How much liquid do I need?  As long as there is a small column height of liquid that the PocketTip can find, and this may depend on the labware used, you are fine.  While most of our examples and videos show as much as 20μL of liquid aspirating into the tip to contact the Pocket, many scientists do not receive that much source liquid from their central library, or have to make limited supplies last.  Because the tip aspirates and dispenses back to the same plate, capturing only what is needed to fill or empty the pocket, only a small amount of liquid is actually used.   Hence, as little as 1 μL of source liquid must come in contact with the Pocket to fill it and as little as 2 μL of target liquid to empty it.  

Without any changes to the programmed assay protocol, if you set the aspirate setting to the required height in the tip to reach the pocket (the μL setting), the PocketTip doesn't know and doesn't care if there is more than 20μL or as little as 1μL available.  Hence -- with the same volume setting -- for smaller volumes it simply pulls air behind the liquid in order to reach the Pocket height before returning (dispensing) the liquid back into the plate.   Please consult nAscent BioSciences specialists on low-volume dispensing and also see the low-volume video below.