Multi-element capacitive sensor for non-destructive measurement of the dielectric permittivity and thickness of dielectric plates and shells

Matīss, Imants

doi:10.1016/j.ndteint.2014.05.003

Cited by 16 publications

(14 citation statements)

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“…Active coatings applied to these devices allow detection of moisture, gases, and other substances [1][2]. The measurement of dielectric properties of insulating and semi-insulating materials also provides indirect information about their moisture content [3] and physical properties such as density [4], viscosity [5], porosity [6], and thickness [7]. By designing the electrodes such that the penetration depth can be varied, interdigital devices may in principle be used for three-dimensional imaging, but one difficulty in this regard is the non-uniform distribution of the fringing electric field, which is challenging to model.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the coplanar interdigital capacitive sensor

Huang¹,

Zheng²,

Bowler³

2017

AIP Conference Proceedings

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Parallel double-plate capacitive proximity sensor modelling based on effective theory AIP Advances 4, 027119 (2014) Abstract. Interdigital capacitive sensors are applied in nondestructive testing and material property characterization of lowconductivity materials. The sensor performance is typically described based on the penetration depth of the electric field into the sample material, the sensor signal strength and its sensitivity. These factors all depend on the geometry and material properties of the sensor and sample. In this paper, a detailed analysis is provided, through finite element simulations, of the ways in which the sensor's geometrical parameters affect its performance. The geometrical parameters include the number of digits forming the interdigital electrodes and the ratio of digit width to their separation. In addition, the influence of the presence or absence of a metal backplane on the sample is analyzed. Further, the effects of sensor substrate thickness and material on signal strength are studied. The results of the analysis show that it is necessary to take into account a trade-off between the desired sensitivity and penetration depth when designing the sensor. Parametric equations are presented to assist the sensor designer or nondestructive evaluation specialist in optimizing the design of a capacitive sensor.

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Section: Introductionmentioning

confidence: 99%

Optimization of the coplanar interdigital capacitive sensor

Huang¹,

Zheng²,

Bowler³

2017

AIP Conference Proceedings

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“…The potential distribution over the electrodes can be altered in accordance with definite algorithms and can thus provide the necessary electric field intensity distribution throughout the test sample. The elaboration of mathematical models of capacitance sensors in the form of electrode array is based on the electromagnetic field theory and methods of mathematical physics, particularly, the potential theory [1,2]. Due to the multidimensional nature of the data received from the test object, the handling of such information consists of methods for array processing.…”

Section: Methods and Proceduresmentioning

confidence: 99%

“…h 11 =h 12 = h 13 and h 21 = h 22 = h 23 (1) (in Fig. 2 notations ε 23 , h 13 and h 23 are not shown).…”

Section: Justification Of the Measurement Proceduresmentioning

confidence: 99%

“…In this particular study, evaluation of the recovered input was conducted using the original algorithm already discussed in previous study [1]. This algorithm operates using the data derived through subtracting the measurement readings (C m1 , C m2 and C m3 ) from all entries of the calibrated data file.…”

Section: Justification Of the Measurement Proceduresmentioning

confidence: 99%

“…The paper presents a continuation of the research devoted to the multiparameter measurements of geometric and dielectric characteristics using capacitance techniques [1]. The primary principles -particularly, the design of capacitance sensor, the theoretical assumptions, the scanning of a test sample by electric field of variable topography, and the data processing methodology -are identical to those described in the mentioned previous publication.…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Non-Contact Measurement of the Thickness and Dielectric Parameters of Dielectric Plates and Shells

Matīss

2015

Latvian Journal of Physics and Technical Sciences

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The paper describes a new approach for non-destructive testing of the structural and geometric parameters of dielectric objects using capacitance techniques. The novelty of this approach lies in the design of a capacitance sensor comprising an array of electrodes with changeable potential distribution on them during a measurement process. This makes solvable the problem of measuring independently three input parameters. To demonstrate the capabilities of the developed measurement algorithms, the case studies based on computer simulation have been carried out.

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Wavelet subspace decomposition of thermal infrared images for defect detection in artworks

Ahmad

Khan

Mezghani

et al. 2016

Infrared Physics & Technology

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Monitoring the health of ancient artworks requires adequate prudence because of the sensitive nature of these materials. Classical techniques for identifying the development of faults rely on acoustic testing.These techniques, being invasive, may result in causing permanent damage to the material, especially if the material is inspected periodically. Non destructive testing has been carried out for different materials since long. In this regard, non-invasive systems were developed based on infrared thermometry principle to identify the faults in artworks. The test artwork is heated and the thermal response of the different layers is captured with the help of a thermal infrared camera. However, prolonged heating risks overheating and thus causing damage to artworks and an alternate approach is to use pseudo-random binary sequence excitations. The faults in the artwork, though, cannot be detected on the captured images, especially if their strength is weak. The weaker faults are either masked by the stronger ones, by the pictorial layer of the artwork or by the non-uniform heating. This work addresses the detection and localization of the faults through a wavelet based subspace decomposition scheme. The proposed scheme, on one hand, allows to remove the background while, on the other hand, removes the undesired high frequency noise.It is shown that the detection parameter is proportional to the diameter and the depth of the fault. A criterion is proposed to select the optimal wavelet basis along with suitable level selection for wavelet decomposition and reconstruction. The proposed approach is tested on a laboratory developed test sample with known fault locations and dimensions as well as real artworks. A comparison with a previously reported method demonstrates the efficacy of the proposed approach for fault detection in artworks.

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Multi-element capacitive sensor for non-destructive measurement of the dielectric permittivity and thickness of dielectric plates and shells

Cited by 16 publications

References 1 publication

Optimization of the coplanar interdigital capacitive sensor

Optimization of the coplanar interdigital capacitive sensor

Non-Contact Measurement of the Thickness and Dielectric Parameters of Dielectric Plates and Shells

Wavelet subspace decomposition of thermal infrared images for defect detection in artworks

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