Journal articles: 'Gravimetric sensors'

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Sui, Ruixiu, Horace C. Pringle, and Edward M. Barnes. "Soil Moisture Sensor Test with Mississippi Delta Soils." Transactions of the ASABE 62, no. 2 (2019): 363–70. http://dx.doi.org/10.13031/trans.12886.

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Abstract. One of the methods for irrigation scheduling is to use sensors to measure the soil moisture level in the plant root zone and apply water if there is a water shortage for the plants. The measurement accuracy and reliability of the soil moisture sensors are critical for sensor-based irrigation management. This study evaluated the measurement accuracy and repeatability of the EC-5 and 5TM soil volumetric water content (SVWC) sensors, the MPS-2 and 200SS soil water potential (SWP) sensors, and the 200TS soil temperature sensor. Six 183 cm × 183 cm × 71 cm wooden compartments were built inside a greenhouse, and each compartment was filled with one type of soil from the Mississippi Delta. A total of 66 sensors with 18 data loggers were installed in the soil compartments to measure SVWC, SWP, and soil temperature. Soil samples were periodically collected from the compartments to determine SVWC using the gravimetric method. SVWC measured by the sensors was compared with that determined by the gravimetric method. The SVWC readings from the sensors had a linear regression relationship with the gravimetric SVWC (r2 = 0.82). This relationship was used to calibrate the sensor readings. The SVWC and SWP sensors could detect the general trend of soil moisture changes. However, their measurements varied significantly among the sensors. To obtain accurate absolute soil moisture measurements, the sensors require individual and soil-specific calibration. The 5TM, MPS-2, and 200TS sensors performed well in soil temperature measurement tests. Individual temperature readings from these sensors were very close to the mean of all sensor readings. Keywords: Irrigation, Sensors, Soil types, Soil water content, Soil water potential.

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Krasnov, A. A., A. V. Sokolov, M. I. Evstifeev, I. M. Starosel’tseva, L. S. Elinson, L. K. Zheleznyak, and V. N. Koneshov. "A New Generation of Gravimetric Sensors." Measurement Techniques 57, no. 9 (December 2014): 967–72. http://dx.doi.org/10.1007/s11018-014-0567-0.

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Oprea, Alexandru, and Udo Weimar. "Gas sensors based on mass-sensitive transducers. Part 2: Improving the sensors towards practical application." Analytical and Bioanalytical Chemistry 412, no. 25 (July 31, 2020): 6707–76. http://dx.doi.org/10.1007/s00216-020-02627-3.

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Abstract Within the framework outlined in the first part of the review, the second part addresses attempts to increase receptor material performance through the use of sensor systems and chemometric methods, in conjunction with receptor preparation methods and sensor-specific tasks. Conclusions are then drawn, and development perspectives for gravimetric sensors are discussed.

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Zheng, Zhou, Guodong Zhang, Xiaomin Wang, and Xu Kong. "Comparative Study of Gravimetric Humidity Sensor Platforms Based on CMUT and QCM." Micromachines 13, no. 10 (September 30, 2022): 1651. http://dx.doi.org/10.3390/mi13101651.

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Humidity sensors with comprehensive performance are of great interest for industrial and environmental applications. Most sensors, however, have to compromise on at least one characteristic such as sensitivity, response speed, and linearity. This paper reports a gravimetric humidity sensor based on a capacitive micromachined ultrasonic transducer (CMUT) with exceptional all-around performance, and presents a side-by-side comparative investigation of two types of gravimetric humidity sensors for a better understanding of their characteristics and sensing mechanisms. For these purposes, a circular CMUT and a quartz crystal microbalance (QCM) with a resonance frequency of 10 MHz were designed and fabricated. Poly(vinyl alcohol) (PVA) was employed as the humidity sensing layer for its hydrophilicity and ease of film formation. The electrical properties of the sensors, including the electrical input impedances and quality factors, were characterized by a vector network analyzer. The relative humidity (RH) sensing performance of the sensors was evaluated and compared from RH levels of 11% to 97%. Both sensors exhibited good repeatability and low hysteresis. The unique microscale resonant structure of the CMUT humidity sensor contributed to a high sensitivity of 2.01 kHz/%RH, short response and recovery times of 8 s and 3 s, respectively, and excellent linearity (R2 = 0.973), which were far superior to their QCM counterparts. The underlying mechanism was revealed and discussed.

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Park, Donggeun, Geon-Woo Yoo, Seong-Ho Park, and Jong-Hyeon Lee. "Assessment and Calibration of a Low-Cost PM2.5 Sensor Using Machine Learning (HybridLSTM Neural Network): Feasibility Study to Build an Air Quality Monitoring System." Atmosphere 12, no. 10 (October 7, 2021): 1306. http://dx.doi.org/10.3390/atmos12101306.

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Commercially available low-cost air quality sensors have low accuracy. The improved accuracy of low-cost PM2.5 sensors allows the use of low-cost sensor systems to reasonably investigate PM2.5 emissions from industrial activities or to accurately estimate individual exposure to PM2.5. In this work, we developed a new PM2.5 calibration model (HybridLSTM) by combining a deep neural network (DNN) optimized in calibration problems and a long short-term memory (LSTM) neural network optimized in time-dependent characteristics to improve the performance of conventional calibration algorithms of low-cost PM sensors. The PM2.5 concentrations, temperature and humidity by low-cost sensors and gravimetric-based PM2.5 measuring instrument were sampled for a sufficiently long time. The proposed model was compared with benchmarks (multiple linear regression model (MLR), DNN model) and low-cost sensor results. The gravimetric measurements were used as reference data to evaluate sensor accuracy. For root-mean-square error (RMSE) for PM2.5 concentrations, the proposed model reduced 41–60% of error when compared with the raw data of low-cost sensors, reduced 30–51% of error when compared with the MLR model and reduced 8–40% of error when compared with the MLR model. R2 of HybridLSTM, DNN, MLR and raw data were 93, 90, 80 and 59%, respectively. HybridLSTM showed the state-of-the-art calibration performance for a low-cost PM sensor. In other words, the proposed ML model has state-of-the-art calibration performance among the tested calibration algorithms.

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M. Siqueira, Jucilene, Teresa A. Paço, José Machado da Silva, and José C. Silvestre. "Biot-Granier Sensor: A Novel Strategy to Measuring Sap Flow in Trees." Sensors 20, no. 12 (June 22, 2020): 3538. http://dx.doi.org/10.3390/s20123538.

