3D tomogram using on-chip ECT with ac-based capacitance measuring system

Abstract

The emergence of microfluidics technology has inspired the development of on-chip tomogram to replace the bulky microscopic methods. This paper proposes an on-chip 3D imaging technique using an electrical capacitance tomography (ECT) with an AC-based measuring system. To accomplish the sensing of the 34 electrodes equipped by the on-chip ECT, an AC-based measuring system that comprises 34 measuring channels with the measuring frequency of 10 kHz was developed. The system was designed using the commercially available analogue integrated circuits (ICs), which suits well for the common laboratorial usage with low fabrication cost. To validate the AC-based system, its performance was assessed based on the accuracy, signal-to-noise ratio (SNR), and standard deviation, using the standard capacitors ranging from 1 pF to 10 nF. The assessment showed that the accuracy was high with relative error around 6% for capacitance values higher than 10 pF. It was found that the minimum SNR was 12.98 dB and the maximum standard deviation was 7.37 pF. Subsequently, employing the developed AC-based system, the 3D images of a cubic agar with encapsulated Saccharomyces cerevisiae cells, were reconstructed successfully by the on-chip ECT. The evaluation results suggest that the presented design offers a potential solution for the on-chip 3D imaging.