Electrical Capacitance Tomography (ECT) detects changes in the distribution of transparency in enclosed areas or pipes. Until now, various methods have been used to determine the optimum ECT sensor for a particular application. Some important parameters that affect the sensitivity of the sensor cannot be ignored. Design factors discussed in this paper study the needs in industry by producing the best image, without affecting the operation of the process. From previous studies many parameters influence the quality and effectiveness of an ECT sensor. The parameters that play important roles in ECT sensor design include the thickness and type of material in the pipe wall between the electrodes and the sensing zone, the thickness and material of the pipe wall separating the electrodes and the screen, the size of the electrodes, the guarding used, example radial guards or plane axial guards, and whether end guards are used. Other matters of concern regarding the dimension and the distance between the electrodes with guardians it is important design factor. Electrodes positioned either inside or outside the vessel will affect the cost factor design to the type of system to be used. This overview of the study is a basic guide for the essential requirements for an ECT sensor system design.

No abstract

Conventional electrical capacitance tomography (ECT) is widely used for monitoring the fluids flow in a pipeline. As the emergence of microfluidics, the tomography system has been miniaturized and integrated into the microfludic platform for imaging purposes. The on-chip ECT is designed to monitor the permittivity distribution of the micro-platform by integrating the planar electrodes with the sensing region. However, limited research has been reported on the electrode design of on-chip ECT, especially for three-dimensional imaging. Thus, this study investigated the electrode design of an on-chip ECT that is capable for image reconstruction in three-dimensions. Four different electrode configurations with different numbers of electrode and arrangements are investigated by simulation to determine the appropriate configuration for three-dimensional imaging. The electrode dimension is optimized based on the sensitivity distribution using the sensitivity variation parameter (SVP). The simulation results shows that the electrode configuration with dual sensing planes enable three-dimensional imaging. The central electrode of each sensing plane is crucial for restoring a floating object. In experiment, the imaging object that was positioned at different vertical and horizontal locations was reconstructed successfully with an average correlation coefficient of 0.4370 using linear back projection (LBP) algorithm. This work has disclosed the appropriate electrode configuration for the three-dimensional imaging of an on-chip ECT system.



This paper describes the process of developing a miniature device with planar sensors utilizing electrical capacitance measurement. The project investigates the feasibility and characterization of a miniaturized planar sensor integrated on a polydimethylsiloxane (PDMS) chamber. A 16-planar-electrodes array, with each dimension of the electrode, 4 mm × 2 mm (length × width) was fabricated using a printed circuit board (PCB) technology due to its low cost advantage. The measurement chamber for the sensing area was fabricated using PDMS. The PDMS chamber was bonded on the PCB with a semi cured PDMS to create a round sensing area for sample loading. The mould to develop the PDMS chamber was designed using AutoCAD 2010 and was fabricated using a 3D printer. Capacitance measurement of the planar electrodes was carried out using water as the sample and was validated using a theoretical calculation.  Experimental result shows that the distance of the measured electrodes is inversely proportional to the capacitance value. The range of the measured capacitances of the measurement varies from 10 pF to 20 pF. The result shows that the planar sensors are able to provide capacitance measurement within the miniaturized platform where the measured capacitance showed good agreement with the theoretical calculation.

No abstract