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The Biot-Granier (Gbt) is a new thermal dissipation-based sap flow measurement methodology, comprising sensors, data management and automatic data processing. It relies on the conventional Granier (Gcv) methodology upgraded with a modified Granier sensor set, as well as on an algorithm to measure the absolute temperatures in the two observation points and perform the Biot number approach. The work described herein addresses the construction details of the Gbt sensors and the characterization of the overall performance of the Gbt method after comparison with a commercial sap flow sensor and independent data (i.e., volumetric water content, vapor pressure deficit and eddy covariance technique). Its performance was evaluated in three trials: potted olive trees in a greenhouse and two vineyards. The trial with olive trees in a greenhouse showed that the transpiration measures provided by the Gbt sensors showed better agreement with the gravimetric approach, compared to those provided by the Gcv sensors. These tended to overestimate sap flow rates as much as 4 times, while Gbt sensors overestimated gravimetric values 1.5 times. The adjustments based on the Biot equations obtained with Gbt sensors contribute to reduce the overestimates yielded by the conventional approach. On the other hand, the heating capacity of the Gbt sensor provided a minimum of around 7 °C and maximum about 9 °C, contrasting with a minimum around 6 °C and a maximum of 12 °C given by the Gcv sensors. The positioning of the temperature sensor on the tip of the sap flow needle proposed in the Gbt sensors, closer to the sap measurement spot, allow to capture sap induced temperature variations more accurately. This explains the higher resolution and sensitivity of the Gbt sensor. Overall, the alternative Biot approach showed a significant improvement in sap flow estimations, contributing to adjust the Granier sap flow index, a vulnerability of that methodology.

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El Sabahy, Julien, Florence Ricoul, and Vincent Jousseaume. "Porous SiOCH thin films for gravimetric gas sensors." Microporous and Mesoporous Materials 330 (January 2022): 111560. http://dx.doi.org/10.1016/j.micromeso.2021.111560.

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Wang, Z., J. D. N. Cheeke, and C. K. Jen. "Sensitivity analysis for Love mode acoustic gravimetric sensors." Applied Physics Letters 64, no. 22 (May 30, 1994): 2940–42. http://dx.doi.org/10.1063/1.111976.

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Loergen, J. W., C. Kreutz, J. Bargon, P. Krattiger, and H. Wennemers. "Diketopiperazine receptors: highly selective layers for gravimetric sensors." Sensors and Actuators B: Chemical 107, no. 1 (May 2005): 366–71. http://dx.doi.org/10.1016/j.snb.2004.10.028.

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Fanget, S., S. Hentz, P. Puget, J. Arcamone, M. Matheron, E. Colinet, P. Andreucci, L. Duraffourg, Ed Myers, and M. L. Roukes. "Gas sensors based on gravimetric detection—A review." Sensors and Actuators B: Chemical 160, no. 1 (December 2011): 804–21. http://dx.doi.org/10.1016/j.snb.2011.08.066.

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Molgaard, Mathias J. G., Jesper M. F. Hansen, Mogens H. Jakobsen, and Erik V. Thomsen. "Sensitivity Optimization of Wafer Bonded Gravimetric CMUT Sensors." Journal of Microelectromechanical Systems 27, no. 6 (December 2018): 1089–96. http://dx.doi.org/10.1109/jmems.2018.2868864.

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Lopez Aldaba, Aitor, Diego Lopez-Torres, Miguel Campo-Bescós, José López, David Yerro, César Elosua, Francisco Arregui, et al. "Comparison between Capacitive and Microstructured Optical Fiber Soil Moisture Sensors." Applied Sciences 8, no. 9 (September 1, 2018): 1499. http://dx.doi.org/10.3390/app8091499.

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Soil moisture content has always been an important parameter to control because it is a deterministic factor for site-specific irrigation, seeding, transplanting, and compaction detection. In this work, a discrete sensor that is based on a SnO2–FP (Fabry-Pérot) cavity is presented and characterized in real soil conditions. As far as authors know, it is the first time that a microstructured optical fiber is used for real soil moisture measurements. Its performance is compared with a commercial capacitive soil moisture sensor in two different soil scenarios for two weeks. The optical sensor shows a great agreement with capacitive sensor’s response and gravimetric measurements, as well as a fast and reversible response; moreover, the interrogation technique allows for several sensors to be potentially multiplexed, which offers the possibility of local measurements instead of volumetric: it constitutes a great tool for real soil moisture monitoring.

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Nguyen, Chi Doan Thien, and Hien Thi To. "Evaluating the applicability of a low-cost sensor for measuring PM2.5 concentration in Ho Chi Minh city, Viet Nam." Science and Technology Development Journal 22, no. 3 (October 7, 2019): 343–47. http://dx.doi.org/10.32508/stdj.v22i3.1688.

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Introduction: Continuous monitoring provides real-time data which is helpful for measuring air quality; however, these systems are often very expensive, especially for developing countries such as Vietnam. The use of low-cost sensors for monitoring air pollution is a new approach in Vietnam and this study assesses the utility of low-cost, light-scattering-based, particulate sensors for measuring PM2.5 concentrations in Ho Chi Minh City. Methods: The low-cost sensors were compared with both a Beta attenuation monitor (BAM) reference method and a gravimetric method during the rainy season period of October to December 2018. Results: The results showed that there was a very strong correlation between two low-cost sensors (R = 0.97, slope = 1.0), and that the sensor precision varied from 0 to 21.4% with a mean of 3.1%. Both one-minute averaged data and one-hour averaged data showed similar correlations between sensors and BAM (R2 = 0.62 and 0.69, respectively), while 24-hour averaged data showed excellent agreement (R2 = 0.95, slope = 1.05). In addition, we also found a strong correlation between those instruments and a gravimetric method using 24-hour averaged data. A linear regression was used to calibrate the 24-hour averaged sensor data and, once calibrated, the bias dropped to zero. Conclusion: These results show that low-cost sensors can be used for daily measurements of PM2.5 concentrations in Ho Chi Minh City. The effect of air conditions, such as temperature and humidity, should be conducted. Moreover, technical methods to improve time resolution of lowcost sensors need to be developed and applied in order to provide real-time measurements at an inexpensive cost.

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Barauskas, Dovydas, Mindaugas Dzikaras, Dovydas Bieliauskas, Donatas Pelenis, Gailius Vanagas, and Darius Viržonis. "Selective Ultrasonic Gravimetric Sensors Based on Capacitive Micromachined Ultrasound Transducer Structure—A Review." Sensors 20, no. 12 (June 23, 2020): 3554. http://dx.doi.org/10.3390/s20123554.

