Current source considerations for broadband bioimpedance spectroscopy

2011 ◽  
pp. 71-82
Keyword(s):  
Current Source ◽  
Bioimpedance Spectroscopy

scholarly journals Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy

2021 ◽  
Vol 12 (1) ◽  
pp. 135-146
Author(s):  
Tobias Menden ◽  
Jascha Matuszczyk ◽  
Steffen Leonhardt ◽  
Marian Walter
Keyword(s):  
Patient Safety ◽  
Current Source ◽  
The Body ◽  
Voltage Source ◽  
Bioimpedance Spectroscopy ◽  
Laboratory Measurements ◽  
Output Impedance ◽  
Frequency Range ◽  
Common Mode ◽  
High Bandwidth

Abstract Bioimpedance measurements use current or voltage sources to inject an excitation signal into the body. These sources require a high bandwidth, typically from 1 kHz to 1 MHz. Besides a low common mode, current limitation is necessary for patient safety. In this paper, we compare a symmetric enhanced Howland current source (EHCS) and a symmetric voltage source (VS) based on a non-inverting amplifier between 1 kHz and 1 MHz. A common mode reduction circuit has been implemented in both sources. The bandwidth of each source was optimized in simulations and achieved a stable output impedance over the whole frequency range. In laboratory measurements, the output impedance of the EHCS had its -3 dB point at 400 kHz. In contrast, the VS reached the +3 dB point at 600 kHz. On average over the observed frequency range, the active common mode compensation achieved a common mode rejection of -57.7 dB and -71.8 dB for the EHCS and VS, respectively. Our modifications to classical EHCS and VS circuits achieved a low common mode signal between 1 kHz and 1 MHz without the addition of complex circuitry, like general impedance converters. As a conclusion we found VSs to be superior to EHCSs for bioimpedance spectroscopy due to the higher bandwidth performance. However, this only applies if the injected current of the VS can be measured.

Current Source Design for Electrical Bioimpedance Spectroscopy

2008 ◽  
pp. 359-367 ◽  
Author(s):  
Fernando Seoane ◽  
Ramón Bragos ◽  
Kaj Lindecrantz ◽  
Pere Riu
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Biological Tissue ◽  
Electrical Impedance ◽  
Current Source ◽  
Electrical Impedance Spectroscopy ◽  
Bioimpedance Spectroscopy ◽  
Electrical Bioimpedance ◽  
Electronic Instrumentation ◽  
Passive Electrical Properties

The passive electrical properties of biological tissue have been studied since the 1920s, and with time, the use of Electrical Bioimpedance (EBI) in medicine has successfully spread (Schwan, 1999). Since the electrical properties of tissue are frequency-dependent (Schwan, 1957), observations of the bioimpedance spectrum have created the discipline of Electrical Impedance Spectroscopy (EIS), a discipline that has experienced a development closely related to the progress of electronic instrumentation and the dissemination of EBI technology through medicine.

A Design Based on Bioimpedance Spectroscopy Method in Human Abdominal Adipose Measurement System

2012 ◽  
Vol 263-266 ◽  
pp. 241-245 ◽  
Author(s):  
Zhang Yong Li ◽  
Fei Ba Chang ◽  
Xiao Bo Chen ◽  
Rui Leng ◽  
Wei Wang
Keyword(s):  
Measurement System ◽  
Current Source ◽  
Impedance Measurement ◽  
Bioelectrical Impedance ◽  
Abdominal Fat ◽  
Signal Generator ◽  
Constant Current ◽  
Phase Detection ◽  
Bioimpedance Spectroscopy ◽  
Constant Current Source

This article describes a measurement of human abdominal fat device designed based on BIS (bioimpedance spectroscopy), the device adopts four electrodes multi-frequency bioelectrical impedance measurement system, including the programmable signal generator module and the amplitude and phase detection module. Program controlled signal generator module can generate the high output impedance of the constant current source in the eight frequency points constant current source between 5KHz and1MHz; amplitude phase detecting module can detect the human body electrical impedance real part and imaginary part information. Therefore, the device can be accurate measurement of human abdominal impedance information in the whole frequency range. Meanwhile, according to the selected electrode fixed position and the appropriate measurement scheme, can calculate the corresponding depth of abdominal fat content.

scholarly journals Design of Bioimpedance Spectroscopy Instrument With Compensation Techniques for Soft Tissue Characterization

2015 ◽  
Vol 9 (2) ◽  
Author(s):  
Robert E. Dodde ◽  
Grant H. Kruger ◽  
Albert J. Shih
Keyword(s):  
Tissue Characterization ◽  
Dynamic Range ◽  
Ex Vivo ◽  
Current Source ◽  
Extracellular Fluid ◽  
Parasitic Capacitance ◽  
Bioimpedance Spectroscopy ◽  
Element Analysis ◽  
Spleen Tissue ◽  
High Impedance

Bioimpedance spectroscopy (BIS) has shown significant potential in many areas of medicine to provide new physiologic markers. Several acute and chronic diseases are accompanied by changes in intra- and extracellular fluid within various areas of the human body. The estimation of fluid in various body compartments is therefore a simple and convenient method to monitor certain disease states. In this work, the design and evaluation of a BIS instrument are presented and three key areas of the development process investigated facilitating the BIS measurement of tissue hydration state. First, the benefit of incorporating DC-stabilizing circuitry to the standard modified Howland current pump (MHCP) is investigated to minimize the effect of DC offsets limiting the dynamic range of the system. Second, the influence of the distance between the bioimpedance probe and a high impedance material is investigated using finite element analysis (FEA). Third, an analytic compensation technique is presented to minimize the influence of parasitic capacitance. Finally, the overall experimental setup is evaluated through ex vivo BIS measurements of porcine spleen tissue and compared to published results. The DC-stabilizing circuit demonstrated its ability to maintain DC offsets at less than 650 μV through 100 kHz while maintaining an output impedance of 1 MΩ from 100 Hz to 100 kHz. The proximity of a bioimpedance probe to a high impedance material such as acrylic was shown to increase measured impedance readings by a factor of 4x as the ratio of the distance between the sensing electrodes to the distance between the bioimpedance probe and acrylic reached 1:3. The average parasitic capacitance for the circuit presented was found to be 712 ± 128 pF, and the analytic compensation method was shown to be able to minimize this effect on the BIS measurements. Measurements of porcine spleen tissue showed close correlation with experimental results reported in published articles. This research presents the successful design and evaluation of a BIS instrument. Specifically, robust measurements were obtained by implementing a DC-stabilized current source, investigating probe-material proximity issues and compensating for parasitic capacitance. These strategies were shown to provide tissue measurements comparable with published literature.

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