2018/12/30 by Xander F. van Kooten, van Kooten, Xander F., Moran Bercovici +3
Engineering · #Electrowetting and Microfluidic Technologies #FOS: Biological sciences #Microfluidic and Bio-sensing Technologies #Microfluidic and Capillary Electrophoresis Applications #Quantitative Methods (q-bio.QM)
paper · pdf · doi:10.48550/arxiv.1812.11497
openalex publication_date 2018/12/30 · openalex created_date 2022/08/01 · openalex updated_date 2026/07/28
Microchip electrokinetic methods are capable of increasing the sensitivity of\nmolecular assays by enriching and purifying target analytes. However, their use\nis currently limited to assays that can be performed under a high external\nelectric field, as spatial separation and focusing is lost when the electric\nfield is removed. We present a novel method that uses two-phase encapsulation\nto overcome this limitation. The method uses passive filling and pinning of an\noil phase in hydrophobic channels to encapsulate electrokinetically separated\nand focused analytes with a brief pressure pulse. The resulting encapsulated\nsample droplet maintains its concentration over long periods of time without\nrequiring an electric field and can be manipulated for further analysis, either\non- or off- chip. We demonstrate the method by encapsulating DNA\noligonucleotides in a 240 pL aqueous segment after isotachophoresis (ITP)\nfocusing, and show that the concentration remains at 60% of the initial value\nfor tens of minutes, a 22-fold increase over free diffusion after 20 minutes.\nFurthermore, we demonstrate manipulation of a single droplet by selectively\nencapsulating amplicon after ITP purification from a polymerase chain reaction\n(PCR) mix, and performing parallel off-chip detection reactions using the\ndroplet. We provide geometrical design guidelines for devices implementing the\nencapsulation method, and show how the method can be scaled to multiple analyte\nzones.\n