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This review paper discusses the advances of the gravimetric detection devices based on capacitive micromachined ultrasound transducers structure. Principles of gravimetric operation and device modeling are reviewed through the presentation of an analytical, one-dimensional model and finite element modeling. Additionally, the most common fabrication techniques, including sacrificial release and wafer bonding, are discussed for advantages for gravimetric sensing. As functional materials are the most important part of the selective gravimetric sensing, the review of different functional material properties and coating and application methods is necessary. Particularly, absorption and desorption mechanisms of functional materials, like methylated polyethyleneimine, with examples of applications for gas sensing and using immune complexes for specific biomolecules detection are reviewed.

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Ogwo, V., K. N. Ogbu, C. C. Anyadike, O. A. Nwoke, and C. C. Mbajiorgu. "Development and testing of a capacitive digital soil moisture sensor with printed circuit board as a probe." Nigerian Journal of Technology 39, no. 3 (September 16, 2020): 911–17. http://dx.doi.org/10.4314/njt.v39i3.33.

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The quantity and quality of water present in the soil determine to a greater extent the performance of agricultural crops. Real-time determination of moisture content has a greater advantage over the traditional gravimetric method of determining soil moisture content. Thus, this work was based on the design and construction of a cost effective digital capacitive soil moisture sensor for real-time measurement. The moisture sensors comprised four integrated units namely: power supply unit with a 9V DC battery as a power source, sensor unit with a locally sourced Printed Circuit Board (PCB) as the single sensing probe, control unit made up of PIC16f877 microcontroller programmed with a C language and the C source code compiled in Corporate Computer Services Compiler (CSS C) compiler development environment, and a 16x2 display unit which displays the readings in percentage moisture content (%MC) and capacitance (μF) of the soil obtained from the sensor on its screen. Standard gravimetric moisture content was carried out to get the calibration factor which was used to calibrate the sensor for reliability. The validation was done by taking the reprogrammed (calibrated) sensor to the field for further measurement, after which soil samples were collected for further gravimetric analysis. A regression equation was obtained by plotting the moisture content obtained from gravimetric method (%MCG) against that from sensor reading (%MCS) with a high degree correlation coefficient (R2) of 0.998. The developed capacitive soil moisture sensor is cheap, portable, reliable and easy to use even by local farmers. Keywords: Calibration, Capacitive sensor, Printed circuit board, Soil moisture content, Validation.

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Thalmayr, Florian, and Gerhard Fischerauer. "Sensor signal processing for gravimetric chemical sensors based on a state-space model." Sensors and Actuators B: Chemical 144, no. 1 (January 29, 2010): 27–36. http://dx.doi.org/10.1016/j.snb.2009.10.014.

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Ferrari, Vittorio, Daniele Marioli, and Andrea Taroni. "Thick-film resonant piezo-layers as new gravimetric sensors." Measurement Science and Technology 8, no. 1 (January 1, 1997): 42–48. http://dx.doi.org/10.1088/0957-0233/8/1/007.

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Jen, C. K., J. E. B. Oliveira, J. C. H. Yu, J. D. Dai, and J. F. Bussiere. "Analysis of thin rod flexural acoustic wave gravimetric sensors." Applied Physics Letters 56, no. 22 (May 28, 1990): 2183–85. http://dx.doi.org/10.1063/1.102962.

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Ge, Li-Feng. "Micro load theory of surface acoustic wave gravimetric sensors." Journal of the Acoustical Society of America 140, no. 4 (October 2016): 3248. http://dx.doi.org/10.1121/1.4970277.

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Vogt, Matthias, Philipp Schneider, Nuria Castell, and Paul Hamer. "Assessment of Low-Cost Particulate Matter Sensor Systems against Optical and Gravimetric Methods in a Field Co-Location in Norway." Atmosphere 12, no. 8 (July 27, 2021): 961. http://dx.doi.org/10.3390/atmos12080961.

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The increased availability of commercially-available low-cost air quality sensors combined with increased interest in their use by citizen scientists, community groups, and professionals is resulting in rapid adoption, despite data quality concerns. We have characterized three out-the-box PM sensor systems under different environmental conditions, using field colocation against reference equipment. The sensor systems integrate Plantower 5003, Sensirion SPS30 and Alphasense OCP-N3 PM sensors. The first two use photometry as a measuring technique, while the third one is an optical particle counter. For the performance evaluation, we co-located 3 units of each manufacturer and compared the results against optical (FIDAS) and gravimetric (KFG) methods for a period of 7 weeks (28 August to 19 October 2020). During the period from 2nd and 5th October, unusually high PM concentrations were observed due to a long-range transport episode. The results show that the highest correlations between the sensor systems and the optical reference are observed for PM1, with coefficients of determination above 0.9, followed by PM2.5. All the sensor units struggle to correctly measure PM10, and the coefficients of determination vary between 0.45 and 0.64. This behavior is also corroborated when using the gravimetric method, where correlations are significantly higher for PM2.5 than for PM10, especially for the sensor systems based on photometry. During the long range transport event the performance of the photometric sensors was heavily affected, and PM10 was largely underestimated. The sensor systems evaluated in this study had good agreement with the reference instrumentation for PM1 and PM2.5; however, they struggled to correctly measure PM10. The sensors also showed a decrease in accuracy when the ambient size distribution was different from the one for which the manufacturer had calibrated the sensor, and during weather conditions with high relative humidity. When interpreting and communicating air quality data measured using low-cost sensor systems, it is important to consider such limitations in order not to risk misinterpretation of the resulting data.

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Bellot, Cristian Marro, Marco Sangermano, Massimo Olivero, and Milena Salvo. "Optical Fiber Sensors for the Detection of Hydrochloric Acid and Sea Water in Epoxy and Glass Fiber-Reinforced Polymer Composites." Materials 12, no. 3 (January 25, 2019): 379. http://dx.doi.org/10.3390/ma12030379.

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Optical fiber sensors (OFSs), which rely on evanescent wave sensing for the early detection of the diffusion of water and hydrochloric acid through glass fiber-reinforced polymers (GFRPs), have been developed and tested. Epoxy and GFRP specimens, in which these sensors were embedded, were subjected to tests in artificial sea water and hydrochloric acid. The sensors were able to detect the diffusion of chemicals through the epoxy and GFRP samples on the basis of a drop in the reflected signal from the tip of the optical sensor probe. Water and hydrochloric acid diffusion coefficients were calculated from gravimetric measurements and compared with the experimental response of the OFSs. Furthermore, mechanical tests were carried out to assess the influence of the sensors on the structural integrity of the GFRP specimens.

