Note: Temperature effects in the modified Howland current source for electrical bioimpedance spectroscopy

2017 ◽  
Vol 88 (7) ◽  
pp. 076103 ◽  
Author(s):  
S. Fernandez Santos ◽  
P. Bertemes-Filho
Keyword(s):  
Temperature Effects ◽  
Current Source ◽  
Bioimpedance Spectroscopy ◽  
Electrical Bioimpedance

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.

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.

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