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Cui Z, Yang P, Li X, Wang H. An alternative excitation method for electrical impedance tomography. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:044710. [PMID: 35489953 DOI: 10.1063/5.0083681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 04/03/2022] [Indexed: 06/14/2023]
Abstract
Electrical impedance tomography (EIT) can be utilized to image the conductivity distribution of material under test. The EIT measurements depend on the quality in the current injection and voltage measuring circuits. The current source plays a vital role in the EIT instruments. In most of the research studies, the push-pull current sources were employed for the source and sink signal generation. It usually requires frequent calibration to achieve proper functioning, especially for the sweeping frequency measurements. In this paper, an alternative excitation method has been proposed for simplifying the design of the current source in EIT instruments, which aims to achieve the performance of the push-pull current source by using a single-ended current source. It could offer the following advantages: (1) hardware simplification and (2) reduced requirements on current source calibration. The corrected measurements could be consistent with that using push-pull excitation, as confirmed by the numerical simulations. In addition, the reconstructed images have also been investigated to illustrate the effectiveness of the proposed method.
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Affiliation(s)
- Ziqiang Cui
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Pengyu Yang
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Xuan Li
- Department of Mathematics, Tianjin University of Finance and Economics Pearl River College, Tianjin 301811, China
| | - Huaxiang Wang
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
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2
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Paivana G, Barmpakos D, Mavrikou S, Kallergis A, Tsakiridis O, Kaltsas G, Kintzios S. Evaluation of Cancer Cell Lines by Four-Point Probe Technique, by Impedance Measurements in Various Frequencies. BIOSENSORS 2021; 11:345. [PMID: 34562935 PMCID: PMC8466278 DOI: 10.3390/bios11090345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 09/11/2021] [Accepted: 09/14/2021] [Indexed: 12/14/2022]
Abstract
Cell-based biosensors appear to be an attractive tool for the rapid, simple, and cheap monitoring of chemotherapy effects at a very early stage. In this study, electrochemical measurements using a four-point probe method were evaluated for suspensions of four cancer cell lines of different tissue origins: SK-N-SH, HeLa, MCF-7 and MDA-MB-231, all for two different population densities: 50 K and 100 K cells/500 μL. The anticancer agent doxorubicin was applied for each cell type in order to investigate whether the proposed technique was able to determine specific differences in cell responses before and after drug treatment. The proposed methodology can offer valuable insight into the frequency-dependent bioelectrical responses of various cellular systems using a low frequency range and without necessitating lengthy cell culture treatment. The further development of this biosensor assembly with the integration of specially designed cell/electronic interfaces can lead to novel diagnostic biosensors and therapeutic bioelectronics.
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Affiliation(s)
- Georgia Paivana
- Laboratory of Cell Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 11855 Athens, Greece; (G.P.); (S.K.)
| | - Dimitris Barmpakos
- microSENSES Laboratory, Department of Electrical and Electronics Engineering, Faculty of Engineering, University of West Attica, 12244 Athens, Greece; (D.B.); (A.K.); (O.T.); (G.K.)
| | - Sophie Mavrikou
- Laboratory of Cell Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 11855 Athens, Greece; (G.P.); (S.K.)
| | - Alexandros Kallergis
- microSENSES Laboratory, Department of Electrical and Electronics Engineering, Faculty of Engineering, University of West Attica, 12244 Athens, Greece; (D.B.); (A.K.); (O.T.); (G.K.)
| | - Odysseus Tsakiridis
- microSENSES Laboratory, Department of Electrical and Electronics Engineering, Faculty of Engineering, University of West Attica, 12244 Athens, Greece; (D.B.); (A.K.); (O.T.); (G.K.)
| | - Grigoris Kaltsas
- microSENSES Laboratory, Department of Electrical and Electronics Engineering, Faculty of Engineering, University of West Attica, 12244 Athens, Greece; (D.B.); (A.K.); (O.T.); (G.K.)
| | - Spyridon Kintzios
- Laboratory of Cell Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 11855 Athens, Greece; (G.P.); (S.K.)