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Jia, Hao, Pengcheng Xu, and Xinxin Li. "Integrated Resonant Micro/Nano Gravimetric Sensors for Bio/Chemical Detection in Air and Liquid." Micromachines 12, no. 6 (May 31, 2021): 645. http://dx.doi.org/10.3390/mi12060645.

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Resonant micro/nanoelectromechanical systems (MEMS/NEMS) with on-chip integrated excitation and readout components, exhibit exquisite gravimetric sensitivities which have greatly advanced the bio/chemical sensor technologies in the past two decades. This paper reviews the development of integrated MEMS/NEMS resonators for bio/chemical sensing applications mainly in air and liquid. Different vibrational modes (bending, torsional, in-plane, and extensional modes) have been exploited to enhance the quality (Q) factors and mass sensing performance in viscous media. Such resonant mass sensors have shown great potential in detecting many kinds of trace analytes in gas and liquid phases, such as chemical vapors, volatile organic compounds, pollutant gases, bacteria, biomarkers, and DNA. The integrated MEMS/NEMS mass sensors will continuously push the detection limit of trace bio/chemical molecules and bring a better understanding of gas/nanomaterial interaction and molecular binding mechanisms.

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AFONIN, Alexander A., and Andrey S. SULAKOV. "Analysis of structure and algorithm features of new type strapdown gravimetric navigation system." INCAS BULLETIN 12, S (July 28, 2020): 5–19. http://dx.doi.org/10.13111/2066-8201.2020.12.s.1.

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The paper presents a structure and improved functional algorithms of a strap-down satellite inertial gravimetric navigation system of minimum hardware configuration. Various options of traditional loosely coupled and a new modification of closely coupled architectures were studied, which allowed for authors achieving sufficient precision of vector gravimetry and finding parameters of orientation and navigation. There were also studied potentials of increased accuracy and reliability of SGS as a component of functionally redundant cone-shaped accelerometer modules. The paper described the specifics of use of functional redundancy inertial measuring units. A specific version of a future modification of a closely related architecture is proposed, which opens up additional possibilities for evaluating and correcting errors of a satellite navigation system, which leads to an increase in the overall accuracy and reliability of determining orientation, navigation, and gravimetric parameters. The advantages of use of streamlined redundant raw data sensors were estimated qualitatively and quantitatively.

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Aylaz, Gülgün, and Müge Andaç. "Affinity-Recognition-Based Gravimetric Nanosensor for Equilin Detection." Chemosensors 10, no. 5 (May 3, 2022): 172. http://dx.doi.org/10.3390/chemosensors10050172.

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The estrogenic hormones that are widely used in postmenopausal hormone supplements for women contaminate natural water resources. Equilin (Equ) is one of the estrogenic hormones that have a maximum contaminant level of 0.35 µg/L in the chemical pollutants list. In this study, estrogenic hormones were precisely detected in a short time by affinity-recognition-based interactions in Quartz Crystal Microbalance (QCM) sensors. The QCM sensors were modified with 11-mercaptoundecanoic acid forming a self-assembled monolayer and with amino acids, namely tyrosine, tryptophan and phenylalanine. The affinity interactions between Equ and amino acids were studied using docking tools and confirmed by QCM experiments. The LODs of Equ were obtained as 4.59, 5.05 and 6.30 ng/L for tyrosine-, tryptophan- and phenylalanine-modified QCM nanosensors, respectively, with linear dynamic detection in the range of 25–500 nM. In terms of the LOD, selectivity and sensitivity calculations, the tyrosine-modified QCM nanosensor was found to have the highest performance for Equ detection compared to the tryptophan- and phenylalanine-modified ones.

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Horender, Stefan, Georgi Tancev, Kevin Auderset, and Konstantina Vasilatou. "Traceable PM2.5 and PM10 Calibration of Low-Cost Sensors with Ambient-like Aerosols Generated in the Laboratory." Applied Sciences 11, no. 19 (September 28, 2021): 9014. http://dx.doi.org/10.3390/app11199014.

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This work builds upon previous efforts at calibrating PM (particulate matter) monitors with ambient-like aerosols produced in the laboratory under well-controlled environmental conditions at the facility known as PALMA (Production of Ambient-like Model Aerosols). In this study, the sampling system of PALMA was equipped with commercial PM2.5 and PM10 impactors, designed according to the EN 12341:2014 standard, to select different aerosol size fractions for reference gravimetric measurements. Moreover, a metallic frame was mounted around the PM impactor to accommodate up to eight low-cost PM sensors. This sampling unit was placed at the bottom of the 2-meter-long aerosol homogenizer, right above the filter holder for the reference gravimetric measurements. As proof of principle, we used the upgraded PALMA facility to calibrate the new AirVisual Outdoor (IQAir, Goldach, Switzerland) and the SDS011 (InovaFitness, Jinan, China) low-cost PM sensors in a traceable manner against the reference gravimetric method according to the EN 12341 standard. This is the first time that PM2.5 and PM10 calibrations of low-cost sensors have been successfully carried out with complex ambient-like aerosols consisting of soot, inorganic species, secondary organic matter, and dust particles under controlled temperature and relative humidity.

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Varga, Marián, Alexandr Laposa, Pavel Kulha, Marina Davydova, Jiri Kroutil, Miroslav Husak, and Alexander Kromka. "Fabrication of Diamond Based Quartz Crystal Microbalance Gas Sensor." Key Engineering Materials 605 (April 2014): 589–92. http://dx.doi.org/10.4028/www.scientific.net/kem.605.589.

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Synthetic diamond has remarkable properties comparable with natural diamond and hence is a very promising material for many various applications (sensors, heat sink, optical mirrors, cold cathode, tissue engineering, etc.). Nowadays, deposition of diamond films is normally employed in chemical vapor deposition (CVD) usually at high temperatures (800900 °C), what limit its application to high melting substrates. Gravimetric (mass) sensors belong to the major categories of chemical sensors and the most common type of mass sensor is the bulk acoustic quartz crystal microbalance (QCM). This contribution deals with a nanocrystalline diamond (NCD) growth from the H2/CH4/CO2gas mixture at low temperature (400 °C) by pulsed linear antenna microwave plasma system on 10 MHz circular AT-cut quartz resonators substrate. Gas sensor based on the NCD-coated QCM was developed for detection of ammonia (NH3) at room temperature. Measurements not only confirmed the functionality of this first published NCD-coated QCM sensor, but in addition its sensitivity was twofold to a virgin QCM sensor with a gold active layer.

