Integrated Microfluidic Compact Disc Device with Potential Use in Both Centralized and Point-of-Care Laboratory Settings

Reducing the size of reaction volumes in immunodiagnostic procedures can reduce not only reagent cost but also analysis time. With reduced sample and reagent volumes and use of a flow-through mode, reactions reach completion rapidly, potentially decreasing turnaround time and making such systems suitable for point-of-care testing. However, decreased reaction volumes typically lead to other problems, such as imprecision of liquid metering, liquid evaporation, and problems related to the increased surface-to-volume ratio. To address these challenges, we have developed a new bioanalytical system composed of a disposable microfluidic compact disc (CD) device (Gyrolab Bioaffy™) that is intended for sandwich immunoassays and an instrument for automatic processing of CDs (Gyrolab™ Workstation). The Gyrolab Bioaffy CD (diameter, 120 mm) contains 104 parallel microstructures conveniently fitting into the CD, each covering a surface area of ∼2 × 15 mm. The CD is manufactured by injection molding using a cycloolefin polymer. The CD is covered with a lid in which appropriately placed holes enable liquid introduction by the robot into the microstructures; the lid protects liquids from evaporation once in the CD. Liquid movement and localization are achieved by a combination of capillary action, centrifugal force, and hydrophobic barriers within the microstructure. Each microstructure contains a 15-nL particle-based column coupled with streptavidin in which reactions take place (Fig. 1⇓ ). The Gyrolab Bioaffy is designed to be an open system; i.e., it is compatible with various assays that use biotinylated reagents, which bind to the streptavidin column …