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Vizvari Z, Gyorfi N, Odry A, Sari Z, Klincsik M, Gergics M, Kovacs L, Kovacs A, Pal J, Karadi Z, Odry P, Toth A. Physical Validation of a Residual Impedance Rejection Method during Ultra-Low Frequency Bio-Impedance Spectral Measurements. SENSORS (BASEL, SWITZERLAND) 2020; 20:E4686. [PMID: 32825145 PMCID: PMC7506680 DOI: 10.3390/s20174686] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 01/19/2023]
Abstract
Accurate and reliable measurement of the electrical impedance spectrum is an essential requirement in order to draw relevant conclusions in many fields and a variety of applications; in particular, for biological processes. Even in the state-of-the-art methods developed for this purpose, the accuracy and efficacy of impedance measurements are reduced in biological systems, due to the regular occurrence of parameters causing measurement errors such as residual impedance, parasitic capacitance, generator anomalies, and so on. Recent observations have reported the necessity of decreasing such inaccuracies whenever measurements are performed in the ultra-low frequency range, as the above-mentioned errors are almost entirely absent in such cases. The current research work proposes a method which can reject the anomalies listed above when measuring in the ultra-low frequency range, facilitating data collection at the same time. To demonstrate our hypothesis, originating from the consideration of the determinant role of the measuring frequency, a physical model is proposed to examine the effectiveness of our method by measuring across the commonly used vs. ultra-low frequency ranges. Validation measurements reflect that the range of frequencies and the accuracy is much greater than in state-of-the-art methods. Using the proposed new impedance examination technique, biological system characterization can be carried out more accurately.
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Affiliation(s)
- Zoltan Vizvari
- Department of Environmental Engineering, Faculty of Engineering and Information Technology, University of Pecs, Boszorkany str. 2, H-7624 Pecs, Hungary; (N.G.); (A.K.)
| | - Nina Gyorfi
- Department of Environmental Engineering, Faculty of Engineering and Information Technology, University of Pecs, Boszorkany str. 2, H-7624 Pecs, Hungary; (N.G.); (A.K.)
| | - Akos Odry
- Institute of Information Technology, University of Dunaujvaros, Tancsics M. str. 1/A, H-2401 Dunaujvaros, Hungary; (A.O.); (P.O.)
| | - Zoltan Sari
- Department of Information Technology, Faculty of Engineering and Information Technology, University of Pecs, Boszorkany str. 2, H-7624 Pecs, Hungary;
| | - Mihaly Klincsik
- Department of Mathematics, Faculty of Engineering and Information Technology, University of Pecs, Boszorkany str. 2, H-7624 Pecs, Hungary;
| | - Marin Gergics
- 1st Department of Medicine, Clinical Centre, University of Pecs, Ifjusag str. 13, H-7624 Pecs, Hungary;
| | - Levente Kovacs
- Physiological Controls Research Center, University Research and Innovation Cetner, Obuda University, Becsi str. 96/b, H-1034 Budapest, Hungary;
| | - Anita Kovacs
- Department of Environmental Engineering, Faculty of Engineering and Information Technology, University of Pecs, Boszorkany str. 2, H-7624 Pecs, Hungary; (N.G.); (A.K.)
| | - Jozsef Pal
- Institute of Physiology, Medical School, University of Pecs, Szigeti str. 12, H-7624 Pecs, Hungary; (J.P.); (Z.K.); (A.T.)
| | - Zoltan Karadi
- Institute of Physiology, Medical School, University of Pecs, Szigeti str. 12, H-7624 Pecs, Hungary; (J.P.); (Z.K.); (A.T.)
| | - Peter Odry
- Institute of Information Technology, University of Dunaujvaros, Tancsics M. str. 1/A, H-2401 Dunaujvaros, Hungary; (A.O.); (P.O.)
| | - Attila Toth
- Institute of Physiology, Medical School, University of Pecs, Szigeti str. 12, H-7624 Pecs, Hungary; (J.P.); (Z.K.); (A.T.)
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Abstract
The biogas production technology has improved over the last years for the aim of reducing the costs of the process, increasing the biogas yields, and minimizing the greenhouse gas emissions. To obtain a stable and efficient biogas production, there are several design considerations and operational parameters to be taken into account. Besides, adapting the process to unanticipated conditions can be achieved by adequate monitoring of various operational parameters. This paper reviews the research that has been conducted over the last years. This review paper summarizes the developments in biogas design and operation, while highlighting the main factors that affect the efficiency of the anaerobic digestion process. The study’s outcomes revealed that the optimum operational values of the main parameters may vary from one biogas plant to another. Additionally, the negative conditions that should be avoided while operating a biogas plant were identified.
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