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Wang, Z., J. D. N. Cheeke, and C. K. Jen. "Unified approach to analyse mass sensitivities of acoustic gravimetric sensors." Electronics Letters 26, no. 18 (1990): 1511. http://dx.doi.org/10.1049/el:19900970.

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Mehravar, Moura, Hanrui Yang, David J. Webb, Wei Zhang, Sina Fadaie Sestelani, and David N. Chapman. "Soil water content measurement using polymer optical fibre Bragg gratings." Proceedings of the Institution of Civil Engineers - Smart Infrastructure and Construction 174, no. 1 (March 1, 2021): 11–21. http://dx.doi.org/10.1680/jsmic.21.00029.

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Measuring soil water content is crucially important and can affect soil strength, which is a key parameter in the analysis, design and monitoring of geo-structures. In this study, an optical fibre Bragg grating sensor inscribed in polymer optical fibre was developed, and for the first time, its ability to measure soil water content was investigated. The sensitivity of the sensor to different values of gravimetric soil water content under the different compaction conditions of loose and normal compaction was tested. The effect of soil temperature on the sensor’s performance was considered. To assess the sensor’s implementation, accuracy and reliability, a commercial soil water content probe (SM150), which measures volumetric soil water content was employed. The results indicate that the developed sensor, when calibrated correctly, is able to provide detailed data on any minor variation of soil water content (e.g. 0.5%) with high precision. The outcomes of this study define an additional capability of the polymer optical fibre Bragg grating sensors, which is significantly important for the long-term performance monitoring of geo-structures.

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Attia, Ghada, Zineb Khaldi, Seyfeddine Rahali, Najla Fourati, Chouki Zerrouki, Rachida Zerrouki, Mahamadou Seydou, Nourdin Yaakoubi, and Rafik Ben Chaabane. "Design of Surface Acoustic Wave Sensors Functionalized with Bisphenol S Based Molecules for Lead Ions Detection." Proceedings 2, no. 13 (November 26, 2018): 872. http://dx.doi.org/10.3390/proceedings2130872.

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This study concerns the design of surface acoustic wave sensors functionalized with bisphenol S based molecules for lead ions detection. (4-hydroxyphenyl, 4′-benzyloxyphenyl) sulfone (M1), (4-hydroxyphenyl,4′-anthrylmethyloxyphenyl) sulfone (M2) and (4,4′-bis (anthrylmethyloxyphenyl)) sulfone (M3) were synthesized and then drop-coated on the SAWs sensing areas. Gravimetric results indicate that the limit of detection of the three sensors is in the picomolar range and that the M3/SAW sensor has the highest affinity towards lead ions compared to M1/SAW and M2/SAW. Density functional theory (DFT) calculations were investigated to support experimental results and to understand the nature of interactions involved between lead ions and the three synthetized molecules.

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Ataka, Mioko, Yuji Kominami, Takafumi Miyama, Kenichi Yoshimura, Mayuko Jomura, and Makoto Tani. "Using Capacitance Sensors for the Continuous Measurement of the Water Content in the Litter Layer of Forest Soil." Applied and Environmental Soil Science 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/627129.

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Little is known about the wetting and drying processes of the litter layer (Llayer), likely because of technical difficulties inherent in nondestructive water content (WC) monitoring. We developed a method for continuously measuring the WC of leaf litter (the “LWC method”)in situusing capacitance sensors. To test variants of this approach, five (for the LWC_5) or ten (for the LWC_10 method)Quercus serrataleaves were attached around capacitance sensors. The output voltage used for each LWC method was linearly correlated with the gravimetric WC (LWC_5:R2=0.940; LWC_10:R2=0.942), producing different slopes for each calibration line. Forin situcontinuous measurements of WC in theLlayer, two sensors were used, one placed on top of theLlayer and the other at the boundary between theLand mineral layers. The average continuous WC of theLlayer was then calculated from the output voltage of the two sensors and the calibration function, and this value was linearly correlated with the gravimetric WC(R2=0.697). However, because theLlayer characteristics (e.g., thickness, water-holding capacity, and species composition) may differ among study sites, appropriate approaches for measuring this layer’s moisture properties may be needed.

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De Vos, Bruno, Nathalie Cools, Arne Verstraeten, and Johan Neirynck. "Accurate Measurements of Forest Soil Water Content Using FDR Sensors Require Empirical In Situ (Re)Calibration." Applied Sciences 11, no. 24 (December 7, 2021): 11620. http://dx.doi.org/10.3390/app112411620.

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Monitoring volumetric soil water content (θv) is the key for assessing water availability and nutrient fluxes. This study evaluated the empirical accuracy of θv measurements using standard and in situ calibrated frequency domain reflectometers (FDR) with gravimetric water content and bulk density measurements of 1512 samples gathered from 15 profiles across 5 ICP Forests level II intensive monitoring plots. The predicted θv, calibrated with standard functions, predominantly underestimated the real water content. The measurement error exceeded the threshold of 0.03 m3 m−3 in 93% of all soil layers. Layer specific calibration removed bias and reduced the overall prediction error with a factor up to 2.8. A simple linear regression often provided the best calibration model; temperature correction was helpful in specific cases. To adequately remove bias in our study plots, a calibration dataset of up to 24 monthly observations was required for topsoils (whereas 12 observations sufficed for subsoils). Based on estimated precision errors, 3 sensors per soil layer proved to be sufficient, while up to 16 sensors are needed to meet the required accuracy in organic topsoils. Validating FDR sensor outputs using in situ gravimetric measurements is essential for quality control and assurance of long term θv monitoring and for improving site specific instrumentalization.

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Birol, Hansu, Thomas Maeder, Caroline Jacq, Giancarlo Corradini, Marc Boers, Sigfrid Straessler, and Peter Ryser. "Structuration and Fabrication of Sensors Based on LTCC (Low Temperature Co-Fired Ceramic) Technology." Key Engineering Materials 336-338 (April 2007): 1849–52. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1849.

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The purpose of this paper is to demonstrate sensors and structures fabricated using the LTCC technology, which has been addressed and employed increasingly as a smart packaging approach for several applications. The focus will be on inclination and cantilever force sensors and micro-fluidic structures. Motivation for selection of LTCC for these applications in addition to fabrication and structuring of the devices will be explained in details. TGA (thermo-gravimetric analysis), dilatometer analysis, SEM (scanning electron microscopy), electronic equipment for measuring sensor performance will be extensively used for explanation of the results. It will also be shown that, compared to classical thick-film technology on alumina, LTCC allows a considerable increase in sensitivity, and is therefore better suited for the sensing of minute forces and pressures.

