Towards optimal strategies for moving droplets in digital microfluidic systems

In digital microfluidic systems, analyte droplets (volume typically less than 1 μl) are transported across a planar electrode array by dielectrophoretic or electrowetting effects. This paper outlines a high-level approach to optimally control digital microfluidic systems, i.e., to develop efficient algorithms that generate a sequence of control signals for moving one or many droplets from start to goal positions in the shortest number of steps, subject to constraints such as minimum required separation between droplets, obstacles on the array surface, and limitations in the control circuitry. However, optimality may be prohibitive for large-scale configurations because of the high asymptotic complexity. Alternative solutions include (1) an investigation of still useful but more limited system configurations; and (2) approximation algorithms that trade off optimality of the control sequences with higher efficiency of the algorithms that generate these control sequences.