Eddy Current Measurement for Planar Structures

Xia, Zihan; Huang, Ruochen; Chen, Ziqi; Yu, Kuohai; Zhang, Zhijie; Salas-Avila, Jorge Ricardo; Yin, Wuliang

doi:10.3390/s22228695

Cited by 16 publications

(10 citation statements)

References 158 publications

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“…They have advantages such as a simple structure, low price, high sensitivity, wide frequency band, resistance to influence from oily media, and strong anti-interference ability. They are widely used in measurements of displacement, vibration, rotation speed, thickness of metal films, geometric dimensions of metal components, surface roughness, temperature, and other physical quantities [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. They play important roles in industrial production, aerospace manufacturing, the nuclear industry, the petrochemical industry, safety testing, etc.…”

Section: Introductionmentioning

confidence: 99%

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Xu,

Feng,

Liu

et al. 2024

Micromachines

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To measure the micro-displacement reliably with high precision, a single-ended eddy current sensor based on temperature compensation was studied in detail. At first, the principle of the eddy current sensor was introduced, and the manufacturing method of the probe was given. The overall design plan for the processing circuit was induced by analyzing the characteristics of the probe output signal. The variation in the probe output signal was converted to pulses with different widths, and then it was introduced to the digital phase discriminator along with a reference signal. The output from the digital phase discriminator was processed by a low-pass filter to obtain the DC component. At last, the signal was amplified and compensated to reduce the influence of temperature. The selection criteria of the frequency of the exciting signal and the design of the signal conditioning circuit were described in detail, as well as the design of the temperature-compensating circuit based on the digital potentiometer with an embedded temperature sensor. Finally, an experimental setup was constructed to test the sensor, and the results were given. The results show that nonlinearity exists in the single-ended eddy current sensor with a large range. When the range is 500 μm, the resolution can reach 46 nm, and the repeatability error is ±0.70% FR. Within the temperature range from +2 °C to +58 °C, the voltage fluctuation in the sensor is reduced to 44 mV after temperature compensation compared to the value of 586 mV before compensation. The proposed plan is verified to be feasible, and the measuring range, precision, and target material should be considered in real-world applications.

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Section: Introductionmentioning

confidence: 99%

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Xu,

Feng,

Liu

et al. 2024

Micromachines

View full text Add to dashboard Cite

show abstract

“…Consequently, over the last decades, the fast, contactless and non-destructive characterization of samples using eddy current sensing methods has proven to be a valuable tool [ 10 , 11 , 12 ]. Among the differences, one must note that the eddy currents penetrating into a material are frequency-dependent and that the four-point probe measures along a specific line, whereas the eddy current setup is able to average the measure over a specific area.…”

Section: Introductionmentioning

confidence: 99%

Broadband Eddy Current Measurement of the Sheet Resistance of GaN Semiconductors

Belkacem,

Loete,

Phulpin

2024

Sensors

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Although the classical four-point probe method usually provides adequate results, it is in many cases inappropriate for the measurement of thin sheet resistance, especially in the case of a buried conductive layer or if the surface contacts are oxidized/degraded. The surface concentration of dislocation defects in GaN samples is known to challenge this kind of measurement. For the GaN sample presented in this study, it even totally impaired the ability of this method to even provide results without a prior deposition of gold metallic contact pads. In this paper, we demonstrate the benefits of using a new broadband multifrequency noncontact eddy current method to accurately measure the sheet resistance of a complicated-to-measure epitaxy-grown GaN-doped sample. The benefits of the eddy current method compared to the traditional four-point method are demonstrated. The multilayer-doped GaN sample is perfectly evaluated, which will allow further development applications in this field. The point spread function of the probe used for this noncontact method was also evaluated using a 3D finite element model using CST-Studio Suite simulation software 2020 and experimental measurements.

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“…The air-core sensor [ 21 , 22 , 23 , 24 , 25 , 26 ] and the I-core sensor [ 27 , 28 , 29 , 30 ] are utilised in eddy current testing of coatings [ 31 , 32 , 33 , 34 ], stratified conductors [ 35 , 36 , 37 , 38 ] and thermal barrier coating (TBC) [ 3 , 5 , 6 ]. The weakness of sensors of this type, however, lies in the occurrence of the leakage of some part of the magnetic flux into the air.…”

Section: Introductionmentioning

confidence: 99%

Eddy Current Testing of Conductive Coatings Using a Pot-Core Sensor

Tytko

2023

Sensors

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Conductors consisting of thin layers are commonly used in many industries as protective, insulating or thermal barrier coatings (TBC). Nondestructive testing of these types of structures allows one to determine their dimensions and technical condition, while also detecting defects, which significantly reduces the risk of failures and accidents. This work presents an eddy current system for testing thin layers and coatings, which has never been presented before. It consists of an analytical model and a pot-core sensor. The analytical model was derived through the employment of the truncated region eigenfunction expansion (TREE) method. The final formulas for the sensor impedance have been presented in a closed form and implemented in Matlab. The results of the calculations of the pot-core sensor impedance for thin layers with a thickness above 0.1 mm were compared with the measurement results. The calculations made for the TBC were verified with a numerical model created using the finite element method (FEM) in Comsol Multiphysics. In all the cases, the error in determining changes in the components of the pot-core sensor impedance was less than 4%. At the same time, it was shown that the sensitivity of the applied pot-core sensor in the case of thin-layer testing is much higher than the sensitivity of the air-core sensor and the I-core sensor.

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Eddy Current Measurement for Planar Structures

Cited by 16 publications

References 158 publications

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Broadband Eddy Current Measurement of the Sheet Resistance of GaN Semiconductors

Eddy Current Testing of Conductive Coatings Using a Pot-Core Sensor

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