Customizing droplet contents and dynamic ranges via integrated programmable picodroplet assembler

• Published in: Microsystems & nanoengineering Vol. 5; no. 1; pp. 1 - 12
• Main Authors: Zhang, Pengfei, Kaushik, Aniruddha, Hsieh, Kuangwen, Wang, Tza-Huei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2019; Springer Nature B.V
• Subjects: 639/166; 639/925/927; Combinatorial analysis; Customization; Droplets; Engineering; Microfluidics; Platforms; Plugs; Reagents; Sensitivity
• ISSN: 2055-7434; 2096-1030; 2055-7434
• DOI: 10.1038/s41378-019-0062-5

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. Microfabrication: new platform to produce customized picodroplets Researchers in the United States have developed a system to produce tunable groups of picoliter-scale droplets (picodroplets) with customized contents. A team led by Tza-Huei Wang of Johns Hopkins University designed and tested the Integrated Programmable Picodroplet Assembler, which combines microvalves and flow focusing to enable the dynamic tuning of picodroplet number and content. Programmable microvalves are used to combine samples, reagents, and buffers into nanodrops. These nanodrops are then propelled through a flow-focusing junction which divides them into a specific number of picodroplets. Picodroplet content and picodroplet number can be dynamically tuned by adjusting the microvalves. This new approach combines the precision and on-demand control of microvalves with high throughput, offering researchers a tunable system to assemble multiple samples or reagents for clinical or industrial applications.