A comparison study of electrodes for neonate electrical impedance tomography

Abstract

Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat and ARBO) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kOmega at 10 kHz and 337 Omega at 1 MHz; for the tissue impedance, the respective values were 987 Omega and 29 Omega. Overall, the Ambu BRS, Kendall ARBO and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications.

Comparison of representative skin pretreatment methods for body surface biopotential measurement

“…We used three types of emblematic electrodes [17]: Nihon Kohden's standard limb clamp-electrode (with the model number of SF450), silicone ball-electrode (pz26) and MEDITRACE adhesive electrode (200) produced by American Kendall. Six skin surface pretreatments mentioned above were adopted on each kind of electrodes [18] conditions of experiments were made up with these three kinds of electrodes and six skin pretreatments.…”

A wideband CMOS current driver for bioimpedance applications with output DC regulation

“…The difference of the 4 input terminals is performed at the output node (node 3). The output stage is formed by transistors M8, 9,11,14. Transistors M15A-B are operating in the triode region and provide common mode feedback (CMFB) [12].…”

“…The magnitude of the load impedance can vary significantly throughout the frequency band. In [9] the electrode-tissue impedance characteristic was studied using typical Ag/AgCl electrodes in the frequency range between 10Hz -1MHz. Reported values of approximately 10 kΩ at 100 Hz, 559 Ω at 100 kHz, and 494 Ω at 1 MHz were encountered.…”

Electrode Challenges in Amplitude-Integrated Electroencephalography (aEEG): Research Application of a Novel Noninvasive Measure of Brain Function in Preterm Infants

“…It reflects the quality of the electrode-skin contact (Emery, Hebert, Aguirre Vila-Coro, & Prager, 1991). High electrode impedances increase the susceptibility of the measurement system to several sources of common mode noise that are typical in clinical or laboratory environments, such as lighting, ventilation, computer, IV infusion, and other electrical systems (Rahal, Khor, Demosthenous, Tizzard, & Bayford, 2009), and thus may affect aEEG interpretation accuracy. Because of its importance, aEEG devices continuously measure and simultaneously display impedance with the aEEG tracing.…”