Patent ID: 6152194
Filing Date: 2000-11-28
Classification: B01L,G01F,G01N

Abstract:
A method for producing portions of liquid (20) by use of a suction tip (4) containing a liquid space (18) confined by a filter (17) permeable to an air stream but impermeable to said liquid and a bellows (1) defining an air space (2) connected through an air channel (3) to said suction tip, the method comprising drawing liquid to said suction tip by means of a movement of the bellows, and injecting said liquid from the suction tip by means of reversed movement of the bellows, characterized in that a plurality of liquid portions (20) of a specified size are produced in a series operation which comprises the steps of drawing an amount of liquid to the suction tip (4), said amount being a multiple of an individual portion (20) to be produced, and then injecting said portions one by one at a number of subsequent injection steps, by use of an actuator (6) producing sequential movements of the bellows each with a change of the volume of said air space (2) corresponding to the size of the liquid portion that is injected and wherein the suction tip (4) is cleaned by letting the bellows (1) blow air through it immediately before the suction of the liquid to the suction tip (4).