A Microfluidic System with Active Mixing for Improved Real-Time Isothermal Amplification

Abstract

To improve the performance of real-time recombinase polymerase amplification (RPA), a microfluidic system with active mixing is developed to optimize the reaction dynamics. Instead of adopting a single typical reaction chamber, a specific reactor including a relatively large chamber in center with two adjacent zig-zag channels at two sides is integrated into the microfluidic chip. Active mixing is achieved by driving the viscous reagent between the chamber and the channel back and forth periodically with an outside compact peristaltic pump. To avoid reagent evaporation, one end of the reactor is sealed with paraffin oil. A hand-held companion device is developed to facilitate real-time RPA amplification within 20 min. The whole area of the reactor is heated with a resistance heater to provide uniform reaction temperature. To achieve real-time monitoring, a compact fluorescence detection module is integrated into the hand-held device. A smartphone with custom application software is adopted to control the hand-held device and display the real-time fluorescence curves. The performances of two cases with and without active on-chip mixing are compared between each other by detecting African swine fever viruses. It has been demonstrated that, with active on-chip mixing, the amplification efficiency and detection sensitivity can be significantly improved.

Keywords

recombinase polymerase amplification (RPA) / microfluidic chip / active mixing / optical detection / smartphone