Coordinating Multiple Droplets in Planar Array Digital Microfluidics System

Abstract

This paper presents an approach to coordinate the motions of droplets in digital microfluidic systems used for biochemical analysis. A digital microfluidic system typically consists of a planar array of cells with electrodes that control the droplets. The primary challenge in using droplet based systems is that they require the simultaneous coordination of a potentially large number of droplets on the array as the droplets move, mix, and split. This paper describes a general-purpose system that uses simple algorithms and yet is versatile. First, a semi-automated approach to generate the array layout in terms of components is explained. Next, simple algorithms to select destination components for the droplets and a decentralized scheme for components to route the droplets on the array are discussed. These are then combined into a reconfigurable system that has been simulated in software to perform DNA polymerase chain reaction and other analyses. The algorithms have been able to successfully coordinate hundreds of droplets simultaneously and perform one or more chemical analyses in parallel. Since it is challenging to analytically characterize the behavior of such systems, methods to detect potential instabilities are proposed.