Electromagnetic moisture measurement

Hübner, Christof; Kaatze, U.

doi:10.17875/gup2016-958

Cited by 7 publications

(5 citation statements)

References 422 publications

(728 reference statements)

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“…The water content in the trunk of a tree affects permittivity. This will appear as changes in the frequency measurements due to the polarisation mechanism [ 32 ]. An oscillator is used to produce a repetitive sinusoidal waveform; the frequency of oscillation decreases as the electrical permittivity increases.…”

Section: Wood Dielectric and Permittivitymentioning

confidence: 99%

“…Equation (17) can be mathematically expanded using Taylor series expansion, which is used in numerical methods to approximate any smooth function as a polynomial by predicting the function value at one point in terms of the function value and its derivatives at another point [ 32 ]. Taylor series expansion is selected due to the polynomial approximation it provides to get a form close to the expected single frequency relation demonstrated in Equation (5).…”

Section: Mathematical Modeling Of Moisturementioning

confidence: 99%

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Moisture Detection in Tree Trunks in Semiarid Lands Using Low-Cost Non-Invasive Capacitive Sensors with Statistical Based Anomaly Detection Approach

Ali

Ali²,

Abaluof³

et al. 2023

Sensors

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This paper focuses on building a non-invasive, low-cost sensor that can be fitted over tree trunks growing in a semiarid land environment. It also proposes a new definition that characterizes tree trunks’ water retention capabilities mathematically. The designed sensor measures the variations in capacitance across its probes. It uses amplification and filter stages to smooth the readings, requires little power, and is operational over a 100 kHz frequency. The sensor sends data via a Long Range (LoRa) transceiver through a gateway to a processing unit. Field experiments showed that the system provides accurate readings of the moisture content. As the sensors are non-invasive, they can be fitted to branches and trunks of various sizes without altering the structure of the wood tissue. Results show that the moisture content in tree trunks increases exponentially with respect to the measured capacitance and reflects the distinct differences between different tree types. Data of known healthy trees and unhealthy trees and defective sensor readings have been collected and analysed statistically to show how anomalies in sensor reading baseds on eigenvectors and eigenvalues of the fitted curve coefficient matrix can be detected.

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Section: Wood Dielectric and Permittivitymentioning

confidence: 99%

Section: Mathematical Modeling Of Moisturementioning

confidence: 99%

Moisture Detection in Tree Trunks in Semiarid Lands Using Low-Cost Non-Invasive Capacitive Sensors with Statistical Based Anomaly Detection Approach

Ali

Ali²,

Abaluof³

et al. 2023

Sensors

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“…A detailed schematic of the TDT principle is shown in ref. [33]. The oscillating frequency is a few hundred MHz.…”

Section: Ceramic and Sensor Propertiesmentioning

confidence: 99%

“…In our sensor principle, the dielectric constant of a porous ceramic disk is determined with a high-frequency measurement. The porous ceramic disk is in hydraulic equilibrium with the surrounding soil [33]. In this way, water is transported into or out of the ceramic depending on the water potential.…”

Section: Introductionmentioning

confidence: 99%

Robust Soil Water Potential Sensor to Optimize Irrigation in Agriculture

Menne

Hübner²,

Trebbels³

et al. 2022

Sensors

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Extreme weather phenomena are on the rise due to ongoing climate change. Therefore, the need for irrigation in agriculture will increase, although it is already the largest consumer of water, a valuable resource. Soil moisture sensors can help to use water efficiently and economically. For this reason, we have recently presented a novel soil moisture sensor with a high sensitivity and broad measuring range. This device does not measure the moisture in the soil but the water available to plants, i.e., the soil water potential (SWP). The sensor consists of two highly porous (>69%) ceramic discs with a broad pore size distribution (0.5 to 200 μm) and a new circuit board system using a transmission line within a time-domain transmission (TDT) circuit. This detects the change in the dielectric response of the ceramic discs with changing water uptake. To prove the concept, a large number of field tests were carried out and comparisons were made with commercial soil water potential sensors. The experiments confirm that the sensor signal is correlated to the soil water potential irrespective of soil composition and is thus suitable for the optimization of irrigation systems.

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“…In terms of electromagnetic methods, the incomplete definition of the properties of bound water are discussed in [6]. However, the idea, that is widely accepted from a long time, that the relaxation frequency of bound water should be positioned between the relaxation of liquid water (10 GHz) and that of ice (5 kHz) [7].…”

Section: Introductionmentioning

confidence: 99%

Quantification of free and bound water in selected materials using dielectric and thermo-coulometric measurement methods

et al. 2018

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Broadband electromagnetic characterization offers useful tools for the quantitative estimation of water content in a insulating solid materials. However, the correlation between electromagnetic characteristics and the amount of water in solids needs to be characterized using precise direct measurement methods. In this study, a two-port coaxial transmission cell has been characterized for water content estimation based on a study with the thermo-coulometric water detection method. The latter allows us to determine the proportions of the different water bonding forms that can exist in the material. The purpose of this paper is to provide a dielectric relaxation behavior study of the kaolinite clay from 10 MHz to 1.5 GHz, which was preceded by an experimental analysis of α-D-lactose monohydrate and the calcium oxalate monohydrate, which have stable water content under various humidity conditions.

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Electromagnetic moisture measurement

Cited by 7 publications

References 422 publications

Moisture Detection in Tree Trunks in Semiarid Lands Using Low-Cost Non-Invasive Capacitive Sensors with Statistical Based Anomaly Detection Approach

Moisture Detection in Tree Trunks in Semiarid Lands Using Low-Cost Non-Invasive Capacitive Sensors with Statistical Based Anomaly Detection Approach

Robust Soil Water Potential Sensor to Optimize Irrigation in Agriculture

Quantification of free and bound water in selected materials using dielectric and thermo-coulometric measurement methods

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