Electrical capacitance tomography (ECT) is a method for determination of the dielectric permittivity distribution in the interior of an object from external capacitance measurements. It is a close relative of

electrical impedance tomography Electrical impedance tomography (EIT) is a noninvasive type of medical imaging in which the electrical conductivity, permittivity, and impedance of a part of the body is inferred from surface electrode measurements and used to form a tomographic ...

and is proposed as a method for industrial process monitoring. Although capacitance sensing methods were in widespread use the idea of using capacitance measurement to form images is attributed to Maurice Beck and co-workers at UMIST in the 1980s. Although usually called

tomography Tomography is imaging by sections or sectioning that uses any kind of penetrating wave. The method is used in radiology, archaeology, biology, atmospheric science, geophysics, oceanography, plasma physics, materials science, astrophysics, quantu ...

, the technique differs from conventional tomographic methods, in which high resolution images are formed of slices of a material. The measurement electrodes, which are metallic plates, must be sufficiently large to give a measureable change in capacitance. This means that very few electrodes are used, typically eight to sixteen electrodes. An N-electrode system can only provide N(N−1)/2 independent measurements. This means that the technique is limited to producing very low resolution images of approximate slices. However, ECT is fast, and relatively inexpensive.

Applications

Applications of ECT include the measurement of flow of fluids in pipes and measurement of the concentration of one fluid in another, or the distribution of a solid in a fluid. ECT enables the visualization of multiphase flow, which play an important role in the technological processes of the chemical,

petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...

and

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...

industries. Due to its very low spatial resolution, ECT has not yet been used in medical diagnostics. Potentially, ECT may have similar medical applications to electrical impedance tomography, such as monitoring lung function or detecting ischemia or hemorrhage in the brain.{{cite journal , last1= Jiang , first1= Y. D., last2= Soleimani , first2= M. , date= 2019, title= Capacitively Coupled Electrical Impedance Tomography for Brain Imaging , journal= Transactions on medical imaging, volume= 38 , pages= 2104-2113, doi= 10.1109/TMI.2019.2895035

References

Electrical engineering Nondestructive testing Inverse problems

Applications

See also

References