Sample preparation for droplet-based microfluidics

Sample preparation plays an essential role in most biochemical reactions. Raw reactants are diluted to solutions with desirable concentration values in this process. In this paper, a survey of existing techniques addressing sample preparation on digital microfluidic biochips (DMFBs) is given. The fundamentals of DMFBs are introduced first. Next, we explain how dilution operations are performed on DMFBs and how the constraint on mixing models comes due to the DMFB architecture limit. Then, we divide the existing techniques into four groups according to the count of target concentration values as well as the number of different reactant types, and briefly introduce selected major research works in each category.