Automatic pipetting device with cleaning mechanism

Claim 1

A pipetting device comprising: a) only one pipetting needle having a tip end and an open end; b) a transport means secured to the pipetting needle for moving the pipetting needle to a plurality of pipetting positions and to a cleaning position; c) a metering syringe having an outlet; d) a first tube having a first end and a second end, the first end of the first robe secured to the open end of the pipetting needle; and e) means for cleaning the pipetting needle with a cleaning fluid when the pipetting needle is positioned in the cleaning position, said cleaning means comprising: i) a plunger pump; ii) a second tube having a first end and a second end; iii) a first valve; iv) a second valve; v) a third tube having a first end and a second end, the second end of the third tube immersed in said cleaning fluid; wherein, 1) the second end of the first tube is in fluid communication with both the outlet of the metering syringe and the first valve; 2) the first end of the second tube is in fluid communication with the first valve; 3) the second end of the second tube is in fluid communication with both the plunger pump and the second valve; and 4) the first end of the third tube is in fluid communication with the second valve; and vi) control means for activating the plunger pump and for opening and closing the first valve and the second valve, so as to establish a predetermined pressure of cleaning fluid in the second tube while the first and second valves are dosed and subsequently to force the cleaning fluid through the pipetting needle while the first valve is open and the second valve is closed.