Abstract:The electrical resistance tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films. Images of the sheet conductance spatial distribution and local conductivity values are obtained. Test samples are tin-oxide films on glass substrates, with electrical contacts on the sample boundary. Some samples are deliberately patterned in order to induce null conductivity zones of known geometry, while others contain higher conductivity inclusions… Show more
“…3b has a full width at half maximum (measured over the sample diagonal) of 2.69 mm, to be compared with the average distance between two adjacent contacts of 2 mm. Other test measurements on the same material, with different geometries, are reported in a previous work 14 .Figure 3Test of the ERT method. Conductivity maps of a FTO sample were measured ( a ) before and ( b ) after performing a thin straight cut (red line).…”
Section: Methodsmentioning
confidence: 92%
“…The image resolution depends primarily on the amount of available boundary measurements and it is thus limited by the number of contacts. In practice, features smaller than the inter-electrode distance are smeared out 14,35 . Other factors that can affect the image resolution are the mesh density and the amount of regularisation.…”
Section: Methodsmentioning
confidence: 99%
“…3 is a commercial fluorine-doped tin-oxide film (FTO; SnO 2 :F) on a glass substrate. FTO is highly doped and its electrical behaviour is metallic 14 . A laser scriber was used to define the sample geometry and to cut the defect line of Fig.…”
Section: Methodsmentioning
confidence: 99%
“…For these applications, the goal is to get high image contrast, to highlight inhomogeneities and to record the temporal evolution of the samples rather than to accurately measure conductivity values. However, since ERT can be considered as a kind of highly-redundant vdP method, accurate quantitative measurements should also be possible: in fact, the authors have recently shown that ERT can provide accurate conductivity maps of thin film samples 14 .…”
Electronic applications of large-area graphene films require rapid and accurate methods to map their electrical properties. Here we present the first electrical resistance tomography (ERT) measurements on large-area graphene samples, obtained with a dedicated measurement setup and reconstruction software. The outcome of an ERT measurement is a map of the graphene electrical conductivity. The same setup allows to perform van der Pauw (vdP) measurements of the average conductivity. We characterised the electrical conductivity of chemical-vapour deposited graphene samples by performing ERT, vdP and scanning terahertz time-domain spectroscopy (TDS), the last one by means of a commercial instrument. The measurement results are compared and discussed, showing the potential of ERT as an accurate and reliable technique for the electrical characterization of graphene samples.
“…3b has a full width at half maximum (measured over the sample diagonal) of 2.69 mm, to be compared with the average distance between two adjacent contacts of 2 mm. Other test measurements on the same material, with different geometries, are reported in a previous work 14 .Figure 3Test of the ERT method. Conductivity maps of a FTO sample were measured ( a ) before and ( b ) after performing a thin straight cut (red line).…”
Section: Methodsmentioning
confidence: 92%
“…The image resolution depends primarily on the amount of available boundary measurements and it is thus limited by the number of contacts. In practice, features smaller than the inter-electrode distance are smeared out 14,35 . Other factors that can affect the image resolution are the mesh density and the amount of regularisation.…”
Section: Methodsmentioning
confidence: 99%
“…3 is a commercial fluorine-doped tin-oxide film (FTO; SnO 2 :F) on a glass substrate. FTO is highly doped and its electrical behaviour is metallic 14 . A laser scriber was used to define the sample geometry and to cut the defect line of Fig.…”
Section: Methodsmentioning
confidence: 99%
“…For these applications, the goal is to get high image contrast, to highlight inhomogeneities and to record the temporal evolution of the samples rather than to accurately measure conductivity values. However, since ERT can be considered as a kind of highly-redundant vdP method, accurate quantitative measurements should also be possible: in fact, the authors have recently shown that ERT can provide accurate conductivity maps of thin film samples 14 .…”
Electronic applications of large-area graphene films require rapid and accurate methods to map their electrical properties. Here we present the first electrical resistance tomography (ERT) measurements on large-area graphene samples, obtained with a dedicated measurement setup and reconstruction software. The outcome of an ERT measurement is a map of the graphene electrical conductivity. The same setup allows to perform van der Pauw (vdP) measurements of the average conductivity. We characterised the electrical conductivity of chemical-vapour deposited graphene samples by performing ERT, vdP and scanning terahertz time-domain spectroscopy (TDS), the last one by means of a commercial instrument. The measurement results are compared and discussed, showing the potential of ERT as an accurate and reliable technique for the electrical characterization of graphene samples.
“…As a fast, nonradiation, nonintrusive, and low-cost imaging technique, electrical resistance tomography (ERT) [1] has been developed for visualizing the internal conductivity distribution of industrial processes, by providing 2D/3D images. ERT has been widely used for chemical [2], food processing [3], biology [4], geology [5], and other industrial applications [6]. In ERT, usually a current is injected to a pair of electrodes and the boundary voltages are measured from other pairs of electrodes [7].…”
Electrical resistance tomography (ERT) is used to reconstruct the resistance/conductivity distribution. Usually, a uniform distribution is assumed as the initial condition to obtain a generic sensitivity matrix, which may be very different from a theoretical sensitivity matrix, resulting in a large error. The aim of this study is to analyse the difference between a generalized sensitivity matrix and a theoretical sensitivity matrix and to improve image reconstruction. The effect of the generic sensitivity matrix and theoretical sensitivity matrix on image reconstruction is analyzed. The error caused by the use of the generic sensitivity matrix is estimated. To reduce the error, an improved iterative image reconstruction algorithm is proposed, which is based on calculation of the error between the generic sensitivity matrix and the theoretical sensitivity matrix, and a correction coefficient with a penalty. During the iterative process, the resistivity distribution and sensitivity matrix are alternatively corrected. Simulation and experimental results show that the proposed algorithm can improve the quality of images, e.g., of two-phase distributions.
Electrical impedance tomography (EIT) is a potential and promising tomographic technique. It is known that image reconstruction of EIT is mathematically an ill-posed inverse problem that leads to poor reconstruction quality. To improve the quality of reconstructed images, a novel image reconstruction method based on modified bird swarm optimization algorithm is proposed in this paper. An image of conductivity distribution acquired by Newton's onestep error reconstruction algorithm performs as initial population. Then a modified bird swarm optimization algorithm is proposed to optimize the initial conductivity distribution. By introducing a dynamic inertia weight parameter, flight interval of the bird swarm varies with the number of iterations. With the proposed method, a strong global search capability in the initial stage and a strong local search capability in the later stage are ensured during the optimization. To verify the effectiveness of the proposed method, simulation work and experimental validation are carried out. Also, reconstructed images are compared with the results obtained by iterative Landweber method and Newton-Raphson method. Meanwhile, the impact of noise on the reconstruction is investigated. The simulation and experimental results have demonstrated the superior performance of the proposed method in visualizing conductivity distribution.
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