The Digital Revolution: A New Paradigm for Microfluidics

Abstract

The digital revolution has come to microfluidics. In digital microfluidics (DMF), discrete droplets are manipulated by applying electrical fields to an array of electrodes. In contrast to microchannels, in DMF each sample and reagent is individually addressable, which facilitates exquisite control over chemical reactions. Here, we review the state‐of‐the‐art in DMF, with a discussion of device formats, actuation physics, and biological and nonbiological applications. Along the way, we identify the key players in the field, and speculate on the advances and challenges that lie ahead. As with other fronts in the digital revolution, there have been and will be unexpected developments as DMF matures, but we posit that the future is bright for this promising technology.

Basic Technologies for Droplet Microfluidics

“…Studies from fluid mechanics perspectives, which focus on the understanding of the basic fluid dynamic phenomena involved in droplet or multiphase microfluidics in general, have been summarized in recent reviews [18][19][20][21] and are not detailed here. Digital microfluidics [22] that generate and manipulate relatively bigger droplets based on electro-wetting will not be covered in this review.…”

Transmittance tuning by particle chain polarization in electrowetting-driven droplets

“…8,9 In addition to manipulating fluids or lights along continuous microchannels, discrete droplets employed in digital microfluidics have also been applied to optofluidics. Digital microfluidics, 10 on the one hand, plays an important role in the fields of lab-on-a-chip ͑LOC͒, micrototal analysis systems ͑TAS͒, and other microelectromechanical systems ͑MEMS͒ applications because the droplets can be regarded as isolated microenvironments for chemical reactions 11 or sample carriers for biomedical detections. 11 On the other hand, when taking advantage of the optical properties of the droplets, the manipulated droplets become tunable optical microcomponents in micro-opto-fluidic-systems ͑MOFS͒.…”

Simplified Ground-type Single-plate Electrowetting Device for Droplet Transport

“…where θ 0 , θ V , c, γ lv , and V are the inherent contact angle, the changed contact angle by electrowetting, the capacitance per unit area of the dielectric layer (in F/m 2 ), the liquidvapor interfacial tension (in N/m or J/m 2 ) and the applied voltage across the dielectric (in V), respectively [ Fig. 1(a)].…”

“…The electrowetting system has advantages of low power consumption and fast response. Thus, it has wide applications, not only in digital microfluidics, but also in liquid lenses and displays [1][2][3][4].…”