to limit the present invention in any way a separation chamber in accordance with the present invention can have notches in one or more compartments of the separation chamber or no notches at all in the embodiment of the present invention demonstrated in fig1 the separation chamber is surrounded by a wall 1 which is used to carry an optically transparent lid not shown allowing for optical observation and to contain the liquid sample the separation chamber is divided into two compartments by a separation wall 2 which has separation channels on top of it details of different embodiments for separation wall 2 are shown in fig2 and 4 returning to fig1 fluid fills the first compartment through a sample entrance 3 which is surrounded by an extension 11 of wall 1 and moves into the first compartment 4 of the chamber upon proceeding the liquid encounters a first notch 5 displaced laterally across the flow path the notch creates a momentary barrier to progression of the advancing fluid meniscus until the meniscus has contacted the notch across the whole width of the chamber eventually the fluid wets into the notch allowing the fluid to advance to the next notch 6 where the meniscus is again evened out the fluid advance continues in this manner until it reaches the separation wall 2 the fluid continues to advance through the.