Droplet microfluidic technology is becoming increasingly useful for high-throughput and high-sensitivity detection of biological and biochemical reactions. Most current droplet devices function by passively discretizing a single sample subject to a homogeneous or random reagent/reaction condition into tens of thousands of picoliter-volume droplets for analysis. Despite their apparent advantages in speed and throughput, these droplet devices inherently lack the capability to customize the contents of droplets in order to test a single sample against multiple reagent conditions or multiple samples against multiple reagents. In order to incorporate such combinatorial capability into droplet platforms, we have developed the fully Integrated Programmable Picodroplet Assembler. Our platform is capable of generating customized picoliter-volume droplet groups from nanoliter-volume plugs which are assembled in situ on demand. By employing a combination of microvalves and flow-focusing-based discretization, our platform can be used to precisely control the content and volume of generated nanoliter-volume plugs, and thereafter the content and the effective dynamic range of picoliter-volume droplets. Furthermore, we can use a single integrated device for continuously generating, incubating, and detecting multiple distinct droplet groups. The device successfully marries the precise control and on-demand capability of microvalve-based platforms with the sensitivity and throughput of picoliter droplet platforms in a fully automated monolithic device. The device ultimately will find important applications in single-cell and single-molecule analyses.

液滴微流体技术在生物和生化反应的高通量和高灵敏度检测中变得越来越有用。大多数当前的液滴装置通过被动地将单个样品在均匀或随机的试剂/反应条件下离散成数万个皮升体积的液滴来进行分析。尽管它们在速度和吞吐量方面具有明显优势，但这些液滴设备本质上缺乏定制液滴内容的能力，以便针对多种试剂条件测试单个样品或针对多种试剂测试多个样品。为了将这种组合能力整合到液滴平台中，我们开发了完全集成的可编程 Picodroplet Assembler。我们的平台能够根据需要在原位组装的纳升体积插头生成定制的皮升体积液滴组。通过结合使用微阀和基于流动聚焦的离散化，我们的平台可用于精确控制生成的纳升体积塞的含量和体积，然后控制皮升体积液滴的含量和有效动态范围。此外，我们可以使用单个集成设备连续生成、孵化和检测多个不同的液滴组。该设备成功地将基于微阀的平台的精确控制和按需能力与全自动单片设备中皮升液滴平台的灵敏度和吞吐量结合起来。