Figure 27 shows another exemplary device 1270 incorporating an array of
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`droplet generators 1272. Device 1270 may be structured as a plate and may have any
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`of the features described above for plate 1220 (see Figs. 22-26).
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`Each droplet generator 1272 may include a plurality of ports, which may be
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`structured as wells 1274-1278.
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`In particular, droplet generator 1272 may have a three-
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`port configuration of an oil well 1274 to receive a carrier fluid, a sample well 1276 to
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`receive a sample (e.g., a prepared sample that
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`is an assay mixture, such as an
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`amplification mixture), and an emulsion well 1278 to receive an overflow portion of an
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`emulsion generated by the droplet generator.
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`Figure 28 shows a bottom view of droplet generator 1272, taken after generation
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`of droplets 1280 to form an emulsion 1282. The droplet generator may include a
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`network of channels 1284 that carry fluid from oil well 1274 and sample well 1276 to a
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`site or intersection 1286 of droplet generation. A pair of channels 1284 may extend from
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`oil well 1274 to site 1286 and another channel 1284 may extend from sample well to
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`site 1286, to form a cross structure at which droplets are formed by flow focusing of fluid
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`from the sample well by carrier fluid disposed on opposing sides of fluid stream from the
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`sample well.
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`Droplets 1280 may flow from droplet generation site 1286 to emulsion well 1278
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`via an outlet channel 1288. The outlet channel may widen as it extends from site 1286
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`to form a chamber 1290. The chamber may have a high aspect
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`ratio, with a
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`height/thickness that generally corresponds to the diameter of the droplets, to promote
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`formation of a monolayer 1292 of droplets in the chamber. Droplets also may flow past
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`chamber 1290 to emulsion well 1278. However, emulsion well 1278 may function
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`predominantly as an overflow site to collect excess emulsion.
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`In other embodiments,
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`emulsion well 1278 may be omitted. In any event, chamber 1290 may be connected to a
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`vent 1294, which may be disposed generally downstream of the chamber,
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`to permit
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`escape of air as an emulsion flows into the chamber.
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`Figure 29 shows a sectional view of droplet generator 1272 and illustrates how
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`droplets may be generated and then imaged with an imager 1296 from below plate
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`1270. To generate droplets, oil well 1274 may be loaded with a carrier fluid 1298 and
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`sample well 1276 with a sample (e.g., an assay mixture 1300). Pressure may be applied
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`10
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`15
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`20
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`25
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`30
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`64
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`