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Smolyaninova, D. M., E. V. Bizina, M. Yu Larina, and T. N. Ermolaeva. "MAGNETIC NANOCOMPOSITES IN PIEZOELECTRIC SENSORS FOR DETERMINATION OF GLYPHOSATE." http://eng.biomos.ru/conference/articles.htm 1, no. 19 (2021): 383–85. http://dx.doi.org/10.37747/2312-640x-2021-19-383-385.

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Piezoelectric gravimetric sensors based on magnetic nanocomposites: polymers with molecular imprints (MIP) Fe3O4@MIP N - (phosphonmethyl) - glycine have been developed. It was found that the optimal concentration ratio of template: functional monomer: cross-monomer is 1: 3: 25. The best synthesis time is 3h with constant stirring at a speed of 60 rpm and heating to 60 °C.

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Rabus, D., J. Friedt, S. Ballandras, G. Martin, E. Carry, and V. Blondeau-Patissier. "High-sensitivity open-loop electronics for gravimetric acoustic-wave-based sensors." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 60, no. 6 (June 2013): 1219–26. http://dx.doi.org/10.1109/tuffc.2013.2685.

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Xu, Jiaqiang, Qi Zheng, Yongheng Zhu, Huihui Lou, Qun Xiang, and Zhixuan Cheng. "Gravimetric Chemical Sensors Based on Silica-Based Mesoporous Organic–Inorganic Hybrids." Journal of Nanoscience and Nanotechnology 14, no. 9 (September 1, 2014): 6551–58. http://dx.doi.org/10.1166/jnn.2014.9352.

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Pereira, Ednângelo Duarte, Manoel Nelson de Castro Filho, Denizard Allison Santos Bueno, Rolando Ismael Corella Caballero, Rafael Ravanelli Chagas, Ronaldo Silva Gomes, and Derly José Henriques da Silva. "Performance Assessment and Calibration of Low-cost Moisture Sensors at Multiple Oxisol Depths." Research, Society and Development 11, no. 4 (March 20, 2022): e35211427420. http://dx.doi.org/10.33448/rsd-v11i4.27420.

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Monitoring of soil moisture is a key component in irrigation management and can be carried out with the aid of low-cost electromagnetic sensors. This study aimed to develop calibration equations for the HFM2030 sensor at different depths (0-20; 20-40; 40-60; 60-80; 100 cm) of Oxisols and to assess the accuracy levels of calibration equations used in the continuous monitoring of soil moisture. Reference values of soil moisture content were measured by a standard gravimetric method, converted to volumetric moisture, and then compared with sensor readings to develop calibration equations. The fit of the regression function was evaluated based on the determination coefficient (R2). The results indicated that the calibration equations were linear at different soil depths. Calibrating the HFM2030 sensor improved the estimate of volumetric water content by 31.21%, 23.46%, 24.93%, 31.93%, and 41.18% in the 0-20, 20-40, 40-60, 60-80 and 80-100 cm layers, respectively. Here, it is demonstrated that the correct calibration of HFM2030 should precede the installation and use of these sensors in the field. The results of this study represent another step toward the development of criteria aiming for greater precision in the use of sensors in irrigation management. The calibration equations developed in this study can be applicable and useful for farmers and researchers working with HFM2030 sensors in similar soil conditions in other regions of Brazil and globally.

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Kao, Ping, Ashish Patwardhan, David Allara, and Srinivas Tadigadapa. "Human Serum Albumin Adsorption Study on 62-MHz Miniaturized Quartz Gravimetric Sensors." Analytical Chemistry 80, no. 15 (August 2008): 5930–36. http://dx.doi.org/10.1021/ac8005395.

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Jekeli, Ch. "On Precision Kinematic Accelerations for Airborne Gravimetry." Journal of Geodetic Science 1, no. 4 (January 1, 2011): 367–78. http://dx.doi.org/10.2478/v10156-011-0016-9.

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On Precision Kinematic Accelerations for Airborne GravimetryAdvances in accelerometer technology promise many orders of magnitude improvement in sensitivity; which, consequently, also suggest progress in Earth Science applications, such as through new airborne gravimetric systems. However, a new capability for one sensor then usually demands commensurate requirements from auxiliary sensors in order to realize its full potential. Specifically, airborne gravimetry would benefit from improved inertial accelerometry only if the kinematic acceleration derived from vehicle tracking or positioning is equally precise. The latter is investigated in this study to determine the limits in precision due to errors in modeling the numerical derivative and due to errors in the positions, themselves. Simulations with actual aircraft trajectories show that the kinematic acceleration using current positioning capability (that is, GPS or similar satellite navigation systems) can be determined to an accuracy at the sub-milligal level only with sufficient smoothing over intervals of 60 s or longer. The effects of position error still dominate over the model error, and both are many orders of magnitude greater than the predicted precision of state-of-the-art accelerometry. This suggests that airborne gravity field determination likely will profit more if the advances in inertial sensor technology are directed toward gravity gradiometry.

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Marković, Monika, Goran Krizmanić, Andrija Brkić, Atilgan Atilgan, Božica Japundžić-Palenkić, Davor Petrović, and Željko Barač. "Sustainable Management of Water Resources in Supplementary Irrigation Management." Applied Sciences 11, no. 6 (March 10, 2021): 2451. http://dx.doi.org/10.3390/app11062451.

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Watermark, Tensiometer and Time Domain Reflectometry (TDR) are commonly used soil water sensors in irrigation practice whose performance depends on soil type, depth and growing conditions. Here, the results of sensor performance evaluation in different soil depths as well as the field and laboratory testing in silty clay loamy soil are presented. Gravimetric soil moisture samples were taken from sensor installation depths (10, 20, 30 and 45 cm) and used as reference Soil Water Content (SWC). The measurements varied significantly (p < 0.05) across the monitoring depths. On average across the soil depths, there was a strong negative linear relationship between Watermark (r = −0.91) and TDR (r = 0.94), and a moderate negative (r = −0.75) linear relationship between SWC and Tensiometer. In general, Watermark and Tensiometer measured SWC with great accuracy in the range of readily available water, generated larger Mean Difference (MD) than TDR and overestimated SWC, while TDR underestimated SWC. Overall, laboratory testing reduced the root mean square error (RMSE, Watermark = 1.2, Tensiometer = 2.6, TDR = 1.9) and Mean Average Error (MAE, Watermark = 0.9, Tensiometer = 2.04. TDR = 1.04) for all tested sensors.

