Abstract: A sensor device for monitoring bioelectric data from the thoracic region of a human body and/or for inducing stimulating signals to said region comprises a plurality of finger-like substrate portions of a flexible dielectric material. The substrate portions are releasably attachable to the thoracic region of a human body and the lateral spacing between the substrate portions is adjustable in accordance with the physiology of the body. A plurality of electrodes are provided on each substrate portion each having a respective lead connectable to an apparatus for inducing stimulating signals to, and/or receiving physiological signals from the electrodes. Indicia or other positioning elements are provided on at least one substrate portion for indicating the correct position of the assembly in use.