A 60-micron particle approaches the cross channel from the left and is registered by an optical sensor (not visible). The sensor sends an opening signal to a high-speed valve located on top of the Venturi cross (not visible). The valve opens a flow of liquid (a darker diagonal flow from top to right), which blocks the horizontal channel and deflects flow downwards through the bottom opening. An approaching particle is blocked by this cross flow and deflected downwards.  The deflected or “sorted” particle is visible in the droplet.

A high-speed video record of a bead deflection process