An insertion device (10), by which a medical instrument or an electrode line or a guide wire or a medical therapeutic agent may be inserted into a body cavity, comprises a lumen section (11) manufactured from a flexible plastic material, having a longitudinal axis, a proximal end and a distal end, and a distal end area enclosing the distal end, at least one electrically conductive means (20) in the distal end area to sense physiological signals or stimulate the surrounding body tissue suitably, as well as at least one conductor, which extends from the proximal end to the distal end and is capable of conducting physiological signals to the proximal end and / or stimulation pulses to the distal end. The at least one electrically conductive means is produced from a flexible, not exclusively metallic, electrically conductive substrate.