METHOD AND APPARATUS FOR DISPENSING A LIQUID WITH A PIPETTING NEEDLE

摘要

A method and a micropipetting apparatus for dispensing a liquid volume into a vessel by means of a pipetting needle and without any contact between said needle and a liquid contained in said vessel. The method comprises forming a drop (17) at the delivery tip (22) of the pipetting needle (11), said drop being retained at the tip by adhesion forces, and ejecting said drop (17) from said tip (22) by focusing at the tip of the pipetting needle (11) a mechanical excitation wave applied to an excitation point at some distance from said tip (22) of the pipetting needle (11). The apparatus comprises a pipetting needle (11), an electromechanical transducer (32) mechanically connected with said pipetting needle (11), electrical signal generating means (33) for generating an excitation pulse signal (26) and for applying this signal to said electromechanical transducer (32) for mechanically exciting said pipetting needle (11) with a pulse of mechanical waves that propagate through said needle.