the first channel segment and the first fluid junction is at least 95% eliminated.

20. The method of claim 1 , wherein the differential driving force between the first end of the first channel segment and the first fluid junction is at least 99% eliminated.

21. The method of claim 1 , wherein the differential driving force between the second fluid junction and the second end of the first channel segment is at least 90% eliminated.

22. The method of claim 1, wherein the differential driving force between the second fluid junction and the second end of the first channel segment is at least 95% eliminated.

23. The method of claim 1 , wherein the differential driving force between the second fluid junction and the second end of the first channel segmentis at least 99% eliminated.

24. A microfluidic system, comprising: a first channel segment having first and second ends; a second channel segment communicating with the first channel segment at a first fluid junction, the first fluid junction being disposed between the first and second ends of the first channel segment; a third channel segment communicating with the first channel segment at a second fluid junction, the second fluid junction being disposed between the first fluid junction and the second end of the first channel segment; and a flow controller operably coupled to at least one of the first and second ends of the first channel segment and the second and third channel segments, and set to: apply a first differential driving force between the first and second ends