On-chip biochemical sample preparation using digital microfluidics

Sample preparation plays a pivotal role in bioassay operations on digital microfluidic biochips (DMFBs). This paper proposes a dilution/mixing method with high utilization of intermediate droplets for preparing biochemical samples of multiple target concentrations on DMFBs. It provides the first solution to the problem of generating samples of multiple target concentrations. Unlike prior work in which the preparation of droplets of multiple target concentrations has to be carried out sequentially, this proposed approach takes a global view and all the target concentrations are processed concurrently. In addition, this is also the first approach that minimizes the number of waste droplets by utilizing intermediate droplets. Finally, the number of mixing steps can be reduced, leading to reduced completion time for sample preparation. The number of waste droplets is minimized by reducing the number of intermediate concentrations produced during sample preparation. Usable intermediate droplets are subsequently utilized to further reduce wastage. Simulation results show that the proposed method can achieve up to 71% reduction in the number of waste droplets and up to 50% reduction in sample preparation time.