Cannula insertion system

A cannula insertion system for inserting a cannula into a blood vessel of a human or animal, comprising:

• one or more sensors to provide one or more sensor signals representative for a location of the blood vessel,
• a processing device to determine a location of the blood vessel on the basis of the one or more sensor signals,
• a cannula insertion device to insert the cannula into the blood vessel,
• a positioning system supporting the cannula insertion device, and
• a control device arranged to control the positioning system to position, on the basis of the determined location of the blood vessel, the cannula insertion device in a suitable position to insert the cannula into the blood vessel,
• wherein the one or more sensors comprise a contact sensor to be placed on a target area of the skin of the human or animal to enable measurement with said contact sensor, and
• wherein the cannula insertion system comprises a coupler liquid application device to apply before and/or during measuring with the contact sensor coupler liquid on the target area of the skin of the human or animal, wherein the coupler liquid is used as contact liquid between the contact sensor and the skin to improve measurement accuracy of the contact sensor, wherein the coupler liquid application device is operated by the cannula insertion system, and wherein the coupler liquid application device is a spray device arranged to spray coupler liquid on the target area.