Electrode array

An electrode array 1 for measuring impedance across a patients (e.g. an infant or a neonatal baby) lung comprises two or more electrodes 40 mounted on a substrate and being connectable to an electrical impedance segmentography monitor, and an adhesive surface (95 in figure 3) for attaching the electrodes to the patients skin. The array may comprise five electrodes distributed in an x-shaped configuration, with the four electrodes at the extremities of the cross positioned on the patients skin proximal to the quadrants of the lung, and the fifth on a position on the skin equidistant from the other four to be used as a reference electrode. The electrodes may be connected to wires 35-39 or printed tracks connectable to an electrical impedance segmentography (EIS) monitor. The substrate may be an adhesive liner 5 removably attached to the electrodes. It can be provided in two sections 10, 15 and at least one non-adhesive tab 25, 30 for assisting its removal. An EIS monitoring system may comprise an EIS monitor and two electrode arrays attached on a newborns chest and back, so that they are a mirror image of each other.