Coordinating Multiple Droplets in Planar Array Digital Microfluidic Systems

Abstract

In this paper we present an approach to coordinate the motions of droplets in digital microfluidic systems, a new class of lab-on-a-chip systems 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. In this paper we describe a general-purpose system that uses simple algorithms and yet is versatile. First, we present a semi-automated approach to generate the array layout in terms of components. Next, we discuss simple algorithms to select destination components for the droplets and a decentralized scheme for components to route the droplets on the array. These are then combined into a reconfigurable system that has been simulated in software to perform analyses such as the DNA polymerase chain reaction. The algorithms have been able to successfully coordinate hundreds of droplets simultaneously and perform one or more chemical analyses in parallel. Because it is challenging to analytically characterize the behavior of such systems, simulation methods to detect potential system instability are proposed.

High-throughput screening approaches and combinatorial development of biomaterials using microfluidics

“…Droplets are finely controlled emulsion objects generated by microfluidic stream breaks [131,132], existing either physically entrapped in arrays [133][134][135] or free in suspension [132,136,137]. As opposed to conventional methods to produce droplets, microfluidics-generated droplets can be highly monodisperse, easily engineered in geometry and content, and available for modular arrangements [131,132], owing to technical possibilities that allow precise generation, handling [138,139] and dispensing [140][141][142].…”

Towards automated optoelectrowetting on dielectric devices for multi-axis droplet manipulation

“…Hence, motion planning of droplets plays a critical role in lightdriven droplet manipulation systems. Droplet coordination and scheduling on digital microfluidic systems has been previously explored only for EWOD devices [19], [20], [21]. Recently Ma and Akella [22] presented algorithms for the problem of coordinating multiple droplets in light-actuated digital microfluidic systems.…”

Droplet position control in digital microfluidic systems

“…Droplets A and B are commanded to move from cell (x 6 ,y 4 ) to cell (x 5 ,y 4 ) and from cell (x 2 ,y 4 ) to cell (x 3 ,y 4 ), respectively. During simultaneous movement of multiple droplets, fluidic constraints must be maintained at all times in order to avoid unintentional merging of two or more droplets (Griffith and Akella 2005). The fluidic constraints say that both the current and next destination cell of a droplet must have all the adjacent cells empty.…”

“…The schedule of assay operations, binding of resources to these operations (Rickets et al 2006) and the architecture (Yuh et al 2006) of the DMS are determined at the higher level of the synthesis of DMS. The lower level finds the optimum algorithms to coordinate multiple droplets (Griffith and Akella 2005;Böhringer 2006), test the DMS for faulty cells (Xu and Chakrabarty 2007) and reconfigure the DMS (Su and Chakrabarty 2006). Recently, the need for a control system in the DMS has started to draw attention.…”