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Liu JZ, Li XB, Xiong H. A FPGA-based adaptive differential current source for electrical impedance tomography. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:094707. [PMID: 34598505 DOI: 10.1063/5.0062640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
A high output impedance current source with a wide bandwidth is needed in electrical impedance tomography systems. Limitations appear mainly at higher frequencies and non-simple loads. In order to adjust the output current, the amplitude and phase are made to achieve the expected value automatically. A current source based on the field programmable gate array is designed. In this paper, we proposed a double DAC differential current source structure. By measuring the voltage of the sampling resistor in series with the load and using the proposed dynamic reference point demodulation algorithm, the actual current amplitude and phase on the load can be quickly obtained. Through the adaptive compensation module, the output current is adjusted to the expected value. The experimental results show that the output resistance of the current source can reach 10 MΩ and the output capacitance can be less than 0.8 pF in the frequency range of 10 kHz-1.28 MHz. At the same time, the current amplitude attenuation is less than 0.016%, and the phase error is less than 0.0025° after compensation. Therefore, the proposed current source achieves widebands, biocompatibility, and high precision.
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Affiliation(s)
- J Z Liu
- The School of Control Science and Engineering, Tiangong University, Tianjin 300387, People's Republic of China
| | - X B Li
- The School of Control Science and Engineering, Tiangong University, Tianjin 300387, People's Republic of China
| | - H Xiong
- The School of Control Science and Engineering, Tiangong University, Tianjin 300387, People's Republic of China
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Saulnier GJ, Abdelwahab A, Shishvan OR. DSP-based current source for electrical impedance tomography. Physiol Meas 2020; 41:064002. [PMID: 32603311 DOI: 10.1088/1361-6579/ab8f74] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE EIT systems, particularly those that use a parallel, multiple source architecture, require current sources with very high output impedance. To meet this requirement, sources often use complex analog circuits and require manual or electronically-controlled adjustments. The goal is to implement a current source with simple, adjustment-free analog electronics with high effective output impedance even with significant stray impedance at its output. APPROACH The excitation provided to the voltage-to-current converter is adjusted to accommodate the current lost in the finite output and stray impedances. The adaptive algorithm uses the measured voltage and the previously-measured output and stray impedance to determine the needed current adjustment. MAIN RESULTS The structure of the source is presented along with an implementation, and experimental results that show the effectiveness of the approach for frequencies up to 1 MHz. The measured output impedance with and without the adaptive compensation are presented as well as measurements of resistive and complex loads. SIGNIFICANCE The new current source has low analog complexity, operates over a wide range of frequencies, and can compensate for a significant stray shunt impedance. It can be used to implement improved parallel or serial EIT systems.
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Affiliation(s)
- Gary J Saulnier
- Electrical and Computer Engineering, University at Albany, State University of New York, Albany, NY, United States of America
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Jaikla W, Adhan S, Suwanjan P, Kumngern M. Current/Voltage Controlled Quadrature Sinusoidal Oscillators for Phase Sensitive Detection Using Commercially Available IC. SENSORS 2020; 20:s20051319. [PMID: 32121276 PMCID: PMC7085565 DOI: 10.3390/s20051319] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/27/2020] [Accepted: 02/27/2020] [Indexed: 11/16/2022]
Abstract
This paper presents the quadrature sinusoidal oscillators for a phase sensitive detection (PSD) system. The proposed oscillators are design by using the commercially available ICs (LT1228). The core oscillator consists of three LT1228s: two grounded capacitors and one resistor. By adding four resistors without the requirement of additional active devices, the amplitudes of two quadrature waveforms become adjustable. The quadrature output nodes are of low impedance, which can be connected to the impedance sensor or other circuits in a phase sensitive detection system without the need of buffer devices. The amplitudes of the quadrature waveform are equal during the frequency of oscillation (FO) tuning. The frequency of oscillation is electronically and linearly controlled by bias current or voltage without affecting the condition of oscillation (CO). Furthermore, the condition of oscillation is electronically controlled without affecting the frequency of oscillation. The performances of the proposed oscillators are experimentally tested with ±5 voltage power supplies. The frequency of the proposed sinusoidal oscillator can be tuned from 8.21 kHz to 1117.51 kHz. The relative frequency error is lower than 3.12% and the relative phase error is lower than 2.96%. The total harmonic distortion is lower than −38 dB (1.259%). The voltage gain of the quadrature waveforms can be tuned from 1.97 to 15.92. The measurement results demonstrate that the proposed oscillators work in a wide frequency range and it is a suitable choice for an instrument-off-the-shelf device
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Affiliation(s)
- Winai Jaikla
- Department of Engineering Education, Faculty of Industrial Education and Technology, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand; (S.A.); (P.S.)
