On the application of frequency selective common mode feedback for multifrequency EIT. (26th May 2015)

• Record Type: Journal Article
• Authors: Langlois, Peter J; Wu, Yu; Bayford, Richard H; Demosthenous, Andreas
• Is Part Of: Physiological measurement. Volume 36:Number 6(2015:Jun.)
• Page Start: 1337
• Page End: 1350
• Publication Date: 2015-05-26
• Subjects: bioimpedance -- common mode error -- common mode feedback -- current drive -- imbalance -- multifrequency; Physiology -- Measurement -- Periodicals; Patient monitoring -- Periodicals; 612
• DOI: 10.1088/0967-3334/36/6/1337
• Languages: English
• ISSNs: 0967-3334

Abstract

Abstract: Common mode voltages are frequently a problem in electrical impedance tomography (EIT) and other bioimpedance applications. To reduce their amplitude common mode feedback is employed. Formalised analyses of both current and voltage feedback is presented in this paper for current drives. Common mode effects due to imbalances caused by the current drives, the electrode connections to the body load and the introduction of the body impedance to ground are considered. Frequency selective narrowband common mode feedback previously proposed to provide feedback stability is examined. As a step towards multifrequency applications the use of narrowband feedback is experimentally demonstrated for two simultaneous current drives. Measured results using standard available components show a reduction of 62 dB for current feedback and 31 dB for voltage feedback. Frequencies ranged from 50 kHz to 1 MHz.