Digital Microfluidics: Techniques, Their Applications and Advantages

Digital microfluidics uses discrete samples of liquids or rather drops/droplets for performing the functions as those of continuous microfluidics discretely, analogous to the difference between Analog and Digital Microfluidics[1,2]. As in continuous microfluidics streams of liquids in micro-channels with flow rates in μL are used for analysis while in Digital Microfluidics individual droplets are used instead of a continuous flow of liquid. The devices used are somewhat similar to that of conventional microfluidics, except for the additional circuits for creation and transport of droplets. In some cases additional hardware is required to perform more operations like cutting, merging etc. The physics governing microfluidics [3] is applicable to digital microfluidics and has been well verified. But there are some rare exceptions for droplets as the reduction in size poses difficulties like rapid evaporation, electric breakdown, wetting etc. Use of micropumps and other micro-scale mechanical elements is reduced as electronic actuation is preferred due to miniaturization of electrodes and the ease of integration into a single device which decreases effective size [4]. Silicon and its other derivatives like PDMS (Poly-dimethylsiloxane) are the preferred material for fabrication of digital microfluidic devices.