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Voigt, Christian, Karsten Schulz, Franziska Koch, Karl-Friedrich Wetzel, Ludger Timmen, Till Rehm, Hartmut Pflug, Nico Stolarczuk, Christoph Förste, and Frank Flechtner. "Technical note: Introduction of a superconducting gravimeter as novel hydrological sensor for the Alpine research catchment Zugspitze." Hydrology and Earth System Sciences 25, no. 9 (September 20, 2021): 5047–64. http://dx.doi.org/10.5194/hess-25-5047-2021.

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Abstract. GFZ (German Research Centre for Geosciences) set up the Zugspitze Geodynamic Observatory Germany with a worldwide unique installation of a superconducting gravimeter at the summit of Mount Zugspitze on top of the Partnach spring catchment. This high alpine catchment is well instrumented, acts as natural lysimeter and has significant importance for water supply to its forelands, with a large mean annual precipitation of 2080 mm and a long seasonal snow cover period of 9 months, while showing a high sensitivity to climate change. However, regarding the majority of alpine regions worldwide, there is only limited knowledge on temporal water storage variations due to sparsely distributed hydrological and meteorological sensors and the large variability and complexity of signals in alpine terrain. This underlines the importance of well-equipped areas such as Mount Zugspitze serving as natural test laboratories for improved monitoring, understanding and prediction of alpine hydrological processes. The observatory superconducting gravimeter, OSG 052, supplements the existing sensor network as a novel hydrological sensor system for the direct observation of the integral gravity effect of total water storage variations in the alpine research catchment at Zugspitze. Besides the experimental set-up and the available data sets, the gravimetric methods and gravity residuals are presented based on the first 27 months of observations from 29 December 2018 to 31 March 2021. The snowpack is identified as being a primary contributor to seasonal water storage variations and, thus, to the gravity residuals with a signal range of up to 750 nm s−2 corresponding to 1957 mm snow water equivalent measured with a snow scale at an altitude of 2420 m at the end of May 2019. Hydro-gravimetric sensitivity analysis reveal a snow–gravimetric footprint of up to 4 km distance around the gravimeter, with a dominant gravity contribution from the snowpack in the Partnach spring catchment. This shows that the hydro-gravimetric approach delivers representative integral insights into the water balance of this high alpine site.

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Ranucci, Elisabetta, Laura Putelli, Paolo Ferruti, Vittorio Ferrari, Daniele Marioli, and Andrea Taroni. "Use of poly(amidoamines) as CO2- and Si2-sensitive material for gravimetric sensors." Mikrochimica Acta 120, no. 1-4 (March 1995): 257–70. http://dx.doi.org/10.1007/bf01244436.

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Jen, C. K., J. D. Dai, J. C. H. Yu, Z. Wang, and J. D. N. Cheeke. "An analysis of thin-rod flexural acoustic wave gravimetric sensors immersed in liquid." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 38, no. 3 (May 1991): 312–14. http://dx.doi.org/10.1109/58.79618.

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Schilardi, C., J. Morábito, and L. Martín. "Field Calibration of FDR Sensors-Limitations and Potentialities." Agrociencia 19, no. 3 (December 2015): 71. http://dx.doi.org/10.31285/agro.19.285.

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Monitoring soil moisture content is an appropriate method to optimize agricultural irrigation. The use of capacitance sensors has increased over the last years because they have a convenient cost-benefit ratio when compared to neutron moisture gages or time domain reflectometers, which are the most accurate methods to estimate soil moisture content. This project is about the field calibration of a capacitance sensor in clay soils. Two calibration models were applied: a linear model and a quadratic one, which correlate the gravimetric content measured in field soil moisture samples with the excitation received by the sensor (mV) and with the measured dielectric permittivity (?b). The calibration equations were subsequently validated at two different depths at four field sampling sites. Despite the clay soil texture, high organic matter content and compaction of the soils, the equations correctly estimated soil moisture content with an estimation error of ± 0.02 m3m-3, a considerable improvement over the manufacturer's calibration equation, which has an average estimation error of ±0.12 m3m-3. A better understanding of sensor performance in the field should result in more precise water applications. A recommendation is made to perform tests in saline and different textured soils to ascertain the stability and sensitivity of these calibration equations.

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Abdali, Hanan, Bentolhoda Heli, and Abdellah Ajji. "Cellulose Nanopaper Cross-Linked Amino Graphene/Polyaniline Sensors to Detect CO2 Gas at Room Temperature." Sensors 19, no. 23 (November 28, 2019): 5215. http://dx.doi.org/10.3390/s19235215.

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A nanocomposite of cross-linked bacterial cellulose–amino graphene/polyaniline (CLBC-AmG/PANI) was synthesized by covalent interaction of amino-functionalized graphene (AmG) AmG and bacterial cellulose (BC) via one step esterification, and then the aniline monomer was grown on the surface of CLBC-AmG through in situ chemical polymerization. The morphological structure and properties of the samples were characterized by using scanning electron microscopy (SEM), and thermal gravimetric analyzer (TGA). The CLBC-AmG/PANI showed good electrical-resistance response toward carbon dioxide (CO2) at room temperature, compared to the BC/PANI nanopaper composites. The CLBC-AmG/PANI sensor possesses high sensitivity and fast response characteristics over CO2 concentrations ranging from 50 to 2000 ppm. This process presents an extremely suitable candidate for developing novel nanomaterials sensors owing to easy fabrication and efficient sensing performance.

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Aziz, Marjan, Madeeha Khan, Naveeda Anjum, Muhammad Sultan, Redmond R. Shamshiri, Sobhy M. Ibrahim, Siva K. Balasundram, and Muhammad Aleem. "Scientific Irrigation Scheduling for Sustainable Production in Olive Groves." Agriculture 12, no. 4 (April 15, 2022): 564. http://dx.doi.org/10.3390/agriculture12040564.