- Correspondence: ; Tel.: +66+813-05-1643
| | - Suchin Adhan
- Department of Engineering Education, Faculty of Industrial Education and Technology, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand; (S.A.); (P.S.)
| | - Peerawut Suwanjan
- Department of Engineering Education, Faculty of Industrial Education and Technology, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand; (S.A.); (P.S.)
| | - Montree Kumngern
- Department of Telecommunications Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
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Khalighi M, Mikaeili M. A floating wide-band current source for electrical impedance tomography. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:085107. [PMID: 30184672 DOI: 10.1063/1.5028435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
The quality of reconstructed images in Electrical Impedance Tomography (EIT) depends on two essential factors: first, precision of the EIT hardware in current injection and voltage measurement and second, efficiency of its image reconstruction algorithm. Therefore the current source plays an important and a vital role in EIT instruments. Floating-load current sources constructed using sink and source drivers have better performance and higher output impedance than grounded-load (single-ended) current sources. In addition, a main feature of this kind is that the current source is not connected to the ground potential directly but via a large impedance. In this paper, we first focus on recent studies on designed EIT current sources, and after that, a practical design of a floating-load high output impedance current source-operating over a wide frequency band-will be proposed in detail. Simulation results of the proposed voltage-controlled current source (VCCS), along with some other models, will be shown and compared. At the end, the results of practical tests on the VCCS and a few EIT images, taken using our prototype EIT system coupled with the mentioned VCCS, will be illustrated which proves the quality of the proposed current source.
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Affiliation(s)
- M Khalighi
- Biomedical Engineering Group, Department of Engineering, Shahed University, Tehran, Iran
| | - M Mikaeili
- Biomedical Engineering Group, Department of Engineering, Shahed University, Tehran, Iran
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Hao Z, Cui Z, Yue S, Wang H. Singular value decomposition based impulsive noise reduction in multi-frequency phase-sensitive demodulation of electrical impedance tomography. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:064702. [PMID: 29960571 DOI: 10.1063/1.5021058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
As an important means in electrical impedance tomography (EIT), multi-frequency phase-sensitive demodulation (PSD) can be viewed as a matched filter for measurement signals and as an optimal linear filter in the case of Gaussian-type noise. However, the additive noise usually possesses impulsive noise characteristics, so it is a challenging task to reduce the impulsive noise in multi-frequency PSD effectively. In this paper, an approach for impulsive noise reduction in multi-frequency PSD of EIT is presented. Instead of linear filters, a singular value decomposition filter is employed as the pre-stage filtering module prior to PSD, which has advantages of zero phase shift, little distortion, and a high signal-to-noise ratio (SNR) in digital signal processing. Simulation and experimental results demonstrated that the proposed method can effectively eliminate the influence of impulsive noise in multi-frequency PSD, and it was capable of achieving a higher SNR and smaller demodulation error.
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Affiliation(s)
- Zhenhua Hao
- Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Ziqiang Cui
- Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Shihong Yue
- Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, People's Republic of China
| | - Huaxiang Wang
- Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, People's Republic of China
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