Abstract: The invention relates to a device (1) for dispensing or aspirating/dispensing liquid samples, including a pump (2) and a micro-ejection device (3), the micro-ejection device (3) having a pulse generator (4) with a chamber (5). The pulse generator (4) is used to produce pressure waves in the liquid in order to cause the samples of a liquid to be dispensed. The micro-ejection device (3) also comprises an end piece (6) and a liquid line (7) which connects the pulse generator (4) to the end piece (6) the pulse generator comprises a micro-actuator (10) which is configured to function in the same direction as that in which the pressure wave leaves the chamber (5). The inventive devices are characterised in that the chamber (5), in the area of the end facing away from the end piece (6), or the corresponding connecting element (14) has a narrowed section (16) which restricts any expansion of the pressure waves in the direction of the pump (2). The invention also relates to systems with multiple devices of this type.

Abstract: The invention relates to a device (1) for dispensing or aspirating/dispensing liquid samples, comprising a pump (2) and a micro-ejection device (3), said micro-ejection device (3) having a pulse generator (4) with a chamber (5). Said pulse generator (4) is used to produce pressure waves in the liquid in order to cause the samples of a liquid to be dispensed. The micro-ejection device (3) also comprises an end piece (6) and a liquid line (7) which connects the pulse generator (4) to the end piece (6). The pulse generator comprises a micro-actuator (10) which is configured to function in the same direction as that in which the pressure wave leaves the chamber (5). The inventive devices are characterised in that the chamber (5), in the area of the end facing away from the end piece (6), or the corresponding connecting element (14) has a narrowed section (16) which restricts any expansion of the pressure waves in the direction of the pump (2).

Abstract: A delivery apparatus has, in a housing (13), a cannula (8) whose rear end is connected to a diluter (17) via a connecting tube (16). A piezoelectric actuator (10) increases in length under the action of a control signal and acts on a membrane (6) pierced by the cannula tip (9) and belonging to an interchangeable polypropylene pipette tip mounted on the delivery apparatus and adhering to the housing (13) by means of a collar (7) 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 (17) and whose accurately adjustable volume is between 1 nl and 1 &mgr;l is ejected from an outlet orifice (4). After a pipetting process the pipette tip is ejected by means of a slide (15). If the level of the sample liquid in the pipette tip always remains below the cannula tip (9), virtually no carry-over occurs.