Automated Nanoliter Volume Assay Optimization on a Cost-Effective Microfluidic Disc

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