Tecan Trading Ag

Mario Benedetti

Nikolaus Ingenhoven

Stefano Fornito

Agathe Hodac

Werner H&auml;lg

A delivery apparatus has, in a housing ( ), a cannula ( ) whose rear end is connected to a diluter ( ) via a connecting tube ( ). A piezoelectric actuator ( ) increases in length under the action of a control signal and acts on a membrane ( ) pierced by the cannula tip ( ) and belonging to an interchangeable polypropylene pipette tip mounted on the delivery apparatus and adhering to the housing ( ) by means of a collar ( ) resting against said housing, and causing said membrane to sag, with the result that a drop of a sample liquid which was previously sucked in by means of the diluter ( ) and whose accurately adjustable volume is between 1 nl and 1 &mgr;l is ejected from an outlet orifice ( ). After a pipetting process the pipette tip is ejected by means of a slide ( ). If the level of the sample liquid in the pipette tip always remains below the cannula tip ( ), virtually no carry-over occurs.

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Pfäffikon, Switzerland

Mario Benedetti