July 1, 2001
This schematic illustrates the method of selective withdrawal to confine one fluid as a tube within a second fluid. The photograph shows this method applied to a lower fluid of water that is drawn through an upper fluid of oil. The third figure is a confocal microscope image of a 200 micron bead taken around its equator. The bead is coated with a poly(ethylene glycol) that is labeled with a fluorescent dye.