Multifrequency Impedance Tomography System for Research on Environmental and Thermal Processes

Abstract

The possibility for spatial and temporal monitoring of environmental, chemical or thermal processes is of high importance for their better understanding thus control and optimization. Therefore, measurement methods that enable such opportunities might be especially valuable for researchers and process engineers. For this reason, in this paper the novel Electrical Impedance Tomography system is proposed that enables the visualization of the processes in which the electrical conductivity of material is changing. The proposed EIT system is based mostly on general purpose equipment. It consists of three laboratory-grade devices: a signal generator, a switching device and a data acquisition card for voltage measurement. In addition to those devices, the current source was constructed to complete the system. The EIT system was designed to have the ability of sourcing the current of frequency up to 250 kHz. A set of validation experiments were carried out to verify the EIT system accuracy. The validation tests consisted of object detection, distinguishing between objects of different conductivity, multifrequency imaging and visualization of slow-changing processes. The obtained results were also compared with the numerical simulations. The proposed system was proven to have the ability of correct imaging of irregularity inside the area of the sensor.

Keywords

• electrical impedance tomography
• multifrequency
• general purpose instruments
• EIDORS
• process monitoring