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 (11) and without any contact between said needle and a liquid contained in said vessel. The method comprises (a) forming a drop (17) at the delivery tip of a pipetting needle (11), said drop being retained at the tip by adhesion forces, and (b) ejecting said drop (17) from said tip by focusing a mechanical wave at the tip of the pipetting needle.

<Paragraphs id="pa02" num="0002" xmlns:base="http://www.sipo.gov.cn/XMLSchema/base">The apparatus comprises
(a) a pipetting needle (11) having a substantially constant cross-section over the portion thereof that ends in a delivery tip, said portion extending over more than one half of the total length of said needle(b) an electromechanical transducer (32) mechanically connected with said pipetting needle (11), and(c) electrical signal generating means (33) for generating an excitation pulse signal and for applying this signal to said electromechanical transducer (32) for mechanically exciting said pipetting needle (11) with a pulse that propagates along said needle and is focused at the end tip thereof, said mechanical excitation thereby causing release of a drop (17) from that tip of the needle.