Adding fluid through a liquid bridge to a chamber with fluid walls

Overview
Microtiter plates are essentially arrays of miniature test tubes; individual chambers with solid plastic walls typically hold a few micro-liters. Much smaller volumes can be contained in arrays of chambers (GRIDs) with fluid walls (Soitu C et al, 2018, Proc Natl Acad Sci USA 115, E5926-E5933). This YouTube movie illustrates why nano-liter volumes of one liquid can be delivered by a pipet to chambers with fluid walls without detectable 'carry-over' between chambers. At the beginning of the video, we see 3 square chambers (2.25 x 2.25 mm) at the edge of a 16 x 8 'GRID'; two chambers contain blue dye, and a third a larger volume of red dye. All chambers are overlaid with a transparent and immiscible liquid to prevent evaporation. Each chamber is separated from the next by a wall of immiscible liquid. A colorless aqueous liquid will be ejected continuously from the tip of a pipet positioned below the surface of the overlay but above the red dye. At 0 s, ejected liquid forms a bubble in the immiscible overlay. By 9 s, the bubble has grown sufficiently to touch the surface of the chamber, and a 'liquid bridge' forms. Note there is no detectable transfer upwards of red dye through this bridge. By 11 s, the bridge has broken, and no red dye can be detected in the bubble on the tip. After 13 s, a new bridge forms, and again no dye is being transferred upwards. The tip will now be moved to a new position above another chamber, and liquid delivered to it. This movie shows how essentially no red dye will be transferred between chambers during this process.

Nuclear Structure and Function Research Group

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