Patent ID: 7691636
Filing Date: 2010-04-06
Classification: G01N

Abstract:
1. For use with a flow cytometer, a method of controlling the point at which droplets are controllably charged and break off from a carrier fluid containing particles to be sorted, said method comprising the steps of: (a) monitoring a prescribed zone within a particle fluid transport chamber having a change in cross-sectional width along the length thereof for the presence of a particle traveling therethrough, and producing an output pulse having a width that is representative of the length of time that said particle is within said prescribed zone as it travels through said particle fluid transport chamber; (b) calculating a composite time delay for the particle based on the change in cross-sectional width of said particle fluid transport chamber and the position of said particle relative to the axis of a stream of the carrier fluid, between the time that said particle is sensed in step (a) as being present in said prescribed zone and the time at which a droplet containing said particle will break off from said carrier fluid; and (c) using said composite time delay calculated in step (b) to controllably charge said particle as said particle breaks off from said carrier fluid.