Fig. 1

a Positioning of the 16 electrodes (Ei, i ϵ [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]) according to a 4 × 4 matrix. This matrix is shifted slightly towards the right due to the physiological dextrorotation of the uterus. b Twelve bipolar signals are obtained (Vbi, i ϵ [1,2,3,4,5,6,7,8,9,10,11,12]) by vertical subtraction of 2 adjacent unipolar signals