NIPAAm nanogel and used as the sensor. In the second type of SAW-based humidity sensor aluminum interdigital transducers (IDT) are fabricated over YZ lithium niobate piezoelectric substrate using metallization and lithography techniques. The fabricated IDTs have the pitch length of 34 μm and a resonance frequency of 51.6 MHz. Response of sensor to RH is measured by measuring the scattering parameters of both the types of sensors and reference devices recorded using the network analyzer.
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Francesca, Sanna, Deboli Roberto, and Calvo Angela. "Variability of tomato in protected environment in response to meteorological parameters." Plant, Soil and Environment 64, No. 6 (May 31, 2018): 247–54. http://dx.doi.org/10.17221/772/2017-pse.
Повний текст джерелаАнотація:
An experimental site for the measurement of meteorological parameters in protected environment and the evaluation of the tomato cultivar variability is presented in this paper. The site was equipped with cultivation structures with different covering materials and calibrated sensors traceable to the International System of Units. The microclimate conditions were monitored by sensors for solar radiation (from 290 nm to 2800 nm), air temperature (from –10°C to 40°C) and relative humidity (from 10% RH to 98% RH) inside and outside the tunnels. Specific procedures were used to calibrate the instruments. The following aspects were evaluated: microclimate and solar radiation within different cultivations; morphological observations of the tomatoes in response to the different environments; optical and radiometric properties of the films used as covering material. High temperatures recorded (over 40°C) changed the transmissive feature of the films and consequently affected the growth, anthesis, leaf area index and fruit setting of tomatoes.
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TAHIR, MUHAMMAD, MUHAMMAD HASSAN SAYYAD, FAZAL WAHAB, FAZAL AHMAD KHALID, FAKHRA AZIZ, SHAZIA NAEEM, and MUHAMMAD NAEEM KHALID. "ENHANCEMENT IN THE SENSING PROPERTIES OF METHYL ORANGE THIN FILM BY TiO2 NANOPARTICLES." International Journal of Modern Physics B 28, no. 05 (February 6, 2014): 1450032. http://dx.doi.org/10.1142/s0217979214500325.
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This paper reports the enhancement in the sensing properties of organic dye methyl orange (MO) by introducing TiO 2 nanoparticles. For this purpose, two surface type Ag/MO/Ag and Ag/MO : TiO 2/ Ag multifunctional sensors were fabricated by spin coating a 3.0 wt.% solution of MO and 3.0:0.3 wt.% of MO : TiO 2 composite on pre-patterned silver (Ag) electrodes. The gap between Ag electrodes was 40 μm. The Ag/MO/Ag and Ag/MO : TiO 2/ Ag structures were characterized to investigate their response towards humidity and temperature variations. The Ag/MO : TiO 2/ Ag sensor exhibited better sensitivity and response time than Ag/MO/Ag sensor. The large surface to volume ratio of TiO 2 nanoparticles is the primary reason for the higher sensitivity of Ag/MO : TiO 2/ Ag sensor. The sensors can be used to detect humidity variations from 30% to 95% RH and temperature variation from 30°C to 200°C with good stability. Surface morphologies of the film were investigated by scanning electron microscope (SEM).
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Reinis, Pauls Kristaps, Lase Milgrave, Kristians Draguns, Inga Brice, Janis Alnis, and Aigars Atvars. "High-Sensitivity Whispering Gallery Mode Humidity Sensor Based on Glycerol Microdroplet Volumetric Expansion." Sensors 21, no. 5 (March 3, 2021): 1746. http://dx.doi.org/10.3390/s21051746.
Повний текст джерелаАнотація:
We demonstrate a highly sensitive whispering gallery mode (WGM) relative humidity (RH) sensor based on a glycerol microdroplet. WGMs were excited using a 760 nm tunable semiconductor laser. We used free space coupling, which is effective when using a liquid resonator. A detailed analysis of different parameters influencing the sensor’s characteristics (sensitivity, hysteresis, resolution, stability, and temperature) is presented. The sensitivity of the sensor is one of the highest reported (2.85 nm/% RH in the range 50–70% RH with the resolution 1 × 10−4% RH). This type of humidity sensor has several advantages, such as high sensitivity, extended lifetime, good repeatability, and low cost, as well as the use of a non-toxic and environmentally friendly liquid.
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Zheng, Tongshu, Michael H. Bergin, Karoline K. Johnson, Sachchida N. Tripathi, Shilpa Shirodkar, Matthew S. Landis, Ronak Sutaria, and David E. Carlson. "Field evaluation of low-cost particulate matter sensors in high- and low-concentration environments." Atmospheric Measurement Techniques 11, no. 8 (August 22, 2018): 4823–46. http://dx.doi.org/10.5194/amt-11-4823-2018.
