IOP PUBLISHING PHYSIOLOGICAL MEASUREMENT Physiol. Meas. 34 (2013) N1–N7 doi:10.1088/0967-3334/34/1/N1 NOTE Towards true unipolar bio-potential recording: a preliminary result for ECG Gaetano D Gargiulo 1 , 2, 3 , Alistair L McEwan 2 , Paolo Bifulco 3 , Mario Cesarelli 3 , Craig Jin 2 , Jonathan Tapson 1 , Aravinda Thiagalingam 2 and Andr´ e van Schaik 1 1 The MARCS Institute, The University of Western Sydney, Sydney, NSW, Australia 2 EIE School, The University of Sydney, Sydney, NSW, Australia 3 DIBET ‘Federico II’ The University of Naples, Naples, Italy E-mail: g.gargiulo@uws.edu.au Received 13 September 2012, accepted for publication 31 October 2012 Published 18 December 2012 Online at stacks.iop.org/PM/34/N1 Abstract We present a bio-potential front-end capable of recording unipolar ECG leads without making use of the Wilson central terminal (WCT). The information contained in the new unipolar recordings may yield unique diagnostic information as it avoids the need to essentially subtract data or make use of the averaging effect imposed by the WCT. The system also allows a direct, real-time software calculation of signals corresponding to standard ECG leads for standard diagnosis. These calculated standard ECG leads have a correlation in excess of 92% with a gold standard ECG recorded in parallel. The circuit is wideband, compatible with both the standard and the dry electrodes, and of low power (requiring less than 20 mW powered at 12 V). It is therefore well suited for long-term applications. Keywords: ECG, bio-potential recording, unipolar bio-potential (Some figures may appear in colour only in the online journal) 1. Introduction Standard bio-potential amplifiers (such as for ECG) rely on a differential electrode configuration which consists of two sensing electrodes placed across the subject’s body to form a sensing lead. Often a third electrode, the driven right leg (DRL) electrode, is used as a reference for common-mode voltage reduction. Therefore, any ECG lead can be regarded as the result of a double-difference operation. First, each component (such as left and right arms composing Lead I) is a result of the voltage difference between one point and the reference; second, a differential amplifier calculates the difference between the two components. Traditionally, the use of a differential amplifier is regarded as an advantage because of the high input impedance and high common mode 0967-3334/13/010001+07$33.00 © 2013 Institute of Physics and Engineering in Medicine Printed in the UK & the USA N1