a cannulation device is provided that includes : an elongated flexible sheath having a lumen and a distal end ; a segmented tip including one or more segmental elements disposed at the distal end ; a control member disposed in the lumen and fixed to a distal most segmental element of the one or more segmental elements ; and an actuator for selectively tensioning and relaxing the control member to decrease and increase , respectively , a flexibility of the segmented tip .