Pipette Tip Extension, Pipette Tip, Assembly of Pipette Tip and Pipette Tip Extension, and Method of Use

A pipette tip extension attachable to a pipette tip inserted thereto, comprising a proximal end, a distal end, and an exterior wall extending between the proximal end and the distal end, the exterior wall having an outer side and an inner side and enclosing an inner cavity which is delimited by the inner side of the exterior wall,

• wherein the exterior wall forms at the proximal end a reception aperture for inserting a pipette tip, and at the distal end a dispense aperture,
• wherein the pipette tip extension further comprises:
• one or more distance elements arranged at the inner side of the exterior wall and protruding into the inner cavity, the distance elements being dimensioned to establish a fluid uptake area adjacent to the inner side of the exterior wall, the fluid uptake area extending from the dispense aperture up to the reception aperture and being in fluid connection with a surrounding atmosphere at the reception aperture, and
• a constriction element for controlling an insertion depth of the inserted pipette tip within the pipette tip extension, the constriction element defining a fixed gap from a distal end of the inserted pipette tip to the distal end of the pipette tip extension, wherein the fixed gap has a height in a range of 0.1 mm and 1 mm and fluidly connects the fluid uptake area adjacent to the inner side of the exterior wall with an inner cavity of the inserted pipette tip;
• wherein the constriction element is formed by a distal end of the one or more distance elements, each distal end being an additional protrusion of the distance element towards a medial axis of the pipette tip extension and provides an abutment for the distal end of the inserted pipette tip, to position the distal end of the inserted pipette tip at an offset to the distal end of the pipette tip extension, the offset corresponding to the gap height;
• and
• wherein the pipette tip extension is configured to transfer a fluid from the inner cavity into the inserted pipette tip.