Automated Nanoliter\nVolume Assay Optimization on a\nCost-Effective Microfluidic Disc

Optimizing multireagent assays often requires successive\ntitration\nof individual components until the optimal combination of conditions\nis achieved. This process is time-consuming, laborious, and often\nexpensive since parallelized experimentation requires bulk consumption\nof reagents. Microfluidics presents a solution through miniaturization\nof standard processes by reducing reaction volume, executing multiple\nparallel workflows, and enabling automation. While single-digit microliter\nreactions can be effective, scaling to nanoliter volumes without employing\ndroplets is difficult. We describe a cost-effective, customizable\ncentrifugal microdisc for optimizing assays pertinent to a broad array\nof applications. An automated two-stage metering process leverages\ntunable, laser-actuated valves that retain defined fluidic volumes\nupon opening and meter discrete nanoliter volumes into downstream\narchitecture. We demonstrate that ∼150 nL volumes could be\nmetered and tuned for specific applications. We illustrate the potential\nfor controlled metering of up to four reagents with high parallelization\nfor rapid, cost-effective assay optimization with minimal manual intervention.