Particle Extraction in Plug-based Microfluidics

We describe a novel method to extract magnetic particles from plugs in plug-based microfluidic devices. In general, the extraction of particles from plugs is difficult as the high surface energy of an aqueous phase dispersed in a non-polar carrier liquid usually prevents the penetration of particles through this interface. Key to our approach is to achieve particle extraction by generating channel surface consisting of a hydrophilic patch in a hydrophobic surrounding: The interfaces of plugs contacting this patch, merge with the patch-interface enabling easy extraction. This approach lowers the limit of the concentration of particles, which can be still successfully extracted by more than three orders of magnitude compared to the state of the art.