The present invention concerns a sensor (100) for venous networks of a part (50) of a living body, comprising:an infrared illumination source (102),a waveguide (104) illuminated by said infrared illumination source (102) and having, on one face (112), at least one extraction zone (106) intended to extract the infrared rays (114) from said waveguide (104) in at least one main extraction direction (116),an image acquisition means (108) disposed opposite said face (112) so as to define between them a passage (118) through the entrance of which said part (50) of the living body can enter, and comprising a sensitive element (110),the or each extraction zone (106) being such that the or each main extraction direction (116) of said extraction zone (106) is oriented so as not to intercept said sensitive element (110).
