Channel-to-droplet extractions for on-chip sample preparation

Abstract

We report a new capability in on-chip sample preparation for digital microfluidic lab-on-chip systems: “channel-to-droplet” sample extraction by integrating proven capillary electrophoretic (CE) separation and electrowetting-on-dielectric (EWOD) droplet manipulation. This sample preparation approach consists of: a) separating particles within a channel using conventional in-channel CE methods and then b) extracting the concentrated particle bands from a channel opening in a mobile droplet form using EWOD actuations. The extraction enables the concentrated sample droplet to be further processed on chip or presented to ancillary devices for amplifications or sensing. The concept is successfully demonstrated by separating two types of bead particles by CE separations in a channel and extracting particles from a channel opening in droplet form with EWOD. Integration of proven CE technology with new droplet-based EWOD digital microfluidics will enable highly flexible sample separation and transport options while minimizing sample and reagent consumptions.