Figure 29.

(a) Schematic of the hydrodynamic trap. The pipette is positioned approximately one tip radius above a supported lipid bilayer (left). The application of negative pressure to the upper opening of the pipette causes suction at the pipette tip drawing liquid into it (center). Resulting viscous drag forces move molecules protruding from the bilayer toward the area below the tip, where they accumulate and become trapped (right). (b) Trapping of fluorescently labeled SA. Images show the fluorescence intensity from streptavidin bound to an SLB at different times. The hydrodynamic trap was turned on at t = 56 s and off at t = 153 s. Reprinted from ref 292. Copyright 2012 United States National Academy of Sciences.