Повний текст джерелаАнотація:
Abstract. Low-cost particulate matter (PM) sensors are promising tools for supplementing existing air quality monitoring networks. However, the performance of the new generation of low-cost PM sensors under field conditions is not well understood. In this study, we characterized the performance capabilities of a new low-cost PM sensor model (Plantower model PMS3003) for measuring PM2.5 at 1 min, 1 h, 6 h, 12 h, and 24 h integration times. We tested the PMS3003 sensors in both low-concentration suburban regions (Durham and Research Triangle Park (RTP), NC, US) with 1 h PM2.5 (mean ± SD) of 9±9 and 10±3 µg m−3, respectively, and a high-concentration urban location (Kanpur, India) with 1 h PM2.5 of 36±17 and 116±57 µg m−3 during monsoon and post-monsoon seasons, respectively. In Durham and Kanpur, the sensors were compared to a research-grade instrument (environmental β attenuation monitor, E-BAM) to determine how these sensors perform across a range of PM2.5 concentrations and meteorological factors (e.g., temperature and relative humidity, RH). In RTP, the sensors were compared to three Federal Equivalent Methods (FEMs) including two Teledyne model T640s and a Thermo Scientific model 5030 SHARP to demonstrate the importance of the type of reference monitor selected for sensor calibration. The decrease in 1 h mean errors of the calibrated sensors using univariate linear models from Durham (201 %) to Kanpur monsoon (46 %) and post-monsoon (35 %) seasons showed that PMS3003 performance generally improved as ambient PM2.5 increased. The precision of reference instruments (T640: ±0.5 µg m−3 for 1 h; SHARP: ±2 µg m−3 for 24 h, better than the E-BAM) is critical in evaluating sensor performance, and β-attenuation-based monitors may not be ideal for testing PM sensors at low concentrations, as underscored by (1) the less dramatic error reduction over averaging times in RTP against optically based T640 (from 27 % for 1 h to 9 % for 24 h) than in Durham (from 201 % to 15 %); (2) the lower errors in RTP than the Kanpur post-monsoon season (from 35 % to 11 %); and (3) the higher T640–PMS3003 correlations (R2≥0.63) than SHARP–PMS3003 (R2≥0.25). A major RH influence was found in RTP (1 h RH =64±22 %) due to the relatively high precision of the T640 measurements that can explain up to ∼30 % of the variance in 1 min to 6 h PMS3003 PM2.5 measurements. When proper RH corrections are made by empirical nonlinear equations after using a more precise reference method to calibrate the sensors, our work suggests that the PMS3003 sensors can measure PM2.5 concentrations within ∼10 % of ambient values. We observed that PMS3003 sensors appeared to exhibit a nonlinear response when ambient PM2.5 exceeded ∼125 µg m−3 and found that the quadratic fit is more appropriate than the univariate linear model to capture this nonlinearity and can further reduce errors by up to 11 %. Our results have substantial implications for how variability in ambient PM2.5 concentrations, reference monitor types, and meteorological factors can affect PMS3003 performance characterization.
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Stajanca, Pavol, Konstantin Hicke, and Katerina Krebber. "Distributed Fiberoptic Sensor for Simultaneous Humidity and Temperature Monitoring Based on Polyimide-Coated Optical Fibers." Sensors 19, no. 23 (November 30, 2019): 5279. http://dx.doi.org/10.3390/s19235279.
Повний текст джерелаАнотація:
Along temperature, humidity is one of the principal environmental factors that plays an important role in various application areas. Presented work investigates possibility of distributed fiberoptic humidity monitoring based on humidity-induced strain measurement in polyimide (PI)-coated optical fibers. Characterization of relative humidity (RH) and temperature response of four different commercial PI- and one acrylate-coated fiber was performed using optical backscattering reflectometry (OBR). The study addresses issues of temperature-humidity cross-sensitivity, fiber response stability, repeatability, and the influence of annealing. Acrylate-coated fiber exhibited rather unfavorable nonlinear RH response with strong temperature dependence, which makes it unsuitable for humidity sensing applications. On the other hand, humidity response of PI-coated fibers showed good linearity with fiber sensitivity slightly decreasing at rising temperatures. In the tested range, temperature sensitivity of the fibers remained humidity independent. Thermal annealing was shown to considerably improve and stabilize fiber RH response. Based on performed analysis, a 20 m sensor using the optimal PI-coated fibers was proposed and constructed. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Using OBR, distributed dual temperature-RH monitoring with cm spatial resolution was demonstrated for the first time.