Nonlinear Localization for Electrowetting-Based Digital Microfluidic Actuation

The method described in this paper introduces a new multiplexing format for cross-referencing of DMF systems through the simultaneous use of threshold-based voltage actuation (which sets a minimum voltage to initiate droplet motion) and bi-polar voltage activation on the overlying and underlying electrodes. The design makes use of bi-polar voltage activation and threshold effects to eliminate inter-droplet interference and overcome addressability limitations. In the proposed DMF multiplexer structure, these two requirements must both be satisfied for 2-D multiplexed addressability. Experimental characterization of the threshold voltage associated with the first requirement is presented. With regard to requirement two, the bi-polar voltage activation scheme is applied to a fabricated DMF multiplexer, and independent microdroplet motion is shown. The technique can be applied in actuating isolated microdroplets or microdroplet groups (simultaneously) in large-scale/highly-parallel DMF devices.