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The present study aimed at investigating scientific irrigation scheduling (SIS) for the sustainable production of olive groves. The SIS allows farmers to schedule water rotation in their fields to abate crop water stress and maximize yields, which could be achieved through the precise monitoring of soil moisture. For this purpose, the study used three kinds of soil moisture sensors, including tensiometer sensors, irrometer sensors, and gypsum blocks for precise measurement of the soil moisture. These soil moisture sensors were calibrated by performing experiments in the field and laboratory at Barani Agricultural Research Institute, Chakwal in 2018 and 2019. The calibration curves were obtained by performing gravimetric analysis at 0.3 and 0.6 m depths, thereby equations were developed using regression analysis. The coefficient of determination (R2) at 0.3 and 0.6 m depth for tensiometer, irrometer, and gypsum blocks was found to be equal to 0.98, 0.98; 0.75, 0.89; and 0.82, and 0.95, respectively. After that, a drip irrigation system was installed with the calibrated soil moisture sensors at 0.3 and 0.6 m depth to schedule irrigation for production of olive groves as compared to conventional farmer practice, thereby soil moisture profiles of these sensors were obtained to investigate the SIS. The results showed that the irrometer sensor performed as expected and contributed to the irrigation water savings between 17% and 25% in 2018 and 2019, respectively, by reducing the number of irrigations as compared toother soil moisture sensors and farmer practices. Additionally, olive yield efficiencies of 8% and 9%were observed by the tensiometer in 2018 and 2019, respectively. The outcome of the study suggests that an effective method in providing sustainable production of olive groves and enhancing yield efficiency.

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Peyman, Setoodeh, Khayatian Alireza, and Farjah Ebrahim. "Attitude Estimation By Divided Difference Filter-Based Sensor Fusion." Journal of Navigation 60, no. 1 (December 15, 2006): 119–28. http://dx.doi.org/10.1017/s037346330600405x.

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Strapdown inertial navigation systems (INS) often employ aiding sensors to increase accuracy. Nonlinear filtering algorithms are then needed to fuse the collected data from these aiding sensors with measurements of strapdown rate gyros. Aiding sensors usually have slower dynamics compared to gyros and therefore collect data at lower rates. Thus the system will be unobservable between aiding sensors' sampling instants, and the error covariance, which shows the uncertainty in the estimation, grows during the sampling period. This paper presents a divided difference filter (DDF)-based data fusion algorithm, which utilizes the complementary noise profile of rate gyros and gravimetric inclinometers to extend their limits and achieve more accurate attitude estimates. It is confirmed experimentally that DDF achieves better covariance estimates compared to the extended Kalman filter (EKF) because the uncertainty in the state estimate is taken care of in the DDF polynomial approximation formulation.

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Kreutz, Chrisitan, Jürgen Lörgen, Boris Graewe, Joachim Bargon, Mayumi Yoshida, Zachary Fresco, and Jean Frèchet. "High Frequency Quartz Micro Balances: A Promising Path to Enhanced Sensitivity of Gravimetric Sensors." Sensors 6, no. 4 (April 7, 2006): 335–40. http://dx.doi.org/10.3390/s6040335.

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Mazouz, Zouhour, Seyfeddine Rahali, Najla Fourati, Chouki Zerrouki, Nadia Aloui, Mahamadou Seydou, Nourdin Yaakoubi, Mohamed Chehimi, Ali Othmane, and Rafik Kalfat. "Highly Selective Polypyrrole MIP-Based Gravimetric and Electrochemical Sensors for Picomolar Detection of Glyphosate." Sensors 17, no. 11 (November 9, 2017): 2586. http://dx.doi.org/10.3390/s17112586.

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Wandy, Yose, Marcus Vogt, Rushit Kansara, Clemens Felsmann, and Christoph Herrmann. "Sensor-Based Machine Learning Approach for Indoor Air Quality Monitoring in an Automobile Manufacturing." Energies 14, no. 21 (November 3, 2021): 7271. http://dx.doi.org/10.3390/en14217271.

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The alternative control concept using emission from the machine has the potential to reduce energy consumption in HVAC systems. This paper reports on a study of alternative inputs for a control system of HVAC using machine learning algorithms, based on data that are gathered in a welding area of an automotive factory. A data set of CO2, fine dust, temperatures and air velocity was logged using continuous and gravimetric measurements during two typical production weeks. The HVAC system was reduced gradually each day to trigger fluctuations of emission. The data were used to train and test various machine learning models using different statistical indices, consequently to choose a best fit model. Different models were tested and the Long Short-Term Memory model showed the best result, with 0.821 discrepancy on R2. The gravimetric samples proved that the reduction of air exchange rate does not correlate to escalation of fine dust linearly, which means one cannot rely on just gravimetric samples for HVAC system optimization. Furthermore, by using machine learning algorithms, this study shows that by using commonly available low cost sensors in a production hall, it is possible to correlate fine dust data cost effectively and reduce electricity consumption of the HVAC.

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Ferrarezi, Rhuanito Soranz, Thiago Assis Rodrigues Nogueira, and Sara Gabriela Cornejo Zepeda. "Performance of Soil Moisture Sensors in Florida Sandy Soils." Water 12, no. 2 (January 28, 2020): 358. http://dx.doi.org/10.3390/w12020358.

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Soil moisture sensors can improve water management efficiency by measuring soil volumetric water content (θv) in real time. Soil-specific calibration equations used to calculate θv can increase sensor accuracy. A laboratory study was conducted to evaluate the performance of several commercial sensors and to establish soil-specific calibration equations for different soil types. We tested five Florida sandy soils used for citrus production (Pineda, Riviera, Astatula, Candler, and Immokalee) divided into two depths (0.0–0.3 and 0.3–0.6 m). Readings were taken using twelve commercial sensors (CS650, CS616, CS655 (Campbell Scientific), GS3, 10HS, 5TE, GS1 (Meter), TDT-ACC-SEN-SDI, TDR315, TDR315S, TDR135L (Acclima), and Hydra Probe (Stevens)) connected to a datalogger (CR1000X; Campbell Scientific). Known amounts of water were added incrementally to obtain a broad range of θv. Small 450 cm3 samples were taken to determine the gravimetric water content and calculate the θv used to obtain the soil-specific calibration equations. Results indicated that factory-supplied calibration equations performed well for some sensors in sandy soils, especially 5TE, TDR315L, and GS1 (R2 = 0.92) but not for others (10HS, GS3, and Hydra Probe). Soil-specific calibrations from this study resulted in accuracy expressed as root mean square error (RMSE) ranging from 0.018 to 0.030 m3 m−3 for 5TE, CS616, CS650, CS655, GS1, Hydra Probe, TDR310S, TDR315, TDR315L, and TDT-ACC-SEN-SDI, while lower accuracies were found for 10HS (0.129 m3 m−3) and GS3 (0.054 m3 m−3). This study provided soil-specific calibration equations to increase the accuracy of commercial soil moisture sensors to facilitate irrigation scheduling and water management in Florida sandy soils used for citrus production.

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Journal articles on the topic 'Gravimetric sensors'

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