Enhanced Biomolecular Binding to Beads on a Digital Microfluidic Device

Abstract

Digital microfluidic (DMF) technology is being utilized for commercial applications such as point-of-care diagnostics, sample processing and genomic library preparation. Advances in this field offer exciting possibilities into immunoassays, enzymatic analysis, and next-generation sequencing. However, typical biomolecular protocols performed in laboratories are far more complex, requiring large reagent volumes, long processing times and provide a low throughput analysis. Using a DMF platform enables overcoming experimental barriers of manual laboratory protocol execution, allowing for scaling the platform geometry, assay times, volumes of reagents used, and minimizing the use of external mechanical equipment. The DMF platform also allows for easy integration with detection systems enabling real-time data analysis and efficient resource allocation. This thesis explores theoretical and experimental approaches for carrying out enhanced biomolecular binding to magnetic beads on a DMF platform as part of a sample preparation protocol. Different DMF prototypes were designed using standard microfabrication procedures to compare passive mixing, active mixing on electrode arrays and local bead actuation on an integrated current-wire electrode, whereby current is sequenced through copper wires fabricated on the electrode to generate magnetic-fields on-chip that cause the magnetic beads in the assay to move relative to the antibody. By making use of an integrated fluorescence detection system, the binding efficiency for each of these approaches is determined. The current-wire device design proves to be a valuable tool in creating an integrated DMF system to carry out intensive bead binding in an assay allowing for lower reagent volumes, shorter assay times and reduced surface area, thus impacting device yield.