The present invention relates to 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 for extracting the infrared rays (114) from said waveguide (104) in at least one main direction of extraction (116) an image acquisition means (108) placed opposite said face (112) so as to define between them a passage (118) by the inlet of which said part (50) of the living body can penetrate and comprising a sensitive component (110) the or each extraction zone (106) being such that the or each main direction of extraction (116) of said extraction zone (106) is oriented so as not to intercept said sensitive component (110).
