Abstract
In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL), which significantly reduces the need for a costly and precious biological and physiological sample volume and, thus, diagnostic time. Despite the importance of discrete droplet volume handling, the ability of continuous microfluidics to process larger sample volumes at a higher throughput cannot be easily reproduced by merely using droplets. To bridge this gap, in this work, parallel channels are formed and programmed to split into multiple droplets, while droplets are programmed to be split from one channel, transferred and merged into another channel. This programmable handling of channels and droplets combines the continuous and digital paradigms of microfluidics, showing the potential for a wider range of microfluidic functions to enable applications ranging from clinical diagnostics in resource-limited environments, to rapid system prototyping, to high throughput pharmaceutical applications.
Highlights
Automation of microfluidic functions, such as transport, storage and fluid manipulation in small volumes, is critical for successful implementation of lab-on-a-chip platforms
We characterized the aqueous red dye (Sun Chemical) used for all demonstrations of electrowetting functionality, as well as the reagents associated with a colorimetric glucose assay (Cayman Chemical)
As the droplets separated from Channel 1, there is a reduction in volume greater than the volume of the separated droplets and a subsequent equilibration to the original volume of the channel
Summary
Automation of microfluidic functions, such as transport, storage and fluid manipulation in small volumes, is critical for successful implementation of lab-on-a-chip platforms. Digital microfluidic systems exhibit such functionality and are able to manipulate discrete sample volumes (droplets) Such systems have been demonstrated in a variety of lab-on-a-chip applications using electrowetting transport [9,10,11,12], dielectrophoresis [13,14] and a combination of both [15,16,17,18]. We extend our work to combine pressure-driven continuous channel formation, programmed transition between complex microfluidic structures and interaction between continuous microfluidic structures through automated droplet manipulation This is accomplished by using an array of 360 addressable electrodes controlled through a graphical user interface (GUI). The successful implementation of this assay on our device strongly suggests the adaptability of this technique for reprogrammable electrowetting devices
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