Imaging wetting front propagation dynamics using electrical impedance tomography measurements

J. A. Gutierrez-Gnecchia, F. Landeros-Páramo, A. Méndez Patiñoa, A Tellez-

Anguianoa, E. Reyes-Archundiaa, D. Lorias Espinozab

a Instituto Tecnologico de Morelia, Departamento de Ingenieria Electronica, Avenida Tecnologio 1500, Morelia, Mich., C.P.

58000, Mexico

b CINVESTAV/IPN, Departamento de Ingenieria Electrica, Seccion Biotecnologia, Av. Instituto Politécnico Nacional 2508, C. P.

07360, México, D. F., Mexico.

Abstract

Measurement of soil hydraulic conductivity properties is essential for achieving true precision agriculture practices. A large number of methods have been implemented to measure and model how the water propagates through soil. Some of the methods rely on devices located on the soil surface to estimate the soil hydraulic conductivity of an area. Other methods install a measurement device in the soil sample at specified depths. However, in most cases the measurements are point or volumetric. Since soils are rarely uniform along different depths, and the properties of soil change continuously, volumetric measurements do not represent correctly the changes of conductivity properties. In order to obtain accurate information about the hydraulic conductivity properties along the soil depth, the authors present an electrical impedance tomography device based on a linear array of 16 electrodes installed in the soil sample to measure the soil impedance changes as water propagates after irrigation. The resulting measurements are used to feed a backprojection algorithm to produce images of the of soil impedance. Results indicate the equipment can measure wetting front propagation properties of multi-layered soils.

Keywords: Biompedance measurements; Electrical Impedance Tomography; Analogue Design; Instrumentation; breast cancer diagnosis